Antagonistic pleiotropy in mice carrying a CAG repeat expansion in the range causing Huntington's disease.

Antagonist pleiotropy, where a gene exerts a beneficial effect at early stages and a deleterious effect later on in an animal's life, may explain the evolutionary persistence of devastating genetic diseases such as Huntington's disease (HD). To date, however, there is little direct experimental evidence to support this theory. Here, we studied a transgenic mouse carrying the HD mutation with a repeat of 50 CAGs (R6/2_50) that is within the pathological range of repeats causing adult-onset disease in humans. R6/2_50 mice develop characteristic HD brain aggregate pathology, with aggregates appearing predominantly in the striatum and cortex. However, they show few signs of disease in their lifetime. On the contrary, R6/2_50 mice appear to benefit from carrying the mutation. They have extended lifespans compared to wildtype (WT) mice, and male mice show enhanced fecundity. Furthermore, R6/2_50 mice outperform WT mice on the rotarod and show equal or better performance in the two choice discrimination task than WT mice. This novel mouse line provides direct experimental evidence that, although the HD mutation causes a fatal neurodegenerative disorder, there may be premorbid benefits of carrying the mutation.

Opinions of veterinarians about the age at which kittens should be neutered.

The mean age recommended by veterinary practices for neutering kittens is 22.6 weeks, with only 28 per cent of veterinarians considering it appropriate to neuter 12- to 16-week-old kittens. Multivariable logistic regression was used to identify variables associated with veterinarians' opinion that 12 to 16 weeks is an appropriate age at which to neuter kittens. Significant risk factors included time since graduation, perception of the problem of there being too many unwanted domestic cats and their practice's policy on the recommended neutering age. Veterinarians who thought that neutering eight- to 11-week-old rescue kittens before homing was justified and veterinarians who had neutered 12- to 16-week-old domestic kittens within the previous year were more likely to consider that neutering 12- to 16-week-old kittens was appropriate. Veterinarians who thought that surgical complications, anaesthetic complications and lower urinary tract disease were, or might be, more likely to occur in kittens neutered at 12 to 16 weeks than in those neutered at six months of age, were significantly less likely to think that neutering 12- to 16-week-old kittens was appropriate.

Observations on assistance dog training and use.

Trained service dogs assist and also add pride, self-reliance, and personal satisfaction to an individual's daily life. However, well-bred, trained dogs are very expensive. To explore decreasing the cost of a service dog by increasing the number of dogs successfully completing training, the authors analyzed tasks that service dogs are expected to perform, measuring some of the inherent physical stresses the dogs encounter and considering training techniques to better prepare the dogs for more successful completion of tasks. Observing working dogs, the authors found that undue stress was placed on many of the dogs while performing tasks; that motivational gestures for performance were not fully extended; and that, many times, handlers did not instruct the dogs properly. The working dogs observed often were required to perform tasks that put them at risk of injury and performance failure. Important future considerations for training and handling working dogs will include proper training of handlers and a better understanding of the complexities of the instinctive and physical capabilities and limitation of dogs.