Equine Veterinary Journal

Published by Wiley
Online ISSN: 2042-3306
Print ISSN: 0425-1644
Publications
Clinical indications for hydroxyethyl starches (HES) in horses include rapid plasma volume expansion and oncotic support during periods of hypoproteinaemia. Side effects such as coagulopathies associated with HES administration pose limitations to their use in veterinary medicine. In humans, tetrastarch [hydroxyethyl starch (130/0.4)] has demonstrated less profound effects on coagulation compared to 1st and 2nd generation HES. To evaluate the haemostatic and oncotic effects of tetrastarch (130/0.4) administered at 10, 20 and 40 ml/kg bwt in healthy horses. Randomised crossover experiment. Tetrastarch (130/0.4) was administered to 6 healthy pony mares at 10, 20 and 40 ml/kg bwt with a 2-week washout period. Packed cell volume (PCV), total solids (TS), plasma colloid oncotic pressure (pCOP), platelet count and thromboelastography (TEG) was measured at baseline, immediately after infusion (0 h), 1, 6, 12, 24, 48, and 96 h after tetrastarch infusion. All TEG variables remained within normal reference ranges in all 3 treatment groups. Administration of tetrastarch at 40 ml/kg bwt resulted in a prolonged K-time (P = 0.049) at 6 h post-infusion, and decreased maximum amplitude at 0 (P<0.001), 1 (P = 0.022), 6 (P = 0.006), 24 (P<0.001) and 48 h (P = 0.013) post-infusion compared to baseline. Administration of tetrastarch increased mean pCOP values above baseline in all 3 treatment groups, persisting to 24, 6 and 48 h for the 10, 20 and 40 ml/kg bwt dose respectively. Although still within established reference ranges, compared to lower dosages, the administration of 40 ml/kg bwt tetrastarch (130/0.4) is more likely to induce changes in coagulation as measured by TEG. Tetrastarch increased pCOP at all dosages evaluated in healthy horses. Tetrastarch (130/0.4) at 10 and 20 ml/kg bwt has potential as a synthetic colloid for resuscitation and provision of oncotic support in horses.
 
Surveillance of equine influenza viruses has suggested that strains included in currently licensed vaccines are a poor match for those predominantly circulating in the field. To assess the ability of Duvaxyn IE-T Plus to provide cross protection against the newly evolved South Africa/4/03 (H3N8) strain of equine influenza virus. The vaccine efficacy was evaluated by challenge infection with influenza strain A/eq/South Africa/4/03 (H3N8) 2 weeks after a primary course of 2 vaccinations with Duvaxyn IE-T Plus given at a 4-week interval. The outcome of challenge in vaccinated ponies was compared with that in unvaccinated animals. At the time of challenge, all vaccinated ponies had high levels of antibody to Newmarket/1/93, Newmarket/2/93 and South Africa/4/03 strains measured by single radial haemolysis. After challenge infection, there were statistically significantly decreased clinical scores and virus shedding was significantly lower in the vaccinated ponies compared to unvaccinated controls. Two doses of Duvaxyn IE-T Plus provides good clinical and virological protection against challenge with a variant virus 2 weeks after the 2 doses of vaccine. When variant strains of equine influenza virus first emerge, booster immunisations with currently available vaccines may limit infection provided sufficiently high antibody levels are achieved, suggesting that vaccination in the face of an outbreak may be beneficial.
 
Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were removed by successive dilutions in PBS + 15% v:v fetal calf serum (FCS) containing decreasing concentrations of the cryoprotectants. Pregnancy was diagnosed ultrasonographically in 53.3%, 13.3% and 0% of the mares in Groups 1, 2 and 3 respectively. Ultrastructural analysis showed differences between frozen/thawed and fresh embryos. In the former, embryonic cells were deformed and showed dilation of the intercellular and perivitelline spaces, a decrease of desmosome number in the junctional complexes, few microvilli on the apical surface of the trophectoderm and an almost total absence of pinocytotic vesicles. Most of the mitochondria showed regions containing dilation and irregularities on the cristae, which appeared electron-dense. The results obtained with Groups 2 and 3 embryos showed that the cryoprotectants employed were not effective in protecting the embryos against damage during freezing and thawing. Indeed, the ultrastructural changes observed in the Group 3 embryos explained the absence of any established pregnancies in this group of mares.
 
Patient data, physiological variables and recovery quality were extracted from 1,314 records of equine anaesthetics covering a 7-year period and analysed retrospectively. Better recovery quality was significantly associated with shorter duration of anaesthesia, longer recovery times, less invasive surgery, a lower pulse rate at induction and higher pulse and respiratory rates during anaesthesia. Nineteen animals suffered serious anaesthetic-related problems (1.4% incidence) and 9 died (0.68% incidence). Clinical treatment of hypotension during anaesthesia significantly reduced the hypotensive index but did not significantly alter the recovery quality or incidence of post-anaesthetic myopathy. The severity of the myopathy was, however, markedly reduced in the animals treated for hypotension.
 
There is considerable debate regarding the ergogenic effects of sodium bicarbonate (NaHCO3) on racing performance in horses. Anecdotal evidence suggests that NaHCO3 improves performance by increasing the buffering capacity of the blood and delaying the onset of hydrogen ion-induced fatigue. In a cross-over study, 16 Thoroughbred racehorses were given an aqueous solution of NaHCO3 (0.4 g/kg in 1 litre H2O) or a control treatment (1 litre H2O) before a 1600-m race. Treatments were administered 3 h before the race, which was the time to peak buffering capacity (2.5-3.0 h) determined in a separate study. Before the race, there was a significant increase in venous HCO3- and pH in the NaHCO3-treated horses. After the race, there was a significant increase in venous blood pH and lactate in the NaHCO3-treated horses. Collectively, the data suggest an improved buffering capacity of the blood after NaHCO3 treatment. However, there was no change in race times or venous partial pressure of carbon dioxide. Therefore, the administration of NaHCO3 provided no ergogenic benefit to horses competing in a 1,600-m race.
 
Circulatory and respiratory effects of five h of constant 1.06 per cent alveolar halothane in oxygen were identified in eight healthy horses, which breathed spontaneously, were otherwise unmedicated and positioned in sternal recumbency. Only a few important significant (P less than 0.05) changes occurred with time. Total peripheral resistance was about 15 per cent lower after two hours of constant dose halothane than after 30 mins of constant dose (P less than 0.05) and accounted for the significant 10 per cent reduction in mean carotid arterial blood pressure. By 5 h, the reduction in resistance and arterial blood pressure was 20 and 25 per cent respectively. Heart rate increased progressively with time and the increase became significant at 5 h (15 per cent increase). However, the heart rate change was not large enough to alter cardiac output. There were no major time-related changes in PaO2 or PaCO2. Three of four horses recovered from anaesthesia had markedly elevated serum creatine kinase levels and clinical signs of severe post anaesthetic myopathy.
 
