Dogs are natural hosts for heartworms, a parasite that can cause extensive health issues and even death in dogs. With that said, most dog owners are aware that their pet should be on heartworm prevention medication. In the case that your dog is infected with heartworm disease, early treatment is important and drastically raises your dog’s chance of survival. Even if your dog is on preventative heartworm medication, it is still important to recognize the signs of heartworm disease, so you can seek treatment as soon as possible, in the unlikely event that your pet gets heartworms.

Warning Symptoms of Heartworms in Dogs

Heartworm disease in dogs is known as a silent killer, because it can take months before your dog shows symptoms. In the early stages of infection, most dogs show little to no symptoms at all, and the more the disease progresses, the more likely apparent symptoms will develop. Pay attention to these warning signs of heartworms in dogs, and take your pet to the vet if these symptoms persist.

  1. A dry unproductive cough. Once heartworms make their way into the lungs and begin reproducing in the lungs and surrounding veins, your dog will begin exhibiting a dry cough, typically after exercising. In some cases, these coughing fits might end in fainting, even after light exercise.
  2. Inactivity or laziness. Pay attention to your dog’s energy levels. If your pet seems more tired than usual, doesn’t want to go outside, or partake in physical activity, there is a good chance that your pet is sick. Dogs with heartworm infections will feel weaker, and will find it harder to remain active, even in low-energy activities.
  3. Weight loss and loss of appetite. In more advanced stages of heartworm infections, your dog will find it hard to complete normal physical tasks like eating. If you notice weight loss and a lack appetite in your dog, then you should take him to the vet immediately to rule out heartworms and other illnesses.
  4. Shallow and rapid breathing. When worms inhabit your dog’s lungs and the surrounding veins, respiratory problems will also occur. Along with coughing, the areas around the blood vessels in the lungs will begin to retain fluid, making it harder for your dog to receive oxygen, resulting in shallow, more rapid breaths.
  5. Distended chest. A swollen, bulged, or distended chest is typically a symptom of an adult heartworm infection. Usually this symptom is caused by weight loss, anorexia, and fluid buildup.
  6. Allergic reactions. While symptoms of allergic reactions are more common in cats with heartworms, dogs may also sometimes exhibit asthmatic symptoms similar to an allergic reaction in response to heartworm infection.
  7. Collapsing or fainting. Once a large population of heartworms enter the heart and causes a blockage of blood flow, known as caval or vena cava syndrome, fainting will occur. Collapsing usually correlates with shock and red blood cell destructions. At this point, the disease has progressed to a level where death can occur within days.

Heartworms can also cause nosebleeds, pneumonia, high blood pressure, seizures, blindness, and excessive sleeping. When heartworms reach places other than the heart and lungs, like the brain and eyes, dogs will experience seizures and blindness. However, these symptoms are rare for heartworms, and could be a sign of another condition.

As heartworm disease progresses, the treatments required becomes more invasive. This is why it is important to be aware of your dog’s normal behavior, so more subtle symptoms like inactivity doesn’t get disregarded.

Diagnosing Heartworms in Dogs

During routine vet exams, we will recommend a heartworm test, which requires a small blood sample that detects the existence of heartworm proteins. If your dog tests positive for heartworms, we will recommend further testing to determine the course of treatment.

When Should Dogs Be Tested for Heartworms?

Dogs should be routinely tested for heartworms during preventative vet visits. Below is a good guideline on the timing for your dog’s heartworm tests:

  • Puppies under the age of 6 months can receive their first heartworm prevention medication, without undergoing a heartworm test, since it takes 6 months for a dog to test positive for heartworms after its been infected. However, you should take your puppy to receive heartworm testing again 6 months afterwards, then once a year to guarantee they continue to test negative for heartworms.
  • Adult dogs over the age of 6 months who haven’t taken preventative medication should be tested for heartworms, before beginning a year round preventative regimen, then testing again six months later, then once a year to guarantee continued negative tests for heartworms.
  • If your dog has missed one or more doses in their heartworm prevention, your dog should be tested immediately, then tested again six months afterwards.

Routine heartworm testing is important, even for dogs on year-round prevention, in order to make sure the medication is working. While heartworm medication is generally successful, there is still a small possibility your dog could become infected, due to circumstances, like vomiting the pill or rubbing away the topical medication.

Is your dog showing symptoms of heartworm disease? Remember that the sooner we detect a heartworm infection, the more likely we will be able to save his life. Call our office today to learn more about heartworm prevention, diagnosis, and treatment.