Heartworm Treatment Cost by Dog Size
Weight is the single biggest driver of the bill, because the main adulticide drug (melarsomine) and the antibiotic course are priced by how much your dog weighs. The figures below cover the full American Heartworm Society (AHS) style protocol at a general vet: confirmation tests, bloodwork and chest x-rays, the antibiotic course, three injections with day hospitalization, and the retest.
| Dog size | General vet (full protocol) | Low-cost / shelter clinic (injection package) |
|---|---|---|
| Small dog (under 20 lb) | $700–$1,400 | About $300 + extras |
| Medium dog (20–50 lb) | $1,000–$1,900 | About $425–$650 + extras |
| Large dog (50–90 lb) | $1,300–$2,500 | About $650–$850 + extras |
| Giant dog (90+ lb) | $1,600–$3,000 | $850+ or quote on request |
Most owners of a medium-sized dog pay around $1,400 at a general practice. The low-cost column is based on a published shelter clinic fee schedule (SPCA of Texas: $300 for 3–20 lb up to $850 for 81–100 lb), which covers the injections, bloodwork and x-rays but charges separately for the consultation, antibiotics and prevention. Nonprofit programs like this often have waiting lists or age limits.
Dogs with advanced disease can cost far more. If worms block blood flow through the heart (caval syndrome), emergency surgical removal typically runs $3,000–$6,000 before aftercare.
What’s Included in the Price: The Treatment Stages
Heartworm treatment is not a single appointment. The AHS approach is spread over several months, and each stage has its own line on the invoice. Your vet decides the exact plan and timing for your dog.
| Stage | What happens | Typical cost |
|---|---|---|
| 1. Diagnosis and confirmation | Positive antigen test, a second different test to confirm (often a microfilaria test), bloodwork, chest x-rays | $280–$565 |
| Optional: heart ultrasound | Echocardiogram for dogs with signs of heart damage | $300–$1,000 |
| 2. Stabilization | Heartworm preventive started, a month-long doxycycline course, often steroids, strict rest | $50–$200 |
| 3. Melarsomine injections | Usually three deep-muscle injections over about a month, each with a day or overnight hospital stay for monitoring | $500–$1,500 (by weight) |
| 4. Recovery | Several weeks of exercise restriction, rechecks, continued monthly preventive | $50–$150 per recheck |
| 5. Retest | Antigen test about 9 months after treatment ends, plus a microfilaria check | $55–$115 |
Individual line items reported by vet cost guides: heartworm antigen test $35–$75, confirmatory microfilaria test $20–$40, chest x-rays $125–$250, pre-treatment bloodwork $100–$200, doxycycline $30–$150 and steroids $10–$40. The injections and hospitalization together are the largest single cost.
What Affects the Cost of Heartworm Treatment
Size and weight
Melarsomine and doxycycline are both weight-based, so a 90 lb dog can cost two to three times as much as a 15 lb dog for the same protocol. Larger dogs may also need larger x-ray studies and more preventive over the treatment period.
How advanced the disease is
Dogs caught early with few signs usually need only the standard protocol. Dogs with coughing, exercise intolerance or heart changes may need an echocardiogram, extra medications, longer hospital stays or more rechecks. Caval syndrome surgery is the most expensive scenario.
Age and overall health
Senior dogs and dogs with kidney, liver or heart issues often need more bloodwork and closer monitoring. Some low-cost programs don’t treat dogs above a certain age, which can push owners toward full-price clinics.
Clinic type
Shelter and nonprofit clinics offer the lowest prices, general practices sit in the middle, and specialty or emergency hospitals charge the most, especially if a dog arrives in crisis. The same protocol can differ by $1,000 or more between clinic types.
Region
Heartworm is most common in the Southeast and along the Gulf Coast and Mississippi River, where many clinics treat it often and competitive packages exist. Urban practices in high-cost areas typically charge more for the same services.
Complications and retreatment
If the retest is still positive, some dogs need additional injections; PetMD puts a repeat round at roughly $500–$1,000. Side effects after injections, such as soreness or breathing changes, can mean extra visits.
Could pet insurance cover a bill like this?
Accident & illness plans typically reimburse 70–90% of eligible vet costs after the deductible, if the condition is not pre-existing and the waiting period has passed. Premiums for dogs average about $62/month and for cats about $32/month (NAPHIA, 2025).
Coverage is subject to each policy’s terms, exclusions and state availability.Does Pet Insurance Cover Heartworm Treatment?
It depends heavily on the policy. Heartworm is an illness, so some accident-and-illness plans reimburse diagnosis and treatment if the infection is diagnosed after the waiting period. Others limit or exclude it because it is considered preventable, and some require that your dog has been kept on year-round prevention. Several cost guides note that treatment often isn’t covered, so read the exclusions list before you rely on it.
