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Latero-Oblique Radiography as a Diagnostic Tool for Equine Cervical Osteoarthritis
Abstract
Equine cervical osteoarthritis is a common disease known to contribute to both neck pain and cervical vertebral compressive myelopathy. There are no published studies demonstrating the usefulness of latero-oblique radiography as a diagnostic tool for cervical osteoarthritis. To determine the sensitivity, specificity and positive and negative predictive values of latero-oblique radiography as a diagnostic tool for cervical articular process joint osteoarthritis. Prospective cadaver study. Latero-oblique radiographs and CT images were collected, and post mortem examinations performed, on 27 cadaver necks from Thoroughbred-type horses of various ages and sexes. Two equine clinicians independently reviewed each set of images for the presence of osteoarthritis. The authors, under the guidance of a veterinary pathologist, reviewed all articular process joints for bony changes indicative of osteoarthritis. The prevalence of osteoarthritis identified on CT images was 57.9% (Assessor A) and 23% (Assessor B). The prevalence of lesions identified on post mortem examination was 25.6%. Latero-oblique radiography showed a low sensitivity for identifying osteoarthritis when compared to both CT imaging (6.3–16.1%) and post mortem examination (2.2–4.4%). However, it showed a high specificity when compared to both CT imaging (92.1–97.8%) and post mortem examination (87.2–95.0%). The positive predictive value for identifying osteoarthritis was moderate (40.9–80.0%) when compared to CT imaging and poor (4.2–18.2%) when compared to post mortem examination. The negative predictive value was moderate when compared to both CT imaging (42.9–76.3%) and post mortem examination (78.0–79.8%). Latero-oblique radiography has low sensitivity, but high specificity for the detection of cervical osteoarthritis when compared to both CT imaging and post mortem examination. Further investigation comparing the sensitivity, specificity and positive and negative predictive values of latero-oblique radiography vs. laterolateral radiography would determine whether taking latero-oblique radiographs, which can be more difficult to obtain and interpret, is necessary for the diagnosis of cervical osteoarthritis in practice. Ethical animal research: Ethical committee oversight not currently required by this congress: The study was performed on material obtained from an abattoir. Sources of funding: None. Competing interests: None.
... In addition to SCC, DJD to the APJs might result in narrowing or obliteration of the intervertebral foramina and compression of the cervical spinal nerve roots where they exit the vertebral column, causing neck pain, stiffness, and forelimb lameness.4,18 While oblique radiographic views arguably provide more accurate radiographic evaluation of the APJs than latero-lateral views, when compared with CT imaging, the sensitivity for identification of DJD is low, although the specificity is relatively high.19 Regardless, further evaluation of the cervical vertebral column can be advantageous in horses presenting for neurological dys-function that includes ataxia or deficits in proprioception, abnormal head carriage or position, focal muscle wastage, lameness that cannot be localized with diagnostic anesthesia to the pelvic or thoracic limbs and abnormal or occasionally sudden exaggerated behavioral responses, in particular in response to flexion or extension of the neck. ...
Background
Three‐dimensional computed tomographic (CT) evaluation of the cervical vertebral column enables more accurate identification of osseous and soft tissue lesions than traditional latero‐lateral radiography. However, examination of the complete cervical vertebral column has been limited by horse size, preventing evaluation of the caudal cervical vertebrae.
Objectives
To describe a technique to enable CT myelography of the complete cervical spine and describe the findings in 51 horses.
Animals
Records of 51 horses presented for evaluation of cervical vertebral lesions.
Methods
A retrospective review of clinical records from all horses presented for CT myelography to further investigate possible cervical vertebral lesions was performed. A description of a novel approach to CT myelography in horses and retrospective review of the findings in clinical cases has been included.
Results
Degenerative joint disease was identified at 1 or more dorsal articular process joint in 50/51 horses, of which 44/51 had a site of grade 2 or greater. Spinal cord compression was observed on CT myelography in 31/51 horses, whereas attenuation of the dorsal contrast column was identified radiographically in 11/50 horses. Thirty‐three horses showed narrowing or obliteration of the intervertebral foramina at 1 or more site and osteochondral fragments were seen in 11/51 horses.
Conclusions and Clinical Importance
Computed tomography myelography is relatively safe and an easily performed technique with the correct equipment, enabling evaluation of the cervical vertebral structures of horses in all planes and volumetrically. It is possible that lesion extent might be underestimated with this diagnostic modality, hence interpretation should be complimented with flexed and extended views radiographically.
This Chapter discusses the indications for radiography of the cervical spine of the horse, radiographic technique and the radiographic diagnosis of condition affecting the cervical spine. These conditions include cervical stenotic myelopathy, osteochondrosis, degenerative joint disease and fracture. Both subjective and objective evaluation of radiographs taken from horses is explained.
