Journal of Equine Veterinary Science

Published by WB Saunders
Online ISSN: 0737-0806
Publications
Fructokinase C is expressed throughout the intestines in mice
Serum Fructose levels increase in a Horse eating Pasture-rich Fructans
Article
Fructose is a simple sugar present in honey and fruit, but can also exist as a polymer (fructans) in pasture grasses. Mammals are unable to metabolize fructans, but certain gram positive bacteria contain fructanases and can convert fructans to fructose in the gut. Recent studies suggest that fructose generated from bacteria, or directly obtained from the diet, can induce both increased intestinal permeability and features of metabolic syndrome, especially the development of insulin resistance. The development of insulin resistance is driven in part by the metabolism of fructose by fructokinase C in the liver, which results in oxidative stress in the hepatocyte. Similarly, the metabolism of fructose in the small bowel by intestinal fructokinase may lead to increased intestinal permeability and endotoxemia. While speculative, these observations raise the possibility that the mechanism by which fructans induce laminitis could involve intestinal and hepatic fructokinase. Further studies are indicated to determine the role of fructanases, fructose and fructokinase in equine metabolic syndrome and laminitis.
 
Article
Two hundred mares of mixed breeding were examined with ultrasound for pregnancy on 273 occasions, between Days 13 and 16 after ovulation, and found to be empty. At this stage the visible presence of any corpora lutea were noted including the side and level of echogenicity. The uterus was examined for endometrial edema and free luminal fluid. The cervix was palpated per vagina for tone, relaxation and edema. Interovulatory intervals were recorded.The corpus luteum (CL) was clearly visible on the side ipsilateral to the recorded ovulation in 73% of 134 cases examined on Day 13, 65% on Day 14, 43% on Day 15 and 42% on Day 16. No CL was visible in 17 cases (Day 13), 19 (Day 14), 15 (Day 15)and 9 (Day 16) and of these 14, 12, 6 and 4 cases were thought to have suffered premature luteolysis due to luteal phase bacterial endometritis. The mean interovulatory interval for this group was 15.9, 17.9, 15.7 and 16.0 days, respectively, compared with 21.9, 2 1.6, 21.9 and 21.3 days for normal mares where the CL was still visible.
 
Article
We retrospectively evaluated the medical records and obtained follow-up information for nine horses which had been treated for cecocolic intussusception (CCI) between January 1982 and April 1998. During the 16-year study period, CCI was diagnosed in nine of 748 horses in which exploratory celiotomy was undertaken for abdominal pain, representing an incidence of 1.2%. Most affected horses (78%) were less than four years of age (median age was 12 months, age range was five months to 15 years). Cecocolic intussusception affected male horses (78%) more commonly than female horses. The most common clinical presentation was abdominal pain of a severe, acute nature or milder but recurrent signs of abdominal pain persisting in spite of conservative treatment for several days. Correction of CCI by either simple reduction or reduction followed by partial typhlectomy was successful if compromise of the intestine by devitalization and adhesion formation was not found at surgery. Definitive diagnosis of CCI necessitates exploratory celiotomy, although an ultrasonographic examination of the abdomen may confirm the diagnosis in some cases. When recognized early during the course of disease, surgical correction of CCI is associated with a favorable outcome; of the eight horses which underwent surgery in our series, five horses (63%) survived surgical correction of CCI. Handling of compromised gut during reduction of CCI necessitates extreme caution because the risk of intestinal tearing is quite high.
 
Article
The possible existence of nationalistic bias in the scoring of dressage tests in the competition at the 1988 Seoul Summer Olympic Games was investigated. A panel of 5 judges simultaneously scored each performance, with scores totaled for each competitor. Team competition required riding the FEI Grand Prix de Dressage test. A national team consisted of 4 horse-rider pairs, with the top 3 scores counted for the national team total. Four out of 5 judges scored horse-rider pairs from their own nation, for a total of 16 out of 53 competitors scored by co-national judges. Nineteen riders, 9 of whom were scored by co-national judges, competed for individual medals by riding the prescribed FEI Grand Prix Special test. The scores of judges rating their co-nationals were compared by analysis of variance with scores of judges rating competitors from other nations.
 
Article
Efficacy of ivermectin treatment (0.2 mg/kg) against 28-day experimental infections of Parascaris equorum was determined in 18 pony foals6–17.5 weeks old. There were 6 foals in each group: nontreated control, ivermectin injectable or oral paste. In comparison with larvae found in the nontreated controls, ivermectin injectable or paste was 96.0% and 99.9% efficacious. There was a distinct difference in drug effect against the larger (ca 26mm.) vs the smaller (13–19mm) larvae by the 2 formulations of ivermectin. There were no adverse signs related to treatment of the young foals.
 
Article
Septic arthritis was diagnosed in 34 horses. In 16 horses a penetrating wound was found; in 4 cases a puncture wound of the sole was present. In 5 horses the infection was iatrogenically induced. Three of these horses had received corticosteroids intra-articularly. A diagnostic intra-articular anesthesia, performed by the local veterinarian, was the cause of infection in one case. One horse suffered from sepsis and metastatic arthritis after a purulent thrombophlebitis. In 9 horses no exact cause was apparent. The average time before presentation at the hospital was 13 days. On clinical examination severe lameness, which had worsened over a short period of time, was apparent and the affected joint was swollen and painful on manipulation. Treatment consisted of high levels of antibiotics, systemically administered, followed by long-term administration of oral sulfonamides. In 26 cases antibiotics were injected into the joint. Immobilization of the joint was done when possible and was the best additive treatment regime combined with systemically administered antibiotics. Following treatment 9 horses recovered completely, 2 horses returned to stud and were not visibly lame but were not worked; 3 horses improved but when worked hard suffered from residual lameness. Six horses remained lame as a result of osteoarthritis. Thirteen horses were destroyed; one horse was lost for follow up.
 
Article
Eight mature horses were administered a single intramuscular injection of 500 mg polysulfated glycosaminoglycan (PSGAG) labeled with 2.044 mCi tritium. Synovial fluid samples were collected from the antebrachiocarpal (carpal), metacarpophalangeal (fetlock), tibiotarsal (hock) and coronopedal (coffin) joints prior to injection and at 2, 4, 8, 12, and 24 hours after injection. The samples were subjected to scintillation counting in decays per minute and were converted to μg PSGAG per ml. The levels achieved in the synovial fluid of the various joints were compared to levels of PSGAG described as adequate to inhibit enzymes which degrade articular cartilage matrix components and hyaluronic acid and adequate to stimulate production of new matrix components and hyaluronic acid in diseased joints.Mean synovial fluid 3H-PSGAG levels indicated that peak concentrations of 3H-PSGAG were achieved 2 hours post injection in all joints and that these concentrations were within the therapeutic range for PSGAG. The peak concentrations were not significantly different among the joints except between the antebrachiocarpal and the metacarpophalangeal joints. The areas under the concentration-time curves (AUC) for each joint were computed by the trapezoidal method from hour 0 through hour 24 and by empirical exponential decay beyond hour 24. These values were subjected to an analysis of variance (ANOVA). The overall multivariate test of AUC among all joints was not significant.The data from this study indicate that a single intramuscular 500 mg injection of PSGAG provided therapeutic levels of the drug in the equine antebrachiocarpal, metacarpophalangeal, tibiotarsal, and coronopedal joints within 2 hours of injection. While there were differences in levels between joints at certain time points, the AUC values suggest similar distribution of the drug in all joints tested.
 
