Heartworms are blood-borne parasites that can cause lung disease, heart failure, and even death in cats. Today, our Dallas vets explain why preventing heartworm disease is so important, and why even indoor cats need heartworm prevention.
What is heartworm disease in cats?
Heartworm disease is mainly caused by a parasitic worm (Dirofilaria immitis), which is spread through a mosquito's bite.
You might hear of cases of heartworm in dogs and wonder if cats get heartworm disease. The answer is yes - cats, dogs, and ferrets can become a 'definitive host' for this parasite after being bitten by an infected mosquito. This means that the worms mature while living inside your pet. They then mate and produce offspring. Heartworms live within the blood vessels, heart, and lungs of an infected pet and may cause significant damage.
How common is heartworm disease in cats?
While cats are relatively resistant to heartworm infection compared to dogs, the disease can still happen. Though heartworms are indeed spread by mosquitoes, outdoor cats aren't the only ones at risk. Mosquitoes are sneaky and can easily make their way inside your home. The American Heartworm Society states that one in four cases of heartworm infection in cats occurs in indoor kitties.
Is heartworm in cats contagious?
Heartworms cannot be transmitted from one cat to another without an immediate vector, such as a mosquito.
Symptoms of Heartworm Disease in Cats
Because there are no specific clinical signs of heartworm disease to watch for in cats, the condition can be difficult to diagnose. The most common symptoms are the sudden onset of coughing and rapid breathing. Unfortunately, these symptoms can also be caused by numerous other illnesses. Other signs of heartworm disease in cats are vomiting and weight loss.
Is heartworm in cats fatal?
Sadly, heartworm disease can be fatal in cats. Sometimes, cats that had no previous symptoms can suddenly develop severe respiratory distress or die. It's thought that this occurs due to a reaction in the lungs to young heartworms or from living or dead heartworms that enter pulmonary arteries and block blood flow to your cat's lungs.
How will my vet check my cat for heartworms?
Your veterinarian can run blood tests at the vet's office to check for the presence of heartworms. Your pet's blood will be analyzed for signs of antigens produced by heartworms. These antigens can be detected about five months after your pet has been bitten by an infected mosquito, but not before this point.
Imaging tests such as radiographs (X-rays) and cardiac ultrasound (echocardiography) may also be recommended. X-rays allow your veterinarian to see the size and shape of your cat's heart, and measure the diameter of the pulmonary arteries.
In many cats with heartworms, the pulmonary arteries are larger, or they may appear blunted (suddenly come to an apparent stop) on their way to the lungs, due to worms blocking them. However, many other cats with heartworms have no abnormal findings on X-rays, especially if the infection is in its early stages.
A cardiac ultrasound allows your vet to see the heart's internal structures and surrounding vessels. The condition and function of the heart can also be assessed with this diagnostic test. Adult heartworms can be seen in many cats with heartworm disease. However, this does not always occur because most infected cats have a low number of worms.
Can heartworm in cats be cured?
There is no drug approved for treating heartworm in cats. One of the drugs that is available for dogs with heartworm has been used in cats but causes significant side effects, including acute lung failure. Due to the severity of the side effects this treatment is not recommended.
There are two options for helping a cat with heartworms.
1. Treat the symptoms such as congestive heart failure in hopes that the cat outlives the worms. Heartworms live in cats for 2-3 years (as opposed to 5-7 in dogs). Symptom management treatment is a long, difficult process. It involves continual medication and periodic oxygen treatment if the cat is in acute distress. In many cats, this treatment can reduce their symptoms and improve their quality of life but the risk of sudden death or respiratory failure still exists as the treatment doesn't directly target the heartworms.
2. The heartworms can be surgically removed. Unfortunately, up to 40% of cats may die during or after this procedure, so surgery is only recommended for those cats who have severe disease and a poor prognosis without surgery.
How can I prevent my pet from getting heartworm disease?
Prevention is the best protection. It is now recommended that all cats, indoors and out, be placed on a monthly preventive medication. It is much easier, safer, and cost-effective to prevent your feline friend from developing heartworm in the first place than to try and treat it.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.
