Heartworm Disease in Dogs and Cats

Heartworm disease is a serious and potentially fatal condition that affects dogs and cats worldwide. It is caused by the parasitic worm Dirofilaria immitis, which primarily resides in the heart and pulmonary arteries of infected animals. While heartworms primarily affect dogs, they can also infect cats, albeit less frequently. Understanding the risks, prevention methods, and treatment options is crucial for pet owners to safeguard their furry companions' health.

The Risks of Heartworm Disease

Heartworms are transmitted through the bite of an infected mosquito. When a mosquito bites an infected animal, it picks up microscopic heartworm larvae. These larvae mature within the mosquito over a period of about two weeks and can then be transmitted to another animal when the mosquito bites again.

In dogs, heartworm disease can lead to severe and potentially life-threatening complications, including:

• Cardiopulmonary Issues: As the worms mature and multiply, they can cause inflammation and damage to the heart, lungs, and associated blood vessels.
• Respiratory Distress: Infected dogs may experience coughing, difficulty breathing, and exercise intolerance.
• Heart Failure: In advanced cases, heartworm disease can result in congestive heart failure, leading to lethargy, weakness, and fluid accumulation in the abdomen and chest.

• Respiratory Issues: Cats infected with heartworms may exhibit coughing, wheezing, and difficulty breathing, which can mimic symptoms of other respiratory conditions.
• Vomiting and Anorexia: Infected cats may experience gastrointestinal symptoms such as vomiting and decreased appetite.
• Sudden Death: Heartworm disease can lead to sudden and unexpected death in cats, often without prior clinical signs.

Prevention is Key

Preventing heartworm disease is far easier and safer than treating an infected pet. Fortunately, several preventive measures are available for both dogs and cats:

Monthly Preventive Medications

Veterinarians recommend monthly heartworm preventive medications for dogs and cats. These medications are typically administered orally or topically and are highly effective at protecting pets from heartworm infection when administered consistently.

Annual Heartworm Testing

Annual heartworm testing is essential for both dogs and cats, even if they are on preventive medication. Early detection allows for timely intervention and treatment if an infection is detected.

Mosquito Control

Minimizing exposure to mosquitoes can help reduce the risk of heartworm transmission. Pet owners should eliminate standing water around their homes, use mosquito repellents, and consider using mosquito screens on doors and windows.

Treatment Options

Treatment for heartworm disease can be challenging and expensive, particularly in advanced cases. Treatment typically involves a combination of medication, rest, and careful monitoring. In dogs, treatment may include:

• Adulticide Therapy (used to kill adult heartworms). This treatment can be risky, as the dying worms can cause severe inflammation and potentially block blood flow in the lungs.
• Anti-inflammatory medications may be prescribed to reduce inflammation and alleviate symptoms during treatment.
• Dogs undergoing heartworm treatment must be kept quiet and restricted from strenuous activity to minimize the risk of complications.

Unfortunately, there is no specific treatment for heartworm infection in cats, and management focuses primarily on alleviating symptoms and supportive care.

International Travel

If your pet is traveling internationally, heartworm treatments or testing may be required, depending on the final destination. New Zealand, for example, requires dogs to have a heartworm antigen ELISA test AND be treated with a heartworm prevention product prior to travel. South Africa also requires both a specific blood test and an approved heartworm preventive treatment. South Africa additionally requires dogs entering the country to travel with a 6-month supply of heartworm preventive medication since they do not have easily accessible products there. 

Heartworm disease poses a significant threat to the health and well-being of dogs and cats. However, with proper preventive measures and regular veterinary care, pet owners can minimize the risk of infection and ensure their furry companions lead long, healthy lives. Remember, prevention is key, so talk to your veterinarian about the best heartworm prevention plan for your pets today.

*Photo by Michael Oxendine on Unsplash