Heartworm disease: Two simple steps that can save your pet’s life

Heartworm disease is a serious and potentially fatal disease in pets in the United States.  Protecting pets from heartworm disease requires annual testing and year-round preventative therapy. Read the following facts to learn about the disease and to protect your pet.

Heartworm disease is a serious and potentially fatal disease in pets in the United States. Protecting pets from heartworm disease requires annual testing and year-round preventative therapy. Read the following facts to learn about the disease and to protect your pet.


What causes heartworm disease?

It is caused by foot-long worms that live in the heart, lungs and blood vessels of affected pets. These worms cause severe lung disease, heart failure, and damage to other organs.

What animals are affected by heartworm disease?

Heartworm disease affects dogs, cats and ferrets. It can also live in other animals like wolves, coyotes, foxes, and sea lions.

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How does heartworm disease affect dogs?

Heartworm disease causes permanent damage to the heart, lungs and arteries. It can also impact a dog’s health even after the parasites are eliminated.

How is heartworm disease transmitted between dogs?

Mosquitos! An infected dog creates “baby worms” that live in the bloodstream. When a mosquito bites an infected animal, it picks up these baby worms. When the infected mosquito bites another dog or cat, larvae enter the animal. They mature into adult heartworms and can live for 5 to 7 years in dogs and up to 2 or 3 years in cats.

What are the signs of heartworm disease in dogs?

Early in the disease process, there are virtually no symptoms. Signs of heartworm disease include coughing, exercise intolerance, fatigue, decreased appetite, and weight loss. As heartworm disease advances, pets may develop heart failure. Dogs with a lot of heartworms can develop life-threatening cardiovascular collapse.

How likely is it that my pet will get heartworm disease?

Heartworm disease has been diagnosed in all 50 states but is more likely in certain areas. And because infected mosquitoes can come inside, both outdoor and indoor pets are at risk. In 2013, there was an average of 25-50 cases per veterinary clinic in southeastern Michigan.

What do I need to know about heartworm testing?

Heartworm disease is a serious disease that worsens over time. The earlier it is detected and treated, the better the pet’s prognosis. There are virtually no symptoms early in the illness, so detecting the disease with a blood test is essential for the best outcome.

When should my pet be tested?

Puppies should be tested at 1 year of age and annually for life. Any dog who has not been on preventative consistently needs to be tested before starting prevention, again after receiving prevention for 6 months, and annually for life.

My dog is takes heartworm preventative year-round, why do I have to test every year?

Heartworm preventative is very effective but not 100% so there is a small chance that a dog can become infected. If one monthly dose is missed or given late, the dog can become infected. Even if you give the medication as prescribed, your dog may spit out or vomit the heartworm medication (or rub off a topical medication).

My dog tested positive for heartworm disease…now what?

The goal is to first stabilize your dog if he is showing signs of disease, then kill all adult and immature worms while keeping the side effects of treatment to a minimum. Treatment involves strict exercise restriction, stabilizing the dog’s condition, and administering treatment according to The American Heartworm Society guidelines. Treatment spans several months and can be stressful and painful for the dog. If there is significant disease, the damage will be permanent despite eliminating the worms. It is for this reason that yearly preventative is so important.

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Can my cat get heartworm disease?

Heartworm disease in cats is very different from heartworm disease in dogs. Most worms do not grow to the adult stage in cats yet even the immature worms cause respiratory disease. More importantly, the medication used to treat heartworm disease in dogs cannot be used in cats. Prevention is the only way to protect cats from the effects of heartworm disease.

Signs of heartworm disease in cats vary wildly. Symptoms may include coughing, asthma-like attacks, vomiting, appetite loss, or weight loss. Some cats may faint or have seizures. Sadly, the only sign in some cats is sudden collapse or death.

Testing cats is more difficult. The screening test involves a blood test. Diagnosing heartworm disease in cats may also require radiographs (x-ray) and/or an ultrasound. Because there is no approved treatment for heartworm infection in cats, prevention is critical.

Because a cat is not a good host for heartworms, some infections resolve on their own. The infections, however, can leave cats with respiratory injury. Heartworms can also affect the cat’s immune system and cause symptoms such as coughing, wheezing and difficulty breathing. Heartworms may even migrate to other parts of the body, such as the brain, eye or spinal cord. When the worms die in the cat’s body, this will cause blood clots in the lungs and lung inflammation.

Unfortunately, there is no approved drug treatment for heartworm infection in cats, and the drug used to treat infections in dogs is not safe for cats. The goal in treating cats is to stabilize the cat and determine a long-term medical plan with a veterinarian.

questions? give ccah a call.

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