Objective:
To test the hypothesis that application of a rope restraint device would result in behavioral, electroencephalographic, and humoral changes consistent with sleep and analgesia in neonatal foals.
Animals:
8 healthy neonatal foals.
Procedures:
Following acclimatization to experimental conditions, each foal underwent a series of assessments before and during or at the end of a period of restraint via application of a restraint device (soft linen rope). Assessments included measurements of heart and respiratory rates, rectal temperature, and circulating β-endorphin and steroid hormone concentrations and evaluations of mentation and body position (behavior), electroencephalographic patterns, and pain tolerance.
Results:
All foals were lively with apparently normal behavior prior to restraint. During application of the restraint device, foals assumed lateral recumbency with relaxed, somnolent behavior. Heart and respiratory rates and rectal temperature uniformly decreased as a result of the procedure. Electroencephalographic recordings (completed for 3 foals only) revealed patterns consistent with slow wave sleep. Plasma ACTH, dehydroepiandrosterone sulfate, and androstenedione concentrations significantly increased during restraint, compared with prerestraint values. The foals' tolerance to noxious stimuli significantly increased during restraint; however, this was independent of the concentration of circulating β-endorphin.
Conclusions and clinical relevance:
In neonatal foals, the evaluated form of restraint resulted in a decrease in heart and respiratory rates and rectal temperature. Squeeze-induced somnolence may resemble the effects of compression of the fetus in the birth canal and lead to inhibition of voluntary activity. Use of this technique to safely restrain neonatal foals during minor procedures warrants further evaluation.
Few studies have examined the effect of dietary restriction in horses with equine metabolic syndrome (EMS). This study aimed to determine improvements in insulin sensitivity following dietary restriction for 6weeks, and to determine if the improvement would be greater in horses receiving short-chain fructo-oligosaccharides (sc-FOS). Dietary management involved feeding grass hay, restricted to 1.25% of body mass (BM) as daily dry matter intake and soaked in cold water prior to feeding, with the addition of a vitamin and mineral nutraceutical supplement with or without the addition of sc-FOS (10g/100kg). Soaking the hay resulted in a significant reduction in non-structural carbohydrates (38%, P=0.01), digestible energy (6.78%, P=0.01) and water soluble minerals. Following 6weeks of dietary restriction with soaked grass hay and nutraceutical supplement, horses lost an average of 6.8% BM and showed reductions in body condition score (BCS) and belly circumference. Sensitivity to insulin improved overall, as determined by the total insulin response during the combined glucose insulin test. The magnitude of improvement in insulin sensitivity was associated with the degree of insulin resistance recorded at outset, and the extent of overall losses in BM and BCS, but was independent of the addition of sc-FOS. The nutraceutical supplement was highly palatable and no adverse effects were noted. From the findings of this study a strict dietary program in combination with a specifically designed vitamin and mineral nutraceutical supplement can be recommended to obtain rapid improvements in BM, BCS and insulin sensitivity of animals presenting with EMS.
Evidence-based, weight loss management advice is required to address equine obesity. Changes in body mass (BM), body condition score (BCS), heart (HG) and belly circumference (BG), direct (ultrasonographic) and indirect (D(2)O dilution, bioelectrical impedance analysis [BIA]) measures of body fat as well as indices of insulin resistance (IR) were monitored in 12 overweight (BCS⩾7/9) horses and ponies of mixed breed and gender for 16weeks. Animals were randomly assigned to two groups (Group 1, n=6, BCS 7.6/9±0.6, 489±184.6kg; Group 2, n=6, BCS 8.1/9±0.6, 479±191.5kg). Daily dry matter intake (DMI) was restricted to 1.25% BM as one of two, near-isocaloric (DE ∼0.115MJ/kgBM/day), forage-based diets (Group 1, 0.8% BM chaff-based feed: 0.45% BM hay; Group 2, 1.15% BM hay: 0.1% BM nutrient-balancer). Statistical modelling revealed considerable between-animal heterogeneity in proportional weight losses (0.16-0.55% of Week 1 BM weekly). The magnitude of weight loss resistance (WLR) or sensitivity to dietary restriction was independent of diet or any measured outset variable and was largely (65%) attributed to animal identity. Predicted rates of weight loss decreased over time. BCS and BIA were poor estimates of D(2)O-derived body fat%. Reciprocal changes in depths of retroperitoneal and subcutaneous adipose tissues were evident. Changes in BG were associated with losses in retroperitoneal fat and BM (r(2), 0.67 and 0.79). Indices of IR improved for 9/12 animals by Week 16. For obese animals, weight loss should be initiated by restricting forage DMI to 1.25% BM. Subsequent restriction to 1% BM may be warranted for WLR animals.
