As a follow up to our last blog on heartworms, which you can read here, we are going to discuss what heartworms are like for dogs. Dogs and cats can both contract heartworms, but for each animal it is different.
What are the signs of heartworm disease in dogs?
In the early stages many dogs show few, or no, symptoms of having them. The longer the infection continues, the more symptoms will become apparent. Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after activity, decreased appetite, and weight loss. As heartworm disease advances, dogs can develop heart failure and a swollen belly due to excess fluid in the abdomen. In extreme cases dogs can develop a sudden blockages within the heart leading cardiovascular collapse. Without quick surgical removal of the heartworm blockage, few dogs live.
When should my dog be tested?
All dogs should be tested annually for heartworm infection. Annual testing is necessary, even if your dogs are on heartworm prevention year-round, this ensures that the prevention is working. While heartworm preventions is effective, your dog can still become infected. If you miss just one dose of a monthly medication it can leave your dog unprotected. Your dog also might spit or vomit the pill or chew up. Topical can be rubbed off too.
The American Heartworm Society’s guidelines on testing and timing:
Puppies under 7 months of age can be started on heartworm prevention without a heartworm test (it takes at least 6 months for a dog to test positive after it has been infected), but should be tested 6 months after your initial visit, tested again 6 months later and yearly after that to ensure they are heartworm-free.
Adult dogs over 7 months of age and previously not on a preventive need to be tested prior to starting heartworm prevention. They, too, need to be tested 6 months and 12 months later and annually after that.
You need to consult your veterinarian, and immediately re-start your dog on monthly preventive—then retest your dog 6 months later. The reason for re-testing is that heartworms must be approximately 7 months old before the infection can be diagnosed.
What happens if my dog tests positive for heartworms?
Once a dog tests positive on an antigen test, the diagnosis should be confirmed with an additional test. This is due to the fact that the treatment regimen is expensive and complex and we want to make use it is necessary.
Next, you will need to restrict your dog’s exercise. Your dog’s normal physical activities will need to be restricted as soon as the diagnosis is confirmed. The reason for this is that physical activity increases the rate at which the heartworms damage the heart and lungs.
After that we might need to stabilize your dog's disease. Before heartworm treatment can begin, your dog’s condition may need to be stabilized. This normally occurs in severe cases of heartworm disease or if there is another serious condition.
Once we have determined your dog is stable and ready for heartworm treatment, we will recommend a treatment protocol, which involves several steps. Dogs with no signs or mild signs of heartworm disease typically have a high success rate with treatment. More severe cases can also be successfully treated, but they have a higher chance of complications. Please remember that the severity of heartworm disease does not always correlate with the severity of symptoms.
Last we test again. Around 6 months after treatment is completed, your dog will have heartworm test to confirm that all heartworms have been eliminated. We will also prescribe heartworm prevention for the rest of your dog’s life.