Light-microscopic investigations on the retinae of dogs carrying the Merle factor

Some Practical Solutions to Welfare Problems in Dog Breeding

This paper reviews the history of the establishment of dog breeds, summarizes current health and resultant welfare problems and makes some positive suggestions for their resolution. Some breed standards and selection practices run counter to the welfare interests of dogs, to the extent that some breeds are characterized by traits that may be difficult to defend on welfare grounds. Meanwhile, little selection pressure seems to be exerted on some traits that would improve animal welfare and produce dogs better suited to modern society. Unfortunately, the incidence of certain inherited defects in some breeds is unacceptably high, while the number of registered animals of certain breeds within some countries is so low as to make it almost impossible for breeders to avoid mating close relatives. There are several constructive ways to overcome these challenges. Breed associations can ensure that reduction of welfare problems is one of their major aims; they can review breed standards; they can embrace modern technology for animal identification and pedigree checking; they can allow the introduction of ‘new ‘ genetic material into closed stud-books; and they can encourage collaboration with geneticists in identifying and using DNA markers for the control of inherited disorders. There should be a concerted effort to produce and evaluate as companion animals first-cross (F1) hybrids from matings between various pairs of breeds. Finally, geneticists must learn to communicate their science better and in a language that non-geneticists can understand.

A comparative approach to anterior segment dysgenesis

The role of animal models in our developing understanding of anterior segment dysgenesis is outlined. Research in avian models shows the importance of the neural crest in the development of the anterior segment and the failure of terms such as anterior segment cleavage adequately to describe the embryology of this area. Study of the anatomical differences between the anterior segment of the primate and that of the sub-primate mammal explains the differences seen in the dysplastic changes occurring in the iridocorneal angle in man and those occurring in sub-primate mammals such as the rabbit or the dog. Such work gives an improved understanding of congenital lesions seen ophthalmologically in man as well as those encountered in veterinary ophthalmology.