Nedele: Heartworm Disease |

Nedele: Heartworm Disease

Carrie Nedele, DVM
Courtesy Photo |

Heartworm disease, also known as dirofilaria immitis, is a potentially fatal disease and can be a very confusing topic. It used to be a disease considered not present at altitude due to cold nights and hard freezes, but the average Colorado veterinary clinic now reports 1-5 positive heartworm cases annually.

Dogs and other wild canids (ie: coyotes, wolves, foxes) are the natural host for heartworm disease, though cats and humans may also be affected. This disease is transmitted when a mosquito takes a blood meal from an animal infected with adult female heartworms. The mosquito takes in baby heartworms, called microfilaria, from the infected animal’s blood and then the baby heartworms mature within the mosquito for 10-14 days. When the mosquito bites a new host, the matured baby heartworms are deposited onto the skin and then enter the host through the mosquito’s bite wound. It takes approximately six months for the baby heartworms to mature into adult worms within the host. Adult heartworms are approximately one foot long and live in the heart, lungs, and blood vessels of infected animals.

In general, dogs with heartworm disease may show no or very few symptoms in the early stages. As the disease persists, common symptoms include coughing, exercise intolerance, decreased appetite, and weight loss. Cats with heartworm disease show symptoms more quickly, which include coughing, asthma-like attacks, fainting, seizures, vomiting, weight loss, and anorexia. If left untreated, heartworm disease ultimately results in death of the infected animal.

The American Heartworm Society recommends that dogs begin heartworm prevention by the age of six months old and continue with monthly preventative given year-round. Dogs should be tested for this disease yearly, which consists of a small blood sample that can be drawn during an annual wellness appointment.

Heartworm disease is a very serious and potentially fatal disease of dogs and cats that can easily be prevented. Testing annually is a good way to scan for disease and will allow for it to be caught early enough in order for it to be treated.

Carrie Nedele is the owner of Grand Animal Hospital in Fraser and will be contributing articles to the Sky-Hi News on pet health.

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