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April has been recognized as Heartworm Prevention Month

To bring awareness to the danger that heartworm disease can bring to cats, dogs, and other mammals, April has been recognized as Heartworm Prevention Month. Although responsible pet parents and pet sitting professionals do their best to follow the guidelines for heartworm prevention, the American Heartworm Society (AHS) estimates that millions of animals currently have or are susceptible to the disease.

Heartworm disease is described as a serious, potentially fatal disease that affects both dogs and cats, as well as other mammals. Because wild species such as wolves and coyotes are often spotted in urban areas, they are important carriers of the disease, which is caused by foot-long worms that can live in the heart, lungs, and various blood vessels of many mammals.         

Heartworm disease is transmitted from one animal to another by mosquitos. Female heartworms that live in an infected mammal produce microscopic baby worms called microfilari. When a mosquito draws blood from a mammal such as a wolf, it also takes the microfilari, which grow into “infective stage” larvae over a period of 10 to 14 days. Later, when the mosquito bites a pet, the infective larvae enter the pet’s bloodstream via the bite wound. Once inside the new host, it takes 6 months for the larvae to mature into adult heartworms that reproduce and damage the heart tissues. Mature heartworms can live for 5-7 years in dogs, and up to 2-3 years in cats. Some dogs have been found to have up to several hundred heartworms in their body.

Heartworm disease is different in dogs than cats. Dogs that are in early stages of the disease show few symptoms, or even none at all. Once the disease progresses, symptoms may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As the disease continues to progress, dogs may develop heart failure and a swollen belly due to excess fluid in the abdomen.

In cats, most heartworms do not survive to be adults. The symptoms of heartworm disease in a cat can be either very subtle or very dramatic, and include coughing, asthma-like attacks; periodic vomiting; lethargy; lack of appetite; weight loss; difficulty walking; or seizures. Unfortunately, in some cases the first sign of heartworm in a cat is collapse or sudden death. While heartworms often go undiagnosed in cats, it is important to know that immature heartworms can cause damage and a condition known as Heartworm-Associated Respiratory Disease (HARD).

Treatment for heartworm is only available to dogs, not cats, because cats’ bodies cannot withstand the chemicals necessary to cure heartworm disease. The treatment for dogs is difficult, risky, and expensive. The only medication known to kill adult heartworms contains arsenic, which causes further illness to the dog (though temporary), and can result in death if the dog is not strong enough to withstand the treatment. Further, there is a shortage in the U.S. of the medication, which has necessitated the use of less effective treatments. Therefore, prevention is key! Even if all worms have been killed, dogs can suffer lasting damage to the heart, lungs and arteries, which can affect the dog’s health and quality of life.

Even though pet parents cannot entirely control the risk factors of their pet contracting the disease, the AHS recommends that pet parents “Think 12,” meaning (1) get their pet tested every 12 months for heartworm and (2) give their pet heartworm preventive 12 months a year. It’s a small way to prevent a big problem!