Late summer is prime mosquito season, and that means your pet can contract deadly heartworm disease if you don’t protect her. According to the Companion Animal Parasite Council, Ohio veterinarians diagnosed heartworm disease in more than 2,500 dogs and 1,500 cats in 2018. In other words, more than 4,000 Ohio pets contracted this preventable disease because they were left vulnerable to infection. Luckily, ValuVet Wellness Veterinary Clinic offers affordable heartworm prevention options to help you protect your beloved pet.

What are heartworms?

Heartworms, or Dirofilaria immitis, are large, nematode worms that live in the heart and lung vessels of dogs and cats. Larval heartworms enter a pet’s body and migrate to the lungs, where they mature over approximately six months. The fully grown worms, which can reach 12 inches in length, begin to reproduce and exponentially multiply. Dogs are the preferred heartworm host, and they can develop a large worm burden and advanced infection. Cats are considered dead-end hosts in that the few heartworms that enter their body can grow to maturity, but cannot reproduce. 

How can pets contract heartworms?

Heartworms are transmitted to pets by mosquitoes. A mosquito that bites an infected dog picks up larval worms with its blood meal. After a short development period, the worms can be transmitted to another pet the mosquito bites. After transmission, larval worms migrate through the new host’s body, mature, and begin reproducing. New larval worms can then be transferred by another mosquito, completing the life cycle.

Heartworms cannot be directly transmitted from one infected pet to another without a mosquito, since the development period in the mosquito’s body is a required part of their life cycle. 

How does heartworm disease affect pets?

Heartworms in a dog’s body can cause several problems, including:

  • Blood flow obstruction through the heart and lungs
  • Inflammation from the worms’ presence 
  • Breathing difficulties when fluid leaks into the lungs

Without prompt diagnosis and treatment, heartworm disease will progress to congestive heart failure and death in affected dogs. 

Cats can also develop heartworm disease, although they are not the intended host. A few worms living in a cat’s body can cause significant inflammation that can become fatal.

What are heartworm disease signs in pets?

As newly transmitted worms migrate through a pet’s body and mature, there are typically no signs of the quietly developing disease. Clinical signs, which often don’t appear in dogs until many generations of adult worms have reproduced and a significant number of worms have accumulated, may include:

  • Decreased appetite
  • Coughing
  • Lethargy
  • Vomiting
  • Difficulty breathing
  • Collapsing suddenly

In cats, clinical signs are caused by inflammation incited by the few worms’ presence, rather than a large worm burden. Cats may display similar symptoms to dogs, but often show no clinical signs, and can collapse or die suddenly.

How is heartworm disease diagnosed in pets?

In dogs, heartworm disease is diagnosed through a simple test performed on a few drops of blood that detects adult female worms. If your dog tests positive, adult female worms are present and have likely already begun reproducing, so your dog is in danger of severe heart and lung disease. Further tests, such as X-rays, blood work, and ultrasound, may be performed to determine disease severity before developing a treatment plan.

In cats, the presence of only a few worms—that may be all males—requires a different test that detects antibodies the cat’s immune system makes against the worms. The antibody test also requires only a few drops of blood.

How is heartworm disease treated in pets?

Heartworm disease treatment includes several medication types to address multiple disease components, including:

  • Medication to kill adult heartworms, which is injected into the dog’s back muscles and requires several doses spaced one month apart
  • Medication to kill immature worms before they develop into adults
  • Antibiotics to kill the bacteria carried by the heartworms that trigger inflammation
  • Anti-inflammatories to decrease the inflammation caused by heartworms

During treatment, dead and dying worm pieces can lodge in important blood vessels and cause sudden death. The risk increases with larger worm burdens and increased activity, so dogs must be crated or confined to a small area to minimize activity and reduce the possibility of death. 

No medication is approved to kill heartworms in cats, so treatment focuses on decreasing worm-induced inflammation and treating symptoms that may arise.

How can I protect my pet from heartworm disease?

Fortunately, heartworm disease is easily preventable, and a number of medications are available. ValuVet Wellness Veterinary Center is pleased to announce that we now offer ProHeart®12, an injectable heartworm preventive that protects your dog for an entire year. Dogs one year of age and older can receive the ProHeart®12 injection, and you can enjoy a year without worrying about missing a monthly preventive dose and leaving your beloved companion unprotected.

During the month of September, clients who purchase a ProHeart®12 injection will receive a free heartworm test to confirm their pet’s heartworm-free status before starting prevention. 

If you have questions about heartworm disease, or you would like to schedule an appointment to discuss heartworm prevention or purchase a ProHeart®12 injection for your pet, contact us.