It is a slow, silent disease, more common in older dogs: by the time the first signs appear, the kidneys have already lost much of their function. It can't be cured, but it can be slowed, and diet is the tool with the strongest evidence. Here is what to know.
In short
In chronic kidney disease the kidneys lose function little by little, over months or years. The first sign is often that the dog drinks and pees more; weight loss, poor appetite and vomiting come later. It is diagnosed with blood and urine tests. A renal diet, with less phosphorus and less but high-quality protein, is the treatment with the best evidence: in dogs with advanced disease it tripled survival compared with an ordinary food. Your vet chooses it, together with medicines and check-ups. Water at all times, and no home-made diets without a veterinary nutritionist.
It is the slow, irreversible loss of kidney function: the kidneys can no longer filter the blood properly. Waste products of metabolism, especially those that come from protein, build up and make the dog unwell.
It becomes more common with age: according to the Merck Veterinary Manual it increases from 5-6 years onwards and affects up to 10% of older dogs. In a British study of more than 100,000 dogs, median survival after diagnosis was 226 days, but with big differences depending on the stage at which the disease was found: that is why finding it early matters.
The vet classifies the disease in stages (the IRIS system, from 1 to 4) based on test results: diet and treatment depend on the stage.
The first sign is often that the dog drinks and pees more than usual. It usually appears when about two thirds of the tissue that filters the blood has already been lost. Then, in the later stages:
Because there are no signs for months or years, from 5-7 years of age it is worth doing blood and urine tests once a year: creatinine, SDMA, urine concentration and protein, and blood pressure.
A renal diet chosen by the vet: it is the treatment with the strongest evidence. In a study of dogs with advanced kidney disease, those fed a renal diet had 70% fewer uraemic crises and a median survival three times longer than dogs fed a maintenance food.
A renal diet usually has:
To give an idea, EU rules for dietetic feeds supporting kidney function set a maximum of 220 g of protein and 5 g of phosphorus per kg (at 12% moisture). When to start it is the vet's decision, based on the stage: for example, the IRIS guidelines recommend a lower-protein diet, together with medicines, when too much protein is being lost in the urine.
It happens often: the waste products that build up cause nausea. A few things help:
Eating enough matters as much as the right diet: a dog that loses weight loses muscle and strength. If it eats little for more than a few days, talk to your vet straight away.
As much as it wants: water should never be restricted. A dog with kidney disease pees a lot and needs to drink a lot to make up for it, but it doesn't always manage.
Read also how to recognise and prevent dehydration.
Only if it is formulated by a veterinary nutritionist. In an American study, 39 home-made recipes for dogs with kidney disease found in books and websites were analysed: none provided all the necessary nutrients. In more than 3 recipes out of 4, protein or at least one amino acid was below the minimum, and almost all were low in choline; selenium, zinc and calcium were often short too.
A home-made diet for a dog with diseased kidneys must be worked out for that individual dog and rechecked with blood tests: "rice and white meat" is not enough.
Mainly older dogs, and some breeds more than others.
To be clear: our recipes are not a renal diet. They contain 275 to 446 g of protein per kg (at 12% moisture), above the 220 g/kg limit that EU rules set for renal diets, and their phosphorus content is not calculated for a dog with diseased kidneys. If your dog has kidney disease, the right diet is your vet's.
For a healthy dog it is different: a high-protein diet has not been shown to cause kidney disease in healthy animals, as we explain in our guide to older dogs.
It depends a lot on the stage at which it is found and on treatment. In a British study, median survival after diagnosis was 226 days, but dogs found early and followed with a renal diet and check-ups can live much longer.
Yes, but in the amount your vet decides: a renal diet contains less, high-quality protein, not zero protein. Cutting protein too much makes the dog lose muscle.
Foods high in phosphorus and salt, and treats that are not part of the diet: bones, cheese, cold meats, leftovers. And no supplements without your vet's advice.
It can't be cured, because kidney damage doesn't reverse, but it can be slowed: a renal diet, medicines, water at all times and regular check-ups.
A wet texture helps the dog take in more water, but what matters is that it is a renal diet: lower in phosphorus and protein. Your vet chooses it.
Written by the Pappa Fresh editorial team from published veterinary studies (see sources). Not a substitute for your vet's advice.
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