Multivariable analysis of predictive factors for generalised seizures
Although many studies have been performed to classify seizures by type in humans and small animals, a similar study in horses is lacking. The purpose of this study was to: 1) characterise the distribution of seizure types in 104 horses presented for seizure disorders to a referral veterinary hospital, and 2) further characterise the various types of seizures by identifying associated clinical factors. Retrospective analysis of clinical records. Seizures were classified based on seizure type, according to the most recent accepted definitions in both human and small animal epileptology. History, clinical and neurological examinations, diagnostic investigations and postmortem examinations, when available, were recorded for univariable and multivariable logistic regression analyses. Seizures were categorised as primary generalised in 23% of horses, focal without secondary generalisation in 42% of cases and secondary generalised in 24% of cases. The type of seizures could not be classified in 11% of cases. Significant associations were found between seizure type and: 1) gender; 2) frequency of seizures; and 3) presence of seizures during hospitalisation. Seizure type was not significantly associated with aetiology. For a horse with recurrent seizures, the odds of having focal seizures was 3.7 times higher (P = 0.02) compared to a similar horse with non-recurring seizures in the final logistic regression model. The majority of the seizures described were focal seizures with or without secondary generalisation. The clinical presentation was independent of the underlying disease.
 
An understanding of the normal events of foaling, causes of dystocia and clinical outcomes is important for equine practitioners. The goals of the present study were to: 1) evaluate factors that influence gestation length; 2) report duration of Stage II labour; 3) determine the frequency of dystocia and premature placental separation; and 4) determine the relationship between problems at foaling and foal survival. Foaling records of 1047 mare births were evaluated. The average gestation length was 341 +/- 0.3 days, with no effect of mare age or breed observed. Mares carrying male fetuses had a longer gestation (P < or = 0.001) than mares carrying female fetuses. A majority (52.8%) of mares foaled at night between 2000 h and 0200 h when the facility was quiet. Dystocia occurred in 10.1% of all births and the incidence rate was higher in Thoroughbred mares than in Quarter Horse mares. The most common cause of dystocia was abnormalities of fetal posture. A delay in foal delivery beyond 40 min of Stage II of labour was associated with a significant increase in foal mortality. In addition, an increase in foal morbidity and mortality was noted when the interval from birth to standing or birth to nursing was prolonged. Early detection and rapid appropriate intervention are critical to foal survival in an equine dystocia. Potential relevance: Equine veterinarians should counsel horse owners that early recognition of a foaling problem and rapid, appropriate intervention are critical to the survival of a foal.
 
The clinical features of 106 horses presenting with chronic colic examined over a 5 year period were reviewed. Chronic colic was defined as colic signs observed daily for 3 days or longer, except when masked by analgesics. The diagnosed causes of chronic colic included colonic impaction (31%), peritonitis (16%), enteritis/colitis (7%), colonic displacement/torsion (6%) and lymphosarcoma (4%). A variety of other diseases were diagnosed in a small number of cases, including intestinal adhesions, ileal obstructions, grass sickness, liver disease, caecal impactions, thromboembolic disease, intussusceptions etc. No diagnosis was reached in 8% of cases. Diagnosis was relatively easily achieved in most cases of colonic impaction and peritonitis by results of transrectal palpation and evaluation of peritoneal fluid. Specific clinical features, transrectal palpation, abdominal paracentesis and laboratory evaluations of blood were helpful in the diagnosis of some of the other diseases, but exploratory laparotomy remained necessary in a few cases to achieve a diagnosis.
 
Eleven horses with unilateral distension of the sheath are reported with emphasis on the use of plain and contrast radiography in diagnosis. Six had associated bony abnormalities of the sustentaculum tali, and two of these showed destructive or mixed destructive and proliferative lesions resulting from osteomyelitis. One horse had a fracture of the sustentaculum. In three horses proliferative changes were found. Bony changes were best demonstrated on a dorsomedial-plantarolateral oblique view. Contrast radiography of the tarsal sheath was performed in five cases without, and two horses with, associated bony lesions. In five cases ballooning with or without folding of the proximal aspect of the sheath was demonstrated. Additional band-like filling defects (two cases), triangular filling defect (one case), nodular intra-tendovaginal masses (two cases), or an extra-tendovaginal mass (one case) were noticed. The remaining two horses showed a semicircular collar shape dilation of the proximal aspect of the sheath. Contrast radiography appeared to be a helpful tool for the examination of tarsal sheath lesions. Two horses with associated bony changes were destroyed immediately after diagnosis, one failed to recover following surgical intervention and in three horses the outcome was unsatisfactory after conservative treatment. Three horses without associated bony lesions recovered completely after conservative treatment. One was operated on subsequently; the results are promising but the outcome of this case is not yet known. One was sold shortly after diagnosis and lost to follow up.
 
Tears of the radial head of the deep digital flexor (DDF) have not previously been documented. To describe the presentation, clinical, ultrasonographic and tenoscopic features associated with tears of the radial head of the DDF and to report the results of treatment. Tears of the radial head of the DDF cause lameness and distension of the carpal sheath of the digital flexor tendons. Removal of disrupted tissue that is extruded into the sheath can result in clinical resolution and restoration of function. Case records and diagnostic images of horses in which tearing of the radial head of the DDF was diagnosed were reviewed retrospectively and follow-up information obtained. Eleven cases were identified. Clinical, ultrasonographic and tenoscopic commonality was recorded and treatment techniques were documented. All cases returned post operatively to pre-injury levels of work. Tearing of the radial head of the DDF is a clinical entity with consistent diagnostic features. Tenoscopic removal of the torn tissue is associated with a good outcome. Clinicians evaluating lame horses should include tearing of the radial head of the DDF as a differential diagnosis in animals with distended carpal sheaths. Tenoscopic surgery is a recommended treatment.
 
The aim of this study was to monitor the postnatal radiographic development of the proximal and distal double contours and the modelling of the shape of the proximal articular border. In mature horses, the proximal and distal contours of the navicular bone on dorsopalmar dorsoproximal-palmarodistal oblique (upright pedal) radiographs are commonly visualised as 2 lines, one being the articular border and the second representing the border of the cortex facing the deep digital flexor tendon (flexor border). The shape of the proximal articular border may be concave, undulating, straight or convex in the mature animal. These shapes have been found to be hereditary and to constitute a predisposing factor in the pathogenesis of navicular disease. This predisposing role may result from a shape dependent distribution of the biomechanical forces exerted on this region. There is no agreement in the literature with respect to the moment when the navicular bone takes its mature radiographic appearance. Upright pedal radiographs of the left front foot of 19 Dutch Warmblood foals were made at age 1 month and subsequently at intervals of 4 weeks, until the age of 11 months. The distal double contour developed soon after birth and the radiographic visibility of the articular border improved from ill-defined at 1 or 2 months to clear manifestation at 3 or 4 months. The proximal double contour developed later. The articular border became usually visible at age 3 or 4 months and was clearly visible from age 9 months. The mature shape of the proximal articular border usually became recognisable from age 7 months and was always obvious between 9 and 11 months. This development was associated with a gradual modelling of the lateral and medial extremities of the navicular bone. It was concluded that the navicular bone adopts its mature radiological appearance during the first year postpartum. Considering this early manifestation of the mature shape of the proximal articular border and its previously demonstrated inheritance, a force-dependent development of this shape, as predicted by the trajectional theory/Wolffs law, is improbable. The predisposing role of this shape in the pathogenesis of navicular disease may therefore be explained by a shape-dependent distribution of the biomechanical forces exerted on the navicular bone. Considering the potential application of these findings, from age 1 year shape determination enables identification of the individual and breed susceptibility for the development of navicular disease.
 