Article
In 53 racehorses with a mean age of 4.5 years old presented for poor performance, Small Airway Inflammatory Disease (SAID) was diagnosed by bronchoalveolar lavage (BAL). Thirty of these horses (58.5%) had arterial pCO2 above normal range (> 46 mmHg), while pO2 was within normal range (> 80 mmHg) in both hypercapnic (group A) and normocapnic (group B) horses although pO2 was significantly lower in group A horses. The horses were subsequently subdivided into two groups according to the duration of symptoms (group 1: less than 4 weeks; group 2: longer than 4 weeks). Horses from group 2 had significantly higher values of pCO2 (p < 0.01) , HCO3- (p < 0.01) and TCO2 (p < 0.05) when compared to horses from group 1. It was concluded that the duration of the inflammatory process may play a role in the alteration of blood/alveolar gas exchanges and acid-base status in SAID affected racehorses.
 
Article
A Thoroughbred mare, barren during three years at stud, unresponsive to therapy, and not palpably abnormal anatomically was found to have hypoplasia of the uterine tubes after excision at laparotomy. The cause was an unbalanced genotype. The mosaic karyotype, determined on a blood sample, was indispensible in diagnosis and the case extends the potential for cytogenetic prognostic procedures.
 
Article
A total of 54 mares in seasonal anestrus were assigned to 5 groups to receive depots containing 0, 0.9, 1.8, 3.6, and 5.4 mg/mare of a GnRH analogue (CH 690030 or goserelin acetate) on January 28. Five mares, three classified as transitional mares and two classified in anestrus, when depots were given ovulated between 11 and 21 days after the onset of treatment and subsequently formed a corpus luteum. Reciprocal changes between an increased LH concentration and a decreased FSH concentration commenced 6 days before ovulation, when rapid follicle growth was initiated. Mares that ovulated showed a gradual rise in LH concentration with a 5-day duration of high LH concentrations, reaching a peak during the peri-ovulatory period and followed by a slow decline without returning to the pre-treatment value at the end of the 30-day post-treatment period. The change in FSH was first a rapid rise then an obvious drop with a nadir 3-5 days before ovulation and then a low level maintained until the end of the study. Mares receiving a dose of 3.6 mg had a lower mean post-treatment FSH concentration and a lower mean FSH peak value than the controls (P < 0.05). The intervals to the peak concentration of gonadotropins and maximum follicle size were also significantly shorter for mares dosed with 3.6 mg than for the controls (P < 0.05). The mean LH peak value for mares that ovulated (110.2 ± 29.3 ng/ml) was significantly greater than that for controls (19.3 ± 3.8 ng/ml) and mares dosed with 0.9 mg (28.2 ± 3.3 ng/ml) which did not ovulate (P < 0.05). A dose of 5.4 mg did not cause responses different from those induced by a dose of 3.6 mg. Adose of 3.6 mg is recommended for further investigation based on changes in gonadotropin concentrations and follicle diameters after goserelin treatment.
 
Article
Eighty-five cases of equine nasal cavity and/or paranasal sinus disease (NC-PNSD) at Washington State University were reviewed with respect to incidence, clinical signs, treatment regimen and outcome. Incidence was 1.06 percent of all equine admissions over an 8-year period (July 1, 1977–June 30, 1985). For purposes of review, cases were divided into 6 groups depending upon etiology: 1. traumatic disorders, 2. developmental disorders, 3. neoplasia, 4. primary bacterial sinusitis, 5. sinusitis secondary to dental disorders, and 6. miscellaneous conditions.No correlation between sex or breed with NC-PNSD was identified. Traumatic and developmental disorders were most common in horses under 6-years-of-age and neoplastic conditions were most prevalent in horses over 10-years-of-age.The most common clinical signs of NC-PNSD, regardless of etiology were bony swelling or abnormalities noted externally, nasal discharge, and rhinodyspnea, followed by signs referrable to the oral cavity, external draining tracts, and epistaxis. All clinical signs were usually of a chronic duration (more than 2 weeks). Procedures which were most helpful in establishing a diagnosis were radiography (92% of cases), endoscopy (38%) sinocentesis (21 %), and examination of the oral cavity (20%).Of 74 horses available for follow-up, 49 were treated. Treatment was either not recommended or was declined by the owner in 12 cases, and euthanasia was performed without treatment in 13. Forty-six cases were treated surgically. The outcome of 23 of the cases was judged successful. Five had reduced clinical signs following surgery, and 18 were unsuccessfully treated. Those disorders judged to be traumatic in origin responded best to treatment while those involving neoplasia were the least successfully treated.
 
Article
The objective was to generate evidence for clinical efficacy and acceptability of a second generation coxib, firocoxib, administered orally for 14 days to lame horses under field conditions compared with a classic nonsteroidal anti-inflammatory drug, vedaprofen, in a prospective, randomized, controlled, double-blinded, multicenter field trial. Ninety-six client-owned horses with American Association of Equine Practitioners score of at least grade 3 lameness or grade 2 lameness plus at least a score of 2 for either pain on palpation, range of motion, or joint swelling were analyzed. Horses were administered 0.1 mg/kg firocoxib orally at 24 hour intervals (n = 48) or 1.0 mg/kg vedaprofen paste at 12 hour intervals for 14 days (single loading dose of 2.0 mg/kg vedaprofen) (n = 48). Physical examinations and lameness evaluations were conducted on Day 1 (V1, before treatment) and on Days 7 (V2) and 14 (V3). Blood chemistry and hematology profiles were also evaluated. With regard to the primary variable, clinical improvement, 83% of the firocoxib-treated horses improved at V3 compared with 65% of vedaprofen-treated horses improved meeting the criteria defined to demonstrate noninferiority of firocoxib to vedaprofen. Health and behavioral abnormalities for side effect detection occurred at the rate of 2% (1 horse) and 8% (4 horses) for firocoxib- and vedaprofen-treated horses, respectively. Changes in hematology and blood chemistry values from V1 to V3 were not significantly different between treatment groups. Firocoxib, formulated as an oral paste was highly effective, well tolerated, and acceptable for the control of pain and inflammation associated with lameness in horses under field conditions.
 
