New Insights on the Evolution of Canine Dilated Cardiomyopathy (DCM)

What is DCM and why do we care about it?

Dilated Cardiomyopathy (DCM) is a heart disease that weakens or enlarges the heart, and may lead to congestive heart failure or sudden death.¹ Some breeds, such as Doberman Pinschers and Great Danes, are genetically at higher risk of developing typical DCM.^2,3 Deficiency of taurine, an amino acid commonly found in meat, has been previously shown to cause DCM in breeds without genetic predisposition. Additionally, certain balanced commercial diets — many classified as “grain-free” — have recently emerged as a potential factor in the development of DCM in “atypical” breeds.^4–7

Why are Golden Retrievers of specific concern?

Historically, Golden Retrievers weren’t thought to be particularly susceptible to DCM, and the development of DCM in this particular breed may be different from others.^4,5 Therefore, a recent increase of DCM reports in this breed has understandably alarmed pet parents and veterinarians.^3,8

Some researchers assume that a relative deficiency of taurine and taurine precursors may be responsible, as it’s been observed that DCM symptoms in some Golden Retrievers improved after supplementation with taurine.^4,5 Many (but not all) Golden Retrievers had low levels of taurine in the blood even on balanced commercial diets.⁹

Certain genetic lines of Goldens have been shown to be particularly susceptible to taurine-deficient DCM.⁴ The role of grain-free diets has not yet been conclusively established in this breed,^10,11 but some researchers feel strongly that there is in fact an association.

What’s being done?

With the rising awareness of the disease, vets have increased screening for earlier identification and have been asked to submit detailed reports of any DCM cases with a potential diet association to the FDA.^1,3

To truly identify an association with diet, robust studies, analyzing individual dietary components and specific ingredients must be performed both in the general dog population and in select breeds. The FDA and others have begun to research and gather data to identify whether particular components of dog food are associated with the rise in DCM across breeds, but no conclusive results have yet been obtained.^3,8,12

Why should studies also consider the gut microbiota?

The gut microbiome is known to play a role in nutrient absorption and metabolism and is known to influence taurine resorption. Previous investigations mainly examined intake of taurine and other components of the dog’s diet, but these measurements may not entirely reflect the amount absorbed or excreted in the intestines.

In cats, for example, researchers demonstrated that changing the gut microbiota with antibiotics decreased taurine loss even when their diet remained the same.¹³ We think the gut microbiota might have a similar direct impact on taurine levels in dogs.

Another role the microbiota may play in DCM has to do with its involvement in bile acid metabolism. Taurine is used to make bile acids, which are released into the intestine to help absorb dietary fats.¹⁴ The gut microbiome can metabolize bile acids and therefore has a direct impact on the amount of taurine excreted in the stool.^15,16 

It’s possible that increased loss of these taurine-containing bile acids may lead to a decreased taurine level in the blood. Taurine is thought to help the heart to contract, which may explain why low blood levels can be correlated to DCM.¹⁷

What can I do for my dog right now?

While researchers continue to investigate canine DCM, specifically with diet associations, here’s some tips to help keep your pup healthy.

• Feed your dog a well-balanced diet, made from high quality ingredients, to avoid nutritional deficiencies.¹⁸ 
  
  
• Look for diets with high digestibility, to allow your dog to fully harness all available nutrition. 
  
  
• Try diets high in protein, which are good for muscle function and can also help prevent taurine deficiency.
  
  
• Avoid diets with heavy use of fillers and legumes. 
  
  
• Be careful not to overdo it on fiber — some is beneficial, but too much can lead to decreased nutrient absorption. 
  
  
• Look for companies with rigorous nutritional testing and quality control to ensure nutritional adequacy and minimize contamination.
  
  
• Avoid certain raw plant-based ingredients, which may impact thyroid function and lead to hypothyroidism-induced canine DCM.¹⁸ 
  
• Take your dog to the vet for regular check-ups. While in many cases of DCM there is no cure, early detection can allow your vet to prescribe appropriate medications, supplements and dietary changes to help them live longer and happier.¹⁸

References:

1. Martin MWS, Stafford Johnson MJ, Strehlau G, et al. Canine dilated cardiomyopathy: a retrospective study of prognostic findings in 367 clinical cases. J Small Anim Pract. 2010;51: 428–436.
2. Meurs KM, Fox PR, Norgard M, et al. A Prospective Genetic Evaluation of Familial Dilated Cardiomyopathy in the Doberman Pinscher. J Vet Intern Med. 2007;21: 1016–1020.
3. Center for Veterinary Medicine. FDA Investigates Potential Link Between Diet & Heart Disease in Dogs. In: U.S. Food and Drug Administration. 7 Feb 2019. Available: http://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy
4. Bélanger MC, Ouellet M, Queney G, et al. Taurine-deficient dilated cardiomyopathy in a family of golden retrievers. J Am Anim Hosp Assoc. 2005;41: 284–291.
5. Kaplan JL, Stern JA, Fascetti AJ, et al. Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets. PLoS One. 2018;13: e0209112.
6. Kittleson MD, Keene B, Pion PD, et al. Results of the multicenter spaniel trial (MUST): taurine- and carnitine-responsive dilated cardiomyopathy in American cocker spaniels with decreased plasma taurine concentration. J Vet Intern Med. 1997;11: 204–211.
7. Fascetti AJ, Reed JR, Rogers QR, et al. Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997-2001). J Am Vet Med Assoc. 2003;223: 1137–1141.
8. Center for Veterinary Medicine. Vet-LIRN Update on Investigation into Dilated Cardiomyopathy. In: U.S. Food and Drug Administration. 7 Feb 2019. Available: http://www.fda.gov/animal-veterinary/science-research/vet-lirn-update-investigation-dilated-cardiomyopathy
9. Kramer GA, Kittleson MD, Fox PR, et al. Plasma taurine concentrations in normal dogs and in dogs with heart disease. J Vet Intern Med. 1995;9: 253–258.
10. https://justinshmalberg.com/blog/2019/7/3/dilated-cardiomyopathy-and-grain-free-diets-thoughts-on-the-fda-update
11. https://www.nomnomnow.com/blog/dcm-and-your-dogs-food-what-you-need-to-know
12. Mansilla WD, Marinangeli CPF, Ekenstedt KJ, et al. Special topic: The association between pulse ingredients and canine dilated cardiomyopathy: addressing the knowledge gaps before establishing causation. J Anim Sci. 2019;97: 983–997.
13. Kim SW, Rogers QR, Morris JG. Dietary antibiotics decrease taurine loss in cats fed a canned heat-processed diet. J Nutr. 1996;126: 509–515.
14. Wildgrube HJ, Stockhausen H, Petri J, et al. Naturally occurring conjugated bile acids, measured by high-performance liquid chromatography, in human, dog, and rabbit bile. J Chromatogr. 1986;353: 207–213.
15. Ridlon JM, Kang DJ, Hylemon PB, et al. Bile acids and the gut microbiome. Curr Opin Gastroenterol. 2014;30: 332–338.
16. Backus RC, Rogers QR, Morris JG. Microbial degradation of taurine in fecal cultures from cats given commercial and purified diets. J Nutr. 1994;124: 2540S–2545S.
17. Schaffer SW, Jong CJ, Ramila KC, et al. Physiological roles of taurine in heart and muscle. J Biomed Sci. 2010;17 Suppl 1: S2.
18. McCauley SR, Clark SD, Quest BW, Streeter RM, Oxford EM. Review of canine dilated cardiomyopathy in the wake of diet-associated concerns. J Anim Sci. 2020;98. doi:10.1093/jas/skaa155.