Objective—To evaluate changes in the cortical bone of the proximal phalanx of the fore-limbs of Thoroughbreds in response to training. Animals—Twenty-seven 2-year-old Thoroughbreds (20 females, 2 males, and 5 geldings). Procedures—Horses were principally in training for races in a straight line and in a clockwise direction. Lateromedial and dorsopalmar radiographic views of each metacarpophalangeal joint were obtained before the horses started training and 1 year after starting exercise and racing. Width of the dorsal, palmar, lateral, and medial cortex and the width and thickness of the medulla were measured. Ratios (rather than absolute values) were used to remove the effect of differences in bone size among horses. Results—10 horses were lost from the study. Radiographs were obtained for 17 horses 1 year after starting training (9 horses raced in a clockwise direction, and 8 raced in clockwise and counterclockwise directions). There was no difference between the cortical bone in the right and left forelimbs at the start of the study. After training for 1 year, the palmar cortex in the right forelimb was significantly thicker than that in the left forelimb. Conclusions and Clinical Relevance—The strain patterns, biomechanics of rapid exercise, and type of training most probably determined differences in the adaptive responses of the proximal phalanx. The data reported here can be used in the evaluation of weight-bearing distribution along the proximal phalanx and evaluation of the relationship between exercise and bone remodelling of the proximal phalanx.

Objective—To compare results of body condition scoring by use of a 9-point scale with body composition determined by dual-energy x-ray absorptiometry (DEXA) in indoor-confined neutered domestic shorthair (DSH) pet cats. Animals—72 indoor-confined, adult neutered DSH pet cats (38 females and 34 males). Procedures—All cats underwent a physical examination including assessment of body weight (BW), body condition score (BCS; 1 = emaciated, 5 = ideal, and 9 = grossly obese), and girth. Urinalysis, CBC, and serum biochemical analysis were also performed. After the cats were confirmed healthy, they were anesthetized for body composition measurement via DEXA. Lean body mass, fat mass, and percentage body fat (%BF) were then evaluated. Results—The correlation between %BF and BCS (r = 0.87) was superior to the correlations between %BFand BW (r = 0.74) and between %BF and girth (r = 0.78). Values for %BF differed significantly between all pairs of BCSs except BCSs 8 and 9. Within a BCS, the %BF was similar for male and female cats. The mean %BF for cats with a BCS of 5 was 32, which exceeded the upper reference limit of %BF generally considered ideal (30). Conclusions and Clinical Relevance—The 9-point BCS scale appears useful for assessing %BF in DSH pet cats. Nevertheless, study findings could indicate a need for redefining the ideal BCS for inactive neutered cats to include a BCS of 4.

Objective—To determine the mode of inheritance for cerebellar abiotrophy (CA), a neurologic disease in Arabians. Animals—804 Arabians, including 29 horses (15 males and 14 females) with CA. Procedures—Most horses (n = 755) belonged to 1 of 4 paternal families. Among the 29 CA-affected horses, all had clinical signs consistent with the disease; the disease was confirmed histologically following euthanasia in 8 horses. From the pedigree information, inbreeding coefficients were calculated for 16 affected horses and compared with coefficients for a subgroup of 16 unaffected horses. Complex segregation analysis was used to determine the effect of a putative Mendelian locus on the development of the disease and the probable mode of inheritance of CA. Results—The mean inbreeding coefficient was 0.0871 for CA-affected and unaffected horses, suggesting that all of the Arabians were inbred to the same degree and that affected horses were not more inbred than were unaffected horses. Results of the complex segregation analysis were consistent with a single Mendelian autosomal recessive mode of inheritance. Conclusions and Clinical Relevance—Knowledge of the mode of inheritance of CA should help breeders to make informed decisions regarding the selection of animals for mating when closely related horses have developed CA or produced CA-affected foals.

Objective: To determine the impact of a free-choice diet on nutritional intake and body condition of feral horses. Animals: Cadavers of 41 feral horses from 5 Australian locations. Procedures: Body condition score (BCS) was determined (scale of 1 to 9), and the stomach was removed from horses during postmortem examination. Stomach contents were analyzed for nutritional variables and macroelement and microelement concentrations. Data were compared among the locations and also compared with recommended daily intakes for horses. Results: Mean BCS varied by location; all horses were judged to be moderately thin. The BCS for males was 1 to 3 points higher than that of females. Amount of protein in the stomach contents varied from 4.3% to 14.9% and was significantly associated with BCS. Amounts of water-soluble carbohydrate and ethanol-soluble carbohydrate in stomach contents of feral horses from all 5 locations were higher than those expected for horses eating high-quality forage. Some macroelement and microelement concentrations were grossly excessive, whereas others were grossly deficient. There was no evidence of ill health among the horses. Conclusions and Clinical Relevance: Results suggested that the diet for several populations of feral horses in Australia appeared less than optimal. However, neither low BCS nor trace mineral deficiency appeared to affect survival of the horses. Additional studies on food sources in these regions, including analysis of water-soluble carbohydrate, ethanol-soluble carbohydrate, and mineral concentrations, are warranted to determine the provenance of such rich sources of nutrients. Determination of the optimal diet for horses may need revision.

Objective—To examine the changes in monocarboxylate transporter (MCT) 1 and MCT4 content and in indicators of energy metabolism in the gluteus medius muscle (GMM) of Thoroughbreds during growth. Animals—6 Thoroughbreds (3 males and 3 females). Procedures—Samples of GMM were obtained when horses were 2, 6, 12, and 24 months old. Muscle proteins were separated via SDS-PAGE; amounts of MCT1 and MCT4 and peroxisome proliferator-activated receptor-γ coactivator-1α content were determined by use of western blotting. Muscle activities of phosphofructokinase and citrate synthase were measured biochemically; lactate dehydrogenase isoenzymes were separated by agarose gel electrophoresis and quantified. Results—Compared with findings when horses were 2 months old, MCT1 protein content in GMM samples obtained when the horses were 24 months old was significantly higher; however, MCT4 protein content remained unchanged throughout the study period. Peroxisome proliferator-activated receptor-γ coactivator-1α content was significantly increased at 24 months of age and citrate synthase activity was increased at 6 and 24 months of age, compared with findings at 2 months. Phosphofructokinase activity remained unaltered during growth. The percentage contributions of lactate dehydrogenase 1 and 2 isoenzymes to the total amount of all 5 isoenzymes at 12 and 24 months of age were significantly higher than those at 2 months of age. Conclusions and Clinical Relevance—Changes in protein contents of MCTs and the lactate dehydrogenase isoenzyme profile in GMM samples suggested that lactate usage capacity increases with growth and is accompanied by an increase in the oxidative capacity in Thoroughbreds.