PRA FOUND IN RUSSIAN BLUES IN FINLAND

Progressive Retinal Atrophy (PRA) is a disease of the retina, which is found among some cat and several dog breeds. Today, also four Russian Blues in Finland have been diagnosed with the disease. In addition, there are two uncertain cases of retina degeneration.

The PRA leads to the affected animal’s total blindness. The first symptom is night blindness typically at the age of 2-3 years. To the owner, PRA-affected animal may seem clumsy and avoid moving in an environment it is not used to. However, you need a vet specialised in eye diseases to diagnose the PRA.

A PRA-affected cat can live a normal life in familiar surroundings, if you keep food and water bowls and the cat toilet in places that are easy to access and do not move furniture needlessly. Luckily, other senses will in time compensate for the loss of eyesight.

The PRA found in Russian Blues is most probably caused by one recessive gene, which the affected cat has inherited from both of its parents. Cat found healthy in an eye examination may still carry PRA, that is, it carries one sick gene. Ophthalmoscopic eye examination reveals whether a cat is PRA-affected and/or has another type of eye illness, but it does not reveal possible carriers. Carries can only be ruled out using a DNA test which we unfortunately lack at the moment.

The good news is that the breed council of the Russian Blue Association of Finland is co-operating with researchers in the U.S. to locate the Russian Blue PRA gene and thus to get a DNA test for Russian Blues. The researchers have already ruled out that the PRA would be caused by taurine defiency (known to cause similar symptoms in retina as PRA). Also, they have found out that the PRA cases among Russian Blues do not result from the rdAc mutation as in the Aby and Somali breeds. This means that we are dealing with an entirely new mutation that requires a new DNA test.

HAPPENED SO FAR

The Russian Blue Association of Finland organised an ophthalmoscopic examination event on 7 February 2009. A total of 26 Russian Blues participated in the examination.

The results of the event are encouraging. In addition to one known case of hereditary cataract (HC) and four sure and one uncertain PRA case, only one possible case of PRA was found in an older cat. The results for a clear majority of the cats examined were normal. The examinations were carried out by Sari Jalomäki, a DVM and a specialist in small animal diseases. Jalomäki was happy with the results. According to her, the situation would have been really concerning if more cases of sick cats would have been found. As we are dealing with recessive disease in which sick genes may pass on for many generations until affected individuals are born, the results were as expected. According to Jalomäki, more cats in the pedigrees of affected cats should be examined. Also, she supported the idea of organising more eye examination events in the future.

A majority of the cats examined were found with normal changes in the eyes: small white dots that are harmless. Six cats were diagnosed with the mildest form of multifocal retinal dysplasia (mrd) in one eye. Although a single retinal fold should not be dangerous, Jalomäki pointed out that two cats with mrd should not be put together.

A blood sample was collected from most of cats attending the event. These samples are used for the development of the DNA test for the PRA. The researchers now have enough blood of PRA-healthy cats for developing a DNA test but blood samples of PRA-affected cats are still required. No need to say that these samples are highly important for delivering a functional DNA test in the future.

In addition to the recently organised first eye examination event, the breed council of the Russian Blue Association of Finland has agreed to organise another 2-3 events in different locations in Finland and follow up their results closely.

SUGGESTION TO DECREASE PRA IN RUSSIAN BLUES

Until a DNA test for PRA is available for the Russian Blue breed, it is strongly advised to test all breeding cats over 1.5 years of age using an ophthalmoscopic examination. If the cat is diagnosed with PRA, it should not be used for breeding under any circumstances. If the cat is under 1.5 years of age, its parents should be eye examined instead. The eye examination is the only way to find cats with eye diseases such as PRA and HC. With young cats, it is advisable to re-examine the eyes from time to time.

We would like to request all Russian Blue owners, breeders and breed associations in the Nordic countries and elsewhere to inform us of any old or new cases of PRA, HC and other eye diseases found or known in Russian Blues. In addition, the researchers welcome blood samples of all affected cats. This is a common cause for all interested in the health of our breed!

Russian Blue Association of Finland
Breed Council

Translated by: Katja Kurisjärvi

For more information, contact the breed council rus.jalostustoimikunta@gmail.com or Marianna Ripatti, the President of the Russian Blue Association of Finland.