ProHeart Pricing Calculator — What Your Dog’s Shot Will Cost

Enter your dog’s weight and select pounds or kilograms. The calculator returns the typical cost range for ProHeart 6 (6-month) and ProHeart 12 (12-month) at most U.S. veterinary clinics, plus the FDA-approved dose volume. Actual prices vary by clinic — always confirm with your vet before your appointment.

These are the FDA-approved dose volumes from the official ProHeart 12 prescribing information (Zoetis, 2026). The active ingredient moxidectin is dosed at 0.5 mg per kilogram of body weight (0.23 mg/lb). ProHeart 6 uses the same weight-band system at one-third the moxidectin concentration.

Doses over 3 mL (dogs above ~132 lbs) are divided between two injection sites per the official Zoetis prescribing guidelines. The veterinarian determines exact injection volume based on the dog’s precise body weight at the time of administration.

The questions people search most about ProHeart pricing and safety — answered without the promotional language from the manufacturer’s website or the vague “ask your vet” deflections that don’t actually help.

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  How much does a ProHeart 12 shot cost? Typically $60–$250+ depending on your dog’s weight · Small dogs (under 25 lbs): $60–$120 · Medium dogs (25–50 lbs): $90–$150 · Large dogs (50–100 lbs): $115–$175 · These ranges are for the injection only and do not include exam fees or the required heartworm test

  ProHeart 12 is priced by weight because the dose volume is calculated at 0.5 mg of moxidectin per kilogram of body weight — so a larger dog simply requires more medication. The prices above reflect what real veterinary clinics charge based on publicly available fee schedules; they are not the manufacturer’s suggested price. Mobile and nonprofit veterinary clinics often run 20–40% below standard clinic rates — pop-up vaccination events have been documented charging as little as $60 for small dogs up to 25 lbs. Full-service veterinary hospitals in major metropolitan areas may charge significantly more, particularly if the injection is bundled with an annual wellness exam.
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  Is ProHeart 12 cheaper than monthly heartworm pills? Over a full year, the total cost is usually comparable to 12 months of monthly chewables like Heartgard Plus or Sentinel · The math favors ProHeart when you factor in missed doses · Monthly chewables for a 50-lb dog run roughly $8–$12/month = $96–$144/year · ProHeart 12 for the same dog: $115–$175 for the full year in one shot · No missed dose risk with ProHeart

  Zoetis (ProHeart’s manufacturer) acknowledges directly on their website that the annual cost is “about the same” as 12 months of monthly preventative. What changes the math is compliance: a published study of over 4,600 U.S. veterinary practices found that dogs on ProHeart had significantly better heartworm prevention coverage than dogs on monthly chewables — because owners miss monthly doses at predictable rates. The real cost of a missed monthly dose isn’t the pill price; it’s the risk of infection during that unprotected window, followed by a heartworm treatment costing $1,200–$3,000 or more. For owners who travel frequently, have irregular schedules, or have dogs that resist taking pills, ProHeart’s all-in-one annual injection often works out to be cheaper in practice even if the sticker price is slightly higher.
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  What is ProHeart 6, and is it different from ProHeart 12? Same active ingredient (moxidectin) · ProHeart 6: 6-month protection, approved for dogs 6 months and older · ProHeart 12: 12-month protection, approved for dogs 12 months and older · ProHeart 12 contains 3x the moxidectin concentration · ProHeart 6 costs less per injection but requires two injections per year vs. one · Same manufacturer: Zoetis

  ProHeart 6 was the original long-acting moxidectin injectable, first approved in 2001, then voluntarily pulled in 2004 after serious adverse event reports, then re-approved in 2008 after safety improvements. ProHeart 12 received FDA approval in July 2019 using the same microsphere delivery technology with three times the moxidectin concentration. Both work by storing slow-dissolving microspheres of moxidectin in the dog’s adipose (fat) tissue, which then releases the drug gradually over either 6 or 12 months. A 6-month-old puppy can receive ProHeart 6, then switch to ProHeart 12 once they turn 12 months. The younger age eligibility for ProHeart 6 makes it the preferred choice for puppies who need heartworm protection before they’re old enough for the annual injection.
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  What are the side effects of ProHeart 12? Reported in clinical trials: vomiting, lethargy, diarrhea, anorexia, mild injection site reactions (warmth, swelling, itching) · Rare but serious: anaphylaxis (severe allergic reaction) — can be life-threatening · Highest risk: when given at the same visit as vaccines · Dogs must stay at the clinic for observation after the first injection

