If you own a dog, cat, or ferret, you are probably aware that heartworm disease is a threat. You strive to be the hero your pet sees when they look in your eyes. You are conscientious about their health care to protect them from parasites and the diseases they cause. Our team at Carriage Crossing Animal Hospital wants to educate you about heartworm disease, so you understand the importance of prevention.

How do heartworms infect my pet?

When a mosquito bites an infected pet, the mosquito picks up young heartworms that, over a two-week period, grow to an infectious stage in the insect’s body. Then, when the infected mosquito bites a pet, the heartworms in their larval stage are transmitted to that pet, causing a new infection. Heartworm disease, which cannot be transmitted from pet to pet, affects each species differently.

  • Dogs — Dogs are natural heartworm hosts, and over six months the parasites can grow to an adult, mate, and produce offspring, increasing the number of worms living in your dog. In severe cases, one dog can harbor several hundred heartworms, up to 12 inches long, causing lasting damage to the dog’s heart, lungs, and arteries, and affecting their quality of life. 
  • Cats — Cats are atypical heartworm hosts, meaning that the worms cannot grow to the adult stage inside your cat. Cats usually harbor only one to three worms, but they are extremely sensitive to immature worms, which can cause a serious condition known as heartworm-associated respiratory disease (HARD). Medications used to treat heartworms in dogs are toxic to cats, making prevention critical for your cat’s protection.
  • Ferrets — Ferrets are also natural hosts, but tend not to harbor as many heartworms as dogs. However, their hearts are small, and one worm can cause devastating disease. Like cats, no heartworm treatment is approved for ferrets, making prevention crucial.

What are heartworm signs in my pet?

Early in the disease process, signs may be subtle, or absent. Active animals are more likely to exhibit signs, while sedentary animals likely never will. 

  • Dogs — If dogs exhibit signs, they will include a muffled cough, lethargy, excessive fatigue after light exercise, and weight loss. As the disease progresses, your dog may develop a hacking cough, their heart will become compromised, and their belly may swell as fluid accumulates. In severe cases, blood flow in the heart is blocked, causing sudden collapse. 
  • Cats — Signs include coughing, wheezing, periodic vomiting, and weight loss, and sometimes fainting and seizures. Unfortunately, the first sign in cats may be collapse and sudden death.
  • Ferrets — Signs in ferrets are similar to dogs, but progression is faster because their hearts are tiny.

How is heartworm disease diagnosed in my pet?

Blood tests in two forms are used to diagnose heartworm disease. Antigen tests detect the presence of adult female heartworms, while antibody tests determine if your pet has been exposed to heartworms.

  • Dogs — All dogs should be tested yearly, ideally at their annual wellness visit. For dogs, our veterinary team will typically use the antigen test, although both tests may be performed if the dog’s history is not known.
  • Cats — Diagnosis is more difficult in cats. Since cats do not usually harbor adult worms, the antibody test can miss an infection, and therefore our veterinary team typically performs both tests. We may also recommend chest X-rays or ultrasound to ensure an accurate diagnosis.
  • Ferrets — Antigen testing and a heart ultrasound are usually required for diagnosis.

How is heartworm disease treated in my pet?

Medications to treat heartworm disease are approved only for dogs. Because activity and excitement increase your pet’s heart rate, which in turn allows the heartworms to cause more damage, infected pets must be kept calm and quiet. In severe cases, surgery may be necessary to remove worms.

  • Dogs — Once your dog’s condition has been stabilized, our veterinary team will devise a treatment protocol based on their disease severity and any complicating factors. Treatment may take months, and your dog is totally exercise-restricted during this time.
  • Cats — Since no drug therapy is approved for cats, only supportive care and antibiotics can be used to stabilize their condition, plus steroids in some cases to decrease inflammation. Spontaneous clearing may occasionally occur, but the damage that remains is typically problematic, and regular heartworm prevention is essential to protect against reinfection.
  • Ferrets — Treatment for ferrets is the same as cats, since no drug therapy is approved for ferrets.

Heartworm prevention products come in different forms, including monthly chewable pills, monthly topical treatments, and injectables given every six months. Year-round protection is vital for every pet, including indoor-only pets, to ensure they are not affected by this devastating, potentially fatal, disease.

Our veterinary team at Carriage Crossing Animal Hospital wants to help you be your pet’s hero. Contact us to schedule an appointment so we can perform the appropriate heartworm tests in our Fear Free hospital, and set up the heartworm prevention protocol best for you and your pet.