MDR1 Testing for Australian Shepherds: The Cheek Swab I’d Do Before the Next Vet Visit

Kai is the boss. He’s a red merle Australian Shepherd, born July 2024. I read breed-club pages on a Sunday so I wouldn’t learn this gene in an emergency room.

This is an Australian Shepherd MDR1 test guide for a pet owner, not a breeder catalog. The whole article is Researched. I have not swabbed Kai for this page. I will not invent a genotype. Two prevalence numbers sit on the table. I will not mash them into one marketing stat.

What this page is not

It is not a Kai lab report. It is not a ranking of twelve DNA kits I did not open. Red merle is a coat. MDR1 is a gene. They are not the same conversation. A cheek swab also does not replace hip imaging or an eye exam. That is the honest flaw. I almost treated “get the DNA” as a personality. The gene is one file in a folder.

What MDR1 is, in one screen

MDR1 is the old name. The gene is ABCB1. It helps make P-glycoprotein, a pump that keeps certain drugs out of the brain and helps the body clear them. When the mutation is there, that pump is weaker. Some ordinary medications can hit the nervous system harder than they should. Washington State University, where the canine mutation was characterized, describes possible reactions that include tremors, disorientation, blindness, severe muscle weakness, and death — if the wrong drug, at the wrong dose, meets the wrong genotype.

Herding breeds carry it. Aussies are on the list. Mixed dogs can have it. Looking “not like a collie” is not a test.

ASHGI — the Australian Shepherd Health & Genetics Institute — puts Australian Shepherds at about 50% carrying at least one copy. Their MDR1 FAQ says it in plain language: one in two Aussies has at least one copy of the gene. Their DNA-testing FAQ says the same thing: half of Aussies have at least one copy. WSU’s own breed-frequency table lists Australian Shepherd at 50% as well. Those are breed-club and discovery-lab figures. They are not a swab I ran on Kai.

Embark publishes a different number from a different pile of dogs. On their Australian Shepherd genetic-health page (last updated January 10, 2024, fetched August 2026), they report a snapshot of Embark-tested Aussies that opted into research: 69.7% clear, 27.3% heterozygous (one copy), 2.9% homozygous (two copies). That is not “half.” It is not a contradiction I get to average. It is an opted-in commercial database. ASHGI is talking about the breed as they and WSU have described it. Embark is talking about the dogs who sent them a tube and checked a research box. Cite both. Do not mash them into one fake stat for a headline.

Different samples, different years. The only number that matters for your dog is the PDF with that dog’s name.

ASHGI MDR1 FAQ: ashgi.org MDR1 FAQs. ASHGI DNA testing FAQ: ashgi.org DNA Testing FAQs. Embark Aussie page: embarkvet.com genetic health testing for Australian Shepherds. WSU frequency table: waddl.vetmed.wsu.edu/mdr1-in-dogs.

The three results — and why one copy is not “safe”

Labs usually report something like Normal/Normal, Normal/Mutant, or Mutant/Mutant. Clear. One copy. Two copies. ASHGI is blunt: dogs with even one copy of the mutation should be considered sensitive to listed drugs. Embark calls the inheritance codominant. WSU treats the genotype as something you take to a pharmacologist, not a permission slip to guess.

One copy is not a gold star. One copy is not “basically clear.” One copy is a dog who may react, often less severely than a two-copy dog, to the same problem list. Two copies is not a death sentence either. It is a louder warning. Clear is the result you still keep in the file, because the next ER doctor does not live in your group chat.

Any of the three results goes to a NYC vet the same way: printed, in the chart, said out loud. “What is his MDR1 status?” beats “he’s an Aussie, so maybe skip ivermectin.” Maybe is how dogs get Imodium from a roommate.

Drugs I would flag before they come out of the drawer

WSU keeps a problem-medication list that only includes drugs with peer-reviewed publication behind them. I am not pasting a street-drug menu. I am naming the ones pet owners actually meet in a bathroom cabinet or a routine visit, and I am sending you to WSU for the rest.

• Ivermectin at high doses — the mange-treatment kind of dose, not the tiny preventive dose. This is the classic MDR1 story. High-dose ivermectin is the flag. Labeled heartworm prevention is a different sentence. See below.
• Loperamide (Imodium) — WSU’s line is not soft. At diarrhea doses, this drug will cause neurological toxicity in dogs with the MDR1 mutation. Avoid it in all dogs with the mutation. I would not keep it in the apartment “just in case” and guess.
• Acepromazine — a sedative you might meet before a procedure. WSU says contact MDR1Caddie for dosing recommendations. That means: do not freelance a “he’s only one copy” dose in the lobby.
• Some chemotherapy agents — vincristine, vinblastine, doxorubicin and related drugs sit on the WSU list as “see chemotherapy / contact MDR1Caddie.” If that ever becomes your week, the genotype belongs in the oncologist’s first paragraph.