Article
Serum and colostrum were collected from 50 mares at parturition. Pre- and post-nursing serum samples were obtained from their foals. Bi-weekly serum samples were obtained from 25 of the foals for eight weeks. Hemagglutination-inhibiting (HAI) antibody titers to equine influenza viruses A1 and A2 (EIVA1 and EIVA2) and serum-neutralizing antibody titers to equine herpes virus 1 (EHV1) were measured in serum and colostrum samples. IgG levels in serum and colostrum were determined.No antibody was detected in any foal's pre-nursing serum sample. Foal post-nursing antibody and IgG levels were equivalent to those measured in their dam's sera (EHVA1 p=0.86; EHVA2 p=0.54; EHV1 p=0.91; IgG p=0.58). The half-life of maternally-acquired serum antibody in the foals was determined to be: EIVA1=28.88 days (26.4 to 31.7 days); EIVA2=29.1 days (26.7 to 32.1 days); EHV1=31.0 days (28.1 to 34.8 days). Colostrum contained antibody and IgG at levels ranging from 2 to 8 times higher (4.3 average) than those detected in the mare's serum.
 
Article
The relationship between body weight gain and the onset of bone aberrations (e.g. epiphysitis) is described. A model was derived which described the increase in transverse epiphyseal width, and the major factor found to affect epiphyseal width was average daily gain in body weight. In addition, a radiographic examination of the epiphyseal areas showed a larger number of bone aberrations in groups gaining weight at an above-average rate. Thus, a rapid increase in body weight can be suggested as a significant factor in the onset of epiphysitis.
 
Article
An in utero tibial fracture was examined at necropsy in a seven-month-old male aborted Thoroughbred fetus. Grossly the healed fracture had a smooth cortical surface. Histologically there was no callus formation or excessive osteoclastic or osteoblastic activity.
 
Article
In late April/early May of 2001, for the equine industry in Kentucky, a previously unknown factor led to the loss of up to 40% of the new pregnancies (20-60 days) for that year, with a following significant number of late abortions and ill new born foals. In addition, encephalopathy, ocular lesions, pericarditis, laminitis, and other diseases were suspected to be associated with the syndrome. This occurrence was known as the mare reproductive loss syndrome (MRLS). On examination of the weather data, this period was seen to have an unusual pattern of severe late spring frost. Acute changes in the pasture diet affected the horses gut microflora, allowing the overgrowth of opportunistic pathogens and resulting in the excessive absorption of nitrogen and ammonia from the large bowel. Clinical blood chemistries from the horses on pasture at this time showed abnormally high levels of blood urea nitrogen (BUN). Elevated blood ammonia levels were found in mares and newborn foals affected with MRLS. Ammonia is metabolically one of the most toxic substances to the body. It is present naturally as a breakdown product of nitrogen turnover. If the body nitrogen balance is disturbed for any reason, with nitrogen accumulation exceeding the body's ability to excrete it as urea (BUN), ammonia will accumulate in toxic levels. Ammonia toxicity can cause all the symptoms that were observed in the horses exhibiting MRLS.
 
Article
Twin pregnancies recorded in German Thoroughbred mares were responsible for premature termination of 2.5% of 27 465 pregnancies between 1967 and 1992, and constituted 38.5% of all 1788 abortions (6.5% of all pregnancies) recorded over the same time. Over time, the rate of twin pregnancies dropped from 2.7% before 1984 to 1.7% thereafter (P<0.001). During the last 20 years several methods of treatment of early detected twin pregnancies were evaluated. Crushing of one embryo in 69 cases gave best results when conducted between Days 21 to 26 of pregnancy, resulting in 80% single gestations continuing. Curtailing food intake during early twin pregnancies to enforce regression of the weaker conceptus is difficult to manage. However, reducing feed intake for one cycle prior to breeding in three mares with histories of frequent twin pregnancies resulted in five single pregnancies in five attempts.
 
Article
Physiological responses to weaning procedures were studied in 21 foals assigned to one of five treatments: (1) abrupt, total separation of mare and foal, no preweaning creep feed (TSNC); abrupt, total separation with preweaning creep feed (TSC); partial separation of mare and foal allowing fenceline contact, no preweaning creep feed (PSNC); (4) partial separation with creep feed (PSC); and (5) control (CON) no separation of mare and foal, foals creep fed. Changes in adrenal response to exogenous ACTH, basal and peak plasma cortisol concentrations, plasma triiodothyronine (T3) and thyroxine (T4) concentrations, weight gains and feed consumption were measured. Foals on the total separation treatments had higher adrenal responses (P<.05) and pre-ACTH basal (P<.05) and post-ACTH peak plasma cortisol concentrations (P<.05) than foals on other treatments indicating they were stressed at weaning. The PSNC, PSC and CON treatments did not differ (P>.05) in any cortisol response. No treatment differences were found in thyroid hormone concentrations in this study. On partial separation treatments, creep-fed and non-creep-fed foals consumed similar amounts of feed during the first week postweaning. On total separation treatments, non-creep-fed foals consumed more feed (P<.05) than creep-fed foals. All foals without creep feed gained more weight immediately after weaning (0–2 weeks) than creep-fed foals (P<.05), reflecting higher feed intakes and possible compensatory gains. Total postweaning weight gains (0–8 weeks) of foals were not significantly affected by treatment.
 
Article
A four-year-old mare with fever, weight loss, depression, hematuria and a hind limb lameness was affected with the congenital cardiac anomaly Pentology of Fallot. Vegetative arteritis of the patent ductus arteriosus resulted in embolic renal infarction, renal and hypaxial lumbar muscle abscessation and finally renal failure.
 
Article
Two isolates of the abortion strain (subtype 1) of equine herpes virus 1 (EHV1) were recovered from nasopharyngeal swabs of 3 Thoroughbreds in training in Hong Kong taken during an outbreak of clinical respiratory disease. There are 2 subtypes of EHV1, the abortion (1) and respiratory strains (2) and serologically it is not possible to differentiate between the 2 due to antigen cross-reactivity.4Monocyte counts undertaken by the same experienced technologist on blood films made by a modification of the traditional ‘wedge’ smear taken from blood samples collected from 58 Thoroughbred horses during the outbreak revealed a significant correlation to EHV1 serum titres.This may allow for earlier identification of affected animals during an outbreak especially in situations where virus confirmation facilities are not readily available.
 
