Canine Cardiac Issues
This month’s topic is canine cardiac health. We’ll look at the most common cardiac issues dog face, the breeds with higher predispositions for cardiac issues, and what you can do to help maintain your dog’s heart health. There are a variety of syndromes or diseases that can affect your dog’s heart, but the four most common ones in descending order are: chronic valvular disease, dilated cardiomyopathy, congenital heart disease, and heartworm infestations.
Chronic valvular disease, aka mitral valve disease or mitral regurgitation, is the most common and generally presents as a loud heart murmur over the left side of the chest. It is caused by the hearts valves being degenerated in some form. The mitral valves (and in many cases the tricuspid valves as well) become thickened and distorted until the no longer fit seamlessly and blood is often regurgitated back into the atrium. This is why it is also called mitral valve regurgitation. This disease is most common in toy breeds, but Cavalier King Charles Spaniels are most affected. It is also commonly seen in Toy Poodles, Lhasa Apsos, Yorkshire Terriers, Schnauzers, and Cocker Spaniels. Early signs of the disease include coughing at night or after exercise, lethargy, and fainting spells.
In larger breeds of dogs, dilated cardiomyopathy is more common. In this disease, the heart chambers enlarge and the walls of the ventricles become thinner leading to weaker heart muscles and eventual failure. Diagnosis is based on chest X-rays showing enlarged heart chambers and thinner ventricles. It is most common in Boxers, Doberman Pinschers, Springer Spaniels, Cocker Spaniels, German Shepherds, Great Danes, Old English Sheep dogs, St. Bernards, and Schnauzers with primarily male dogs being affected. Onset can begin at 2 to 5 years and present as weight loss, lethargy, rapid breathing, coughing and tiring easily. Treatments to prevent fluid build-up in the lungs and abdomen should be discussed with your veterinarian.
Congenital heart disease can take on many forms. By definition, these are diseases of the heart that are present at birth. Very severe heart defects may take a dog’s life in less than a year, but mild valvular diseases may do well and not need surgery. Some of these congenital heart diseases include valve malformations [dysplasias], valve narrowing [stenosis], septal defects, patent ductus arteriosus, and Tetralogy of Fallot. Different breeds are prone to different types of these congential heart defects. For example, Great Danes are predisposed to mitral dysplasia, while Samoyeds are prone to atrial septal defects. Puppies are best screened for congenital heart disease at 6 to 8 weeks of age by listening for murmurs. Many murmurs disappear as the dog ages, but a murmur still present at 16 weeks, may need further evaluation by cardiac ultrasound. Speak to your veterinarian to understand all you options if your puppy has a murmur or if the breeder has had puppies with a prior history of heart defects.
Finally heartworms can seriously impact your dog’s heart. Thankfully, heartworms are not common in Washington State. However, if you travel to other states, or if your dog came from another state, you may need to screen your pet for the presences of these deadly cardiac parasites. If he or she tests negative, your pet can take a heartworm preventative to prevent infection. Heartworms are transmitted to dogs by mosquitos. In any region with mosquitos, one can expect a possibility of heartworm infestation. If a dog is found to have heartworms (which can present as coughing and lethargy, and tiring easily); the dog can be treated by a veterinarian. If left alone, heartworms are fatal. Be sure to talk to your veterinarian if your dog requires heartworm testing or prevention.
With regular annual veterinary visits, your vet can screen your dog for cardiac issues. While some may have a poor prognosis, many issues can be managed with diet and medication. Take your dog to the vet every year, and twice a year if needed to be sure your dog has a healthy heart. In our practice, if we detect a heart condition, we utilize a visiting board certified cardiologist such as Dr. Jerry Woodfield. Cardiac health is important, so do not hesitate to bring your dog to us for a full exam.