Little information exists regarding talus fractures in the horse and there have been no previously published case series of racehorses diagnosed with incomplete sagittal fracture of the talus. To describe the diagnosis, treatment and post injury performance of horses with incomplete sagittal fracture of the talus. Medical records of 11 racehorses (8 Standardbreds and 3 Thoroughbreds) admitted between January 1992 and January 1999 were reviewed. Subject details, anamnesis, results of lameness examination, radiographs and nuclear scintigraphic findings were evaluated. Racing performance was assessed by comparing pre- and post injury race records. Nuclear scintigraphic examination, performed in 8 of the 11 horses, revealed focal increased radiopharmaceutical uptake in the proximal aspect of the affected talus. Fractures could best be seen on dorsal 10-20 degrees lateral-plantaromedial oblique radiographs; all had raced pre-injury. All horses were treated conservatively and follow-up information was available for 8 horses, of which 7 raced after injury. Performance in 3 horses was improved, in 1 it was unchanged and in 3 horses performance declined. Horses with incomplete fracture of the talus have a good prognosis for return to racing after conservative management. Incomplete sagittal fracture of the talus should be considered as a cause of hindlimb lameness in racehorses. Further research is necessary to determine the pathophysiology of these fractures.
 
Historically, there has been a consensus that conservative management of subchondral cystic lesions of the distal phalanx carries a poor prognosis. Surgical management has been advocated; however, there are no reports documenting its routine use and successful surgical treatment. To describe arthroscopically-guided curettage of distal phalangeal subchondral cystic lesions (SCLs) and report the qualitative and quantitative results in 11 affected horses age 16-33 months. Medical records of horses with previously treated lameness resulting from SCLs of the third phalanx were reviewed. Arthroscopic debridement of the SCLs was described. Follow-up information was obtained from race records and telephone contact with owners and trainers. The sign-rank test was used to compare performance of operated racehorses to that of unoperated siblings. Ten of the 11 horses (91%) in the study returned to athletic soundness after surgical treatment and had performance records similar to their siblings. Data show that arthroscopic debridement of distal phalangeal SCLs is a viable treatment for affected horses age 16-33 months and can result in a successful return to intended athletic performance. No horses younger than 16 months or older than 33 months were treated and results in horses younger or older than this group may vary in success. The description of treatment and approach used for arthroscopic curettage will increase awareness of this option and increase treatment options for this condition.
 
The social behaviour of a small herd of 10 Exmoor geldings, two Exmoor mares and one Highland pony gelding was studied in order to see whether any specific associations existed between ponies and, if so, whether these applied to all or only some of the ponies' main activities of grazing, eating hay and sleeping. Such relationships were found but only in a small number of cases did they apply to all activities. The results are discussed in relation to the individual histories of these ponies and in relation to the welfare of horses.
 
In a longitudinal study the hocks and stifles of Dutch Warmblood foals were radiographed at age 1 month and subsequently at intervals of 4 weeks. Forty-three foals were radiographed until age 5 months and 19 foals until age 11 months. The chance for the development of osteochondrosis was enhanced by using only offspring from diseased sires with radiographically proven OC at either the intermediate ridge of the distal tibia or the lateral ridge of the femoral trochlea. The radiographic appearances of the intermediate ridge of the distal tibia, the distal aspect of the lateral trochlear ridge of the talus and the midregion of the lateral ridge of the femoral trochlea were classified on a 0-4 scale using a standardised radiographic classification. At age 1 month the appearance of the intermediate ridge of the distal tibia was frequently abnormal (grades 1-3: 67%; grade 4: 1%). Abnormal appearances of the distal aspect of the lateral trochlear ridge of the talus were less common (grades 1-3: 25%; grade 4: 6%). The midregion of the lateral ridge of the femoral trochlea was predominantly normal (grade 0: 98%; grade 1: 2%). Initial abnormalities of the intermediate tibial ridge showed a marked tendency for regression. Progression was less common. Normal appearances rarely turned into abnormal. Only 18% of the hocks were still abnormal at this site at age 11 months. Abnormalities of the distal aspect of the lateral trochlear ridge of the talus showed a strong tendency towards resolution. Progression never occurred. Normal appearances seldom turned into abnormal. Only 3% of the hocks were still abnormal at this site at age 11 months. For both predilection sites in the hock normal and abnormal appearances were permanent from age 5 months. In the stifle, abnormal appearances of the midregion of the lateral ridge of the femoral trochlea became obvious from age 3 or 4 months. Subsequent progression was usually followed by regression and resolution, the appearance returned in most cases to normal at age 8 months. At 5 months, 20% of the stifles were abnormal, but at 11 months this percentage had decreased to 3%. Normal and abnormal appearances were permanent from age 8 months. Osteochondrosis of the main predilection sites in the hock and stifle develops very early in life. The majority of the lesions were temporary, the 'age of no return' was 5 months for the hock and 8 months for the stifle.
 
Histopathology was compared to culture results and cytology from horses with corneal stromal abscess at the Auburn University and the Ohio State University Veterinary Teaching Hospitals. Significant bacteria were not isolated in culture or seen on histopathology in any of the horses. Although most bacteria infecting equine corneas can be isolated with blood and MacConkey's agars, failure to detect bacterial growth may not rule out infection because anaerobic or intracellular bacteria would not be isolated. The inability to visualise bacterial organisms on histological sections did not rule out their presence in the tissue, because there is often destruction of bacteria by neutrophils, macrophages and antibiotic therapy greatly reducing their numbers. Fungal keratitis was diagnosed by histopathology in 4 of 11 eyes (36%) and keratitis with no aetiological agent in 7 of 11 eyes (64%). Nine of 11 horses (82%) had a prominent neutrophilic stromal infiltrate and 2 (18%) had a predominantly pyogranulomatous reaction. Two of the 4 lesions that showed histological evidence of fungal infection were positive for identifiable fungi on culture and cytology. Fungal cultures of the other 2 cases with histological evidence of mycotic keratitis were negative or grew unidentifiable fungi which were considered pathogenic because, on histopathological sections, fungal hyphae were found deep in the corneal stroma surrounded by an inflammatory reaction. In 3 of 6 cases where fungi were recovered on culture, they were considered contaminants based on lack of evidence of organisms in histopathological sections. Histopathology and the use of special stains were important in the interpretation of culture and cytology results.
 
Osteosynthesis of third metacarpal (McIII) and third metatarsal (MtIII) bone fractures in horses is a surgical challenge and complications surrounding the repair are common. Retrospective studies evaluating surgical repair, complications and outcome are necessary to increase knowledge and improve success of long bone fracture repair in the horse. To evaluate clinical findings, surgical repair, post operative complications and outcome of 10 mature horses and 11 foals with McIII or MtIII fractures that were treated with open reduction and internal fixation (ORIF). Medical records were reviewed and follow-up information obtained by means of radiographs and/or telephone questionnaire. Survival was achieved in 62% of the horses (3 mature/10 foals). On long-term evaluation (> 6 months) 11 horses (2 mature/9 foals) were fit for their intended activity, one mature horse had a chronic low grade lameness, and one foal was lost to follow-up because it was sold. The main fracture types were simple transverse (333%) or simple oblique (28.6%) and 71.4% of the fractures were open, 3 Type I (one mature/2 foals) and 12 type II (7 mature/5 foals). The preoperative assessment revealed inadequate emergency treatment in 10 horses (5 mature/5 foals; 47.6%). Survival rate of horses with open fractures was 12.5% (1/8) in mature and 85.7% (6/7) in foals. Post operative incisional infection (4 mature, 3 foals) was only managed successfully in 2 foals. Fracture instability related to inadequate fracture fixation technique occurred in 4 horses (all mature) and was always associated with unsuccessful outcome. Age, bodyweight and infection are strongly associated with outcome in treatment of complete McIII/MtIII fractures. Rigid fixation using plates and screws can be successful in treatment of closed or open, complete diaphyseal McIII/MtIII fractures in mature horses and foals. Instable fixation, infection and a bodyweight > 320 kg are major risk factors for unsuccessful outcome.
 
