FELINE UROLOGIC SYNDROME

Synonyms

FUS, LUTD (Lower Urinay Tract Disease), urinary calculus or "stones", urolithiasis.

Is it true that dryfood promotes the apparition of urinary calculus in cats ?

The idea that dryfood is responsible for the emergence of this disease in cats is still very widespread among cat owners, and even veterinarians. However, this fact has been clearly proved wrong : urolithiasis can be dietetically managed with dryfood as well as with canned food.

Symptoms

The feline urologic syndrome is characterized by frequent and painful urination, blood in the urine (hematuria), or urethral blockade. This last stage is a veterinary emergency : survival expectation is very low if the animal is not treated within 48 hours.

Causes

Most often, symptoms are due to the precipitation of struvite crystals (ammonium phosphate of magnesium) in the urinary tract. However, the generalization of acydifying diets seems to have resulted in a substantial decrease in the numer of FUS cases seen by practitionners. It also unmasked the other causes that have to be screeneed : other kinds of uroliths, (i.e :calcium oxalate crystals), urinary infection, tumor, neurogenic inflammation...

Diagnosis

Clinical diagnosis is based on the observation of the symptoms uplisted ; it can be confirmed by the finding of crystals during the surgical treatment. To be sure that the dietetic recommandations will be adapted to the situation, it is highly recommended to have the uroliths analyzed by a specialized laboratory.

Dietetic treatment of a struvite-associated LUTD

When struvite crystals are responsible for the urolithiasis, it is necessary to slow down their formation and precipitation. Traditionnally, it has been said that phosphorus (_ phosphates), proteins (_ammonia) and magnesium restriction were the key-points for the dietetic rules. But cat is a carnivorous, and he cannot get used to a low animal-protein diet : animal proteic sources are naturally rich in phosphorus. About the magnesium restriction itself, it is efficient and necessary only in case of alcaline urine.

The best and safest way to fight against a struvite-associated LUTD consists in acidifying urine, so as the acid pH is in favor of the dissolution, and prevents the crystals formation. The optimal pH must be between 6,0 and 6,5. Urinary pH can be controlled by the diet : the choice of the ingredients decides of the final urinary pH.

Essential principles for urinary acidification :
• avoid using mineral salts that alcalinize urine, i.e: carbonate of calcium (Ca CO3),
• privilege animal proteins towards vegetable proteins,
• add a well-tolerated acid:ex : phosphoric acid,
• add methionine: this sulfurated amino-acid discharges sulfur under sulfuric acid form.

Everyday, ROYAL CANIN checks the efficiency of these principles : in cattery of the Research Center, urinary pH is systematically measured in routine .

Using limits of acidifying diets

- Acidifying diets are not recommanded for kittens and pregnant queens. Acidification enhances the mobilization of calcium phosphate from the bones, which is not in favour of the good mineralization of the skeleton. Consequently, K 34 has to be advised to kittens and queens from the beginning of the gestation.

Parallelly to the generalization of acidifying diets, more cases of calcium oxalate-associated LUTD have been reported. The pathophysiology of this kind of urolithiasis remains not clearly understood, but one knows that it is promoted by an excessive acidification. ; it is mostly observed in older cats, and Persians would be predisposed. For cats who have already suffered from calcium oxalate-associated LUTD, there is still no specific diet ; waiting for the results of further studies, we can advise K 34.

Conclusion

Urinary acidification is beneficial for the majority of adult cats.
However, we must remember that struvite crystals are not responsible for all cases of Low Urinary Tract Disease: in 50 % of cases with LUTD clinical signs but where it is impossible to find out what the origin is : no urolith or other cause can be found.

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