Have a Heart and Get Ahead of Heartworm! 

By: Melanie Rushforth, Vice President, Veterinary Services SPCA Serving Erie County

Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. It is caused by foot-long worms (heartworms) that live in the heart, lungs, and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body. Sounds awful, right? There are preventive measures that all pet owners should be aware of. Read on!

Heartworm disease is far more prevalent in dogs, since the dog is a natural host for heartworms, which means that heartworms that live inside the dog mature into adults, mate, and produce offspring. If untreated, their numbers can increase, and dogs have been known to harbor several hundred worms in their bodies. Heartworm disease causes lasting damage to the heart, lungs, and arteries, and can affect the dog’s health and quality of life long after the parasites are gone. For this reason, prevention is by far the best option, and treatment—when needed—should be administered as early in the course of the disease as possible.

The mosquito plays the main role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream. When a mosquito bites and takes a blood meal from an infected animal, it picks up these baby worms, which develop and mature into “infective stage” larvae over a period of 10 to 14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal’s skin and enter the new host through the mosquito’s bite wound. Once inside a new host, it takes approximately six months for the larvae to mature into adult heartworms. Once mature, heartworms can live for five to seven years in dogs and up to two to three years in cats. Because of the longevity of these worms, each mosquito season can lead to an increasing number of worms in an infected pet. For something as small as a mosquito, those little insects can really wreak havoc.

In the early stages of the disease, most dogs show few symptoms or no symptoms at all, which is why it is particularly important to take preventative precautions. The longer the infection persists, the more likely symptoms will develop. Active dogs, dogs heavily infected with heartworms, or those with other health problems often show pronounced clinical signs which may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen. Dogs with large numbers of heartworms can develop a sudden blockages of blood flow within the heart leading to a life-threatening form of cardiovascular collapse. This is called caval syndrome and is marked by a sudden onset of labored breathing, pale gums, and dark bloody or coffee-colored urine. Without prompt surgical removal of the heartworm blockage, few dogs survive.

The American Heartworm Society recommends that you “think 12:” (1) get your pet tested every 12 months for heartworm and (2) give your pet heartworm preventative 12 months a year. Some states do have a higher disease risk than others, but heartworm has been reported in all 50 U.S. states and dogs and some cats did test positive for heartworm disease in New York State last year. The mosquito population is determined by climate, mosquito species, and local wildlife. As more animals travel nationally and internationally, the risk of heartworm disease is increasing in each state.

Heartworm disease is easily preventable. There are several excellent products that when given monthly year-round prevent and control common intestinal parasites as well as heartworm disease. If your dog is not currently on heartworm prevention, please contact your veterinarian immediately to establish a preventative treatment schedule or contact the Lipsey Clinic!

The SPCA’s Lipsey Veterinary Clinic offers veterinary services for cats and dogs! To see all available services, please visit LipseyClinic.com. To make an appointment, please call 716-531-4700.