POLYCYSTIC RENAL DISEASE IN PERSIAN CATS

Since 1967, it has been reported cases of cats suffering of a very serious genetic disease, the “ polycystic renal disease ”. This disease culminates in chronic renal failure after a variable clinical course. Persian cats are the most at risk: 50 % would be affected in the USA, 30 % in Sweden. In France, the disease is certainly misdiagnosed. Then, breeders must be informed about it, in order to evict the affected lines from reproduction.

There are 2 forms of this disease:

• the infantile form, that is fatal for kittens within 2 months. This disease is encountered in short-hair kittens.
• the adult form, which is a slowly irreversible disease, generally not diagnosed before the onset of the fist signs of chronic renal failure. This disease affects maily Persian cats or Persian crosses.

In the infantile form, the owners rapidly detect an abnormal enlarged abdomen.

In the adult form, clinical signs are nothing but specific. They are those of chronic renal failure: the cat drinks and urinates a lot, he becomes lethargic, he looses appetite and weight. Without any treatment, the evolution leads to nervous troubles (coma), and death.

Lesions

Fluid-filled cysts develop in the kidney, and grow with age. Older cats’ kidneys may contain hundreds of cysts of 1 mm to 1 cm diameter. These cysts squeeze the renal tissue and prevent it from working normally. The disease almost always affects both kidneys, which explains the fatal evolution.

In more than 60 % of cases, cysts are also found in the liver.

Diagnosis

X-rays examination does not help as long as the cysts have not reached a critical size, responsible for the observation of irregular renal contours. But ultrasonography allows to see cysts as small as 2 mm of diameter. Consequently, this method can be used to confirm the disease in a kitten from 7 weeks-old.
In cats that are likely to become reproductors, this examination should be systematically performed as a screening, before they are bred.

When the disease is diagnosed only when renal failure becomes clinically obvious, it is often too late. The kidney has got a “ reserve ”, and it is able to purify the blood normally, as long as there is still 25 % of functional tissue. So the symptoms usually appear when the cat is rather old. In most cases, the cat has already bred.

Treatment

There is no specific therapy for this disease. At the onset of clinical signs of renal failure, only classical dietetic measures can be applied to try to extend the life expectancy, such as:

• proteic and phosphorus restriction,
• fighting against acidosis,
• increase of energetic intake and potassium supply…

In this situation, the most suitable Royal Canin product is Felist ar S12.

Transmission

Polycystic renal disease is inherited dominant trait in Persian cats: it means that the responsible gene will show up when it is present at birth.

• If both the male and the queen carry the gene, 75 % of the offspring will be affected by the disease.
• If only the male or the queen carry it, about 50 % of the offspring will be affected.

Let’s point out that even if a cat has not shown the disease clinically at the reproduction period, his offspring will be affected anyway.

Conclusion

Prevention relies on a strict genetic selection: of course, an affected cat must be evicted from reproduction, but as the evolution can be long, it is necessary to go further. When there is a case within a family of cats, all the related cats must be suspected also. They should not be used for reproduction before the results of ultrasonographic examination confirm there is no special risk.

Ignoring this disease is in a favour of a larger spreading.

Donated by the Borg Cardona and Co. Ltd. visit Borg Cardona website