Article
Fourteen mature stallions were paired based on age and pretreatment spermatozoal output. One member of each pair was assigned to either 1) control (3 ml corn oil) or 2) treated (132,000 IU retinyl palmitate in 3 ml corn oil) experimental groups. Treatments were added to oat rations every other day. Seminal characteristics (gel free volume, gel volume, total seminal volume, percent progressively motile spermatozoa, number of spermatozoa per ml, percentage morphologically normal spermatozoa and spermatozoal membrane stability) and total scrotal width of each stallion were recorded before (February) and after three months of vitamin A supplementation (June). Plasma vitamin A was measured at 0,6,12,24, and 48 hours following the first and last treatments to document absorption. There were no treatment effects (p>.05) on seminal characteristics or scrotal width. Seasonal increases were recorded in gel-free volume, total seminal volume, percent spermatozoal motility, total spermatozoal output, percentage of morphologically normal spermatozoa, and total scrotal width. Plasma vitamin A was lower during the second collection period (June) than the first (February) in both treatment groups. Peak plasma vitamin A was observed 48 hours following ingestion of the first dose of the vitamin but at 12 hours following the last treatment.
 
Article
A study was conducted to measure water acceptance and intake in Quarter Horse mares after transportation (4 h) to a new location, Armstrong Equine Service (AES). Another objective was to increase that water intake by means of a flavor additive (apple or clover). Twelve mares were randomly assigned either New Mexico State University (NMSU) water or AES water then switched in a crossover design and repeated. Mares wore heart rate monitors to measure an indication of stress pretransit for 45 min, in-transit to AES for 4 h and post-transit for 1 h. Mares were weighed pre-and post- transit. Blood was drawn pre-transit and 4 days later before return to NMSU from AES. At AES, water intake was monitored for 4 days in both experiments. During experiment 1, water intake was similar (P=0.5) for both sources of water, except on day 3 when mares consumed more AES water than NMSU water (35 vs 301). Serum Na values in these mares ranged from 127 to 129 mEq/ 1 (132-146 is normal), while serum C1 ranged from 92 to 94 mEqfl (99-109 is normal). In experiment 2, mares were subjected to the same protocol as experiment 1, except that water was from AES. After 4 h transport, six mares continued to AES, where three received clover-flavored water and three received apple-flavored water. Six mares remained at NMSU after transportation, with three receiving apple and three clover flavoring. Flavored water intake was monitored for 2 days. Mares showed clear preference for apple on day 1 (P<.05) and day 2 (P<.07). Without flavoring, mares con- sumed more (P>.05) water at NMSU than AES. Mares adjusted to a new water more easily in a familiar, rather than unfamiliar, environment.
 
Article
A peripheral vasodilatory agent, isoxsuprine hydro-chloride, was evaluated in a controlled study for its efficacy in the treatment of acute equine laminitis. Eight healthy, adulthorses of variable age and sex were used in the trial. Acute laminitis was induced in 5 of the horses by oral carbohydrate overload. Intravenous isoxsuprine therapy (1.8 mg/kg) was initiated in 3 of the horses receiving carbohydrate overload at first sign of clinical lameness and repeated at 12-hour intervals. Intravenous saline placebos were administered on a similar schedule to 2 control horses which also received a carbohydrate overload. The remaining 3 horses served as further controls. Local and systemic responses to induction of laminitis and isoxsuprine administration were assessed by subjective evaluation of clinical lameness in a double blind trial; nuclear scintigraphy and radiography of the distal forelimbs; and assessment of physical, hematological and biochemical parameters.
 
Article
The study was designed to evaluate the change in creatine kinase (CK) and aspartate aminotransferase (AST) activity in normal horses following a conditioning program, exercise tests and the administration of acepromazine. Nine Thoroughbred horses, with no prior history of muscle disorders and no conditioning for 9 months, were assessed.During 11 weeks of conditioning CK and AST were assessed weekly and all horses had raw and mean CK and AST activities within normal limits. Although changes were noted in CK activity across time, these were not biologically significant.An initial exercise test over 400 meters prior to and then after conditioning, resulted in increased CK and AST activity immediately after and 4 hours after exercise. The increase in CK activity immediately after exercise was attributed to plasma volume changes and muscle leakage, while the increase in AST activity was attributed to plasma volume changes. The changes in CK and AST activity at 4h were attributed to muscle leakage. Conditioning did not affect the response of CK or AST activity to exercise.Increasing the distance and duration of maximal exercise from 400 to 1,000 meters caused increases in CK and AST activity at all sample times after exercise. The increase in CK and AST activity at 30 minutes and 4 hours were attributed to leakage from muscle or increased muscle membrane permeability. The administration of acepromazine IV prior to exercise over 1,000 meters failed to alter the response of CK and AST activity.Although statistically significant changes in CK and AST activity occurred following exercise, in no test were they biologically significant, being within normal limits.
 
Article
Laser Doppler flowmetry was used to determine the effects of acepromazine maleate, isoxsuprine hydrochloride, and prazosin hydrochloride on laminar microcirculatory blood flow. Five adult horses, weighing 450–500 kg and free of evidence of laminitis or other inflammatory conditions of the lower limb were used. Holes were drilled on the dorsum of each front hoof to the depth of the junction of the sensitive and insensitive laminae. Temperature, pulse rate and respiratory rate were obtained before begining the measurements. Pulse rate was measured at 15-minute intervals throughout the measurement period. A laser Doppler probe was placed in each hole. Baseline Doppler flow measurements were obtained. Following baseline determinations either acepromazine maleate (0.066 mg/kg), isoxsuprine hydrochloride (0.6 mg/kg) or prazosin hydrochloride (0.025 mg/kg) were administered intravenously. Drugs were randomly assigned and repeated 3 times in each horse. Laminar microcirculatory blood flow was then measured continuously for 180 minutes. These data were analyzed using univariate (mixed model) repeated measures analysis.None of the drugs evaluated had any significant effect on laminar microcirculatory blood flow. Acepromazine maleate, isoxsuprine hydrochloride and prazosin hydrochloride have no laminar microcirculatory blood flow effect in standing, healthy horses at dosages used. Efficacy in the use of these 3 drugs for the treatment of laminitis is questionable. However, this study was performed in healthy horses and the results may not be applicable in horses with laminitis.
 
