Why You Won’t See Your Dog's Heartworm Symptoms, Until it’s Advanced

Heartworm disease is caused by a mosquito transmitted parasite. If left untreated, it can be a debilitating disease and sometimes prove fatal. Pets infected with heartworms can be found in all states, in spite of the fact that very effective heartworm prevention products are available. The good news is that I’ve noticed more and more pet parents are wondering about the symptoms of heartworm disease. Unfortunately, most of the time you’re not going to see any, and here’s why:

Early signs of heartworm disease in dogs
It would be great news for pets and people if heartworm symptoms were always obvious, but the truth is they are generally invisible or unnoticeable. The development of heartworm disease is insidious until the overt clinical signs occur, and by then the disease has already affected your dog’s heart and lungs. Your dog could appear 100% healthy while the parasites are quietly making themselves right at home.

Later signs of heartworm disease

• Fatigue
• Exercise intolerance
• Weight loss
• Cough
• Sudden death

While none of these symptoms are exclusive to heartworm disease, a dog with heartworm and these symptoms has progressed to the later stage. Heartworm at this stage will require aggressive and expensive treatment.

Is my dog at risk for heartworm disease?
Yes. Unless your dog lives in a vacuum he is at risk. Again, the disease is transmitted by mosquitoes, which could be anywhere. Many of the carrier mosquitoes can survive in a variety of climates and are a year round threat (even in winter) in much of the country. In all likelihood, your dog is bitten by more mosquitos than you.

How can I protect my dog from heartworm disease?
The good news is, protection is simple. There are highly effective preventives that stop the development of heartworms in pets. By administering a preventive year-round, the risk of infection is greatly reduced. You can also try to avoid exposure to mosquitoes by keeping dogs indoors, particularly during twilight hours, when mosquitoes are feeding.

Can I test my dog for heartworm disease?
Absolutely, and your veterinarian will advocate for testing every year. A negative test result in a dog on year-round heartworm prevention is good news and means the preventive measures are working. However, should your dog test positive, he is infected and will need to be treated by your veterinarian.