Heartworm: Symptoms, Treatment, and Prevention

This National Heartworm Awareness Month, the team at AllPets would like to remind pet owners about the dangers of heartworm in both dogs and cats, and how to effectively safeguard their pets from this serious condition.

Heartworm disease is a potentially life-threatening illness caused by the parasitic worm Dirofilaria immitis, more commonly referred to as heartworm.

Heartworms are spread through mosquito bites, as mosquitoes act as carriers for the immature D. immitis larvae. While dogs are the primary hosts for these parasites, cats can occasionally become infected, though they are considered “atypical” hosts.

Once a mosquito bites an animal and passes on the immature heartworm larvae, these parasites travel through the tissues of the host animal, typically settling in the pulmonary arteries - the blood vessels that connect the heart and lungs. It is here that the larvae mature into adult heartworms.

In the early stages, dogs may not display any obvious signs of heartworm infestation, particularly if only a few worms are present.

However, as the heartworm population grows, dogs can begin to experience progressive damage to the lungs and blood vessels. Heartworm can also lead to heart disease, and in severe cases, can affect the liver and kidneys, posing a fatal risk.

Signs of advanced heartworm in dogs may include:

• Persistent cough
• Weight loss
• Lethargy and reduced stamina

As the condition worsens, additional symptoms can appear, such as:

• Signs of heart failure, including fluid accumulation in the chest or abdomen
• Breathing difficulties
• Weakness
• Pale gums
• Fever
• Loss of appetite
• Vomiting
• Jaundice (yellowing of the skin, eyes, or urine due to liver dysfunction)

In cats, heartworm can cause respiratory problems, including coughing, wheezing, and loss of appetite, often referred to as heartworm-associated respiratory disease (HARD). Vomiting is also a common sign in infected cats.

While heartworm disease can be treated, the process is not without risks. Eliminating the heartworms can cause serious inflammation within the pet’s body, and must be carried out carefully and over a prolonged period to avoid dangerous complications.

Fortunately, there are numerous effective preventative measures available for both dogs and cats. Dogs can be protected through long-acting injections or monthly chews or tablets, while cats can be safeguarded with monthly topical treatments.

We recommend keeping pets on preventative treatments all year round, especially those at high risk of exposure to mosquitoes.

If you would like guidance on the best heartworm prevention options for your pet, feel free to get in touch with our team or drop by the clinic for a chat. If you suspect your pet may have been exposed to heartworm without adequate protection, we advise booking an appointment with one of our vets for a thorough evaluation.