Article
The capability of bacteria to adhere to host cells, such as the uterine epithelium, is an essential step for the survival of the infectious agent and subsequent pathogenesis. Some bacteria, but not all, attach to specific sugars on the surface of mucosal cells. Lectins on the surface of the bacteria mediate this type of binding to mucosal sugars by specific “lock and key” interactions. Streptococcus zooepidemicus is one of the bacteria commonly associated with endometritis in susceptible mares. The purpose of this study was to determine: 1 ) which sugar(s) competitively inhibit the attachment of S. zooepidemicus to the endometrium in vitro; 2) whether the sugar attaches to S. zooepidemicus or to the epithelium; 3) if the sugar could displace S. zooepidemicus from the mare's mucosa in vitro. Fresh endometrial biopsies from diestrus uteri, were incubated with S. zooepidemicus (0.5 ml of 109 cells/ml suspension, O.D.= 0.9 at 640 nm) in the presence of: no sugar (control), N-acetyl-d-galactosamine (D-galNAc),D-(+)-mannose, a-D-(+)-glucose or N-acetyl-d-glucosamine (D-gluNAc)(sugar concentration=25 rag/ml). Bacterial colonization was significantly reduced by D-galNAc and D-(+)-mannose when compared to controls (p<;.05). However, the other sugars were ineffective in decreasing the degree of attachment (p<.05). The number of bacteria attached to each colonized cell did not differ significantly from control for any treatment. In the second experiment, incubation of D-galNAc with S. zooepidemicus prior to its contact with tissue, significantly inhibited bacterial colonization of the epithelium. No significant decrease in bacterial attachment was observed when this sugar was incubated with the endometrium prior to the introduction of the bacteria. These results indicate that this sugar acts upon the bacteria and not the endometrium to prevent binding. In the third study, uterine tissue was incubated with S. zooepidemicus for 1 h to establish attachment of the bacteria. Then D-galNAc was added to the culture. This resulted in a significant displacement of the bacteria from the tissue.
 
Article
Six horses were conditioned on a treadmill at a constant speed of 5.6 km/hr on a 12.5% grade for gradually increasing periods of time over 14 days in order to determine the effect of repeated submaximal exercise on the concentrations of plasma free amino acids, protein metabolism, and plasma volume. Following 14-days of training, plasma volume increased (29%, P<0.05), as did total circulating content of plasma protein, albumin and urea. Urinary urea nitrogen excretion decreased (P<0.05) with exercise training. After the first week of training, the concentration of glycine had decreased (P<0.05) and the concentrations glutamic acid, arginine and alanine were increased (P<0.05) when compared to their corresponding pre-training (control week) levels. Compared to pretraining levels, there were decreases (P<0.05) in aspartic acid, histidine, arginine, valine, phenylalanine, isoleucine, and lysine, following the second week of training. Following a week of recovery, all resting concentrations of plasma free amino acids; when compared to their pretraining control; had decreased, with the exception of three nonessential amino acids (glutamic acid,serine, and glycine). Based upon the results of the present study, it would appear that exercise training produced a significant change in the amino acid and protein metabolism of the horse.
 
Article
Thirty-seven mares, barren for at least one year, were diagnosed to have endometrial inflammation by cytological examination and/or bacterial culture. Sixteen of these mares (the control group) were treated with prostaglandin and reevaluated cytologically within 10 days of behavioral estrus. Fifteen out of sixteen (15/16) (93.8%) remained positive for endometrial inflammation. Twenty-one mares (immunologically treated group) were treated with Propionibacterium acnes by injecting 1 ml per each 113.3 kilograms body weight intravenously on days 1, 3, and 7 following the diagnosis of endometrial inflammation. They also received prostaglandin. Twelve of the immunologically treated mares were examined cytologically as were the control mares. One of twelve examined (1/12) (08.3%) was positive cytologically for endometrial inflammation when examined within 10 days after behavioral estrus. The other nine mares in the treated group were bred on the first behavioral estrus following treatment. Nine of nine (9/9) were determined to be pregnant to 60 days gestation. The other treated mares were bred following the cytological evaluation. Eighteen of the twenty-one treated mares (18/21) (85 7%) were confirmed pregnant to 60 days gestation.
 
Article
The effect of using Propionibacterium acnes, (EqStim®)a as an adjunct to conventional therapy in the treatment horses with Equine Respiratory Disease Complex (ERDC) was evaluated. Of the 45 horses entering the study, 25 received EqStim® and conventional therapy while 20 horses (negative controls) received a carrier solution of 12.5% ethanol-saline and conventional therapy. At the end of the 14 day test period, 96% (24/25) of the horses treated with EqStim® and conventional therapy showed clinical improvement or complete recovery as compared to the control group in which 35% (7/20) of the horses (treated with conventional therapy and carrier) showed clinical improvement or complete recovery.
 
Article
Twenty-five crossbred weanling horses were used in a study to determine the influence of stall confinement, plane of nutrition and low heel on the occurrence of acquired forelimb contracture. Treatments included: confinement, normal nutrition, normal heel (CNN); confinement, normal nutrition, low heel (CNL); confinement, over-nutrition, normal heel (CON); confinement, over-nutrition, low heel (COL); pasture, normal nutrition, normal heel (PNN). Venous blood samples were drawn every 21 days for a total of 10 samples per foal and the serum was analyzed for copper and zinc content. Growth parameters, measured every 21 days for a total of 10 measurements per foal, included weight, girth, wither and hip height, 3rd metacarpal and 3rd metatarsal length and circumference.Average serum copper and zinc levels were higher in pasture vs. confinement foals. Over-nutrition groups were on the average significantly heavier, larger in their girth, taller at their withers and hips and longer in 3rd metatarsal length than normal nutrition groups. Cumulative gains in weight and hip height were greater for confinement vs. pasture foals, while over-nutrition foals had greater cumulative gains in weight and girth than the normal nutrition foals.No foals developed acquired forelimb contracture.
 
Article
The investigation of a respiratory syndrome herein described as APD, be- gan early in 1983. Between 1983 and 1991,347 horses were examined for poor performance. The study was carried out in conjunction with a variety of surgical techniques, aimed at reducing the inci- dence ofAPD.This resuRedin adiagnos- tic protocol which is now used to further explain many cases of respiratory poor performance.
 
Article
The purpose of this study was to evaluate the ability of various chemicals to induce capacitation of stallion spermatozoa using 2 different assay systems. In Experiment 1, freshly ejaculated spermatozoa were treated for 0, 3 and 6 h with 10 μ g/ml heparin, 0.5 mM hypotaurine or 5 mM caffeine, or were incubated for 0, 3 and 6 h following 1 min exposure to 0.1 μ M ionophore A23187. The acrosome reaction (AR) in the capacitated spermatozoa was induced by 15 min challenge with 100 μ g/ml lysophosphatidylcholine (LPC). In the BO/BSA-control medium (Brackett and Oliphant medium with 0.3% BSA), mean percentage of AR spermatozoa at 0 h was 30%, and the AR rates increased to 40 and 48% after 3 and 6 h incubation, respectively. There was no significant further increase of the AR rates in the spermatozoa treated with heparin (50% at 6 h) and hypotaurine (58% at 6 h) when compared to the control. Caffeine had a beneficial effect on inducing sperm capacitation after 3 and 6 h incubation (AR rates; 61 and 66%, respectively, P<0.01). Immediately after ionophore A23187 treatment, the AR rate increased to 56%, and reached 68 and 67% after 3 and 6 h incubation, respectively (P<0.01). Spermatozoal motility at any time points did not differ between control and any chemical treatment groups, except one treatment (ionophore; 3 h group).
 