Cervical spinal cord dysfunction is a common problem in equine medicine and the currently available tests give no objective information about the functionality of the nervous tracts. Therefore, transcranial magnetic stimulation (TMS) was performed in 84 healthy horses of different height in order to have an objective measure for the integrity of the descending motor tracts in normal horses.
To obtain reference values for onset latency and peak-to-peak amplitude of magnetic motor evoked potentials (MMEPs) and to evaluate the possible effect of height, age and gender on the neurophysiological measures.
All horses were sedated and stimulated transcranially by using a magnetic coil placed on the forehead. The stimulator triggered the sweep of an electromyogram machine that recorded MMEPs bilaterally from needle electrodes in the extensor carpi radialis and cranial tibial muscles. In that way, it was possible to measure latency between stimulus and onset of response.
A significant difference was found between recordings made in the fore- and hindlimbs; MMEPs recorded in the front legs had a shorter onset latency and higher peak-to-peak amplitude. Mean +/- s.d. normal values for onset latency of 19.32 +/- 2.50 and 30.54 +/- 5.28 msecs and peak-to-peak amplitude values of 9.54 +/- 3.73 and 6.62 +/- 3.62 mV were obtained for extensor carpi radialis and cranial tibial muscles, respectively. The left-to-right difference in onset latency and peak-to-peak amplitude was not significant. In the same horse, differences up to 0.82 and 1.53 msecs for the extensor carpi radialis and cranial tibial muscles, respectively, lie within the 95% confidence limit and are considered normal. In contrast to onset latency, peak-to-peak amplitude showed a very large intra- and interindividual variability, even in the same muscle. To reduce the variability and predict normal values of new individual cases, influence of height, weight, age and sex on the MMEPs were determined. No significant effects of sex were observed on onset latency and peak-to-peak amplitude. The age of the horse had only a small but significant effect on peak-to-peak amplitude, with larger responses in older horses. Height at the withers and weight of the horse, parameters that strongly correlate with the size of the horse, had an important significant influence on onset latency but not on peak-to-peak amplitude. The age of the horse and height at the withers were used to predict peak-to-peak amplitude and onset latency, respectively, in normal horses.
TMS is an excellent addition to the few tools we have for noninvasive imaging of the equine nervous system. Magnetically evoked potentials are highly reproducible and recent advances suggest that the applications of TMS in horses will continue to grow rapidly.
Constriction of the digital flexor tendon sheath (DFTS) and its contents by the palmar/plantar annular ligament (PAL) is well recognised. However, primary injury of the PAL has not been well documented.
To describe the clinical features of PAL injury, determine its prevalence with or without subcutaneous fibrosis and/or concurrent injury within the DFTS, and assess response to treatment.
Horses were selected for inclusion based upon clinical features consistent with PAL injury and the presence of a thickened PAL (> or =2 mm) verified ultrasonographically. A retrospective analysis of case records from 3 clinics was performed. Details of breed, age and use, and results of clinical and ultrasonographic assessments and response to treatment were recorded. Horses were treated conservatively or surgically by desmotomy of the PAL, with or without tenoscopic evaluation of the DFTS. A telephone questionnaire was performed to assess response to treatment.
Seventy-one horses were included in the study and middle aged or older general purpose riding horses predominated. PAL desmopathy occurred more frequently in hind- than in forelimbs. The method of treatment, thickness of the PAL or presence of subcutaneous fibrosis did not significantly affect prognosis; however, <50% of horses were able to return to athletic function. There was a trend for horses with PAL desmopathy alone to have the best outcome. Bilateral thickening of the PAL or concurrent fore- and hindlimb injuries had a negative effect on prognosis, as did the simultaneous presence of subcutaneous fibrosis and lesions within the DFTS.
PAL injury is characterised by a convex contour of the palmar/plantar aspect of the fetlock, associated with thickening of the ligament with or without subcutaneous fibrosis. Bilateral PAL thickening is common in older horses, ponies and cobs; however, bilateral PAL enlargement is often present with only unilateral lameness. Treatment methods used in this study did not appear to influence outcome significantly.
University of Liverpool, UK. Email: c.m.argo@liverpool.ac.uk Reasons for performing study: Soaked grass hays are recommended for the nutritional-management of equine metabolic syndrome
- Matters Mcg
- C Argo
- A H A Dugdale
- C M Mcgowan
MATTERS! McG. Argo, C., Dugdale, A.H.A. and McGowan, C.M. University of Liverpool, UK. Email: c.m.argo@liverpool.ac.uk Reasons for performing study: Soaked grass hays are recommended for the nutritional-management of equine metabolic syndrome (EMS).