Prescription Pet Foods: Do They Really Make a Difference?

Today a pet parent asked me: "My vet recommended a prescription diet for my dog, who has problems with her kidneys. Do prescription diets really make a difference, or is it all just marketing?"

The answer is - yes, there is a difference between prescription pet foods and those sold over the counter!

Pets who don't have any issues with their health generally don't need prescription diets, of course. But prescription diets can make a huge difference to pets with a number of different health problems.

Here are some examples:

Kidney disease: Diets formulated for animals with kidney disease (generally diets that are lower in protein and phosphorous, for example) can make a real difference in the quality of life and longevity of these pets. Several studies have shown this to be the case. There are prescription kidney diets, and there are also recipes for homemade diets for animals with kidney problems. (Be sure any homemade diet you use has been developed and balanced by a veterinary nutritionist .)

Liver disease: In some types of liver disease in which animals develop a problem called "hepatic encephalopathy", special diets can be very helpful. When animals have very poor liver function or a liver "shunt" (an extra blood vessel that allows the blood to bypass the liver), certain toxic substances are not properly filtered from the bloodstream, as they would be by a normally functioning liver. These toxic substances can cause "hepatic encephalopathy", a situation where the animal acts drunk, dizzy, weak, or blind due to the effect of the substances on the brain. By reducing the buildup of these toxic substances, diets for liver disease can help alleviate hepatic encephalopathy.

Hyperlipidemia: This long word refers to a condition where the fat levels in an animal's bloodstream are too high. On a blood test, these fats are called "triglycerides". Animals whose triglyceride levels are too high can suffer problems such as seizures and inflammation of the pancreas if the triglyceride levels are not lowered. Abnormally high triglyceride levels can be caused by certain hormonal imbalances, or by improperly functioning fat-processing systems in the body.  Certain breeds of pets, such as schnauzers, are predisposed to this condition. Prescription low fat diets are often very important in this situation, to help lower the triglyceride levels and prevent or alleviate seizures or pancreatic issues.

Allergies: Animals with food allergies, which may be exhibited by gastrointestinal signs such as diarrhea, or by itchiness of the skin, can be greatly helped by prescription hypoallergenic diets. For a diet to be hypoallergenic, it must contain a protein the animal has never eaten before, and be very pure, i.e., not containing other proteins or other allergy-causing substances.

One problem that vets are encountering is that so many of these special proteins are being used in over-the-counter pet foods. Because people noticed that vets often recommend lamb-based food, for example, they thought it must be good to feed pets lamb. Because of this demand, pet food manufacturers began putting out pet food containing lamb. But the reason vets would recommend lamb for allergic pets was because it was a protein most pets in this country had not eaten before, not because there was something intrinsically healthy about lamb. Once lamb began being used in commercial pet foods, vets had to turn to more exotic sources of protein for allergic pets, such as duck, venison, and rabbit. But once again, pet foods began to be made using these proteins as well, so it is becoming ever harder for vets to find a protein source that an allergic pet has never tried! We are turning to really crazy things like ostrich and kangaroo meat. But pretty soon, these will turn up in commercial pet foods as well. (For this reason, it's a good idea to avoid feeding your healthy pet all these different exotic proteinsl if your pet ever develops a food allergy, there will be nothing hypoallergenic left to try!) 

Urinary tract stones: For pets who have developed stones in the urinary tract (the bladder, kidneys, ureters, or urethra) at some point, prescription diets can help to prevent more stones from forming. Different types of stones can require different diets. The diets that are labeled as "urinary" diets or "good for urinary tract health" in the grocery store are NOT the same as prescription diets, so do not substitute these for a diet your vet has prescribed!

The bottom line: If your vet recommends a prescription diet, there's probably a good reason.  Don't substitute another diet without talking to your vet. If the diet is too pricey for you, or your pet just doesn't like it, there may be other options, and your vet can probably help you find one. Or you may want to seek the help of a board-certified veterinary nutritionist, such as those found at PetDIETS.com and Balance IT . These specialists can work with your vet and with your pet's medical records to help recommend the best food for your pet, whether prescription or homemade.