Dog hereditary diseases

A rare, X-linked form of progressive retinal atrophy 2 (XLPRA2) is an eye disease belonging to the group of diseases of progressive retinal atrophy, in which degeneration of the photoreceptor cells of the retina develops, leading to night blindness, visual field defects and abnormalities of the electroretinogram, which can progress to complete loss of vision. The disease develops simultaneously in both eyes. The age of onset and the rate of retinal degeneration depend on the type of disease. Some forms of PRA are common to many dog ​​breeds, while others are specific to certain breeds. Almost all PRA disorders are autosomal recessive, with the exception of dominant and X-linked PRA (XLPRA) in several breeds such as Old English Mastiffs, Bullmastiffs, Siberian Huskies, and Samoyeds. Rods - photoreceptors, which perceive the overall brightness of an object, are of greatest importance in low light and for night vision, the degeneration of which in PRA primarily leads to night blindness. According to research data, with the development of progressive retinal atrophy, about 95% of photoreceptors die. For dog owners and breeders, PRA is recognized by its "shine" or "increased shine" in the eyes. The disease can progress from an early stage of night blindness to an advanced stage in which secondary cataracts and / or complete loss of vision of the dog can develop. The disease develops to an extreme degree, usually within one year of the onset of the first symptoms. After the death of the rods, oxygen continues to flow through the blood vessels, in a normal state, necessary for the work of photoreceptors, the excess of which has toxic oxidative damage to neighboring tissues and, as a result, the death of cones - photoreceptors that perceive the brightness of individual colors. The death of retinal cells causes local toxic damage to the tissues of the eye, primarily affecting the lens, which leads to its damage and the development of cataracts. XLPRA2 is the second X-linked mutation in progressive retinal atrophy. Previously, the first form of X-linked disease, XLPRA, was described and renamed XLPRA1 to distinguish it from XLPRA2. XLPRA2 can be described as an "early onset" form of PRA. The first symptoms appear after 4 weeks of age. In contrast to XLPRA1, XLPRA2 symptoms are more severe and begin to appear during retinal development.