My Research Begins
After my 15 month old English Cocker Spaniel, Allie, was diagnosed with DCM, I began researching the causes of this disease. I started out knowing very little, and was only vaguely aware of the FDA research about diet related causes.
The cardiologist who did the analysis of her echocardiogram suggested an immediate change from the commercial raw diet she was currently being fed. There was no mention of what I should change it to, so in pursuit for more information I joined a group called Diet-Associated Dilated Cardiomyopathy (DCM) in Dogs (7) . This is a very large group on FaceBook, run by veterinarians, breeders, members of the PH-d and DVM research community, nutritionists, food brand representatives, and concerned dog owners. It supports the FDA research and recommends feeding kibble from one of the top 5 manufacturers who have tested their own brands. The FDA research states that DCM is thought to be caused by a high percentage of pulses (lentils, peas, chickpeas, beans) in kibble — sometimes known as “grain free” or “limited ingredients” kibble. Their updates have been put on hold since 2022 until more research has been completed.
Diet
I went straight to the data provided by the FDA, which showed that out of 500 reported cases, only 9 were attributed to a raw diet. There was no information as to whether these were commercially prepared or home prepared diets. My commercially prepared raw diet didn’t stand out as being a factor at all. I had switched to Purina Pro Plan based on the group suggestions, but now I was questioning that decision.
Raw diets are naturally high in taurine. To put my mind at ease, I contacted the manufacturer of the raw food I was using, and was told the ratio was 0.10g per 100g fed — plenty of taurine as well as all the necessary amino acids. The company follows the NRC guidelines and uses the Genesis Food Formulator to calculate ingredients.
This is a direct quote from the FDA website (1):
“Dilated cardiomyopathy is recognized as a genetic condition in dogs, typically in large or giant breeds, such as the Doberman Pinscher, Great Dane, or the Irish Wolfhound. It is also seen in Cocker Spaniels associated with taurine deficiency.”
Cocker spaniels? I was surprised to see little Cocker Spaniels listed with all these giant breeds. This was the first I’d heard that this breed was even associated with DCM. I’d spoken with several breeders of working English Cocker Spaniels who were also surprised. The general opinion was that it sometimes occurred in show (bench) American Cocker Spaniels, but was unheard of in working English Cocker Spaniels.
Genetic Tests
In humans, mutations in more than 30 genes have been found to cause familial DCM, but in dogs it’s breed specific. A gene mutation that is associated with DCM in one breed, is not necessarily associated in another. Only a handful of genetic tests exist. Unfortunately, a test for Cocker Spaniels is not one of them. These tests will reliably predict if a dog is a carrier, but they are not predictive of disease.
Embark offers genetics tests for these breeds ( https://embarkvet.com/breeders/health/ ):
- Doberman Pinscher – DCM1 (PDK4)
- Doberman Pinscher – DCM2 (TTN)
- Schnauzer – DCM (RBM20)
Laboklin Laboratories in the UK offers genetic tests for these breeds ( https://www.laboklin.co.uk/laboklin/showGeneticTest.jsp?testID=8764 ):
- Welsh Spring Spaniel – A variant of the phospholamban gene
- Manchester Terrier – (JDCM) Juvenile Dilated Cardiomyopathy (ABCC9)
- Nova Scotia Duck Toller – (Gene not specified)
There are two types of DCM; primary, which is presumed to be hereditary, and secondary, which is caused by infections, nutritional deficiencies, environmental factors (4).
Environmental Factors
But what causes the taurine deficiency? The FDA site spoke of research exploring other potential causes in the development of DCM, such as environmental factors like heavy metal exposure or poisonous plant ingestion. This is also mentioned by Lisa M. Freeman, DVM, PhD, DACVIM at the Cummings School Nutritional Clinical Service (4).
As a puppy, Allie was constantly eating bits of wood (hence the surgery!) and bits of debris around the yard, including mortar that had crumbled from our concrete steps. She also ate copious amounts of mud when we went hiking in the forest. Could any of these things have changed how she processed Taurine?
A conversation on ResearchGate got me thinking about our daily hikes. The discussion is about heavy metals being more concentrated in muddy soil than sandy soil (2). The soil where we hike would be classified as clay based soil. I considered ordering a soil sampling kit to have it tested before I found out her littermate had also been diagnosed, and was not a mud eater.
Something I’m still considering from this article published in the University of Chicago Press Journals (5):
“What’s more, some research suggests that clay can bind to nutrients in the stomach, making them hard to digest. If that’s true, it’s not a lack of nutrients that causes geophagy; rather it could be the other way around.”
This article was about geophagy in humans, but is it possible that simply eating mud was causing nutrient deficiencies, including taurine?
Infection and Other Factors
Two viruses known to cause DCM in dogs are parvovirus, and Chagas’ disease (6). I knew Allie never had parvovirus, and Chagas’ disease isn’t seen on the west coast of North America (she was born in Oregon).
This article caught my eye simply because Allie is extremely active. The information suggested muscle overuse could deplete Taurine (3):
“Muscle overuse affects taurine synthesis by producing ROS, and consequently, taurine-induced benefits are compromised.” (ROS refers to oxygen use)
Working cockers are very athletic, active dogs. If she had naturally low levels of taurine, could this have anything to do with creating her taurine deficiency? This is a direct quote from the study (3):
“For example, muscle overuse-induced cysteine oxidation and its intermediate cysteine sulfinic acid oxidation result in a reduced level of taurine and glutathione synthesis (GSH), ultimately compromising the taurine-induced benefits in the muscle, such as influencing GSH level and glutathionylation (Bertolone et al., 2020).”
So many questions, and so many hypotheses! My one burning question at this point is about her life expectancy. More on that in my next post!
References:
(1) (June 27, 2019) Medicine, Center for Veterinary. “FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy.” FDA, 25 Mar. 2020, www.fda.gov/animal-veterinary/outbreaks-and-advisories/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy.
(2) Why are heavy metals more present in muddy samples than in sandy samples? | ResearchGate
(3) Thirupathi, A., Pinho, R. A., Baker, J. S., István, B., & Gu, Y. (2020, August 26). Taurine reverses oxidative damages and restores the muscle function in overuse of exercised muscle. Frontiers. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.582449/full
(4) “Diet-Associated Dilated Cardiomyopathy: The Cause Is Not yet Known but It Hasn’t Gone Away – Petfoodology.” Tufts.edu, 7 Feb. 2023, sites.tufts.edu/petfoodology/2023/02/07/diet-associated-dilated-cardiomyopathy-the-cause-is-not-yet-known-but-it-hasnt-gone-away/. Accessed 14 Aug. 2024.
(5) “Eating Dirt Can Be Good for the Belly, Researchers Find.” ScienceDaily, 4 June 2011, www.sciencedaily.com/releases/2011/06/110602162820.htm.
(6) Dilated Cardiomyopathies in Dogs
(7) Diet-Associated Dilated Cardiomyopathy (DCM) in Dogs https://www.facebook.com/share/XRRtdpvsArP7w4uZ/