Although cats are typically house pets, they can still contract a multitude of infectious and parasitic diseases. One potentially deadly threat many cat owners overlook is heartworm disease. While commonly associated with dogs, heartworm disease can also affect cats, and its consequences can be devastating. In this comprehensive guide, our Just Cats Clinic team will delve into the intricacies of heartworm disease in cats, and explain how you can protect your feline friend.

Understanding heartworm disease in cats

Heartworm disease is caused by Dirofilaria immitis, a parasitic worm that travels through the bloodstream to infiltrate the large blood vessels surrounding the heart and lungs of mammals. While any mammal, including people, can contract heartworms, dogs and wild canines are the preferred host animals. Cats are atypical hosts, so heartworm disease affects them differently than it does canines.

Heartworm disease is transmitted through the bite of one infected mosquito carrying heartworm larvae (i.e., microfilariae). Unlike in dogs, where adult heartworms can grow up to a foot in length and live for five to seven years, heartworms in cats are shorter in length and lifespan. The riskiest time for the patient is when the worms die and is almost always fatal. Additionally, infected cats generally only have a handful of adult heartworms, whereas dogs can have hundreds. However, even a few worms can cause severe health issues in felines because of cats’ small size.

Heartworm disease signs in cats

Heartworm disease in cats is often challenging to diagnose based on clinical signs alone because of the nonspecific nature of its symptoms. Some cats may show subtle signs, while others may have no issues at all until the disease has progressed significantly. 

Clinical signs often appear similar to those for asthma, since heartworm disease is primarily a lung disease in cats. Common heartworm disease signs in cats include:

  • Rapid or difficulty breathing
  • Coughing, wheezing, or gagging
  • Lethargy and decreased activity
  • Weight loss and poor appetite
  • Intermittent vomiting of food or blood
  • Diarrhea
  • Blindness
  • Seizures
  • Collapse or sudden death

It’s important to note that heartworm disease signs can overlap with other feline health issues and is commonly misdiagnosed as Feline Asthma, making diagnosis a complex process that may include blood tests, X-rays, and ultrasound.

Heartworm disease treatment in cats

While FDA-approved drugs exist to help treat dogs with heartworm disease, the same is not true for cats. There are no medications, FDA-approved or otherwise, that treat adult heartworms in cats. Treatment typically focuses on managing clinical signs and providing supportive care, as well as addressing any secondary complications, such as respiratory distress or heart failure.

Heartworm disease prevention in cats

Since no approved adulticide treatment is available for cats with heartworms, prevention is crucial. Here are some essential measures every cat owner should consider:

  • Monthly preventive medication — Several safe and effective medications are available to prevent heartworm disease in cats. These medications typically come in topical or oral forms and should be administered monthly to keep heartworm larvae from reaching adulthood. Some monthly preventives not only protect against heartworms but also target other common parasites, such as fleas, ticks, ear mites, and intestinal worms. Using a broad-spectrum preventive can provide comprehensive protection for your cat.
  • Environmental control — Mosquitoes breed in standing water, so eliminating sources of standing water around your home can help reduce mosquito populations. Regularly emptying water bowls, cleaning gutters, and fixing leaky faucets can contribute to a mosquito-free environment.
  • Regular veterinary care — Annual wellness exams are essential for maintaining your cat’s overall health, including monitoring for heartworm disease. 

Heartworm disease poses a serious threat to the health and well-being of cats, yet it remains relatively unrecognized among cat owners. By understanding the risks associated with heartworm infection and taking steps to prevent it, cat owners can safeguard their feline companions against this potentially deadly disease. 

Remember, regular veterinary care, preventive medication, and environmental management are key components of a comprehensive heartworm prevention plan. Give our Just Cats Clinic team a call to discuss the best heartworm preventives for your cat.