Heartworm in dogs is a life-threatening, mosquito-borne parasitic infection that infects over a million dogs in the United States. For this reason, heartworm prevention for dogs is recommended for puppies, adult dogs, and senior dogs alike.
In this Sploot Vets guide, we talk about heartworm prevention for dogs, the options available for pet parents, and why prevention is considered better and safer than heartworm treatment for dogs.
Quick Facts About Heartworm in Dogs
Dogs can get heartworm from infected mosquitos, which transmit heartworm larvae into the dog’s bloodstream. Once inside the dog’s body, heartworm larvae take around 6 - 7 months before maturing into adult heartworms. These worms then reside in the heart, lungs, and blood vessels, causing damage to these organs over time.
Some of the most notable symptoms of heartworm in dogs include:
- Persistent dry coughing
- Shortness of breath
- Lack of energy & unwillingness to exercise
- Reduced appetite & weight loss
- Vomiting (however, the vomit won’t have heartworms since these parasites are not in the digestive tract)
- A swollen abdomen (more common in heavy infestations, this is caused by heart failure and subsequent fluid accumulation)
→ Learn more - Heartworm in Dogs & Cats: Symptoms, Diagnosis & More
A. Heartworm Prevention for Dogs
Do Dogs Really Need Heartworm Prevention?
Heartworm infections in dogs are common and generally life-threatening. For these reasons, heartworm prevention for dogs is considered an essential part of a dog’s routine care.
There are three main components of heartworm prevention for dogs:
- Heartworm preventatives – This is an oral, topical, or injectable vet-prescribed medication that protects dogs from heartworms. These need to be given on time for maximum effectiveness.
- Yearly heartworm screening – This is generally recommended for all dogs over 7 months of age, including ones that are on consistent preventatives. This measure helps catch any possible infections early.
- Heartworm screening before starting preventatives – This test is typically recommended for dogs over 7 months of age. Vets may also recommend this test for dogs with late or missed heartworm preventatives.
Kinds of Heartworm Preventatives for Dogs
There are three main kinds of heartworm preventatives for dogs, each with their own frequency of administration. These include:
- Oral Heartworm Preventatives – these are prescribed oral medications (usually chewable) given every month. These can provide additional protection from fleas, ticks, and dog intestinal worms, depending on the brand.
- Topical Heartworm Preventatives – these are prescribed liquid medications absorbed through the dog’s skin, typically applied between the shoulder blades every month. They can also provide additional protection from fleas, ticks, and dog intestinal worms.
- Injectable Heartworm Preventatives – these are injected by a licensed veterinarian and can be viable for 6 to 12 months, depending on the injection’s indications. These typically provide protection solely against heartworms.
Note: Heartworm preventatives for dogs can only kill larval stages of heartworm (aka heartworm microfilaria). These preventatives do NOT kill adult heartworms, which further highlights the importance of prevention.
How Long Do Dogs Need Heartworm Prevention?
Heartworm prevention for dogs is needed year-round for life. This includes colder months because mosquitoes (which transmit heartworms) can survive indoors and in warm spells. Consistent prevention is the safest way to protect against this potentially fatal infection.
How To Get Heartworm Prevention Without A Vet
Right now, this isn’t possible. Pet parents need to get a veterinary prescription for heartworm medication—mainly because giving heartworm preventatives to a pet that’s already infected with heartworms can, in some cases, cause serious complications.
This can trigger a shock-like reaction or even death, due to the release of toxins and Wolbachia (the heartworms’ symbiotic bacteria) from dying microfilaria. This is also why a heartworm screening may be recommended, especially for late-starters.
→ Assess your dog’s heartworm risk - take the assessment here: Heartworm in Dogs & Cats: Cause, Prevention & More
B. Heartworm Treatment for Dogs
Do I Really Need To Treat My Dog For Heartworm?
Yes. Once a dog tests positive for heartworm, they need prompt veterinary recommended heartworm treatment.. If left untreated, heartworm disease in dogs can cause progressive, irreversible damage to the lungs and heart, which can result in heart failure and death in pets.
How Is Heartworm Treatment For Dogs Done?
Heartworm treatment for dogs is performed with precision and thoroughness since it is often a year-long protocol requiring the timely dosing of various medications for maximum effectiveness. It typically includes the following:
1. Melarsomine
Heartworm treatment for dogs involves the use of an injectable drug called melarsomine (Immiticide®), which kills adult worms in the heart and blood vessels. Three doses of the injection are given by a licensed veterinarian within a recommended schedule.
Note: Typically, the first dose of melarsomine is followed by 30 days of rest. Then, the last 2 injection doses are given 24 hours apart.
2. Anti-Parasitic & Anti-Inflammatory Drugs
Dogs may also get prescribed anti-parasitic medications (e.g., ivermectin, moxidectin) that kill the heartworm microfilaria or larva. In addition, veterinarians may prescribe anti-inflammatory medications before and/or during treatment to manage inflammation caused by the parasite.
3. Restricted Physical Activity
Dogs need rest during heartworm treatment because even mild physical activity can increase the risk of serious complications, such as blocked blood vessels or lung damage, as the worms die and break apart due to the treatment.
4. Post-Treatment Heartworm Screening
Nine months after treatment, the dog will be screened for heartworm again to confirm if the heartworm treatment was successful.
Can Dogs Be Completely Cured of Heartworms?
Yes, heartworm treatment for dogs can successfully treat the parasitic infection. The main injectable drug used, melarsomine, is 98% effective at killing adult worms.
Does The Slow Kill Method Work For Heartworms?
The slow-kill or soft-kill method of heartworm treatment for dogs involves the use of heartworm preventatives along with doxycycline (a broad-spectrum antibiotic that targets Wolbachia) to help reduce the risk of shock-like complications.
However, the slow-kill method is NOT completely safe nor as effective as the standard heartworm treatment for dogs. For this reason, it’s only recommended as a last resort.
Get Next-Level, All-in-One Dog Vet Care at Sploot Vets
If you have any questions about heartworm prevention or treatment for dogs, we're here to help! Sploot Veterinary Care provides all-in-one vet care, with primary care, urgent care, and emergency vet services, all under one roof.
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Visit one of our vet clinics in Chicago, Denver, & Colorado Springs! Our clinic doors are open 365 days a year, for extended hours.
Easily book an appointment online or through the Sploot Vets app. You can also call our team to arrange an urgent-intake appointment if needed.
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