Heartworm Life Cycle

The heartworm life cycle begins when a mosquito bites an infected animal and ingests tiny heartworm larvae along with the animal's blood. Coyotes, wolves, foxes, and ferrets can also develop heartworm disease in addition to dogs and cats. Next, the larvae develop into an infective stage inside the mosquito. When a heartworm disease-carrying mosquito bites your pet, it transmits the larvae that develop for approximately two months in your pet's tissue. Afterwards, developing and mature adult heartworms can be found in the bloodstream, heart, and lungs. They can also produce tiny heartworm larvae that is released into the blood and is picked up by mosquitoes who repeat the process again.

Heartworm disease is serious and potentially fatal in pets. Worms can grow up to a foot long and live in your pet's heart and lungs. Signs of heartworm infection includes coughing, difficulty breathing, and lethargy.  Some pets may not show signs of the disease. Treatment of heartworm disease is difficult. In cats, there is no approved treatment. Prevention is easy. We recommend a once monthly heartworm preventative medication for dogs and cats regardless of their lifestyle. For more information about disease-carrying mosquitoes in Ventura and Los Angeles County, click here. To read about one of our patient's journey through heartworm treatment, click here.

Parasites in pets… and people

Regular fecal testing for parasites is a very important part of keeping your pet and even you healthy. Intestinal parasites are fairly common in pets and there are several different kinds. Some intestinal parasites are microscopic and cannot be seen with the naked eye while some worms can be seen in feces or on a pet’s bedding.

A few kinds of common parasites in pets are zoonotic which means they can infect people. Giardia and Roundworm are two of the most common zoonotic parasites in our area. Giardia usually causes diarrheal illness in people. It is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it tolerant to chlorine disinfection. While Giardia can be spread in different ways, water (drinking water and recreational water) is the most common method of transmission. Roundworm may cause illness in people including fever, fatigue, coughing, wheezing, abdominal pain, eye inflammation, retinal damage, and even vision loss. The most severe cases of Roundworm infection in people are rare, but are more likely to occur in young children, who often play in dirt, or eat dirt contaminated by dog or cat feces.

Pets who are infected with intestinal parasites might have diarrhea, weight loss, appetite changes, or a large belly but many pets have no symptoms at all. We recommend fecal testing for intestinal parasites including Giardia every 6 months to help keep your pet and you healthy. We also recommend keeping your pets on a monthly preventative for heartworms and other internal parasites that is relatively easy to give and inexpensive.

In honor of American Veterinary Medical Association’s (AVMA) Responsible Pet Ownership Month in September we are donating a portion of every preventative fecal test performed in the month of August to Ventura County Animal Service’s (VCAS) ongoing effort to educate about responsible pet ownership and help keep pets out of shelters.