Dog Disorders Related to Breed Standards

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The George Fleming Prize winner for 2009 has been announced, just in time for tomorrow's 150th Anniversary of the publication of Darwin's Origin of Species. The Fleming prize, which commemorates the founder of The Veterinary Journal, is awarded for the paper of the greatest merit published in the Journal during the previous year.

The winners for 2009 are Lucy Asher, Gillian Diesel, Jennifer F. Summers, Paul D. McGreevy and Lisa M. Collins of the Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London for their article entitled 'Inherited Defects in Pedigree Dogs. Part 1: Disorders Related to Breed Standards' (VJ, August 2009).

A few excerpts from the paper:

The issue of pedigree dog breeding and its consequences for welfare has recently been brought to the attention of the general public. The main sources of inherited defects are (i) deleterious inherited recessive traits expressed as a consequence of closed stud books and inbreeding practices; and (ii) dog breeders aiming to meet the breed standards for multiple aspects of physical conformation.

We carried out a review of inherited defects in the 50 most popular breeds of dog in the UK, according to Kennel Club registrations .... Every one of the 50 most popular pedigree breeds of dog in the UK were found to have at least one aspect of their physical conformation which predisposes them to a heritable defect. Conformation characteristics such as short heads, short legs, excessive facial skin folds, pendulous ears, long backs and curly tails are likely to predispose, or are genetically linked in presenting breeds, to a range of physical problems such as occipital dysplasia, malocclusion of the jaws, hip dysplasia, eye ulceration, chronic otitis, intervertebral disc disease, and spina bifida, respectively.

In many cases, there is an overlap or interaction between conformation and inherited diseases. For example, the spot colouration specified in the breed standards for Dalmatians has a genetic link with deafness. Certain defects were found to cluster by breed type – e.g. the tendency to develop patellar luxation is particularly common in the Terrier and Toy dog breeds, and the potentially fatal condition of gastric torsion is common to the working dog breeds such as Rottweiler, Dogue de Bordeaux, Doberman and Great Dane. . . .

. . . . This report has shown that every one of the 50 most popular pedigree breeds of dog in the UK were found to have at least one aspect of their physical conformation predisposing it to a heritable defect. Conformational features form a large proportion of these problems. From musculoskeletal diseases, such as hip and elbow dysplasia to brachycephalic airway obstruction syndrome, eyelid defects, excessive skin folds and predisposition to gastric dilatation-volvulus in barrel-chested breeds, these defects affect all body systems across a variety of breeds. The association of some of these conditions with official breed standards and the high maintenance implications of some breed features (such as a prolific coat or pendulous ears) makes conformational extremes an important area for consideration when discussing the problems of the purebred dog breeding industry. Also highlighted by this report are the diverse and often severe genetic conditions suffered by dogs of these 50 popular breeds. Inbreeding, population bottlenecks, the use of strictly closed stud-books and breeding towards features genetically linked to deleterious conditions (such as the link between spot size and deafness in Dalmatians) have all contributed to the current situation. . . .

Summary: There are 209 different breeds of pedigree dogs recognised by the UK Kennel Club. In this report, we focused on the top 50 most popular breeds, according to the number of KC registrations in 2007. For these breeds, we found a total of 322 inherited disorders. Of these, 84 were either directly or indirectly associated with conformation.

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