75% of all heart disease in dogs is attributed to degenerative valve disease; 60% of those cases are myxomatous mitral valve disease (MMVD). We came across a 2019 study by a major pet food manufacturer claiming that its proprietary cardiac protection blend food can slow or reverse disease progression in dogs diagnosed with Grade B1 or B2 MMVD. As ‘reverse’ is a bold word to use regarding disease progression, we decided to look into it.
In general, we are cautious about the claims of prescription diets for reasons we discuss later in this post. The company’s research was based on a six-month blinded placebo-controlled study. As the larger pet food manufacturers can fund such research, we should look at what they found objectively.
A total of 36 dogs were enrolled in the study, 19 of which had either Grade B1 or B2 valve degeneration. B1 and B2 are considered preclinical stages of the disease. The other 17 were breed, age, and sex-matched and did not have MMVD. Echocardiograms – which are the best method to diagnose MMVD – were performed on the dogs at the beginning and at various intervals throughout. Dogs from both groups were then split between either the control or the cardiac (experimental) diet.
A control diet is known as a basal diet, which meets basic caloric and essential nutrient needs. The control diet was then enhanced with additional supplementation so that it became the experimental diet.
For this experiment, the basal diet consisted of grains (corn, rice, wheat), proteins (poultry, corn gluten and corn germ meal), dietary fibers (beet pulp, cellulose), vitamins and minerals, and flavoring additives.
Relying on previous research, this group decided to add a combination of heart benefiting fats, vitamins, and amino acids to create the experimental diet. This diet included medium chain triglycerides, long-chain omega-3 fatty acids, lysine and methionine (carnitine precursors), vitamin E (antioxidant), magnesium, and taurine. The fat from the fish oil in the experimental diet was balanced with beef fat in the control diet.
The dogs diagnosed with MMVD placed on the control diet had an average 10% increase over baseline in left atrial diameter and left atrial to aortic root ratio at 6 months. The other MMVD dogs given the experimental diet showed a 3% decrease, which was good.
Some of our questions are: palatability; if a dog might have another concurrent condition that reacts to the diet; what if a dog develops a sensitivity to one of the ingredients; and, why so many basal diets appear to only have these ingredients.
Diet on the Market
We reviewed the current cardiac diet on the market by this manufacturer.
The top 15 ingredients are: oat meal, corn gluten meal, rice, chicken meal, beef fat preserved with mixed-tocopherols, natural flavor, vegetable oil (source of medium-chain triglycerides), cassava root flour, dried beet pulp, potato protein, powdered cellulose, fish meal, fish oil, mono and dicalcium phosphate, calcium carbonate.
We wonder if the marketed diet was created prior to this trial because beef fat was not included in the experimental diet.
Other Diets
We looked into an additional 11 other specially formulated prescription diets for dogs with certain conditions offered by this manufacturer. The top 10 most frequently used ingredients in all of the diets of were:
| Ingredient | Frequency |
|---|---|
| Animal Digest | 4 |
| Animal fat preserved with mixed-tocopherols | 7 |
| Brewers Rice | 8 |
| Chicken Meal | 4 |
| Corn Gluten Meal | 8 |
| Dried Beat Pulp | 4 |
| Mono and Dicalcium Phosphate | 4 |
| Natural Flavor | 5 |
| Poultry By-Product Meal | 5 |
| Powdered Cellulose | 4 |
| Whole Grain Corn | 4 |
The manufacturer’s first ingredient in one food may be brewers rice, and in another formula brewers rice may be the second ingredient.
Other ingredients are readily available. Indeed, beef as a protein source was not listed once in the top ten ingredients. Trout protein and fish oil were listed twice. Fish meal and salmon meal were each listed once in the top ten.
Why is this? The cost of the ingredients and bulk purchasing agreements account for a couple of the reasons.
Overall, the manufacturer starts off with a basic diet it has used for years and then supplements with various amino acids, vitamins, minerals, nutrients, a limited amount of high quality protein for variety, and some fats for certain conditions.
Finding Supplementation for Your Companion Dog with MMVD
This study demonstrated that the combination of additional supplements in their diet may help delay the progressive degenerative nature of MMVD.
Companion pet parents can find similar supplementations by other manufacturers for their companion dogs. We suggest that you speak to your veterinarian or veterinary nutritionist about what you are currently feeding, possibly testing for deficiencies of nutrients (i.e. taurine, vitamin D3, etc.), testing for oxidative stress and food sensitivities/intolerances, and finding out what you can add to enhance the quality of and extend your companion dog’s life.
References
Li, Qinghong et al. “Dietary intervention reduces left atrial enlargement in dogs with early preclinical myxomatous mitral valve disease: a blinded randomized controlled study in 36 dogs.” BMC veterinary research vol. 15,1 425. 27 Nov. 2019, doi:10.1186/s12917-019-2169-1, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6882217.