An in-clinic heartworm antigen test costs USD 30 to 70, GBP 22 to 50, or CNY 150 to 350, and reads positive or negative in 8 to 10 minutes. A bundled 4-way panel with 3 tick-borne diseases runs 45 to 90. The test is the cheap part of heartworm: monthly prevention costs 8 to 20 a month, and treatment of a positive dog runs 1,200 to 2,500. Prices below move 1.5 to 3 times with city and hospital level.
What the 30 to 70 buys
The fee covers a 0.5 to 1 mL blood draw, clot or serum separation for 5 to 10 minutes, 1 antigen test cartridge, and a technician's reading time. It does not cover the office visit, which is 40 to 90 in the US and is often waived if you book the test inside a vaccine appointment. It also does not cover a microfilaria check, which is a separate 20 to 45.
Cats are different. Feline heartworm antigen tests miss 15 to 35% of infections, so most labs pair antigen with an antibody test, and the pair costs 55 to 110. A cat that tests antibody positive but antigen negative is not automatically infected; the antibody only proves exposure.
US, UK, and China price bands
| Test | US (USD) | UK (GBP) | China (CNY) |
|---|---|---|---|
| Antigen test, in clinic, 10 min | 30 to 70 | 22 to 50 | 150 to 350 |
| 4-way panel, heartworm plus 3 tick diseases | 45 to 90 | 35 to 70 | 250 to 500 |
| Microfilaria check, Knott or filter | 20 to 45 | 15 to 35 | 80 to 200 |
| Feline antigen plus antibody pair | 55 to 110 | 45 to 90 | 300 to 650 |
| Send-out lab antigen, result 1 to 2 days | 25 to 55 | 20 to 45 | 120 to 280 |
| Monthly preventive, per month | 8 to 20 | 6 to 15 | 40 to 120 |
The columns are medians: a US suburban practice, a UK first-opinion practice outside London, a tier-2 Chinese private clinic. A send-out lab is often 5 to 15 cheaper than an in-clinic cartridge but pushes the result to the next day, which matters if prevention was due today.
Why the same test costs 1.5 to 3 times more
Three things move it. The cartridge: an in-clinic unit costs the practice 8 to 15 per test, and the markup covers the reader and quality control runs. The labor: 10 minutes of technician time bills at 15 to 30 in a US city. The bundling: a 4-way panel shares 1 blood draw across 4 results, so the marginal cost of the heartworm result inside a panel is often 15 to 25 rather than 30 to 70.
Emergency and referral hospitals sit at the top of the spread and add an after-hours fee of 25 to 40%. A 40 antigen test at 9 p.m. can settle at 65 once that multiplier lands, which is why timing a routine screen inside a daytime appointment is the cheapest version of the same test.
The 3 steps behind a 10 minute result
- Sample: 0.5 to 1 mL of blood into a tube, allowed to clot for 5 to 10 minutes, or spun for 2 to 3 minutes for serum. Hemolyzed or lipemic samples are the most common reason for a repeat draw.
- Assay: the cartridge is loaded with 3 drops of serum and read at 8 to 10 minutes. Reading at 5 minutes or at 15 minutes both produce wrong answers, so ask whether the timer was used.
- Report: a positive line plus the date, the test lot, and the dog's prevention history goes into the record. Without that history, a positive cannot be interpreted, because antigen stays positive for months after adult worms die.
Ask for the lot number when a result surprises you. A single lot with several unexpected positives is a quality-control problem, not an outbreak, and the practice can rerun the sample at no charge.
The monthly line: 8 to 20 a month, 96 to 240 a year
Prevention is prescribed as 1 dose a month, and the annual total is 96 to 240 in the US, 72 to 180 in the UK, and 480 to 1,440 in China. A 12 month supply bought in 1 order usually saves 10 to 15% against 12 monthly purchases. The test before starting costs 30 to 70, and most vets require it once a year, so the true annual heartworm line is 126 to 310, not the 8 to 20 sticker.
Skipping 2 months is the expensive scenario. A dog that misses 2 consecutive monthly doses needs a repeat antigen test 6 months later, which adds 30 to 70, and if that test is positive the case moves into treatment at 1,200 to 2,500. The 16 to 40 saved by skipping is the smallest number in that sequence.
A positive result: the 2 confirmation tests
One positive antigen test is not a diagnosis, and 2 follow-ups settle it. First, a heat-treated antigen test or a repeat antigen at a reference lab, which separates true infection from a false positive caused by immune complexes; false positives run 1 to 5% in low-risk regions. Second, a microfilaria check (Knott's test or a filter test) at 20 to 45, which finds circulating larvae and confirms an adult worm load.
Add imaging when the dog is symptomatic: chest radiographs at 100 to 250 and an echocardiogram at 200 to 400, which can show worms in the right heart and pulmonary arteries. A dog with caval syndrome, where worms block the tricuspid valve, needs surgical removal and blood support, and that is where the bill jumps; see transfusion and dialysis costs for what intensive support adds.
Timing: 5 to 7 months, not 5 weeks
Antigen from adult female worms appears about 5 to 7 months after infection, and microfilaria appear at 6 to 9 months. A test 1 month after a mosquito bite proves nothing. Test 6 months after the last possible exposure, or at the annual visit if exposure is continuous. Puppies started on prevention before 6 months are usually first tested at 6 to 7 months of age, then yearly.
Antigen also stays positive for 3 to 6 months after successful adulticide treatment, so a retest at 30 days tells you nothing. The standard checkpoints are 6 months and 12 months after treatment ends, at 30 to 70 each.
Where the test fits in the yearly bill
A healthy adult dog in the US runs 200 to 400 a year in routine care, and the heartworm line is 126 to 310 of that. A cat's routine year is 150 to 350 with 1 to 2 visits, which is the same arithmetic as how often pets actually need a visit. Skipping the test does not remove the cost: it moves it to treatment, where 1,200 to 2,500 replaces 30 to 70.
4 questions to ask at the counter
- Is this an in-clinic cartridge or a send-out lab, and when is the result ready?
- Does the price include the microfilaria check, or is it a separate 20 to 45?
- Is the 4-way panel cheaper than antigen alone for what my dog needs?
- If positive, what do the 2 confirmation tests add, and who pays for the rerun?
Put the test, the monthly preventive, and the annual visit into the cost calculator before you decide between a 30 in-clinic screen and a 90 panel: the panel wins when the dog also needs tick-disease screening, and loses when it does not.
Frequently asked
How accurate is the in-clinic antigen test?
In dogs the antigen test is roughly 95% sensitive and 95 to 99% specific once adult female worms are present, which takes 5 to 7 months after infection. False positives run 1 to 5% in low-risk regions, mostly from immune complexes, and a heat-treated repeat at 30 to 70 separates the two.
Do I need the test every year if my dog takes prevention monthly?
Most vets require 1 antigen test a year, at 30 to 70, because a missed or vomited dose can break protection without any sign. The test also catches infection acquired before prevention started, and it is the only way to keep a 12 month supply legally refillable in many practices.
Why did my cat get an antibody test as well?
Feline antigen tests miss 15 to 35% of infections because cats often carry few adult worms, so labs pair antigen with antibody. The pair costs 55 to 110. A positive antibody with a negative antigen means exposure, not necessarily active infection, and most vets then repeat imaging in 6 to 12 months.
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