Canine genetics: a very special issue

Hybrid vigour in dogs?

Evidence from other species justifies the hypotheses that useful hybrid vigour occurs in dogs and that it can be exploited for improved health, welfare and fitness for purpose. Unfortunately, most of the relevant published canine studies do not provide estimates of actual hybrid vigour because of inadequate specification of the parentage of mixed-bred dogs. To our knowledge, only three published studies have shed any light on actual hybrid vigour in dogs. There are two reports of actual hybrid vigour between Labrador and Golden retrievers, the first ranging from +2.5% to -6.0% for components of a standardised applied-stimulus behavioural test, and the second being at least +12.4% for chance of graduating as a guide dog. The third study provides a minimum estimate of negative actual hybrid vigour: crossbreds between Labrador retrievers and poodles had a higher prevalence of multifocal retinal dysplasia than the average prevalence in their purebred parent breeds. The lack of estimates of actual hybrid vigour can be overcome by including the exact nature of the cross (e.g. F1, F2 or backcross) and their purebred parental breeds in the specification of mixed-bred dogs. Even if only F1 crossbreds can be categorised, this change would enable researchers to conduct substantial investigations to determine whether hybrid vigour has any utility for dog breeding.

Maximising canine welfare in veterinary practice and research: a review

This article looks at the existing evidence-base by which veterinary surgeons can make welfare-focused treatment choices. Narrative and structured reviews were conducted. Papers were categorised under headings based on (1) themes in the UK Animal Welfare Act (AWA 2006) - behaviour, environment, nutrition, company and health; (2) iatrogenic harm induced by treatment; (3) decision-making methods, and (4) the subjects' context (e.g. home versus laboratory). There is more information available about 'overt' problems (e.g. acute disease), than 'covert' issues (e.g. chronic pain, lack of company and obesity). Forty of 109 papers covered pain, suffering, injury and disease, compared to 69 across four other themes in the AWA. Twelve papers were identified as focusing on welfare assessment and clinical decision-making. Veterinary surgeons should consider each of the five welfare themes described in the AWA in both veterinary practice and in determining veterinary research priorities.