  The FDA’s approved prescribing information is direct about both the common and rare adverse events. Mild GI symptoms — vomiting, loose stools, reduced appetite in the 24–48 hours after injection — occur in a small but documented percentage of dogs. Injection site reactions (localized warmth, minor swelling, brief itching) were observed in six dogs in clinical trials and resolved within 24 hours. The serious risk is anaphylaxis, which has been specifically documented when ProHeart is administered at the same time as routine vaccinations. The official prescribing information advises caution when combining ProHeart with vaccines and recommends veterinary observation after administration. A published safety study found ProHeart 12 was well-tolerated at up to 5x the recommended dose in beagles, which reflects a solid safety margin at standard dosing. The vast majority of adverse reactions that do occur are managed and resolved with veterinary care.
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  Is ProHeart 12 safe for heartworm-positive dogs? No — ProHeart 12 cannot be safely given to heartworm-positive dogs · It is NOT effective against adult heartworms · A required heartworm antigen test before administration is standard protocol · Dogs with heartworm must be treated with melarsomine (adulticide) first · Administering ProHeart to a dog with existing heartworm can cause serious adverse reactions

  This is the most critical safety question surrounding ProHeart, and the FDA prescribing information is unambiguous: a heartworm antigen test is required before the first ProHeart injection, and infected dogs must complete full adulticide treatment before ProHeart can be administered. The mechanism matters here: ProHeart 12 kills heartworm larvae (the tissue stage) but has no effect on adult worms already living in the heart and major vessels. Giving ProHeart to a heartworm-positive dog doesn’t treat the existing infection — and in a laboratory study, dogs with 4 to 6-month-old heartworm infections who were given moxidectin microspheres (at a different dose) experienced vomiting, lethargy, and bloody diarrhea. For a dog that is behind on heartworm testing, the heartworm test is the first requirement before anything else happens at the vet appointment. This adds $25–$45 to the total visit cost but is non-negotiable for safety.
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  How do I calculate ProHeart dose for my dog’s weight in kg? The math: multiply your dog’s weight in kg × 0.05 mL = the dose volume · Example: 20 kg dog × 0.05 = 1.0 mL · Or use lbs: weight in lbs × 0.023 mL = dose volume · The active ingredient dose is always 0.5 mg moxidectin per kg of body weight · This calculation is performed by the vet — never self-administer ProHeart

  The FDA-approved formula for ProHeart 12 dosing is 0.05 mL of constituted suspension per kilogram of body weight, which delivers 0.5 mg of moxidectin per kilogram. In pounds, the equivalent is 0.023 mL per pound. This is a subcutaneous injection that requires preparation — the moxidectin microspheres are stored in a separate vial and must be constituted with a specially formulated sterile vehicle before use. This mixing step, and the precise weight-based calculation, is why ProHeart is a prescription-only, veterinarian-administered product. Dogs over approximately 132 lbs (60 kg) whose calculated dose exceeds 3 mL receive the injection split between two sites. The peak moxidectin blood levels occur 7–14 days after injection, which is why protection begins immediately but reaches full blood concentration during that window.
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  Can ProHeart 12 be given with vaccines at the same appointment? Technically yes, but the FDA specifically warns against it · Adverse reactions including anaphylaxis have been documented when ProHeart is given at the same time as vaccines · Best practice: schedule ProHeart at a separate appointment from vaccine boosters · Many veterinarians recommend a 2–4 week gap between ProHeart and any vaccinations

  This is a genuinely uncovered practical concern that most ProHeart discussions skip entirely. The FDA prescribing information explicitly states: “Adverse reactions, including anaphylaxis, have been reported following the concomitant use of moxidectin microspheres and vaccinations.” This appears in the official Warnings section, not buried in fine print. In practice, many veterinary clinics routinely combine ProHeart with annual vaccines during the same wellness visit for convenience — and most dogs do fine. But for a dog with any history of vaccine reactions, for senior dogs, or for dogs whose immune response to injections has been variable in the past, scheduling ProHeart and vaccines on separate visits is the safer approach worth discussing with your vet before the appointment rather than on the exam table.
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  Who should NOT receive ProHeart 12? Dogs excluded by FDA prescribing information: sick dogs · debilitated dogs · underweight dogs · dogs with recent or ongoing weight loss · dogs previously hypersensitive to moxidectin · dogs under 12 months of age (use ProHeart 6 for dogs 6–12 months) · heartworm-positive dogs (must treat first)

  The exclusion criteria for ProHeart 12 are broader than for standard monthly heartworm pills, and these are the specific situations where a different prevention option is genuinely safer. Dogs with a history of weight loss are specifically excluded because the drug is stored in adipose tissue — and a dog losing weight is mobilizing fat stores, which could alter moxidectin release patterns in unpredictable ways. Debilitated or sick dogs may not metabolize the slow-release formulation normally. For any dog on the exclusion list, ProHeart 6 (6-month) is not automatically safer — the same exclusions apply. In those cases, a monthly oral preventative like Heartgard Plus or Tri-Heart allows easy dose adjustments, immediate discontinuation if problems arise, and does not create a 12-month drug depot that cannot be reversed if the dog’s health changes. Your vet should review your dog’s current weight, health history, and any previous drug reactions before the first ProHeart injection.

ProHeart requires a prescription and must be administered by a licensed veterinarian. Use these to locate your nearest full-service vet, low-cost clinics, and pop-up vaccination events in your area.