heartworm preventioin in dogsDogs are most susceptible to heartworm disease, particularly those that spend long hours outdoors near humid areas or bodies of water. Symptoms are categorized into four classes with increasing severity. Generally, signs of heartworm disease can be seen in chest x-rays during Class 2 and 3 cases:

  • Class 1: Mild symptoms such as cough
  • Class 2: Mild to moderate symptoms such as occasional cough and fatigue after physical activity
  • Class 3: Persistent cough, loss of body condition and fatigue after physical activity. Can also include difficulty breathing and signs of heart failure
  • Class 4: Characterized by Caval Syndrome from heavy worm burdens, where worms form a physical barrier for blood flow into the heart

If left untreated, heartworm disease can be life-threatening, leading to damage of the heart, lungs, liver, kidneys and eventually death.


The detection of heartworms in dogs, or any animal for that matter, cannot be done until at least five months after initial exposure. In fact, most cases cannot be detected until the worms have infected the bloodstream of the host animal.

Two types of blood tests can be used as well as ultrasounds and x-rays to help show advanced symptoms of heartworm disease. Dogs that have not been on heartworm prevention, or have been off of it for over a month, should be tested before starting preventative measures once again.


Heartworm treatment is often heavy on your pet’s health and your wallet. Other than surgery in extreme cases, the treatment options for dogs, cats and ferrets are very limited. When it comes to heartworm disease, prevention is truly the best treatment. There are a variety of FDA approved preventatives that your pet can take.

The experienced veterinarians at Valley Animal Hospital are prepared to answer your questions about heartworm disease and offer the best preventative treatments to keep your pet safe. Call today at (956) 787-2709 to schedule an appointment.

Click here to read more about heartworm disease in cats.