- Pre-existing conditions: a dog that tests positive before enrollment, or during the waiting period, will almost certainly not be covered for heartworm.
- Accident-only plans: do not cover heartworm, since it is an illness.
- Wellness add-ons: some insurers offer optional wellness plans that pay a set amount toward annual heartworm testing and preventive medication.
Coverage is subject to each policy’s terms, exclusions and state availability. For a broader look at the numbers, see whether pet insurance is worth it.
Heartworm Prevention vs. Treatment Cost
Monthly heartworm preventives cost about $6–$18 per month, depending on the product and your dog’s weight. Add an annual heartworm test ($35–$75) and a year of protection costs a fraction of one round of treatment.
| Dog size | Approx. yearly preventive | Plus annual test | Treatment if infected (general vet) |
|---|---|---|---|
| Small (under 20 lb) | $70–$130 | $35–$75 | $700–$1,400 |
| Medium (20–50 lb) | $80–$180 | $35–$75 | $1,000–$1,900 |
| Large (50–90 lb) | $100–$220 | $35–$75 | $1,300–$2,500 |
| Giant (90+ lb) | $120–$250 | $35–$75 | $1,600–$3,000 |
Vetster puts prevention for a 40 lb dog at about $70–$200 a year. Preventives are prescription products: your vet will test first and choose a product and schedule that fits your dog. The AHS recommends year-round prevention and yearly testing even for dogs already on prevention.
Signs to Call Your Vet About
Many dogs show no signs early on, which is why annual testing matters. Book a visit if you notice a mild, persistent cough, tiring quickly on walks, reduced appetite or weight loss.
Call your vet or an emergency vet right away if your dog has sudden labored breathing, collapses, has pale gums, or passes dark, coffee-colored urine. These can be signs of severe heartworm disease and need urgent care. See our guide to emergency vet costs so you know what to expect.
How to Save Money on Heartworm Treatment
- Ask shelters and humane societies: many nonprofit clinics offer heartworm treatment packages priced by weight, often well below private-practice rates.
- Check veterinary schools: teaching hospitals sometimes offer reduced fees, especially in regions where heartworm is common.
- Request an itemized estimate: see each stage separately (tests, antibiotics, injections, hospital stays, retest) so you can plan payments across the months of treatment.
- Use financing if needed: CareCredit and Scratchpay let you spread the cost; treatment usually takes place over several months anyway.
- Buy preventives smartly: ask your vet for a written prescription and compare prices at online pet pharmacies, or look for manufacturer rebates on multi-month packs.
- Keep up annual testing: catching infection early usually means a simpler, cheaper protocol than treating advanced disease.
- Consider a wellness plan: clinic wellness plans or insurer add-ons often bundle the yearly test and preventives into monthly payments.
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Routine testing usually happens at the yearly checkup. See our vet visit cost guide and dog x-ray prices for more on those line items.
Frequently Asked Questions
How much does heartworm treatment cost?
Most dogs cost $1,000 to $3,000 to treat at a general vet, and a medium-sized dog typically runs about $1,400 for the full protocol. Shelter clinics can be much cheaper, while severe cases needing surgery can reach $3,000 to $6,000.
Why is heartworm treatment so expensive?
Treatment involves confirmation tests, bloodwork and x-rays, a month-long antibiotic course, a series of injections priced by weight, hospital stays for monitoring and a retest months later. It spans several months and several visits, and each step is billed.
How long does heartworm treatment take?
The standard protocol usually spans a few months from diagnosis to the last injection, followed by weeks of strict rest. The American Heartworm Society says your vet will retest about 9 months after treatment is completed to confirm the worms are gone.
Is heartworm prevention cheaper than treatment?
Yes, by a wide margin. Monthly preventives cost about $6 to $18 a month depending on product and weight, plus $35 to $75 for a yearly test. One round of treatment often costs ten times a year of prevention.
Does pet insurance cover heartworm treatment?
Some accident-and-illness policies cover it as an illness if it’s diagnosed after enrollment and the waiting period, but others limit or exclude it, or require that the dog was kept on prevention. Prevention itself is usually only covered by optional wellness add-ons. Coverage is subject to each policy’s terms, exclusions and state availability.
- PetMD — How much does heartworm treatment cost for dogs?
- GoodRx Pet Health — Heartworm treatment cost for dogs
- MetLife Pet Insurance — How much does heartworm treatment cost?
- SPCA of Texas — Heartworm treatment clinic pricing
- American Heartworm Society — Heartworm basics
- Vetster — Cost of heartworm prevention vs. treatment
Not veterinary advice. Prices are estimates for budgeting, not quotes. Ask your veterinarian for a written, itemized estimate. If your pet is injured, in pain or acting unwell, contact your vet or an emergency animal hospital right away.
