Rain, Mosquitoes & Heartworm

The St. Louis area has had a particularly rainy summer, and where there’s rain, there’s mosquitoes.  Keep your pet safe from potentially deadly heartworms carried by mosquitoes by learning about the problem and how to keep it from harming your furry friend.

When an infected mosquito bites your pet, it transmits tiny parasitic worms into their blood that travel into your pet’s lungs and heart. As the worms grow, they also reproduce, leading to more worms attaching themselves to the organs and further limiting their functionality. Heartworms can live up to 7 years in a dog and grow to be 12 inches.

Image from the American Heartworm Society

Image from the American Heartworm Society


While cats are not considered an ideal host environment for heartworms, and it is less common to see cases of heartworm in cats, it is still possible for cats to contract heartworms from mosquitoes. Unlike with dogs, there is no approved treatment for heartworm in cats, so it’s important to keep those felines on preventative as well, even if they are indoor cats.

If your dog tests positive for heartworm, there are few options for treatment. Immiticide is an arsenic-based drug that is injected into muscles of dogs to kill the worms. After a series of shots, dogs must be kept quiet and contained for months as the worms die off. Too much activity or exercise can cause the worms to break up too quickly and cause blood clots, leading to complications in the lungs or heart failure. Even when quietly contained during treatment, the toxic effects of arsenic can be damaging to the dog’s organs.

Injections of immiticide are not only difficult on your dog’s body, they are hard on your wallet, too. According to the American Heartworm Society, with bloodwork, x-rays, treatments and vet visits, the total cost of treatment can be up to 15 times the cost of a year’s supply of preventative.

The other common option for treating heartworms is administering a monthly preventative (such as Heartguard Plus) once heartworms are detected. This treatment is much less expensive than immiticide injections, but it only kills off the larvae, called microfilariae, leaving the adult worms in the system. This treatment is a long-term solution that works best in cases where the heartworm is not too advanced.

Neither treatment option is guaranteed to successfully treat heartworms in dogs. The best way to treat heartworms is to stop them from forming. Giving your pets a monthly oral or topical treatment (Heartguard, Advantage Multi, or Revolution, e.g.) is the easiest, most effective way to keep your dogs and cats safe from the dangers of heartworm. Be sure to give them preventatives year-round, since there is no good way to know when mosquitoes have gone for the year or when in the spring they will return. Following these simple precautions will leave your pets healthy and mosquitoes high and dry!


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