Comparison of subjective scoring systems used to evaluate equine laminitis.

This study compared three subjective scoring systems used to assess lameness associated with equine laminitis: (1) visual analogue scale, (2) Obel score and (3) clinical grading system (CGS). Two groups of 12 observers, consisting of equine veterinarians and final-year veterinary students, scored lameness severity after watching video footage of 14 horses on two occasions. Generalizability theory was used to investigate the reliability of the three systems and the effects of observer experience. Overall reliability across all times and observers was high. Intra-observer reliability was higher than inter-observer reliability for all scoring systems, with student reliability being consistently lower than veterinarians, especially for Obel and CGS. All three methods were reasonably reliable tools for assessing lameness, but they were more limited in the hands of inexperienced observers.

Quantitative assessment of increased sensitivity of chronic laminitic horses to hoof tester evoked pain.

REASONS FOR PERFORMING STUDY: To evaluate quantitative sensory testing (QST) of the feet of laminitic horses using a power-assisted hoof tester. HYPOTHESIS: Hoof Compression Thresholds (HCTs) can be measured reliably and are consistently lower in horses with chronic laminitis than in normal horses. METHODS: HCTs of chronic laminitic (n=7) and normal horses (n=7) were repeatedly measured using a hydraulically powered and feedback controlled hoof tester. Data from 2 tests, at 3 sites in both forefeet, during 3 sessions were collected and statistically analysed using linear mixed models. RESULTS: The mean±s.e. HCT for the laminitic horses was 29.6±3.5 kg/cm2 and for horses in the normal group was 59.8±4.3 kg/cm2. Residual variance was the largest of the error components and was greater (P<0.001) for the normal horses; none of the other components significantly differed between the 2 groups. Averaging of HCTs from each foot could produce a test with intraclass correlation coefficients of 0.83 for the normal group and 0.87 for the laminitic group, with an estimated sensitivity of 0.94 and a specificity of 0.93. This test would permit detection with 80% power and 95% confidence of a reduction of over 40% in the difference in mean HCTs between laminitic and normal horses following effective treatment provided that the experimental groups are of 9 or more horses. CONCLUSIONS: HCTs can be safely and reliably measured experimentally using this hoof tester. The level of variability found indicates that, under these conditions, treatments may need to produce at least a 40% improvement to be detected. Simplification of the hoof tester, training of the horse and repeated testing may permit the method to be used clinically to detect changes in the HCTs of individual laminitic horses but these potential improvements will require further investigation. POTENTIAL RELEVANCE: Measurement of HCTs can provide an additional means for assessing the effectiveness of treatments for alleviation of chronic equine laminitis.

Cold comfort pharm.

Cooling of the skin has long been thought to be beneficial in pain states but intense cold is clearly noxious. Does cooling lead to pain or gain? Rapid progress in this controversy has been made since the discovery of specific ion channels of the transient receptor potential (TRP) family that are activated by cooling of sensory nerve cells to below body temperature. This review focuses on the role of one of these, TRPM8, which has been implicated in cool sensation and cold pain by recent knockout mouse studies, but remarkably also appears capable of eliciting a novel analgesic gating control over noxious inputs in chronic pain states. We discuss hypothetical mechanisms that could bring about this composite profile. It is clear that new and highly selective agents will need to be developed to further evaluate the potential therapeutic opportunities offered by low temperature sensitive TRP channels.