There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model. The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation. Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP. Production of a reliable measure of racehorse performance may be possible.
 
There is disagreement among surgeons whether jejunoileostomy (JI) or jejunocaecostomy (JC) is a better method of anastomosis following proximal ileal resection. To compare short- and long-term complications and outcome in horses undergoing jejunojejunostomy (JJ), JI, and JC and to test the hypotheses that a higher proportion of horses undergoing JI would have short-term complications and mortality compared to horses undergoing JC or JJ and that JC would be associated with a higher long-term mortality and occurrence of colic. Retrospective cross-sectional study. Medical records of horses undergoing celiotomy for a small intestinal obstruction and JJ, JI, or JC from 2005-2010 were reviewed. Post-operative complications were recorded. Short-term outcome was alive versus dead at hospital discharge and was analysed using a Chi-squared test. Long-term follow-up was obtained and a Kaplan-Meier estimate of the survivor function was performed. There were 112 horses included. A higher proportion of JI horses had a repeat celiotomy during hospitalisation compared to horses undergoing JC. The number of horses alive at hospital discharge was not different between groups: JJ-79% (95% CI 68-90%), JI-78% (95% CI 61-96%), JC-83% (95% CI 71-96%). Among horses discharged with long-term follow-up, more horses had colic after JC compared to JJ or JI. Long-term post-discharge survival based on the Kaplan-Meier survivor function was lower for horses undergoing JC than JJ or JI (p = 0.04). While there was no difference in short-term outcome between groups, more horses with JI underwent a repeat celiotomy during hospitalisation. Horses with a JC were more likely to have long-term complications with colic. Horses that were euthanised because of colic within 12 months of hospital discharge either had a JC or repeat celiotomy. The results of our study suggest that when possible, a JI may be the preferred method of anastomosis based on more favourable survival and lower occurrence of colic long-term.
 
To determine the incidence of support limb laminitis among horses treated with half limb, full limb or transfixation pin casts and determine potential risk factors. Medical records of 113 horses treated with half limb, full limb or transfixation pin casts at an equine referral hospital from 2000 to 2009 were reviewed. Associations between potential risk factors and development of support limb laminitis were evaluated by bivariable and multivariable logistic regression analyses. Of the 113 horses that received casts, 14 (12%) developed confirmed support limb laminitis. The bodyweight of the horse and duration of casting in weeks were significantly associated with support limb laminitis. Horses requiring full limb casts or transfixation pin casts were more likely to develop this complication than horses requiring half limb casts. There were no significant associations between developing support limb laminitis and weightbearing capacity on presentation to the hospital, the limb affected (fore- or hind), whether there was a fracture present or breed of horse. Support limb laminitis is a relatively common complication among horses treated with half limb, full limb and transfixation pin casts. Greater durations of casting and higher bodyweights increase the likelihood of developing this complication. Support limb laminitis may occur secondary to any painful unilateral lameness and is not necessarily more likely to develop in horses with severe orthopaedic conditions such as fractures. However, heavier horses, those requiring casts for longer periods of time and those that require a full limb or transfixation pin cast as opposed to a half limb cast should be considered to have an increased risk for developing support limb laminitis post operatively.
 
Preputial and penile tumours are more common in horses than in other domestic animals, but no large surveys of male horses with tumours of the external genitalia are available. To present a retrospective analysis of male horses with neoplasms of the external genitalia. The penile and preputial tumours of 114 horses were evaluated. Data recorded included age, gelding or stallion and breed; type and site of lesion; involvement of regional lymph nodes; histopathology (including grading of squamous cell carcinoma); and results of radiographic examination of the thorax. Mean age of horses was 19.5 years with no apparent breed predilection. Common presenting clinical signs were irregularities (e.g. the presence of a mass and/or ulceration) on the integument of the penis and prepuce, and purulent or sanguineous discharge from preputial orifice. Squamous cell carcinoma (SCC) was the most prevalent neoplasm followed by papillomas and melanomas. A basal cell carcinoma, neurofibrosarcoma, adenocarcinoma or fibrosarcoma were each found on single horses. Squamous cell carcinomas with poor differentiation had a higher tendency to metastasise than did more differentiated tumours. Squamous cell carcinoma is the most common urogenital tumour of the male horse and occurs primarily in old horses. Horses with poorly differentiated SCCs tend to have a higher incidence of regional metastases. Pathology of lymph nodes, even when not palpably enlarged, is a valuable diagnostic exercise. Radiology of the thorax to detect lung metastases is of little value.
 
REASON FOR PERFORMING THE STUDY: There are few published data regarding the success rates of cheek tooth (CT) removal by lateral buccotomy in the horse. A retrospective study of 114 horses admitted to 2 private equine referral hospitals over a 10 year period (1999-2009), which underwent CT removal via a lateral buccotomy. Hospital records were analysed and details including case details, presenting complaint and results of all diagnostic tests and surgical reports were documented. Information obtained during post operative reassessment was also available for analysis. Long-term follow-up information (>2 months) was obtained for 112 horses. Short-term complications (<2 months) occurred in 24/77 horses (31%) undergoing exodontia of the maxillary CT and 10/37 horses (27%) involving mandibular CT, with the majority arising from partial wound dehiscence and infection following 16 extractions (47%). All healed well by second intention. Other complications included both temporary (n = 6) and permanent (n = 3) facial nerve paralysis, myositis (n = 4) and the inadvertent establishment of an oroantral fistula (n = 4). One myositis case was subjected to euthanasia 24 h post operatively. Five horses had persistent sinusitis following surgery due to dental remnants (n = 2) and excessive packing material (n = 1) found in the sinuses. No inciting cause could be found in the remaining 2 horses. One further horse suffered a fatal cardiac arrest at induction of anaesthesia. Of all horses, 92% operated on had returned to their previous level of work after >2 months with no complications. Horses with CT removal by a lateral buccotomy have a reasonable prognosis for long-term outcome. Performing a lateral buccotomy is a justified treatment alternative for the surgical removal of equine CT following unsuccessful attempts by standing oral extraction, offering advantages over alternatives such as retropulsion, endodontic therapy and periapical curettage.
 
The medical records of pregnant mares over a 3-year period were reviewed. In all cases persistent pain or progressive abdominal distension were the main reason for referral. The overall survival rate for the 115 mares treated for colic was 73.9% (85 cases). The abortion rate was 20.5% in surgical patients (34 cases), 40% (5 cases) for mares with uterine torsions and 10.8% (46 cases) after medical treatment. The total abortion rate was 16.4%. Clinical evidence of endotoxaemia was, except for 1 mare, present in all the aborting mares after colic treatment. Anaesthesia did not appear to be a problem because abortion occurred in 5/46 medically treated cases as well as in 9/39 mares treated surgically. Abortion occurred in 3 mares that suffered intraoperative hypoxia, but fasting for >30 h did not seem to cause prolonged hypoglycaemia and subsequent abortion. Clenbuterol hydrochloride was used as a tocolytic agent in 9 mares with uterine displacement, abortus imminens and post-operative uterine torsion and 3 mares aborted during treatment.
 
