Dog hereditary diseases

Description
Progressive Retinal Atrophy (PRA) is the general name for a group of diseases of the retina that cause damage to photoreceptor cells (rods and cones) until their death. The rods are the first to degenerate, leading to loss of twilight vision; later degeneration of the cones leads to loss of daytime vision. Form XLPRA1 (X-Linked PRA) is described for husky and samoyed dogs. It is a late-onset recessive form of PRA.

The main difference between this form of PRA from others is the linkage of the disease with the sex X chromosome. Bitches homozygous for the mutation (both X chromosomes are mutated: XmXm) will show all signs of the disease. In heterozygous bitches (XnXm), partial selective atrophy of rods and cones is observed, which depends on the inactivation of the X chromosome - only one X chromosome functions in each cell, the second is inactivated and does not affect the functioning of the cell. These bitches have almost normal vision but are carriers of XLPRA1. For males, the manifestation of XLPRA1 is caused by the presence of one mutant allele (XmY) - in all cells, a single X chromosome is functional. Due to the above-described features of inheritance of the disease, husky and Samoyed males suffer from XLPRA1 much more often than females. At the end of 2009, the ZOOGEN Center for Veterinary Genetics developed a test for detecting XLPRA1 disease at the molecular genetic level. The analysis allows you to determine the genotype of the dog and, accordingly, know whether it is worth fearing the development of progressive retinal atrophy in her and her offspring. This information is of great importance for breeders and owners of dogs and is necessary for competent selection of a pair, which makes it possible to prevent the birth of sick animals. Like any other DNA test, XLPRA1 genetic analysis can be performed from the first days after birth, the results are lifetime.

Symptoms
The first clinical signs of the disease appear, as a rule, at the age of three to five years. A characteristic symptom of the disease is constantly dilated pupils for maximum light capture, the so-called "tunnel vision" develops.

Diagnostics
Characteristic changes in the behavior and physiology of the dog.