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How Nutrition Can Help Three Pet Health Conditions

By Roxanne Hawn

In certain medical situations, your veterinarian may recommend a temporary or permanent change to your dog or cat’s diet.

Gastrointestinal Troubles

All dogs and cats will experience brief bouts of diarrhea at some point. In addition to treating the underlying cause, your veterinarian may recommend feeding an easily digestible veterinary therapeutic diet or home-cooked chicken and rice for a few days.

“People call these diets bland, but that’s really the wrong term because bland in a human connotation is associated with not tasting good, but it’s not that they are not palatable,” says Cailin Heinze, VMD, MS, a board-certified veterinary nutritionist and assistant professor of nutrition at Tufts Cummings School of Veterinary Medicine. “It’s not that they are not spicy, because pet foods aren’t spicy. It’s just that they are highly digestible.”

Some pets, however, suffer from chronic diarrhea. In these cases, food likely plays much more of a treatment role. Finding the right diet for an individual pet, if there is one, takes detective work and trial and error. Veterinarians, often with the help of a veterinary nutritionist, use several strategies:

  1. Rule out food allergies or intolerances, using food elimination trials with novel protein diets or hydrolyzed diets. “True food allergies involving the immune system are pretty uncommon, but there are cases where we need to rule that out so that we can look at other things,” Heinze explains.

    Often what pet owners call food allergies are food intolerances. Either way, sometimes veterinarians find something about a pet’s current diet is causing the diarrhea.
  2. Experiment with dietary fat and fiber levels. In some cases, the issue isn’t specific ingredients but how much fat or fiber is in a pet’s diet. Heinze says, “Often we increase fiber, but it depends because too much fiber can cause diarrhea and not enough fiber can cause diarrhea.”
  3. Find a diet that meets a pet’s specific needs. If a clear dietary solution comes from the dietary testing process, then your veterinarian will recommend an over-the-counter diet, veterinary therapeutic diet, or home-cooked diet that doesn’t include things that cause diarrhea and does include things that make it better.

Heinze says, “Sometimes six months later, we’re coming to the realization there probably is nothing we can do with food, and it probably requires further diagnostics, medications, or what have you… There are some diseases where it absolutely does not matter what diet we feed. It will not make any difference whatsoever.”

Diarrhea caused by some forms of gastrointestinal lymphoma, as well as some cases of irritable bowel disease (IBD) in dogs and cats, don’t respond to dietary changes.

Kidney Disease

“Kidney disease is probably one of the most responsive to diet,” Heinze says. “We have well-designed clinical trials in dogs and cats that suggest diet could double lifespan in animals that have kidney disease.”

For the most common type of kidney disease, veterinarians typically recommend diets that adjust these nutrients:

  • Lower phosphorus, shown to slow the progression of kidney disease
  • Lower protein, helps slow the build up of nitrogenous compounds and often makes pets feel a whole lot better
  • Lower sodium, because high sodium could contribute to high blood pressure, which could make kidney disease worse
  • Lower calcium, typically to keep the calcium in proper ratios with lower phosphorus
  • Supplemental omega-3 fatty acids, because there is some evidence it helps protect the kidneys, though researchers don’t know why
  • Supplemental B vitamins, in theory to make up for what’s lost to more frequent urination

Heinze says, “The protein and phosphorus are pretty well worked out. Everything else is based on a little study here, a little study there. In the studies that showed almost a doubled survival, it wasn’t just one factor in the diet. It was a complete diet that had all or many of these modifications. We know they work clinically because we can see blood values improve. We see pets feel better and potentially the progression slowed down.”

AAFCO sets pet food standards for phosphorus at a minimum of 140 mg per 100 calories. Many pet foods on the market feature 250 mg phosphorous per 100 calories and some close to 500 mg.

Most pet owners don’t have the information to calculate these values. Instead, simply know that if a pet food label says the food meets AAFCO requirements, then it has too much phosphorous for dogs and cats with kidney disease.

Bladder Stones

There are four kinds of uroliths (bladder stones) seen in dogs and cats:

  1. Struvite
  2. Calcium oxalate
  3. Urate
  4. Cystine

Some stones are more common in certain breeds of dogs and cats. Currently, however, there are no tests that would tell you if one animal is more prone than others. Generally, veterinarians don’t try to prevent stones through dietary changes in pets who’ve not had stones. They are more likely to intervene with dietary changes in pets who’ve already shown to have an issue with stones.

The goals of nutritional management for any kind of stone include:

  • Decreasing urine specific gravity (a way to measure urine concentration)
  • Decreasing stone precursors in the diet (cutting back on nutrients that combine in the body to make stones)
  • Adjust urine pH when appropriate
  • Increase stone inhibitors

You cannot accomplish these nutritional adjustments through over-the-counter pet diets. Heinze says, “When you’re dealing with stones, you really need to work with your veterinarian. Each kind of stone requires different management, different diet, and you’re going to need a veterinary therapeutic diet.” 


Cailin Heinze, VMD, MS, DACVN, “Nutritional Management of Renal Disease – What to Feed and When to Start.”

Cailin Heinze, VMD, MS, DACVN, “Nutritional Management of Urolithiasis.”

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