Your Maine Coon SMA Test Result, Explained Simply
A Maine Coon SMA test reads clear, carrier or affected. Signs show at about 3–4 months, and a wobbly kitten needs a vet exam whatever the result.
Table of Contents
Your Maine Coon’s SMA result: start here
An SMA carrier (N/S on the lab report) is a healthy cat. Spinal muscular atrophy (SMA) only develops with two copies of the gene change. See our Maine Coon size, cost and health guide for the wider picture.
Call your vet now if
🚨 Go to a Vet Now If: your Maine Coon has trouble breathing, collapses, or loses function in its back legs. These can signal heart disease, which an SMA result does not rule out. Go to an emergency clinic.
Which result did you get?
- Carrier or clear: see the decoder.
- Wobbly kitten: see the signs.
- Heart worry: see the heart section.
ℹ️ Vet Note: This explains a DNA result; it isn’t a diagnosis. A kitten with weak back legs needs a vet exam regardless.
What clear, carrier and affected mean
A carrier has one copy of the SMA gene change and stays healthy; a clear cat has none, and an affected cat has two.
Clear, carrier, affected in plain words
| Result | Copies | Has SMA? | Passes it on? |
|---|---|---|---|
| Clear (N/N) | 0 | No | No |
| Carrier (N/S) | 1 | No | About half of kittens |
| Affected (S/S) | 2 | Yes | Every kitten |
📊 Sourced: these definitions follow the UC Davis lab’s SMA test page.
Why a carrier stays healthy
SMA is recessive: a cat needs two copies to have it. N is the normal gene and S the SMA variant.
What your result means for a pet, a buyer or a breeder
The lab says SMA testing mainly helps breeders avoid risky matings.
If your cat is a neutered pet
A carrier or clear pet has nothing to treat for SMA. Share the result with your vet.
If you are buying a kitten
A carrier kitten is healthy for SMA. Ask for lab copies, not just “health tested.”
If you breed: kitten odds by parent results
| Parents | Clear | Carrier | Affected |
|---|---|---|---|
| Clear × clear | 100% | 0% | 0% |
| Clear × carrier | 50% | 50% | 0% |
| Carrier × carrier | 25% | 50% | 25% |
| Clear × affected | 0% | 100% | 0% |
| Carrier × affected | 0% | 50% | 50% |
| Affected × affected | 0% | 0% | 100% |
📊 Sourced: carrier × carrier is from the UC Davis SMA page; other rows use the lab’s Punnett square method. Odds apply per kitten.
Wobbly back legs in a Maine Coon kitten: is it SMA?
SMA signs first show at about 3–4 months of age.
What affected kittens show, and when
Affected kittens develop an unsteady gait as spinal nerve cells are lost and the hind-leg muscles shrink.
🐾 Life-Stage Note: Under 3 months, a kitten may show nothing yet.
What your vet will check
Your vet will watch the kitten walk, feel the back legs and decide on testing. Other conditions can also cause weakness.
✅ Do This: Film a walking clip, note when the wobble began, and bring any parent test results.
Not painful, not fatal: what that means
UC Davis states SMA is neither painful nor fatal, but calls it disabling: the weakness is real even without pain.
A clear SMA result doesn’t mean a healthy heart
No: SMA and heart disease have separate tests.
SMA and HCM: two different conditions
Hypertrophic cardiomyopathy (HCM) thickens the heart walls, and Maine Coons are at increased risk. The DNA test checks one gene change; HCM also occurs without it.
What each test and scan shows
| Test | Looks for | Can’t tell you |
|---|---|---|
| SMA DNA test | SMA gene change | Heart health |
| HCM DNA test | One gene change (A31P) | Whether a cat has HCM |
| Echocardiogram | Thickened heart walls | Which gene change a cat has |
📊 Sourced: an echocardiogram is the gold standard; over half of affected cats may show no signs, per UC Davis School of Veterinary Medicine. See our HCM DNA versus echo guide and the UC Davis HCM test page.
Heart emergency signs are different
🚨 Go to a Vet Now If: your cat has trouble breathing, collapses, or loses back-leg function, which a blood clot can cause.
See our heart disease signs guide.
Living with an SMA-affected Maine Coon
An affected cat can live comfortably indoors, with limits.
A comfortable indoor life, with limits
UC Davis describes affected cats as not in pain. Weak back legs make jumping harder, so plan low surfaces.
Making the home easier to move around
Easy-entry litter boxes and floor-level resting spots help. See how many litter boxes per cat.
Working with your vet
Ask how to monitor strength and comfort. Don’t use home remedies or supplements instead of that advice.
How the test works, what it costs and what to ask a breeder
The SMA test is a cheek swab you collect at home.
Cheek swab, price and how to order
UC Davis lists $47 per animal, results in 15+ business days. Order online, swab with household cotton swabs and tape them to the emailed form. Prices change.
Questions to ask a Maine Coon breeder
- Can I see lab result copies for both parents and the kitten?
- Which conditions were tested? SMA and HCM need separate tests.
See our breeder red flags guide.
Maine Coon SMA test: your questions answered
1. Is a Maine Coon SMA carrier sick?
No. A carrier has one copy of the gene change and does not develop SMA.
2. What does N/N mean on a Maine Coon SMA test?
No copies of the SMA gene change were found. The cat is clear and cannot pass it on.
3. Can two SMA carriers be bred together?
Each kitten has a 25% chance of being affected and 50% of being a carrier. Discuss breeding with your vet.
4. Is SMA painful or fatal in Maine Coons?
UC Davis says SMA is neither painful nor fatal. Affected cats can live comfortably indoors, though the condition is disabling.
5. When do SMA signs start in Maine Coon kittens?
At about 3–4 months. A kitten with a weak or swaying back end needs a vet exam.
6. Does a clear SMA test mean no heart disease?
No. Heart disease (HCM) has separate tests; a heart ultrasound is definitive. Ask your vet about screening.
7. Do I need to test my neutered pet Maine Coon?
UC Davis says testing mainly helps breeders. For a neutered pet, ask your vet whether it adds anything.
8. How much does a Maine Coon SMA test cost?
UC Davis lists $47 per animal as of October 12, 2026. Prices change, so check the lab’s page before ordering.
What to do next
A carrier or clear pet needs no SMA treatment; share the result with your vet. A kitten with weak back legs needs an exam. Buyers should ask for lab copies, and anyone worried about the heart should ask about a heart ultrasound.