Article
Fluoroscopic techniques were used to observe the position and movements of a jointed snaffle bit within the horse's oral cavity and to study the effects of using the reins unilaterally or bilaterally. In the resting position the mouthpiece was interposed between the tongue and hard palate, indenting the dorsum of the tongue. By elevation and retraction of the tongue the horse was able to raise the bit between the cheek teeth. This action was facilitated when the bit used was either too wide or was adjusted too low in the horse's mouth. The application of an equal force to both reins simultaneously caused the bit to move caudally, deepening the indentation in the horse's tongue. If the reins were used asymmetrically the net effect depended on the relative forces applied to the active and opposing reins. It was not possible to produce an independent effect on one side of the mouth.
 
Article
Heart rate (HR) is considered to be an effective tool for assessing animals' emotional response to a stimulus. We investigated changes in HR during a series of handling procedures (grooming test) in horses that had different experiences of human interaction. We used four groups of horses: grazing horses (group A), school horses (group B), six ponies, traditionally trained (group C), and six ponies, trained with modulated stimulus intensity (group D). An HR monitor was applied to each horse. The operator began the grooming test, standardized at the following points: (1) trainer's entry into the enclosure/paddock, (2) halter fastened, (3) start of grooming, (4) end of grooming, (5) saddling, and (6) inserting the bit. Group A repeated the grooming test twice: group A1 with a known operator and group A2 with an unknown operator. The data were compared by using analysis of variance (ANOVA) tests. The results showed a significant increase in HR (P ≤ .05) at point 2 compared with baseline in all groups except group D. Other significant differences were found at all points between groups A1 and A2, groups A2 and B, groups A1 and C, groups B and C, and at points 5 and 6 between groups A2 and C, as well as between groups C and D. Even when a scientific assessment of the increase in the HR is of primary importance, the use of this physiologic parameter may be helpful in assessing the horse's perceptions of stimuli presented by people during handling. Our results show that it is not the action “per se” that is important, but the manner in which horses perceive and appraise such actions in relation to the environment and their subject's experiences.
 
Article
The ovarian activities of 7 jennies were studied by serial ultrasonography during seasons of higher and lower sexual activity to determine if follicular development also corresponds to this pattern. The current study showed a seasonal pattern of ovarian activities related to the local environmental factors associated with each season rather than photoperiod, which is the widely known environmental cue determining seasonality in most equines. Jennies produced large numbers of follicles (11.3 follicles) during the long rainy season, compared with the 7.3 and 9.6 follicles during the dry and short rainy seasons, respectively. However, production of larger preovulatory follicles (37.8 ± 1.7 mm vs 31.0 ± 2.7 mm of the dry and 33.2 ± 2.7 mm of the long rainy seasons) and higher incidence of ovulation (77.8%) occurred during the short rainy season. Jennies had shorter interovulatory intervals during the season of higher (short rainy) than the season of lower (dry season) sexual activity. The short rain transition is characterized by higher follicular activity compared with the long rainy transition, indicating the presence of additional factors stimulating ovarian activity other than the mere availability of forage during the short rainy season.
 
Article
Two studies were conducted to evaluate the effects of acute hyperprolactinemia on : 1) the timing of ovulation and 2) the termination of the luteal phase in Standardbred mares. Persistently elevated prolactin levels were established in regularly cycling mares by administering 25 mg metoclopramide (MCP; a dopamine antagonist), i.v., every 2 hours for 4 days, beginning either day 17 (follicular phase) or day 11 (luteal phase) of the estrous cycle. Control mares received saline only. In the first experiment (during the follicular phase), the number of days to ovulation from the start of infusion did not significantly differ between the MCP- and vehicle-treated groups (5.4±0.5 versus 6.3±1.3 days, respectively; P<.10). Profiles of serum concentrations of follicle stimulating hormone (FSH) and of luteinizing hormone (LH) aligned relative to day of ovulation were similar between treatment groups. In the second study (during the luteal phase), neither time to termination of the luteal phase (6.0±0.3 versus 5.3±0.3 days from start of treatment) nor time to ovulation (12.8±1.5 versus 9.8±0.5 days) was different in MCP- compared to vehicle-treated mares, respectively (P>0.05). Profiles of serum concentrations of progesterone, FSH and LH aligned relative to days from previous ovulation were not altered by MCP treatment.We conclude that a short-term elevation in serum prolactin, such as that which occurs during the immediate post-partum period, does not alter luteal function or the timing of ovulation in the cycling horse mare.
 
Article
The effect of acute exercise on serum homocysteine (sHCy) concentration was examined in 10 horses; five Sella Italiana and five Thoroughbreds. All horses underwent standard training before the study (show jumping for Sella Italiana horses and gallop racing for Thoroughbreds). For the study, blood samples were taken at rest, immediately after exercise, and during a recovery period (30 and 60 minutes after exercise) by external jugular venipuncture. sHCy values were determined by high-performance liquid chromatography. Heart rate and blood lactate were monitored to quantify the workloads. In show jumpers, there was a significant effect of sampling time on sHCy (P < .01), which increased significantly after exercise as compared with at rest. In Thoroughbreds, no statistically significant differences were observed in sHCy over time (F(3,12) = 0.89, P = .05). The baseline values of sHcy were higher in Thoroughbreds than in show jumpers (P < .0002). We infer that physical activity causes biochemical changes that can influence the metabolic pathway of homocysteine in show jumpers, whereas the absence of a significant effect of exercise in Thoroughbreds may reflect an adaptive response of the enzymatic antioxidant defense system.
 
Article
Acute aseptic arthritis was induced in 8 healthy donkeys aged 3–4 years and weighing 80–100 kg. The animals were divided into two groups (A and B) of four animals each. Group A served as a control where as in group B pulsed ultrasound therapy was applied for 10 minutes @ 1 Watt/Cm2 from day 2 to 8 after induction of arthritis. The gross changes in the joint capsule, synovial membrane and articular cartilage were quite mild in ultrasound treated animals as compared to controls. Microscopically, the joint capsule showed complete sloughing of the intimal layer and the subintimal layer showed severe inflammatory reaction or even complete necrosis of the fibrous capsule and synovial membrane in untreated animals. The joint capsule of ultrasound treated animals showed an advanced healing stage of the synovial membrane though still some inflammatory reaction was present in the subintimal layer. Synovial membrane of untreated animals showed less of acid mucopolysaccharides material and more of neutral mucopolysaccharides as compared to treated animals. Calcium deposition was not detectable in the joint capsule of the treatment group. Degeneration of articular cartilage was observed microscopically in control animals as marked by fibrillation and desquamation of perichondrial tissue with necrosis of chondrocytes in different layers or even complete sloughing of the articular cartilage. Articular cartilage of ultrasound treated animals had mild changes in the superficial layer (devoid of chondrocytes) and the rest of the cartilage layers were histologically normal.
 