One hundred and fifteen horses with periocular tumours were treated with iridium-192 interstitial brachytherapy. Tumours included squamous cell carcinomas (n = 52) and sarcoids (n = 63). All horses were scheduled to receive 60 Gy (minimal tumour dose) given at a low dose rate (0.034 +/- 0.010 Gy/h). The mean and median follow-up times to last contact or death were 24 and 16 months, respectively. Chronic radiation reactions included palpebral fibrosis (10.4%), cataract (7.8%), keratitis and corneal ulceration (6.9%). Cosmetic changes included permanent epilation (21.7%) and hair dyspigmentation (78.3%). The one year progression-free survival (PFS) rates for sarcoids and carcinomas were 86.6% and 81.8% and the 5 year PFS rates were 74.0% and 63.5%, respectively. The horse age and sex, histopathological type, anatomical subsite and classification (WHO T1-3) were included in the analysis of prognostic factors. The only significant prognostic factor that independently affected PFS time was the WHO T-classification (P = 0.009, relative risk = 0.85). When compared to horses with T1 lesions, horses with T2 and T3 lesions had 1.8-fold and 3.4-fold increased risks, respectively, for tumour recurrence (relative excess risk). The one year PFS rates for T1, T2 and T3 lesions were 95.2%, 89.5% and 66.2%, respectively. The 5 year PFS rates were 72.2%, 74.0% and 53.1%, respectively. The results of this study indicate that irradiation is an effective treatment option for horses with T1-2 lesions and should be part of a combined treatment modality for horses with T3 lesions.
 
Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging veterinary and zoonotic pathogen, associated with increasing reports of disease in horses. To provide an overview of the characteristics of clinical MRSA infections in horses. A retrospective case study was performed on 115 horses admitted to 6 participating veterinary teaching hospitals in Canada and the United States between 2000 and 2006, and diagnosed with clinical MRSA infection. Descriptive statistics, univariate and multivariable analyses for community- (CA) vs. hospital-associated (HA) MRSA infections, and survival vs. nonsurvival at discharge were performed. The age range of MRSA-infected horses was zero (born in hospital) to 31 years. HA (58/114, 50.9%) and CA infections (56/114, 49.1%) were equally common. Infection of surgical incisions was most frequently reported (44/115, 38.0%). Overall 93/111 (83.8%) cases survived to discharge. Previous hospitalisation and treatment with gentamicin were associated significantly with CA-MRSA, whereas infected incision sites were associated significantly with HA-MRSA. Factors significantly associated with nonsurvival included i.v. catheterisation, CA-MRSA infection and dissemination of infection to other body sites. Equine MRSA infections have a broad range of clinical presentations, appear to be primarily opportunistic and the overall prognosis for survival to discharge is good. These results should help direct future research with regard to investigation of risk factors for equine MRSA infection in community and hospital populations.
 
The effectiveness and best method to manage dorsal cortical stress fractures is not clear. This study was performed to evaluate the success of lag screw fixation of such fractures in a population of Thoroughbred racehorses. Lag screw fixation of dorsal cortical stress fractures is an effective surgical procedure allowing racehorses to return to their preoperative level of performance. The records of 116 racehorses (103 Thoroughbreds) admitted to Equine Medical Centre, California between 1986 and 2008 were assessed. Information obtained from medical records included subject details, limb(s) affected, fracture configuration, length of screw used in repair and presence of concurrent surgical procedures performed. Racing performance was evaluated relative to these factors using Fisher's exact test and nonparametric methods with a level of significance of P<0.05. Of 92 Thoroughbred horses, 83% raced preoperatively and 83% raced post operatively, with 63% having ≥5 starts. There was no statistically significant association between age, gender, limb affected, fracture configuration or presence of concurrent surgery and likelihood of racing post operatively or of having 5 or more starts. The mean earnings per start and the performance index for the 3 races following surgery were lower compared to the 3 races prior to surgery; however, 29 and 45% of horses either improved or did not change their earnings per start and performance index, respectively. Data show that lag screw fixation is successful at restoring ability to race in horses suffering from dorsal cortical stress fractures.
 
The histology from rectal biopsy specimens taken 1980-1990 on 131 occasions from 116 horses, age 1-18 years, with clinical signs of intestinal disease was evaluated and classified retrospectively. In 40 horses, autopsy results were studied for comparison. Biopsy specimens (21 horses) and post mortem rectal tissue (9 horses) from 30 healthy horses, age 4-22 years, were used as controls. In 105 clinical cases, a biopsy was performed on only one occasion, while repeat biopsy was performed in 11 cases. Specimens showed pathological changes in 60 horses. The findings were classified into acute, chronic or chronic active simple proctitis, granulomatous enteritis, eosinophilic granulomatosis/gastroenteritis, eosinophilic proctitis, erosive/ulcerative proctitis, pseudomembranous proctitis, proctitis with vasculitis and malignant lymphoma. Mild scattered neutrophil infiltration in the lamina propria was found in controls, but neutrophils in crypt or surface epithelia were abnormal findings. Depletion or hyperplasia of goblet cells sometimes accompanied inflammation. Simple proctitis occurred in association with malignant lymphoma and various inflammatory disorders of the gastrointestinal tract apparent at autopsy. Eosinophilic granulomatosis/gastroenteritis and granulomatous enteritis were diagnosed from biopsy specimens in 6 of 12 and 4 of 9 cases, respectively, of these diseases confirmed at autopsy. Reduction of acid mucins in goblet cells was a prominent feature of eosinophilic granulomatosis. Rectal biopsy was found to be a useful adjunct for evaluation of intestinal disease in the horse.
 
Dorsoproximal-palmarodistal oblique, lateromedial and palmaroproximal-palmarodistal oblique radiographic projections were used with standard techniques to examine 118 horses with clinical signs of navicular disease. All radiological features which have previously been reported as significant changes in the navicular bones of horses with navicular disease were recorded. Comparisons were made between these features in lame limbs and sound limbs in unilaterally lame horses and most lame limbs and least lame limbs in bilateral but asymmetrically lame animals. Their relationship to the degree of lameness was also analysed. No relationships were identified between the characteristics of distal border synovial invaginations, flattening and/or thinning of the flexor cortex and limb distribution or severity of lameness. Defects in the flexor cortex, proximal border remodelling, medullary trabecular disruption and medullary sclerosis appeared to be related to limb affliction and severity of lameness while proximal border enthesophytes, and poor flexor corticomedullary demarcation presented evidence of a relationship to the grade of lameness. Poor flexor corticomedullary demarcation and fragmentation of the distal border were related to the severity of lameness in bilateral but asymmetrically affected horses. The presence of peri-articular osteophytes and mineralisation of the flexor digitorum profundus were too infrequently recognised to permit meaningful data evaluation.
 
The 118 horses diagnosed as suffering from navicular disease by prospective criteria were treated by desmotomy of the ligamenta sesamoidea collateralia (navicular suspensory desmotomy). Three techniques were used and a standard post-operative programme was followed with clinical and radiological evaluations at 6-monthly intervals for periods of 6-36 months after surgery. At 6 and 36 months after treatment, 76% and 42.9% of horses were sound respectively. The clinical features of age, period of lameness, severity of lameness and angular limb deformities adversely affected response to surgery. The presence of flexor cortex defects, proximal border enthesophytes, mineralisation of the flexor digitorum profundus tendon and medullary sclerosis were also associated with a diminished response. There were few (1.7%) changes in the radiological appearance of distal border synovial invaginations during the follow-up period. By contrast, the majority (67.3%) of flexor cortex defects changed. Other radiological features changed at a low frequency but there was no association between radiological change and clinical outcome.
 
