What’s causing unusual cases of dilated cardiomyopathy in dogs? Dietary ingredients, lack of taurine are potential culprits, but the answer remains elusive
By Kim Campbell Thornton
Andrews McMeel Syndication
For several months, the United States Food and Drug Administration’s Center for Veterinary Medicine, in partnership with independent diagnostic laboratories and veterinary cardiologists and nutritionists, has been investigating reports of a trend that began at least two years ago: Some 150 or more dogs (and at least seven cats) that ate pet foods containing plant-based sources of protein among their main ingredients have developed dilated cardiomyopathy (DCM).
Canine DCM is a disease of the heart muscle that causes the heart to enlarge and decreases its ability to pump blood, often leading to congestive heart failure. It has a number of possible causes, including genetic predisposition, infection or toxins, and diet -- in particular, a lack of taurine. Here’s what is known so far.
The reported cases of DCM are unusual because they are occurring in breeds such as golden and Labrador retrievers, whippets, a Shih Tzu, a bulldog, miniature schnauzers and mixed breeds, none of which are typically prone to the genetic form of the disease. (Breeds genetically predisposed to DCM include Doberman pinschers, Great Danes and boxers. Cases of DCM responsive to taurine supplementation have been reported in cocker spaniels.)
Reported cases are also unusual because many of the dogs consistently ate what are popularly described as “grain-free” foods, with high levels of legumes such as peas, beans and lentils; legume seeds (known as pulses); potatoes; or foods with exotic protein sources such as kangaroo.
Investigators have so far been unable to determine why these ingredients might be linked to cases of DCM. In some cases, dogs had not eaten any other food for months or years before exhibiting signs of DCM.
At least four dogs in reported cases had low blood levels of taurine, an amino acid that helps power “excitable” tissues such as the brain, skeletal muscles, retina and heart. Taurine deficiency is documented as a potential cause of DCM.
That said, in four other cases, the dogs had normal blood taurine levels. In some cases seen by cardiologists, though, dogs who were not taurine deficient improved with taurine supplementation and diet change, according to an article by veterinary nutritionist Lisa M. Freeman, a member of the clinical nutrition service at Cummings Veterinary Medical Center at Tufts University. It may be that individual dogs have different taurine requirements based on breed, size or some unknown factor.
The FDA notes that other factors could include nutritional composition of the main ingredients or how dogs process them, sourcing or processing of primary ingredients, and amount of the ingredients used. Various proteins, including meat proteins, have different nutritional profiles and digestibility. Studies have found that certain large dogs fed commercially available complete and balanced lamb and rice diets may have increased risk of developing taurine deficiency-induced DCM. A 2007 study found that giant dogs took in less taurine than small dogs, possibly because of a slower metabolic rate.
Because it is not yet understood how or if grain-free diets are linked to cases of DCM, the FDA recommends consulting a pet’s veterinarian about whether to change a diet. Dogs or cats with signs of DCM or other heart conditions -- such as low energy, cough, difficulty breathing and collapse -- should be seen by a veterinarian immediately. Guidelines released by veterinary cardiologists and nutritionists advise testing blood taurine levels of dogs diagnosed with DCM and changing the diet based on consultation with a veterinary cardiologist. A taurine supplement may be recommended. Improvement after dietary change and supplementation can take up to six months. Report possible dietary cases of DCM to the FDA.
Ways to manage
Q: My cat is allergic to everything: fleas, food, pollen, etc. She has scratched and bitten all the fur off her belly and chews at her legs. How can we manage her condition and help her stay comfortable?
A: That’s a triple-whammy! We often see flea-bite allergies in cats, and environmental allergies aren’t unusual either. Food allergies are less common, but they definitely occur. Signs for all three can be similar: scratching, biting, rubbing and grooming excessively. Other signs include sneezing, watery eyes and ear infections. All of those things add up to one seriously uncomfortable cat!
Treatment is individualized to each cat because they all have different signs. Beyond corticosteroids, your veterinarian may prescribe antihistamines, cyclosporine and allergy shots. All of these may play a role in helping to reduce your cat’s intense itching.
Used with antihistamines, essential fatty acid supplements may contribute to itch relief, too, according to some veterinary dermatologists. In dogs, applying EFAs topically has been found to help improve what’s known as barrier function -- the skin’s ability to repel pathogens that can aggravate atopic dermatitis. We don’t know if that works in cats, but it’s something to ask your veterinarian about.
It can be challenging and time-consuming to determine exactly what your cat is allergic to so you can get her on a program to keep symptoms under control. It may be necessary to restrict her diet -- called an elimination diet -- and then gradually add back specific ingredients to figure out which ones are setting off her allergies. Be prepared for the process to take as long as several months. If possible, enlist the services of a board-certified veterinary dermatologist who can perform allergy testing and recommend other environmental or dietary changes, as well as appropriate medication. Your veterinarian may be able to refer you to someone locally, or you can find one through the American College of Veterinary Dermatology. -- Dr. Marty Becker
Do you have a pet question? Send it to firstname.lastname@example.org or visit Facebook.com/DrMartyBecker.
-- If your dog is fearful of loud noises such as thunder, fireworks, vacuum cleaners, gunshots or traffic sounds, you may be giving him a medication called Sileo (dexmedetomidine), which is FDA-approved to treat noise aversion. The oromucosal gel is administered to the dog’s gums with a special multidose syringe. The FDA warns that dogs can receive too much of the drug if the syringe isn’t set up properly. To prevent accidental overdoses, be sure you understand how to determine the appropriate dose based on your dog’s weight, lock the syringe in place and deliver the drug so the dog doesn’t swallow it. No deaths have been reported, but possible effects of an overdose include sedation, lethargy, sleepiness, slow heart rate, shallow or slow breathing, difficulty breathing, impaired balance, low blood pressure, muscle tremors and loss of consciousness.
-- Love the look of a longhaired cat with a pointed coat? The Birman may be the breed for you. The sweet social butterflies love following their humans around the house and settling into a lap whenever possible. Their silky coats are easy to groom and don't have an undercoat to form mats and tangles, though they still need daily combing to remove loose hair and prevent hairballs.
-- A new system being tested at the port in Mombasa, Kenya, may allow specially trained dogs to search large shipping containers for contraband ivory, rhino horn and other wildlife products using only a small air sample. Called Remote Air Sampling for Canine Olfaction (RASCO), the system will draw air from specific containers and pass it through filters that are then presented to the dogs, trained to sit if they scent anything illicit. The technique could allow the dogs to check many more containers daily, reducing trade of illegal wildlife items. -- Dr. Marty Becker, Kim Campbell Thornton and Mikkel Becker
ABOUT PET CONNECTION
Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/KimCampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.