Learn how to protect your pets from heartworm
Once again the warm weather has brought with it the emergence of mosquitoes, and where there are mosquitoes, there are heartworms.
So once again, it is important to know the facts regarding this serious and sometimes fatal disease.
Heartworms are spread only through the bite of a mosquito and there are some 20 species that can carry and spread the disease.
Irrigation and population growth in the West has expanded the habitat for both the western knot hole mosquito and the Asian tiger mosquito. The former is the primary vector in the West, and the latter is able to live and reproduce in very small containers such as flower pots.
If an infected mosquito bites your pet, the larvae or “microfilaria” make their way into the tissues. Within 3–12 days the larvae molt into a juvenile adult and find their way to the vessels in and around the heart. Another 6–9 months is required for mature adults to develop.
Adult heartworms can grow up to 12 inches long and infections can range from as few as one to as many as several hundred worms living within the pulmonary vessels and right atrium of the heart. Their presence can cause chronic inflammation within the lungs and lining of the heart leading to scarring, asthma, coughing, exercise intolerance, heart failure and sudden death.
While heartworm disease can be effectively treated, the damage done within the heart and lungs is often irreversible. Treatment also is expensive, often running $600–$1,000 dollars in larger dogs and requiring strict cage confinement for 2–3 months.
To add to that, there currently is a shortage of the only approved medication for treatment, so most veterinarians will not have any available for several months after your pet has been diagnosed.
Therefore, sticking to monthly preventives year round is the best ways to assure your pet’s protection.
Yearly testing requirements are simply because of the fact that the monthly preventives are effective only at eliminating the larvae. Once the larvae have developed into the juvenile adults, the preventive is no longer effective. So the test looks for the presence of adult worms that may have developed because of a missed dose, missed timing of dosing or ineffective medication.
Heartworms can, in fact, be contracted during winter months. While it is true that maturation of the larvae within the mosquito comes to a stop below 57 degrees, development quickly resumes once the temperature rises. And, as mentioned previously, some mosquitoes can reproduce in very small “microenvironments” around our homes that may be quite a bit warmer than the air temperature around them.
So recommending when to stop and start giving preventative is just a guess at best. Heartworm larvae have been found inside of mosquitoes in the dead of winter and at elevations as high as 8,000 feet.
Heartworm infections are not limited to our domestic dogs either. Wild canids such as coyotes continue to be a reservoir for infection in suburban and rural areas such as ours.
Cats and ferrets also are susceptible to the disease and your veterinarian can recommend the best options for these pets.
The current recommendations are to start prevention during your puppy’s first visit at around 8–12 weeks of age. A simple 10 minute blood test is performed after 6 months of age and then yearly or as recommended by your veterinarian.
Starting an older dog on prevention requires a test prior to starting medications followed by a second test 6–9 months later.
Many heartworm preventives also are effective against intestinal parasites, giving your pet added protection.
While recommendations may vary slightly, it is best to talk to your veterinarian to determine the right product and options for your pet.