Article
Since exercise stress is associated with multiple changes in immune parameters, we evaluated the effect of acute exercise on 3 indices of immune function in the horse. Six unconditioned thoroughbred horses were subjected to a tread- mill-based exercise challenge. Exerci se intensity was determined by monitoring each horse's heart rate, plasma lactate, and cortisol levels. Concurrently, peripheral blood mono- nuclear cells were used to assess pokeweed mitogen (PWM) -induced blastogenesis, influenza-specific proliferation, and lymphokine activated killer (LAK) cell activity. Heart rate peaked during the gallop on an incline while lactate was highest at the end of the stress test (To) with values of 200 bpm and 9 mM/L respectively. Average plasma cortisol was great- est at TO and T+2o with values 76% higher than unstressed horses. Significantly (P<.05) lower PWM and influenza- associated proliferation of cells collected at TO and T,2o were observed. These results illustrate the complexity of changes in immune function that accompany intense exercise.
 
Article
In this clinical study, 29 acyclic mares with inactive ovaries were treated with an intravaginal device containing 1.9 g progesterone (CIDR-B) for 10 to 12 days. Mares which formed a follicle >30 mm after CIDR-B removal received a subcutaneous implant containing 1.5 mg or 2.2 mg deslorelin, a potent GnRH analog.Twelve mares were treated during the breeding season (BS), 17 during autumn and winter anestrus (AS). During fall-winter anestrus, 77 untreated patient mares served as contemporary controls. Due to the uniformity of response, data were pooled.Twenty-seven out of 29 mares responded to CIDR-B treatment with follicle growth; 22 mares were treated with deslorelin when follicles had reached 38 mm within 2.6+2.3 days after CIDR-B withdrawal and 20 mares ovulated within 2.77+1.66 days. Fifteen mares were inseminated and 10 (66.7%) became pregnant at first breeding.Half of the mares treated during AS with CIDR-B only, and not with deslorelin ovulated; in all other of those mares, the preovulatory-size follicle regressed eventually.
 
Article
Forage acceptability of five cool season annual grasses and four annual clovers to yearling horses was evaluated in Georgia during winter and spring of two years. With cafeteria grazing trials, preference in consumption was determined by difference in forage harvested from mower strips before and after grazing. In four test grazing periods,annual ryegrass was preferred (P<.05) by the yearlings, averaging 75% apparent consumption of the dry forage. Oats and wheat were second in preference, averaging 47 and 41% respectively. Rye and triticale were least preferred, averaging only 35 and 32% apparent consumption, respectively. Of the annual clovers tested, crimson, berseem, and subterranean were all highly palatable (P<.05) to horses with an average consumption of 71% across all three clover varieties. Arrowleaf clover was unacceptable (P<.05), having only 22% apparent consumption. Yearling horses avoided grazing rye, triticale, and arrowleaf clover when other forages were available.
 
Article
Eighteen pregnant mares were randomly allotted to one of two treatment groups. The control group was fed a conventional concentrate and the fat group was fed a concentrate containing 5% feed-grade rendered fat. Both concentrates had the same nutrient:calorie ratio and were fed in amounts required to maintain zero change in percent body fat of the mares. During the study, which began 60 d prior to expected foaling date and ended 60 d postpartum, mares were monitored for feed intake, body weight, rump fat thickness, ration digestibility, plasma glucose and lipid concentrations, milk composition and reproductive efficiency. Birth weight, growth rate, and plasma glucose and lipid concentrations were also measured in foals. Mares fed fat consumed less concentrate (P<.09 during the last 60 d of gestation but consumed similar amounts of concentrate over 60 d of lactation. Protein and ether extract digestion was higher (P<.05 and P<.09, respectively) in the mares fed fat during the postpartum period. Dietary treatment had no influence on plasma glucose or lipid concentrations of the mares or plasma glucose concentrations of their foals, but foals whose dams were fed fat had higher plasma lipid concentrations at birth (P<.01), d 10 and d 30 (P<.05). Percent fat was higher in milk samples from mares fed fat at d 10 (P<.09, 1.23 vs .99%) and d 60 (P<.01, .72 vs .43%) of lactation. Reproductive performance was not significantly different between treatment groups, however there was a trend for a shorter postpartum interval and fewer cycles per pregnancy in the mares fed added fat. Foals from both groups were of similar size and weight at birth and had similar weight gains over 60 d, however, foals nursing mares fed fat tended to gain more weight in the first week of life (1.85 vs 1.56 kg/d) and have more rump fat at d 60 (.53 vs .44 cm) than foals nursing control mares.
 
Article
Twenty-four yearlings were used to evaluate the efficacy of feeding feed-grade fat to growing horses. All horses were started on trial at 13-months-of-age and were fed for 112 days. The experimental diets, containing similar nutrient-to-calorie ratios, were: 1) control (no added fat; 2) 5% added fat and; 3) 10% added fat. There was a trend for yearlings fed the 10% added fat diet to grow faster and eat less feed than those on the control diet. Data from this study indicate that feed-grade fat can be safely fed to growing horses. Feeding fat to yearlings stimulated growth and efficiency of feed utilization initially, but these effects were not maintained as the yearlings grew toward maturity.
 
Article
The effects of dietary fat supplementation on exercise performance and metabolism were studied in 15 Thoroughbred racehorses. The horses ran a 1600-m race while on a control diet in which fat accounted for 2% of the digestible energy. The same horses were then switched to a fat-added diet (dietary fat contributed 12% of total Keal) for 3 weeks, followed by a second 1600-m race. After consumption of the fat-added diet, skeletal muscle glycogen stores and resting plasma glucose levels were increased by 15.8% and 25.9%, respectively whereas resting plasma non-esterified fatty acids and beta hydroxybutyric acid levels were decreased by 71.8% and 41.9%, respectively. Mean race time improved 2.5 seconds (2.1%) after consuming the fat-added diet (I)<0.05) despite a similar utilization of skeletal muscle glycogen. These results suggest that the fat-added diet improved race time independently of muscle glycogen consumption, and 2) resting metabolite levels may influence exercise performance
 
