April Is National Heartworm Awareness Month

April is National Heartworm Awareness Month. Susan Nelson, clinical professor at the Kansas State University Veterinary Health Center in the College of Veterinary Medicine, is reminding pets owners that the risk of heartworm transmission to pets increases as the weather warms up.

Nelson said the American Heartworm Society reminds all pet owners to Think 12: Administer heartworm preventives 12 months a year and test pets for heartworm every 12 months.

Nelson shares the following facts to help pet owners understand more about heartworm disease and how to keep their pets safe.

  1. Heartworm disease is a potentially deadly disease for pets and is spread by mosquitoes.  

Heartworm disease is spread to pets by the bite of a mosquito that is carrying the microscopic infective larval stage, called L3. It takes around six months for the L3 to develop into adult heartworms. Adult heartworms live in the heart and main pulmonary arteries and they can grow up to 12 inches in length.

  1. Dogs are the most common host for heartworm disease.  

Ferrets and wild animals such as wolves, coyotes, foxes and sea lions also can be infected. There are rare cases of human infection as well.

Heartworm disease in dogs often can cause long-term damage to the heart, lungs and arteries and can affect their health and quality of life well after the parasites are gone. Dogs can harbor several hundred worms.

Signs of heartworm disease in dogs range from none in the early stages to coughing; exercise intolerance; reluctance to exercise; decreased appetite; weight loss; swollen belly; collapse; pale gums; dark, bloody or coffee-colored urine; and death.

  1. Cats also can be infected with heartworm disease.  

Cats are not a preferred host for heartworms and most worms are not able to mature into the adults. Cats with adult heartworms usually only have one to three worms, but even a few worms can cause life-threatening disease in cats because of their small heart size.

The immature larval stages also can cause damage to the lungs in cats in a condition known as Heartworm Associated Respiratory Disease, or HARD. Cats with HARD often require treatment of their symptoms, even if they don’t have adult heartworms.

Signs of heartworm disease in cats include coughing, asthmalike attacks, vomiting, decreased appetite, weight loss, difficulty walking, fainting, seizures, swollen belly from fluid accumulation, sudden collapse and sudden death.

  1. Heartworm disease can be found across the United States.

The American Heartworm Society reports that more than 1 million dogs currently have heartworm disease. It has been diagnosed in all 50 states, with a higher prevalence in the more southern states along the Atlantic and Gulf coasts.

There are many variables that contribute to the prevalence of heartworm in your area from year to year, including climate variations, presence of wildlife carriers, mosquito species and the warmer microhabitats around buildings in urban settings. Even indoor pets are at risk because mosquitoes can be found indoors.

  1. Preventives and treatments are available. 

There are many preventives to help keep your dog or cat from contracting heartworm disease, and puppies and kittens should be started on heartworm preventive no later than 8 weeks of age. There are pills and topical preventives for both cats and dogs as well as injectable preventives that last anywhere from six to 12 months for dogs. Many of these preventives deworm for several common intestinal parasites as well.

Dogs older than 7 months of age can be tested for heartworm disease. They should be retested yearly for early detection of any infection that could occur if a dog spits out its pill, vomits soon after taking its pill or rubs off its topical preventive soon after application or if you give the pill late. Additionally, the available preventives are very good, but nothing is 100%.

There are treatments available should your dog contract heartworm disease, and they are more often than not successful at clearing the infection. There can be serious post-treatment complications and treatment can be very costly, so prevention is your best bet.

Detecting a heartworm infection in cats is not as straightforward as it is in dogs and often involves many additional tests to try to prove an infection. Unfortunately, there is also no approved drug therapy for heartworm infection in cats, and the drug used to treat infections in dogs is not safe for cats. It is very important to ensure cats are on a monthly preventive to try to keep them from becoming infected in the first place.