WSU also lists labeled products the manufacturers tested in MDR1 dogs — Heartgard, Interceptor, Revolution, and several isoxazoline chews among them — and reported no extra risk at those labeled doses. That is not “give whatever.” Labeled dose is a different problem than extra-label high dose. Your vet still owns the choice.

WSU problem medications: MDR1 in dogs and the same table at problem medications for dogs.

Researched: which Australian Shepherd MDR1 test to buy

Three honest paths. I have not used any of them on Kai. No winner-take-all chip unless you count “get a result on file.”

No fake stars. No “we tested 12 kits.” Costs are public published figures as of August 2026 research, not invoices from Kai’s file. WSU is linked as a source.

WSU-only, if MDR1 is the only question

WSU is the discovery lab. Their public order page, fetched August 2026, prices the PrIMe MDR1 test at $70 US including a cheek-swab kit. Two brushes in the mail. They batch on Tuesdays; samples in by Monday afternoon can come back that Wednesday. Their how-to-order page also says 2–7 business days after they have the sample. I’m repeating their windows, not clocking a package I didn’t send. Testing with them also opens MDR1Caddie, their pharmacology portal. Their pricing page is blunt about cheaper “screening” tests that say results are not for medical diagnosis. I’d rather pay $70 to the lab that named the mutation. What you do not get: ancestry, CEA, HSF4, DM, or a pretty app. MDR1 only. That’s a feature if that’s the question.

Full panel, if you also want the other Aussie markers

Embark’s Aussie page lists MDR1 as the most common genetic health risk in their opted-in sample, then DM, HSF4 cataracts, and CEA. A panel buys those in one envelope. Consumer panels are often quoted at three to five weeks. I have not timed one. If you want CEA and HSF4 too, the panel is the honest upsell. If you only want the drug gene before Thursday’s appointment, WSU is the cheaper path. I’d rather you mail WSU than wait on a panel that stays in a drawer.

Vet-ordered, if you want it in the chart without a kitchen counter

A clinic can swab or draw blood and send it. WSU accepts EDTA purple-top blood from hospitals. Blood does not go USPS; they want a courier to Pullman. The result tends to land in the record. You pay clinic time. Worth it if you’d lose the envelope. Any of the three paths is a real Australian Shepherd MDR1 test. The failure mode is none of them.

How to swab, if you DIY — researched steps, not a Kai diary

I have not done this on Kai. WSU’s published owner steps, shortened:

• Morning, before breakfast — or wait at least 30 minutes after food. They want cheek cells, not kibble crumbs.
• Read the card before you open the brushes.
• Two brushes. One side of the mouth, twenty seconds, pressure the dog will accept. Other brush, other side. Keep the mouth gently closed so you are not swabbing air.
• Do not touch the bristles. Air-dry 30 minutes. Sleeve. Label the backing with the pet’s name, your name, and the breed, matching the form exactly. Unclear labels do not get tested.
• Mail the same stretch of days you swab. Include the form. USPS can take the swab pouch to their PO Box. Put a return address on the outside.

If the kit is a consumer panel, follow that kit. Cheek, not drool, no food, mail promptly. He has not been claimed as tested. I will not write a fake swab diary.

After the PDF arrives

Put it in the vet file, the sitter notes, and your phone: MDR1 status, lab, date. Still waiting? Write “untested — herding breed — flag loperamide, high-dose ivermectin, acepromazine.” Untested is a status. Pretending he is clear because he “seems fine” is not. Merle is not the mutation. Kai is red merle. That does not change the MDR1 math. Do not let a coat color talk you out of a swab, or into skipping hips.

If the result is one copy or two, the preventatives post is the next tab — still vet-first, still not a chew I tested: MDR1 preventatives for Australian Shepherds. If you are thinking about insurance before a hereditary condition shows up on a record, that is a coverage-category piece, not a ranked best-five: pet insurance for an NYC Aussie.

The honest flaw I almost skipped

I almost treated the Australian Shepherd MDR1 test as one-and-done health. Swab, PDF, personality complete. That is the flaw. A panel still takes weeks you do not have in an ER. It does not grade hips. It does not replace a CAER exam. OFA and a boarded ophthalmologist are still the homework. I wrote this page because the gene can kill a dog in an afternoon. The rest of the folder is on the health hub. The other flaw is mine: I researched this before I swabbed my own dog. I’m publishing that. It is more useful than a fake “Kai is clear.”

Researched August 2026. Sources linked in-line. I am not your vet.