Can you give heartworm preventative to a dog with heartworms?

Heartworm preventives do not kill adult heartworms. Also, giving a heartworm preventive to a dog infected with adult heartworms may be harmful or deadly. If microfilariae are in the dog’s bloodstream, the preventive may cause the microfilariae to suddenly die, triggering a shock-like reaction and possibly death.

While it is convenient to buy all of your dog’s food, treats, flea treatment, and other items at once at the pet store, heartworm medication is not available over-the-counter in the United States. There is a sound medical justification for this; if the dog has heartworms, it is not safe.

The adult heartworm, Dirofilaria immitis, can reach a length of over a foot. When a mosquito bites a dog that has heartworm infection, it transmits the heartworm larvae to the other dog. The heartworm invades the pulmonary arteries and heart in infected dogs. Veterinarians use a different kind of test because it could take five to seven months from the time the dog is bitten until a blood test finds the presence of heartworms.

Before prescribing medication, your veterinarian performs antigen testing on your dog to make sure he is heartworm-free. Heartworm-positive dogs taking the medication could have extremely negative reactions. The bloodstream of affected dogs contains millions of “baby” heartworms, according to the American Heartworm Society. Giving medication to a dog with these microfilaria, as they are officially known, can result in the dog experiencing a shock-like reaction as the microfilaria begin to die off.

If your dog tests positive for heartworms, treatment is available. The Merck Veterinary Manual states that melarsomine dihydrochloride is the only heartworm medication available for treating adult worms. Two injections are needed, one 24 hours after the first. For the following six weeks, as the worms die off, a dog with a high number of worms is at risk for developing pulmonary thromboembolism. It can be challenging to keep him quiet during the recovery period when your dog is active. According to the MVM, other treatment protocols advise giving ivermectin prophylactic doses for one to six months before giving melarsomine, if the worm burden is less severe. As a result, some of the circulating first stage larvae are diminished or eliminated.

If your dog’s heartworm test is negative, your veterinarian will recommend a monthly or daily preventative that can be taken orally, chewed, or applied topically. Your veterinarian will advise you whether to administer the medication year-round or only during the seasons when mosquitoes are active based on your location. Your veterinarian performs an additional test each year when you bring your dog in for his annual checkup to ensure that he is still heartworm-free before prescribing medication.

Before making any dietary, medication, or exercise changes for your pet, always consult your veterinarian. This information is not a substitute for a vet’s opinion.

A writer for more than 20 years, Jane Meggitt She has written for a major newspaper chain in addition to appearing in publications like “Horse News,” “Suburban Classic,” “Hoof Beats,” and “Equine Journal.” She holds an Associate of Arts from the American Academy of Dramatic Arts in New York City and a Bachelor of Arts in English from New York University.

How do monthly heartworm preventives work?

Whether the preventive you choose is given as a pill, a spot-on topical medication or as an injection, all approved heartworm medications work by eliminating the immature (larval) stages of the heartworm parasite. This includes the infective heartworm larvae deposited by the mosquito as well as the following larval stage that develops inside the animal. Unfortunately, in as little as 51 days, heartworm larvae can molt into a juvenile/immature adult stage, which cannot be effectively eliminated by preventives. Because heartworms must be eliminated before they reach this adult stage, it is extremely important that heartworm preventives be administered strictly on schedule (monthly for oral and topical products and every 6 months or 12 months for the injectable). Administering prevention late can allow immature larvae to molt into the adult stage, which is poorly prevented.

I live in the desert where it is very dry and there are very few mosquitoes. My vet says I should use monthly prevention. What should I do?

Arizona has a variety of climates, including microclimates that are influenced by things like irrigated fields, backyard ponds, and artificial golf courses. These factors influence the length and severity of the mosquito season. We also know that wild animals, like coyotes, can carry heartworm infections in some areas, and your dog or cat could contract the disease from these infected animals. Heartworm disease is present in Arizona even though it may not be found there as frequently as in some other states. In fact, nearly every county in the state has been found to have heartworm disease.

Even in states like Arizona, the American Heartworm Society advises year-round prevention. And keep in mind that your dog or cat may be more vulnerable to exposure if you take them out of the country with you or to an area of Arizona where mosquitoes are common.

How significant is my pet’s risk for heartworm infection?

Even if heartworms don’t seem to be a problem in your neighborhood, there are many other things to take into account. Heartworm disease may be more prevalent in your neighborhood than you realize, or you may unintentionally take your pet to a region where heartworms are more prevalent. Additionally, each year, heartworm disease spreads to new areas of the nation. Heartworms can be carried by stray and neglected dogs as well as some types of wildlife like coyotes, wolves, and foxes. Heartworm disease is spread by mosquitoes that are carried far by the wind and by infected animals being moved to previously uninfected areas (this occurred after Hurricane Katrina when 250,000 animals, many of which had heartworms, were “adopted” and shipped across the nation).

Heartworm disease has been identified in all 50 states, and there is no way to predict risk factors for it. Infection rates vary significantly from year to year, even within communities, due to a number of factors, including alterations in the climate and the presence of wildlife carriers. Additionally, both indoor and outdoor pets are at risk because infected mosquitoes can enter from the outside.

Because of this, the American Heartworm Society advises that you “think 12” by doing the following: (1) having your pet tested for heartworm every 12 months; and (2) giving your pet heartworm preventative every 12 months of the year.


What to give a dog that already has heartworms?

Your veterinarian is recommending what is best. The U.S. government has approved only one medication, melarsomine. S. Veterinary hospitals should administer this medication by injection to treat heartworm infection in dogs that have been approved by the Food and Drug Administration (FDA).

Can I give my dog heartworm medicine without a heartworm test?

As it takes at least 6 months for a dog to test positive after infection, puppies under 7 months of age can begin heartworm prevention without a heartworm test, but they should be tested 6 months after your initial visit, again 6 months later, and then yearly after that to make sure they are heartworm-free.

How do you get rid of heartworms in a dog without going to the vet?

With the help of diatomaceous earth, citrus oils, and cedar oils, they can be naturally controlled. Herbs like milk thistle and homeopathic remedies like berberis can help dogs who need conventional treatment by reducing the toxicity of the medications and heartworms that are dying.

How long can a dog last with heartworms?

However, it is generally believed that most dogs with heartworm infection won’t live longer than two years without any kind of treatment. Heartworms, however, can persist in a dog for up to 6 years. If detected early, heartworms in your dog can be cured by adhering to a rigorous treatment schedule.