Comparative cost-effectiveness of ivermectin versus topical organophosphate in feedlot calves

A study was conducted in a commercial feedlot in western Canada to evaluate the impact of treatment with ivermectin versus a topical organophosphate on growth rate and feed efficiency in calves entering a feedlot at an average 275 kg liveweight.

A total of 9527 head of cattle was used. Variables measured included average daily gain, average days occupation, and feed conversion.

Ivermectin treated animals gained an average 0.08 kg per day more than those treated with topical organophosphate. In addition, they required an average 0.23 kg less feed/kg gain. Based on an average 227 kg of gain, this would result in 11 fewer days occupation and 52.3 kg less feed for ivermectin treated animals. This equaled a net benefit of $7.04 per head over treatment costs for ivermectin treatment versus topical organophosphate.

     

Lung worm (Marsupostrongylus spp.) infection in common brushtail possums (Trichosurus vulpecula)

Marsupostrongylus spp. are the metastrongyloid nematodes most commonly associated with verminous pneumonia in Australian marsupials. Currently, there is a scarcity of information regarding this parasite in the common brushtail possum (Trichosurus vulpecula). Thirty-four free-living possums submitted to two wildlife hospitals in Sydney, Australia, between 2008 and 2015 were diagnosed with verminous pneumonia on postmortem examination. The majority of possums presented ill with multiple comorbidities. However, only five cases had clinical signs of respiratory disease. Necropsy and histopathology revealed extensive lung lesions characterised by diffuse, mixed interstitial infiltrates of macrophages, lymphocytes and plasma cells with mild to marked concentrations of eosinophils. Bronchopneumonia, pulmonary oedema, interstitial fibrosis, atelectasis and type II pneumocyte hyperplasia were also present in most cases. Adult nematodes, first-stage larvae and embryonating eggs were present in the large airways and alveolar spaces. The parasites were definitively identified as Marsupostrongylus spp. in eight cases with presumptive diagnoses based on histopathological characteristics reached in a further 26 cases. Twenty-nine of the 34 affected possums were adults with no sex predisposition. A review of the brushtail possum records at Taronga Wildlife Hospital from 1999 to 2015 revealed no lungworm infections were reported in the 45 possums examined before 2008. However, between 2008 and 2015, 30 of 47 possums (63.8%) examined were diagnosed with metastrongyloid lungworms. This case series is the first detailed report of Marsupostrongylus nematodes in common brushtail possums and highlights the clinical and pathological features, along with epidemiological findings.     

Imputation of missing SNP genotypes using low density panels

A population-based imputation procedure was used to predict the most likely genotype of un-typed loci on low density SNP maker panels to improve data integrity before genetic association and selection studies when pedigree information is not available such as in feedlot applications. It is of practical importance to evaluate the accuracy effects of imputed genotypes. In our report, a population consisting of 2246 Angus bulls that were genotyped using both Illumina Bovine3k and Bovin50 BeadChip was used. Several scenarios with varying percentages of missing SNP genotypes under a random missing pattern were simulated. Additionally, several scenarios with varying percentages of animals genotyped using the 3 k and 50 k panels assuming a structured missing pattern were considered. With the random missing scenarios, SNP genotypes on the Bovine50 panel were masked at random until reaching the desired missing percentage. With the structured missing scenarios, all SNP genotypes in the Bovine50 chip were masked, with the exception of those corresponding to the Bovine3 panel. The missing rates considered in this study ranged from 70% to 94% across chromosomes. Population-based imputation software fastPHASE1.2 was used for the separate analysis of each of the 30 pairs of chromosomes in the bovine genome. The results of the imputation of the random-missing SNP genotypes were similar to previous reports and accuracy rates, defined as the percentage of correct prediction of the true missing genotypes, ranging from 68% to 97% were influenced primarily by the proportion of missing genotypes. Moreover, imputation performance using structured-missing-pattern panels was impacted by the amount of individuals in reference population and level of linkage disequilibrium (LD) on each chromosome. In order to further elucidate the potential effect of incorrect imputation on genomic selection, wrongly imputed genotypes were grouped into two groups as a function of the number of incorrectly imputed alleles.     

Chloramphenicol 1. Hazards of use and the current regulatory environment

Chloramphenicol is a broad-spectrum antibiotic which has enjoyed extensive use in both medical and veterinary practice. Shortly after its introduction in the late 1940s, the use of chloramphenicol was associated with the induction of an idiosyncratic form of aplastic anaemia in man. This rare and unpredictable adverse effect has since been associated not only with systemic use but with topical applications, as well as occupational exposure. Recognition of the small risk of a potentially fatal adverse reaction, together with the risk of selection of chloramphenicol-resistant pathogens, has led to restrictions on the veterinary uses of chloramphenicol. In Australia at present, the use of chloramphenicol is only permitted in small animals. Its use is specifically prohibited in food-producing animals, including horses.     

Hyperadrenocorticism in three teddy bear hamsters

Hyperadrenocorticism was diagnosed in three related teddy bear hamsters with presenting complaints of alopecia and hyperpigmentation of the skin. Treatment was attempted in two of the hamsters and was successful in one case. Metyrapone and o,p′-DDD (1,1-dichloro-2-2bis (p-chlorophenyl) ethane) were the drugs used. Necropsy and histopathological examinations revealed a pituitary chromophobe adenoma in one hamster and an adrenocortical adenocarcinoma in a second hamster. The third related hamster was clinically diagnosed as having hyperadrenocorticism but the origin of the disease has not yet been determined.