The clinical features are reported from 118 horses (mean age 9.2 years) which were diagnosed as suffering from navicular disease using predetermined criteria. The animals were used for a variety of purposes and had been lame for periods between 1 and 72 months. The majority of cases (84.7%) had been treated using various techniques before evaluation. The severity of lameness was related to the duration of clinical signs: 78% of horses were bilaterally affected but there was no left:right limb predominance. Broken foot/pastern axes were recorded in 75% of horses while 45% also exhibited mediolateral foot imbalance. Muscle atrophy was recognised in 77% of animals which appeared to be related to limb affliction. The cranial phase of the stride was reduced in 38% and caudal phase shortened in 16% of horses. These abnormalities were related to the degree of lameness. Flexion of the distal joints increased the severity of lameness in 64% of the animals while extension was positive in 41% of instances. Turning in the direction of the lame limb exacerbated lameness in 95% of horses. Only 11% of animals responded to the use of hoof testers and 3% to foot percussion. A range of responses to local analgesia of the palmar digital nerves was recorded but 91% (of 49) of animals exhibited a positive response to local analgesia of the distal interphalangeal joint, and 92% (of 23) of horses responded to local analgesia of the navicular bursa.
 
The case records of 119 young horses (all less than age one year) that underwent an exploratory celiotomy during a 17 year period were examined to determine the surgical findings, short- and long-term outcome, and prevalence of small intestinal disease compared to previous reports in the mature horse. Physical and laboratory values were compared for long-term survivors vs. nonsurvivors and the frequency of post operative intra-abdominal adhesions was determined. The most common cause for exploratory celiotomy was small intestinal strangulation, followed by enteritis and uroperitoneum. Six horses died during surgery, 23 were subjected to euthanasia at the time of surgery due to a grave prognosis, and 17 horses died or were destroyed after surgery, prior to discharge from the hospital; the short-term survival was 61%. Nine horses were lost to follow-up. Forty-one horses survived long-term (at least 6 months after surgery), 15 died or were subjected to euthanasia after discharge for reasons related to the prior abdominal surgery, and 8 died or were destroyed after discharge due to unrelated reasons, making the long-term survival 45%. Fifty-three (45%) of the horses presented as neonates, and 66 (55%) presented age 3-12 months. Uroperitoneum and meconium impaction were the most common disease in the neonate. Intussusception and enteritis were the most common diseases in older foals. The overall prevalence of small intestinal disease was 44%. Significant elevations in packed cell volume, heart rate, nucleated cell counts and total protein in abdominal fluid and rectal temperature were observed in nonsurvivors compared to survivors. Nonsurvivors had significantly decreased serum bicarbonate, chloride, sodium, and venous pH values. There was no evidence that location of the lesion affected long-term survival. Horses with a simple obstruction had a higher survival percentage than those with a strangulating obstruction, and horses that underwent an intestinal resection had a lower long-term survival than those horses undergoing only intestinal manipulation. Nineteen (33%) of the foals examined after the original surgery had evidence of intra-abdominal adhesions. Nine of these (16%) had adhesions that caused a clinical problem.
 
Reasons for performing studyAlthough fractures of the proximal phalanx are one of the most common long bone fractures of Thoroughbred horses in training, limited details on variations in morphology and radiological progression have been published. Objectives To describe in detail the configuration of parasagittal fractures of the proximal phalanx in a group of Thoroughbred racehorses, to report fracture distribution within this group of horses and to document radiological progression of fracture healing in cases treated by internal fixation. Study designRestrospective case series. Methods Case records and radiographs of Thoroughbred racehorses with parasagittal fractures of the proximal phalanx admitted to Newmarket Equine Hospital between 2007 and 2011 were analysed. ResultsOne hundred and twenty-one fractures were identified in 120 Thoroughbred racehorses. Fractures were frequently more complex than was appreciated immediately following injury; a feature that has not been reported previously. There was seasonality of fractures in 2- and 3-year-old horses, but not in older horses. Conclusions and potential relevanceFractures of the proximal phalanx may be more complex than recognised previously, although often their complexity cannot be identified radiographically immediately following injury. The seasonality observed in 2- and 3-year-old horses is most likely to be a consequence of the timing of the turf-racing season in the UK. The Summary is available in Chinese - see Supporting information.
 
Acid-base disturbances are traditionally assessed using the Henderson-Hasselbach equation. The simplified strong ion approach describes more accurately the complex acid-base and electrolyte abnormalities present in endurance horses. To describe acid-base and electrolytes changes in fit horses competing in a FEI*** 120 km endurance race and to compare the traditional vs. strong ion approaches. Thirty horses were initially enrolled in the study. Venous blood samples were obtained before the race (n = 25), at the second (n = 29; 65.4 km) and third vet-gates (n = 23, 97.4 km) and upon race completion (n = 17). Blood gas analysis was performed to determine pH, PCO(2), PO(2), Na(+), K(+) and iCa(++), and calculate HCO(3)(-), base excess and tCO(2). Packed cell volume and total protein, globulin, albumin, lactate, phosphate, glucose and creatinine concentrations, as well as muscle enzymes activities, were also determined. Calculated variables included strong ion difference (SIDm), strong ion gap (SIG) and nonvolatile buffer concentration (A(tot)). A longitudinal linear model using the general estimating equation methodology was used for statistical analysis. Mild but significant increases in PCO(2), SIDm, lactate, plasma protein, globulins and A(tot), as well as a decrease in potassium concentrations were observed from the second vet-gate to race finish when compared to prerace values (P < 0.05). Using the strong ion approach, 67% samples showed acid-base disturbances vs. 70% when using the traditional method, but their interpretations only matched in 24% of measurements. A complex acid-base imbalance characterised by a mild strong ion alkalosis (hypochloraemia attenuated by hyperlactataemia), nonvolatile buffer acidosis and compensatory mild respiratory acidosis were present in most horses, although pH did not significantly change during a 120 km endurance race. The strong ion approach to interpretation of acid-base balance should be favoured over the traditional approach in endurance horses, given the frequent and complex alterations in PCO(2), SIDm and A(tot) during a race.
 
In this study, beta-adrenoceptors of intact equine lymphocytes were identified and subclassified by (-)-[125I]-iodocyanopindolol (ICYP) binding. ICYP binding to intact equine lymphocytes was rapid, saturable (maximal number of binding sites 320 +/- 20 ICYP binding sites/cell, n = 12) and of high affinity (KD value for ICYP 14.4 +/- 1.7 pmol/l, n = 12). Binding was stereospecific as shown by the 10 times greater potency of (-)-propranolol to inhibit binding than its (+)-isomer. Beta-adrenoceptor agonists inhibited ICYP binding with an order of potency: (-)-isoprenaline >(-)-adrenaline >(-)-noradrenaline; the same order of potency was obtained for agonist-induced stimulation of lymphocyte cyclic AMP content. The selective beta2-adrenoceptor antagonist ICI 118,551 was about 1000 times more potent in inhibiting ICYP binding than was the beta1-selective adrenoceptor antagonist CGP 20712A. It is, therefore, concluded that in intact equine lymphocytes, ICYP labels a class of functional beta-adrenoceptors that belong predominantly (>90%) to the beta2-adrenoceptor subtype; a small (<10%) beta1-adrenoceptor component, however, cannot be ruled out completely. ICYP binding to equine lymphocytes might be a suitable model to study function and regulation of the beta-adrenoceptor system in the horse in vivo. The aim of this study was to characterise the beta-adrenoreceptor subtypes present on equine lymphocytes.
 
