By Dr. Nigel Gumley
The Food and Drug Administration in the US recently published the third report looking into a possible link between pet food and heart disease in dogs (see https://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy ). The history behind this investigation started with a concern with dogs being diagnosed with Dilated Cardiomyopathy (DCM) in breeds not usually associated with this condition.
DCM occurs when the heart muscle weakens over time and is unable to pump blood effectively around the body. It is a well-known genetic condition in breeds such as Newfoundland dogs, Great Danes and other giant breeds, but also in Dobermans and King Charles Cavalier Spaniels. Affected dogs can present with an acquired heart murmur or abnormal heart rhythm heard on a routine veterinary exam, or may present clinically with exercise intolerance, coughing and heavy breathing, or even fainting and collapse. In extreme cases, dogs can die suddenly.
Since 1 January 2014 until 30 April 2019, the FDA has received reports of 515 dogs and 9 cats with DCM, but 222 of these have been reported since 1 December 2018, suggesting that more dogs are becoming affected. Many of these dogs are of breeds where DCM is not an expected genetic disease.
An association has been suggested between certain pet foods and dogs developing DCM, with the finding that over 90% of these are “grain-free” and over 93% contained peas and/or lentils. Common brands include Acana, Taste of the Wild, Blue Buffalo, Fromm, Merrick, Natural Balance, Orijen and Nutro, among others. The FDA and affiliate laboratories have failed, to date, to find any difference in these diets and other foods with respect to protein, fat, moisture, fibre, starch, and some amino acids previously associated with heart disease such as cystine, methionine and taurine. Taurine has specifically been suggested since there has been a rise in Golden Retrievers diagnosed with DCM and finding that the dogs are taurine-deficient. While the diets are normal in taurine content, possible factors might be resulting in poor taurine absorption or metabolism.
As of this time, the FDA is conducting more tests and working with owners of affected dogs to investigate for other possible links, such as plant poisonings and exposure to heavy metals. Specialists are collecting blood and urine samples and conducting serial heart checks in affected dogs to look for other evidence of causes. Pet food companies are also working with the FDA to examine how pet food may play a role.
At Cedarview Animal Hospital, we have found two pets this year with suspiciously poor heart contractility and both were being fed grain-free diets. Both dogs were otherwise apparently healthy but has suspicious findings on their exams and routine tests and showed reduced heart function on heart tests. While we can suspect heart disease from clinical signs such as new heart murmurs, coughing, breathing problems, or exercise intolerance, more specific heart tests such as a cardiac ultrasound or echocardiogram are needed to find evidence that DCM is a concern.
We will continue to watch for more information coming out of the FDAs investigation into this syndrome and potential links to pet food. It is unlikely that most dogs fed grain-free foods will develop problems, but anyone concerned with the condition may want to avoid this category of food or any of those listed by the FDA. For clients concerned with whether their pet may be affected clinically with heart disease, please call us for an examination of the pet and discussion about how to investigate further if needed.