Article
Thirty, 19-week-old Quarter Horses were utilized in a 112-d study to compare growth, nutrient utilization and post prandial thyroid hormone concentrations in weanling horses fed fat-supplemented or conventional diets. Concentrates were formulated to contain the same nutrient-calorie ratios and were fed with Coastal Bermuda grass hay in a 70:30 concentrate:hay ratio. Initially and at 28-d intervals the horses were weighed and measured for height, heart girth circumfer ence and subcutaneous fat thickness over the rump and ribs. Radiographs were taken of the right carpal and metacarpal phalangealjoints at the beginning and end of the experimental period for evaluation of bone density and physeal maturation. A digestion trial was conducted on each horse 10 d prior to completion of the study. On d 70, blood samples were col lected from 6 females in each treatment group over a 6-h collection period for evaluation of postprandial insulin, T4 and T3 concentrations in response to the diets. Horses in both groups consumed an average of 2.6% of body weight daily of total feed (Dry Matter). Weanlings consuming the fat-supplemented concentrate tended to have higher (P = .10) average daily weight gains (.80 vs .74 kg) and lower (P<.05) feed:gain ratios (6.3 vs 7.3) than weanlings fed the control diet. Gain in heart girth circumference was greater (P<.05) for the fat fed weanlings (20.1 cm) than the control weanlings (17.9 cm). All other linear measurements of growth were similar between treatments. There were no radiographic indications of abnormalities in the physes of horses on either treatment. Closure of the physes occurred at normal rates in foals on both treatments. Radiographic bone density was not different between treatments, and there was an expected increase in bone density in weanlings on both treatments over time. Digestibilities of protein and energy were similar between treatments, while ether extract and neutral detergent fiber digestibilities were higher (P<.05 and P<.06, respec tively) in those horses consuming the fat-supplemented diet (65.39 vs 57.67% and40.55 vs 35.62%, respectively). These data indicate that fat can be used as an energy source to support growth and development in weanling horses.
 
Article
Plasma concentrations of ivermectin are reported in pregnant mares following their treatment with ivermectin either orally as a paste or in liquid formulation administered by nasogastric intubation. Mares given the liquid formulation had a faster time-to-peak, a higher peak plasma concentration, and more absorbed drug than mares given the oral paste formulation. There were no other observed alterations in the clinically normal condition of the animals after treatment. Based on these findings, one can conclude that the liquid formulation should be at least efficacious as the oral paste formulation.
 
Article
Thirty light-horses, two-year-olds (15 fillies, 15 colts) were evaluated for reproductive performance. The dams of these offspring had been administered either: 1) 2 ml of neobee oil per 44.5 kg body weight (controls)); or 2) 2 ml of altrenogest (2.2 mg/ml) orally per 44.5 kg body weight.. Treatments were administered daily from day 20 to 320. Interval to first ovulation with estrus and duration of estrus, diestrus and estrous cycle were similar (P>0.05) for treated and control fillies. In addition, pregnancy rate per cycle and after 3 cycles was not different (P>0.05) between groups. Age at puberty was similar (P>0.05) for treated and control stallions. In addition seminal characteristics of the last 9 ejaculates prior to castration as well as sexual behavior were not different (P>0.05) between groups. Testicular weight and size and spermatozoal production was not affected by treatment. Thus, treatment of mares with altrenogest during gestation had no affect on reproductive performance of either female or male offspring.
 
Article
Forty mares of light-horse breed were used to evaluate the effects of prostalenea upon postpartum pregnancy rate. Eighteen mares were randomly selected and treated by aseptic subcutaneous injection with 1.0 mg prostalene twice daily beginning on the day of foaling (Day 0) and continuing for 10 consecutive days (Day 10), or until the mare was first bred at foal heat (FH). Twenty-two control mares were randomly selected and injected with 1.0 ml sterile saline by the same technique as the treated group. Seventy-seven (76.9%) percent of treated mares were diagnosed pregnant to FH breeding versus 44.4% of control mares (P=0.07). Sixty-six (66.7%) percent of treated mares bred at their 30-day estrus became pregnant versus 28.6% of control mares (P=0.03). Prostalene, 1.0 mg twice daily for 10 days postpartum, resulted in an increased pregnancy rate to both FH and 30-day postpartum estrus breedings in the mare.
 
Article
On the summer solstice (June 21, 1996), six of 12 intact light horse mares randomly chosen from a larger herd were subcutaneously implanted with ALZET®a osmotic minipumps containing a melatonin solution (16 mg/ml) designed to release approximately 960 μg of melatonin/day. An additional two mares received implants containing only the saline-DMSO vehicle and four remained untreated. Blood samples were collected on days 5, 26, and 59 of treatment to monitor melatonin concentrations and to verify pump function. Prolactin concentrations were determined from blood samples collected via jugular cannulae every 12 min for 8 hours on days 25,46, and 89 after initial implantation. On day 89, samples were collected hourly for 16 hours following the initial 8-hour sampling period. Melatonin and prolactin concentrations were determined in the blood samples by radioimmunoassay. Mean circulating concentrations of melatonin in treated mares (n=6) were found to be significantly elevated when compared to controls (n=6); however, there was no significant difference in prolactin concentrations between the groups. These studies demonstrate that longterm treatment with melatonin is unaccompanied by a change in prolactin secretion.
 
Article
The efficacy of oral supplements containing sulfated glycosaminoglycans (GAGs) for the prevention/treatment of equine joint disease was evaluated in a randomized, blinded, controlled study using an adjuvant induced model of synovitis and degenerative joint disease (DJD) in horses.Twelve horses free of clinical and radiographic evidence of synovitis or DJD were stratified by age and sex and randomly assigned to two groups of six horses. After a 10-day acclimation period, synovitis was induced in the right radiocarpal joint by intra-articular injection of Frcund's Complete Adjuvant (CFA). One group of horses received a commercially available supplement containing sulfated GAGs at the dosage and treatment regimen recommended by the manufacturer. Treatment began 10 days prior tomodel induction and continued until 26 days after model induction. The second groupParameters of efficacy included lameness score, stride length, carpal circumference, maximum carpal flexion, and synovial fluid protein. These were measured prior to model induction and at 5, 12, 19, and 26 clays after model induction. Radiographs of the right carpus were taken prior to and 26 days after model induction.There was no evidence of benefit from the treatment with the sulfated GAG supplement in any parameter measured when compared to untreated controls. We conclude that commercially available orally administered sulfated GAGs at the dosage and treatment regimen recommended by the manufacturer had no anti-inflammatory or chondroprotective activity compared to untreated controls in the CFA induced equine carpitis model.
 
Top-cited authors
Oliver Ginther
  • University of Wisconsin–Madison
ed Squires
  • University of Kentucky
Lawrence Wayne Greene
  • Auburn University
Véronique Julliand
  • Institut national supérieur des sciences agronomiques, de l'alimentation et de l'environnement
Hilary Clayton
  • Sport Horse Science, LC