Should we decrease the protein level in the diet of an ageing dog?

The answer to this question has been “ Yes ” for many years, whereas no clinical study had been performed on dogs to support this hypothesis. Studies were only performed on rats, but renal function does not work the same in dogs and rats. No scientific trial has ever been published that could establish a relationship between the protein level of the diet and the enhancement and the progression of canine renal failure. But by constant believing in something, prooves become unnecessary…

Study conducted by Royal Canin

Royal Canin became soon interested in this question. First trials were started as early as 1974. They were initiated by Drs PAQUIN and CLOCHE, from ROYAL CANIN Research Center. 4 groups of 4 Beagles (9 months old when the trial began), were fed with various diets differing from their proteic content: 20 up to 50 %, which represented 26 to 60 % of the energetic content.

The study kept going during the whole life of the animals. It ended up in 1987. At that time, there were only 7 surviving dogs out of the 16 initially present in the study.

This exceptionnally long term study allowed to confirm the very good adaptation of dogs towards high-protein diets. All the analyzed parameters did not permit to show any abnormality concerning the renal function, whatever the proteic intake was. Within the analysis performed along the study, no significative difference related to the diet was observed.

Renal injuries (diagnosed at the autopsy of the animals) were present in all dogs from 7 years old. They were not aggraved by high-protein diets. Maximal longevity was even observed in dogs fed the higher protein diets. Despite the fact that the groups were not large enough to be really representative, it seemed that these dogs were more able than the others to react against infectious renal diseases (induced by repetitive urinary sampling). This hypothesis has been confirmed by other authors.

Therefore, it is a false idea to pretend that high-protein diets can be harmful for the kidneys. In addition to this study conducted by Royal Canin, other ones can reinforce our observations.

Other studies

• It has been showed that the renal performance of 7-8 years old healthy dogs, with only one kidney left, does not evoluate in an different way according to the proteic level of their diet (Finco, 1994).

In the healthy dog, proteic restriction could even be harmful.

• An old study pointed out the fact that 10-12 years old dogs require more proteins than 1-2 years old dogs to restore a normal level of proteins in the body, after a period of deficiency(Wannemacher, 1966). This suggest that proteic requirements of ageing dogs could be higher.
• The survival rate of senior healthy dogs seems to be higher with high-protein diets (Finco et coll,1992).
• Protido-caloric malnutrition, even moderate, can disturb the immunitary response (Laflamme, 1997).
• In 7 – 9 years old dogs, the muscular mass is better preserved with a high protein diet (46 %) rather than with a low-protein diet (16 %) (Kealy, 1998).

Conclusion

Ageing dogs may stand for a relatively high intake of protein without any harm for their kidneys. A protein restriction becomes necessary only when the kidneys become unable to perform a correct blood filtration. At that stage, clinical signs of chronic renal deficiency become obvious: the dog drinks and urinates more, the blood and urinary parameters evoluate… When this clinical stage is reached, it usually means that 75 % of the kidney at least has been damaged. Only a minority of older dogs are concerned by this problem.

Proteic restriction does not slow down the evolution of chronic renal deficiency. It only helps to reduce the symptoms. Consequently, it is completely useless before their emerging.

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