Heartworm Disease in Dogs
Aug 13, 2021
What is heartworm disease?
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. Heartworm disease affects dogs, cats and ferrets, but heartworms also live in other mammal species, including wolves, coyotes, foxes, sea lions and—in rare instances—humans. Because wild species such as foxes and coyotes live in proximity to many urban areas, they are considered important carriers of the disease.
How do dogs get heartworms?
Only by the bite of an infected mosquito. There’s no other way dogs get heartworms. And there’s no way to tell if a mosquito is infected. That’s why prevention is so important.
Heartworm disease has been reported in all 50 states. And the bite of just one mosquito infected with the heartworm larvae will give your dog heartworm disease.
Heartworm disease has not only spread throughout the United States, but it’s also now found in areas where veterinarians used to say “Oh, we don’t have heartworm disease.” Areas like Oregon, California, Arizona, and desert areas -- where irrigation and building are allowing mosquitoes to survive. And if you have mosquitoes and you have animals, you’re going to have heartworms. It’s just that simple.
It takes about seven months, once a dog is bitten by an infected mosquito, for the larvae to mature into adult heartworms. They then lodge in the heart, lungs, and surrounding blood vessels and begin reproducing. Adult worms can grow up to 12 inches in length, can live 5-7 years, and a dog can have as many as 250 worms in its system.
Heartworm Symptoms in Dogs
As heartworm can be deadly, it is important to know if your dog is playing host to these parasites.
There are often no signs of heartworm disease early on, however as the disease progresses increasingly severe signs may be seen. Here is a quick run down of heartworm symptoms in dogs:
1. Cough
2. Lethargy and exercise intolerance
3. Weight loss
4. Trouble breathing
5. Enlarged abdomen
While puppies can be infested by heartworm from the bite of a mosquito, disease does not occur until the worms mature, which can take 6-7 months. For this reason, heartworm disease is not seen in puppies less than 6 months of age.
When should dogs be tested?
Annual testing is necessary, even when dogs are on heartworm prevention year-round, to ensure that the prevention program is working. Heartworm medications are highly effective, but dogs can still become infected. If you miss just one dose of a monthly medication—or give it late—it can leave your dog unprotected. Even if you give the medication as recommended, your dog may spit out or vomit a heartworm pill—or rub off a topical medication. Heartworm preventives are highly effective, but not 100 percent effective. If you don’t get your dog test, you won’t know your dog needs treatment.
How to prevent heartworm?
Many products are FDA-approved to prevent heartworms in dogs. All require a veterinarian’s prescription. Most products are given monthly, either as a topical liquid applied on the skin or as an oral tablet. Both chewable and non-chewable oral tablets are available. One product is injected under the skin every 6 or 12 months, and only a veterinarian can give the injection. Some heartworm preventives contain other ingredients that are effective against certain intestinal worms (such as roundworms and hookworms) and other parasites (such as fleas, ticks, and ear mites).
Year-round prevention is best!