The Latest Dog Food Scare

Since horse lovers are almost universally dog lovers as well, I want to veer a little bit off path for this blog and discuss a dog food scare that is currently spreading like wild fire.

On July 12, the FDA announced they were investigating a possible link between diets containing potatoes or legumes (soy, peas, lentils, etc.) and dilated cardiomyopathy in dogs. It was one of the most confusing and least informative bulletins ever written.

As the word spread, the description of the diets quickly morphed, and focus was put on diets that were "grain-free", "exotic" and "boutique" (meaning not a major name brand).  Owners were advised to feed diets from companies with a long track record using more "typical" ingredients (which in most cases means corn/corn products as a major ingredient).

Dilated cardiomyopathy (DCM) is one of the most common types of heart disease in small animals. It can be caused by a deficiency of the amino acid taurine which is only found in meat protein. Cats cannot synthesize this amino acid, but dogs can; making taurine from the sulfur-containing amino acids methionine or cysteine.

The findings they cited are as clear as mud.  The FDA notice talked about 8 dogs - 4 of which (3 Golden Retrievers and 1 Lab) were taurine deficient and 4 were not.  A retrospective study of DCM cases by Dr. Adin found 22 cases over a 2-year period in dogs on grain-free foods, but 27 in dogs not fed grain-free. Furthermore, none of the grain-free fed dogs were taurine deficient.  There is also a large online database of taurine levels in dogs on grain-free diets.  Of 169 dogs when I last looked at it, only 68 had low taurine levels in their blood. Of that 68, 22 had no echocardiogram so DCM status was unknown, 24 were positive for DCM, and 22 were normal despite low taurine. Clear as mud!

Historically, taurine deficiency DCM was first reported in Goldens 15 years ago and they were all on big name commercial foods - chicken and corn or lamb and rice based.  Another 15-year old study in Newfoundlands with taurine deficiency DCM found they were fed big name lamb and rice food.  Many lamb and rice-based formulas are still on the market, and most do not contain added taurine despite the known issue.

It has also been found that foods containing beet pulp and other high fiber ingredients can lower taurine levels by interfering with the intestinal reuptake of taurine from bile salts. (Taurine is a major component of bile.)

Not all DCM cases are diet related. Genetic predisposition has been identified in several breeds. It has also been noted that some dogs (Beagles) can conserve taurine by reducing how much is in their urine when diet supply is low, but others cannot.

In summary, it's much more complicated than a "boutique" grain-free diet with peas or potatoes can pose a health risk. Dogs on such a diet may or may not have low taurine - and the same goes for grain-free diets from major companies as well as lamb and rice- based diets.  It may well be true that some breeds or individual lines within breeds do have a requirement for taurine and/or higher levels of the taurine precursors, making these highly vegetarian based diet ingredients, whether grain or not, unsuitable.

To suggest that grain-free diets are more often associated with taurine deficiency, let alone DCM, and that more typical corn-based diets are safer is currently premature and speculative. Only formal feeding studies and large-scale investigations including many different dog food types in dogs both with and without DCM can provide some answers. Hopefully along the way we may even get some useful information about true nutritional requirements of dogs and how to correctly feed them as the carnivores they are or supplement them to prevent adverse health effects if we don't.