Westbury Animal Hospital
713.723.3666 · 4917 S. Willow Dr. Houston, Texas 77035 

The Facts and Myths of Heartworms in the Dog and the Cat

by LD Eckermann


  1. Notice the title!!!  Both DOGS and CATS can get Heartworms.
  2. A mosquito bite transmits the infected larvae into the skin when they suck blood from the pet.
  3. It takes approximately six months for adult heartworms to mature and appear in the heart and pulmonary arteries.
  4. In a cat, one worm can KILL a cat.
  5. In a dog, one worm is RARE; usually 20-40 worms and the dog do not have this acute death. That would be unusual in the dog.
  6. Why is this!!  As we say, cats are not small dogs. The cat lung is quite different than the dog!! When that one worm dies, it can cause a marked anaphylactic like reaction in the cat.
  7. The heartworm lives for approximately Five years in the dog, and approximately Two years in the cat.
  8. The symptoms in the cat are coughing, wheeze, vomit or acute respiratory distress. As mentioned previously, the only symptom may be acute death.
  9. The symptoms in the dog can be similar, however usually not acute death. Dogs can tire easily. One can imagine, this would be difficult to assess in the cat.
  10. The diagnosis in a dog can be relatively easy by a simple blood test. In the cat, due to the small worm burden, other test such as chest x-rays and maybe an ultrasound would be needed.
  11. One other point must be made for the FELINE!! If one thinks that their cat has a hairball, because of a cough / vomit like symptom. MAKE sure that you see the huge slimy wad of hair, and not just some clear vomit with some hair!!! There is a difference. It does not mean heartworms, but your veterinarian needs to know!!!!
  12. The FACT is, Heartworms are a preventable disease by a simple safe and effective monthly medication!!!!  It is up to you. Ask your veterinarian for what is best for your pet.


  1. My animals are inside and are not exposed to mosquitoes. If you live in Houston, Texas, we ALL know the truth.
  2. I do not need to give heartworm prevention in the winter months. Have we not had mosquitoes in January?
  3. My dog has a thick coat and mosquitoes cannot get to the skin! This is absolutely not true.
  4. I will use a mosquito repellant to prevent heartworms. Does this work 100 % for the human?? NO
  5. I give heartworm medication to my dog, but my cat does not need to be prevented!! When you review the “facts list “, we know that this not true.

The take home message is that all the deaths and disease caused by heartworms in the dog and cat can be prevented by one act of kindness to your pet ONCE a MONTH!!!! Please ask your veterinarian for what is best for your animals.  


You are logged in as: