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Heartworm Disease

When heartworms (parasites) invade a pet’s circulatory system and heart.

Signs that your cat or dog has heartworm disease are sudden weight loss, difficulty breathing, soft, persistent cough, tiring easily, listlessness or weakness. In cats, the only sign may be sudden death due to respiratory failure.

When a mosquito bites an infected animal, then bites your dog or cat, heartworm larvae (microfilariae) are transferred to your pet. They migrate through your pet’s blood vessels to the heart and lungs. These larvae become adult heartworms and grow and reproduce in your pet’s heart and lungs. Any pet that is exposed to an infected mosquito is susceptible to getting heartworm disease.

To prevent your dog or cat from getting heartworm disease, you can give him or her monthly preventive. You can choose from chewable tablets or a liquid that is applied between your pet’s shoulder blades. For dogs, an exam and heartworm test must be performed before dispensing the preventive. For cats, just an exam is needed. The American Heartworm Society and Companion Animal Parasite Council (CAPC) recommend year-round preventive in all areas in which heartworm disease is detected, and to protect against intestinal parasites, which can be a year-round problem. In areas where temperatures are cold enough in the winter months, like Colorado, we recommend preventive at least from June through November, when parasite transmission is most likely. If you travel to the coasts, Florida, Texas, or other southern states with your pet, year-round preventive is highly recommended. The American Heartworm Association and Companion Animal Parasite Council both recommend year-round heartworm prevention.

Your veterinarian will do an exam and ask you about your pet’s history. If heartworm disease is suspected in your dog, the vet will run a heartworm test to confirm the diagnosis. Tests that may be done in your dog or cat to reach a diagnosis may also include X-Rays, bloodwork, and an ECG (Electrocardiogram).

Danger if Untreated
If left untreated, symptoms of heartworm disease will get worse and eventually may be FATAL.

If your pet tests positive for heartworm disease, and is able to tolerate the treatment, your veterinarian will start treatment.
For dogs, the usual treatment is to administer a drug that will kill the adult heartworms. Complete rest is essential for the month after treatment so that the pieces of dead heartworms don’t lodge in the heart and lungs and cause heart or respiratory failure. Your doctor may also administer medication to kill the microfilariae (heartworm offspring).
No heartworm treatment medications have been approved for cats. Symptoms of heartworm disease in cats can be treated with different medications.

A heartworm test will need to be done to determine the effectiveness of the treatment in dogs. Heartworm tests are recommended every year to every other year in dogs as well as yearly heartworm preventative.

Exams and adjustment of medication are needed in cats. Yearly heartworm preventative is recommended.

Estimated Cost – Preventing vs. Treating
1 year of Heartworm Preventative for a 20 lb Dog: $81
Heartworm Treatment for a 20 lb Dog: $500+

1 year of Heartworm Preventative for a 90 lb Dog: $117
Heartworm Treatment for a 90 lb Dog: $800+

1 year of Heartworm Preventative for a 10 lb Cat: $99
There Is NO Cure for Heartworm in Cats, but the symptoms can be treated for around $75+ per year.

Having a healthy pet: PRICELESS!


Pets & Friends Animal Hospital, L.L.C.

3625 Baltimore Ave. • Pueblo, CO 81008 • 719-542-2022 / fax 719-545-6261