The rate of clearance of 125I-labelled polyvinyl pyrrolidone (PVP) from blood was measured in mares as an indicator of macrophage function. In three out of four cycling mares, PVP clearance was slower during oestrus than dioestrus. Similarly, administration of oestrogen to four ovariectomised mares tended to depress PVP clearance compared with clearance from the same mares before they received oestrogen. However, the effect of oestrogen was not statistically significant. Mares susceptible to persistent endometritis had rates of PVP clearance which were similar to those of genitally normal mares.
 
Dental disorders are of major clinical importance in equine practice; however, the knowledge of normal dental anatomy, especially that of the pulp remains incomplete. Computed tomography (CT) is being used increasingly in the diagnosis of dental disease, although the normal 2- (2D) and 3-dimensional (3D) CT anatomy has not yet been fully described. To describe the 2D and 3D CT appearance of the enamel, infundibulae and pulp of normal equine cheek teeth. One-hundred-and-twenty-six cadaveric cheek teeth with eruption ages of 0.5-19 years were evaluated; CT scans of each tooth were performed after occlusal surface examination with a dental probe. Three-dimensional reconstructions of the enamel, infundibulae and pulp were created from the CT scans using greyscale thresholding and subsequent polynomial meshing. Each tooth was sectioned coronally or axially into serial slices using a band saw and the sections compared to the corresponding CT images. The CT reconstructions enabled the systematic description of the pulpar anatomy of the mandibular and maxillary cheek teeth in 3D, which has not been described in detail previously. The number of interpulpar communications between pulp horns and the pulpar volume of each tooth was shown to decrease with increasing age. The interpulpar communications of the maxillary cheek teeth were found to be of greater complexity and variety in comparison to their mandibular counterparts. Mandibular and maxillary cheek teeth showed different, but consistent patterns in their pulpar and enamel morphology. The detailed description of the normal 2D and 3D CT appearance of equine cheek teeth provides a reference basis for the diagnosis of dental disease with CT. Additionally, in depth knowledge of the pulpar anatomy of the equine cheek teeth is an essential prerequisite if endodontic therapy is to develop further in the future.
 
There is limited knowledge available of factors influencing response to treatments of the DIP-joint in horses with lameness responding to diagnostic analgesia of the DIP-joint. For this reason a multivariable statistical analysis was performed. Horses with lameness reduced by > or = 75% 10 min after intra-articular analgesia of the DIP-joint, can be treated successfully by intra-articular medication of the joint. Multiple factors influence the response to treatment. The study was performed retrospectively based on clinical records of horses treated with either polysulphated glycosaminoglycan (PSGAG) or methylprednisolone acetate (MPA) in the DIP-joint between January 1996 and January 2003. Information was collected from clinical records and from the owners of the horses via a detailed questionnaire, in which they described their perception of the outcome a minimum of one year after treatment. Allocation of the horses to the 2 treatment groups was done mainly because of a change in treatment policy. In Regime A all horses received 3 intra-articular injections of PSGAG approximately 8 days apart, whereas in Regime B all horses received a single intra-articular injection of MPA as a first treatment. If the horse did not improve sufficiently to return to work by 4 weeks, a series of 3 intra-articular PSGAG injections was administered. Of the horses receiving Regime A, 67% had a successful outcome, compared with 46% of the group receiving Regime B. A significantly better result was obtained in dressage horses than in jumping horses (eventing and showjumping). Other variables such as age, duration of lameness, distribution of lameness, degree of lameness, response to DIP-joint analgesia and radiographic observations were also associated with success of treatment. There is a rationale for using either PSGAG or MPA intra-articularly in the treatment of lameness, reduced > or = 75% within 10 min of analgesia of the DIP-joint.
 
Dynamic upper airway obstruction (UAO) is a cause of respiratory noise and sometimes poor performance in sport horses. Riding, head flexion and airway inflammation may impact upper respiratory tract stability during exercise. To evaluate upper airway mechanical behaviour in ridden sport horses using overground endoscopy and the effect of head flexion, rider intervention and underlying airway inflammation on the pharynx and larynx. Resting and exercising videoendoscopic recordings during ridden exercise were obtained in 129 sport horses referred mainly for respiratory noise, poor performance or routine evaluation. The rider modified poll flexion and way of riding during the test and associated changes in UAO were recorded. Presence of upper and lower airway inflammation was also assessed. Dynamic UAO was diagnosed in 91% (64/70) of the horses referred for respiratory noise and in 71% (29/41) of horses referred for poor performance. Pharyngeal instability was the most frequently diagnosed problem. However, differences were observed between dressage horses and showjumpers. Rider interaction and head flexion exacerbated upper airway instability and promoted the occurrence of complex UAO. Both lower airway inflammation and pharyngeal lymphoid hyperplasia were associated with pharyngeal instability, but not with any other UAO. Rider intervention during ridden exercise (i.e. the various movements a horse might be asked to perform) influences upper airway morphology and function and, in cases of upper airway dynamic obstruction, can contribute to increasing laryngeal and/or pharyngeal instability in sport horses. As these are changes that would not usually be seen with treadmill videoendoscopy, ridden videoendoscopy should be the preferred method for evaluation of the upper airway in sport horses.
 
This report describes the use of ultrasound to diagnose right dorsal displacement of the large colon (RDDLC) in 13 horses prior to surgery. Horses had ultrasonographic examinations performed of the right lateroventral aspect of the abdomen upon admission to the hospital with a 2-5 MHz broadband curvilinear sector scanning transducer after alcohol was used to wet the hair. First, the caecal vessels were identified in the right flank and followed medially and cranially. Next, each intercostal space, from caudal to cranial, was scanned from dorsal to ventral evaluating for abnormally-located mesenteric vessels associated with the large colon. Abnormally-located mesenteric vessels associated with the large colon, distinct from the caecal vessels, were identified in 13 of 23 horses with a diagnosis of RDDLC obtained at exploratory laparotomy. In horses, ultrasonographic visualisation of mesenteric vessels along the right lateral abdomen, dorsal to the costochondral junction in at least 2 intercostal spaces, distinct from the caecal vessels, is consistent with a surgical diagnosis of RDDLC.
 
There is limited information on the treatment of lateral malleolus (LM) fractures in the horse, with no previously published case series for the outcome following arthroscopic removal of such fractures. This report reviews and evaluates findings of a retrospective study of 13 horses admitted to a private equine referral hospital over a 10 year period (1999-2009) that underwent arthroscopic removal of fractures of the LM. Hospital records were reviewed and details including patient history, aetiology of the fracture and limb affected, results of all diagnostic tests and surgical reports were documented. Performance information concerning Thoroughbred horses that went onto race post operatively was collected using an online database. Owners and trainers were contacted regarding the return to performance for non-Thoroughbred cases or those that did not go onto race post operatively. Of the 13 horses presented, 12 were Thoroughbreds, 9 of which were National Hunt racehorses and 3 were Flat racehorses. The other horse in the study was used for general purpose riding. All cases presented with an acute unilateral fracture. Eleven of the 13 had >6 months post operative follow-up and all were nonlame. Of the 12 Thoroughbreds, 10 have raced again, a total of 104 times (median 5 times). The median time from surgery to return to racing was 241 days (180-366 days). It is concluded that horses with fractures of the LM have an excellent prognosis for return to full athletic performance following arthroscopic debridement; and that arthroscopic fragment removal is an appropriate treatment method for fractures of the LM.
 
The presenting signs, treatment and postoperative progress of 13 horses with vesical and urethral calculi are reviewed. Single, discrete stones were present in 10 animals in which the results of treatment were generally good. In three horses with sabulous cystic deposits, urolithiasis was associated with bladder paralysis and the response to treatment was poor.
 
Imidocarb dipropionate is the drug of choice for equine piroplasmosis but its administration causes severe colic and diarrhoea. An imidocarb protocol that reduces these effects is needed. 1) Quantification of the effects of imidocarb dipropionate on equine orocaecal transit time (OCTT), with and without atropine or glycopyrrolate premedication and 2) investigation of an improved pretreatment regimen for imidocarb administration. Treatment with imidocarb dipropionate will result in colic and reduced OCTT as demonstrated by the lactose 13C-ureide breath test which will be ameliorated by premedication with either atropine or glycopyrrolate. The effects of 3 drug therapies on OCTT were compared in 6 healthy horses in a randomised double-blind study vs. a saline control: 1) imidocarb dipropionate 2.4 mg/kg bwt administered intramuscularly (i.m.) with saline administered intravenously (i.v.; imidocarb/saline); 2) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with atropine 0.035 mg/kg bwt administered i.v. (imidocarb/atropine) and 3) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with glycopyrrolate 0.0025 mg/kg bwt administered i.v. (imidocarb/glycopyrrolate). The lactose 13C-ureide breath test was used to measure OCTT in each case and significance of treatment effect determined by a linear model analysis of variance. Imidocarb/atropine treatment caused an increase in OCTT (P < 0.05) whereas imidocarb/saline produced a nonsignificant decrease in OCTT. Imidocarb/saline caused colic and diarrhoea in 4 of 6 horses, which were not seen in any of the horses treated with imidocarb/atropine or imidocarb/glycopyrrolate or administered the saline control. Intestinal borborygmi were increased in imidocarb/saline and decreased in imidocarb/atropine treated horses, respectively. Imidocarb/saline treatment induced colic signs and a potential reduction in OCTT while imidocarb/atropine treatment increased OCTT significantly when compared with imidocarb/saline. Both atropine and glycopyrrolate premedication ameliorated the clinical gastrointestinal effects of imidocarb but atropine produced significant inhibition of gastric and/or small intestinal motility not detected with glycopyrrolate. Premedication with glycopyrrolate is recommended when using imidocarb for treatment of equine piroplasmosis.
 
Changes in plasma 15-keto-13, 14-dihydro-prostaglandin F2 alpha were monitored at frequent intervals before, during and after spontaneous deliveries (three mares) and foalings induced by oxytocin (eight mares). No evidence of increased concentrations of the prostaglandin metabolite was observed in the final 10 days of gestation. In spontaneously delivering mares, there was a marked increase from 3 ng/ml at -125 mins to 18 ng/ml at -65 mins to the highest observed value of 182 ng/ml at 20 mins pre-partum. Following delivery, concentrations declined rapidly to around 0.2 ng/ml. Further release of prostaglandins was seen on Days 1 and 3 post partum. In oxytocin induced mares, maximal concentrations of about 100 ng/ml were observed to occur very close to the time of delivery. Large increases were observed as early as 2 mins following oxytocin injection. The significance of these findings is discussed in relation to parturient and post parturient events and changes in levels of the hormone relaxin during the same period.
 
REASONS FOR STUDY: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor a chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood halfsib families. Based on a history of clinical signs (coughing, nasal discharge, abnormal breathing and poor performance), horses were classified in a horse owner assessed respiratory signs index (HOARSI 1-4: from healthy, mild, moderate to severe signs). Four microsatellite markers (AHT133, LEX041, VHL47, ASB037) were analysed in the offspring of Sire 1 (48 unaffected HOARSI 1 vs. 59 affected HOARSI 2-4) and Sire 2 (35 HOARSI 1 vs. 50 HOARSI 2-4), age 07 years. For both sires haplotypes could be established in the order AHT133-LEXO47-VHL47-ASB37. The distances in this order were estimated to be 2.9, 0.9 and 2.3 centiMorgans, respectively. Haplotype association with mild to severe clinical signs of chronic lower airway disease (HOARSI 2-4) was significant in the offspring of Sire 1 (P = 0.026) but not significant for the offspring of Sire 2 (P = 0.32). Linkage analysis showed the ECA13q13 region containing IL4RA to be linked to equine chronic lower airway disease in one family (P<0.01), but not in the second family. This supports a genetic background for equine RAO and indicates that IL4RA is a candidate gene with possible locus heterogeneity for this disease. Identification of major genes for RAO may provide a basis for breeding and individual prevention for this important disease.
 
Determining if low-dose, low-frequency doxycycline administration is capable of achieving chondroprotective concentrations within synovial fluid (SF) while remaining below Minimum Inhibitory Concentration 90(MIC90) of most equine pathogens would be an attractive option in the management of osteoarthritis (OA). Determine if low-dose, low-frequency oral administration of doxycycline can attain in vivo SF concentrations capable of chondroprotective effects through reduction of MMP-13 activity, while remaining below MIC90 of most equine pathogens. Descriptive pharmacokinetic study with cross-over design. Two groups of 6 horses received oral doxycycline. Plasma and SF doxycycline concentrations were measured using High Performance Liquid Chromatography. Group 1 received 5 mg/kg bwt q24 h with 21 blood and 8 SF samples collected over 120 h; Group 2 received 5 mg/kg bwt q48 h with 27 blood and 11 SF samples collected over 192 h. Cultured synoviocytes were treated with IL-1 alpha (1 ng/ml) for 24 h to stimulate MMP synthesis and then SF was added to the culture media for 96 h. MMP-13 protein and mRNA were measured in synoviocyte culture media and synoviocytes, respectively. Mean doxycycline concentration ≥0.043 μg/ml (previously demonstrated to inhibit MMP-13) was achieved in plasma by t = 0.25 h and SF by t = 48 h in Group 1, and in plasma by t = 0.17 h and SF by t = 1 h in Group 2. Synoviocyte culture media containing doxycycline from Groups 1 and 2 had significantly decreased active MMP-13 protein concentration, and synoviocytes cultured in this media had significantly decreased MMP-13 gene expression compared to controls. Plasma doxycycline concentration in both Groups and SF doxycycline concentration in Group 2 demonstrated a cumulative effect. Low-dose orally administered doxycycline achieves SF concentrations in vivo capable of diminishing MMP-13 expression. This study supports the use of doxycycline as a disease modifying osteoarthritic drug (DMOAD).
 
The clinical features, radiographic findings, management and outcome in 13 cases of traumatic fracture of the hock joint are reported. The principal fracture sites were the distal tibial malleoli (5 cases), the fibular tarsal bone (4 cases), the tibial tarsal bone (3 cases) and the proximal end of metatarsal IV (one case). An additional small chip fracture of the central tarsal was noted in 2 cases. Three horses were destroyed immediately after diagnosis, 2 failed to recover following surgical intervention and one remained lame and was destroyed after 3 months' rest. Seven horses recovered completely and returned to work following periods of rest ranging from 3 to 9 months. The fracture involved the lateral or medial malleolus in 5 of these cases and the fibular tarsal in the other 2.
 
Top-cited authors
Paul René van Weeren
  • Utrecht University
Patricia Harris
Sue Dyson
  • Independent consultant
Raymond J Geor
  • Massey University
Roger K W Smith
  • Royal Veterinary College