Multivariate analysis of morphometric characteristics to evaluate risk factors for cranial cruciate ligament deficiency in Labrador retrievers

Objectives: To determine the combination of conformation characteristics of the pelvic limbs of Labrador Retrievers that best discriminates between limb at risk to develop cranial cruciate ligament (CCL) disease and limbs at low risk using radiographs, computerized tomography (CT) images, and dual‐energy X‐ray absorptiometry (DEXA). Study Design: Cross‐sectional clinical study. Animals: Twelve clinically normal and 9 unilaterally CCL‐deficient Labrador Retrievers. Methods: The pelvic limbs of normal dogs were considered as non‐predisposed to CCL disease and the contralateral limbs of CCL‐deficient dogs as predisposed. Conformation variables, obtained from femur and tibial radiographs, pelvic limb CT images and DEXA studies, of predisposed pelvic limbs were compared with the conformation variables from pelvic limbs of the low‐risk group. An ROC curve analysis was used to assess the discriminating properties of conformation variables for several combinations. Results: We determined that a combination of tibial plateau angle (TPA) and femoral anteversion angle (FAA) measured on radiographs was optimal for discriminating predisposed and non‐predisposed limbs for CCL disease in Labrador Retrievers. Conclusions: Assessing predisposition to CCL disease with a combination of conformational measurements is better than using univariate parameters. In the future, TPA and FAA may be used to screen dogs suspected of being susceptible to CCL disease.     

Evaluation of composite resin materials for maxillomandibular fixation in cats for treatment of jaw fractures and temporomandibular joint luxations

Objective: To identify a method of composite application for maxillomandibular fixation (MMF) in cats that ensures the material will remain bonded during convalescence but be easy to remove with a low complication rate. Study Design: Experimental study Sample Population: Feline cadavers (n=88). Methods: MMF was applied using composite to 4 groups of 22 feline cadaver heads each. The protocols were: group CR: acid etch and composite resin; group CR+: acid etch, bonding agent, and composite resin; group FR50: partial surface acid etch and flowable composite resin; group FR100: complete surface acid etch and flowable composite resin. Removal time and complication rate were noted. Load to failure was determined by tensile loading. Results: Load to failure was similar for groups CR and CR+ and for groups FR50 and FR100; however, load to failure for groups FR50 and FR100 was higher than groups CR and CR+ (P<.01). Time for material removal for group FR100 was longer (P<.01) and the complication rate was higher (P<.01) compared with the groups CR, CR+, and FR50, with no significant differences in removal times and complication rate between the latter groups. The most frequent complication during material removal in group FR100 was crown fracture. Conclusions: Partial coronal surface acid etch before use of flowable composite maintained a strong bond, yet resulted in easy material removal with a low complication rate.     

The characteristics and causes of sheep losses in the Victorian Mallee

SUMMARY The extent and causes of sheep losses in the semi-arid Mallee region of north-western Victoria were assessed by interviewing the owners of 79 randomly selected farms running 241 flocks in 1987/88 and 245 flocks in 1988/89. Mean annual losses were higher in ram flocks (21%) than in ewe flocks (7%), in flocks of non-Merino sheep (rams 24%, ewes 11%, weaners 5%) than in Merino (rams 11%, ewes 6%, wethers 4%, weaners 4%) and in ewe flocks 3 or more years old (10%) than in young ewe flocks (3.5%). In flocks where losses exceeded 5%, the causes most often reported by farmers were blowfly strike (especially in Merino sheep and weaners), ewe losses in autumn close to lambing, and heliotrope (Heliotropium europaeum) poisoning. Heliotrope poisoning was considered by the authors to be the main reason for the higher losses in old ewes than in young ewes and in non-Merino sheep than in Merino sheep. Losses of ewes associated with pregnancy and lambing were considered by the authors to be often predisposed by liver damage caused by heliotrope poisoning, and high losses in non-Merino ram flocks were attributed to both heliotrope poisoning and their ability to escape through boundary fences. Reasons for continuing high losses due to enterotoxaemia are discussed. Losses due to gastro-intestinal parasites, footrot and foot abscess were low.     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.