Friesian Genetic Testing, Explained for Buyers

Friesian buyers often ask whether the breed has a "five-panel" test the way Quarter Horses do. The answer is no — and yes. Friesians have their own short list of genetic conditions, tested through a different set of labs, with a slightly different vocabulary. The same logic applies: confirm the test exists, ask for the results in writing, walk away if neither shows up.

This post is the practical version of the conversation we have with buyers about Friesian genetic testing.

The three conditions to know

The Friesian breed descends from a small founder population — fewer than a thousand horses at the breed's lowest point in the early twentieth century. That narrow gene pool concentrated three recessive conditions that the studbook has been actively testing for and breeding away from for the last fifteen years.

Dwarfism (chondrodysplasia). A skeletal disorder that produces foals with disproportionately short limbs, a normal-sized head, and a normal trunk. Affected foals are usually stillborn or euthanised within months. Caused by a recessive mutation in the B4GALT7 gene. Carriers (one copy) are normal; affected foals (two copies) are not viable.

Hydrocephalus. An accumulation of cerebrospinal fluid that enlarges the foetal skull. Almost always lethal — affected foals die in utero or shortly after birth, and the size of the foal's head can cause serious birthing complications for the mare. Also a recessive condition; carriers are healthy.

Equine Familial Megaesophagus. Causes the esophagus to dilate so the horse cannot properly swallow food. Symptoms range from mild (regurgitation, weight loss) to severe (choke, aspiration pneumonia). Discovered more recently than the other two; testing became commercially available around 2022 and is now standard in KFPS breeding stock.

A fourth concern — aortic rupture in older Friesians — is real but is not currently genetically testable. It is polygenic and partly age-related, and there is no panel test for it.

What the actual test looks like

A Friesian genetic test is a hair sample with the roots intact, mailed to one of the approved labs. The two commonly used by KFPS breeders are VHL Genetics (the Netherlands lab the KFPS uses for its mandatory predicate tests) and UC Davis Veterinary Genetics Laboratory (the US lab most North American buyers use).

A typical result comes back as a one-page PDF or web report showing each condition and a status:

• N/N — clear (two normal copies)
• N/affected or N/HD — carrier (one normal copy, one disease copy)
• affected/affected — affected (two disease copies)

The cost is roughly $70–$90 per horse for the full panel. Results take 10–14 days.

What to ask the seller

The four questions to ask, in order, when you are looking at a Friesian:

1. Has this horse been tested for dwarfism, hydrocephalus, and megaesophagus? If yes, ask for the lab report by email before you commit.

2. What were both parents' results? A carrier parent doesn't disqualify the horse, but you should know — it changes the risk profile if the horse is being bought as a future broodmare or stallion prospect.

3. Has the horse's microchip number been verified against the test result? Genetic test results without a chip-number cross-reference are weak evidence. The lab should print the chip number on the report.

4. If the horse has not been tested, will you have it tested at your cost before the sale closes? A reputable seller will agree. If they refuse, that is information.

Carriers — not the end of the world

A horse with one copy of the dwarfism or hydrocephalus gene is completely healthy. The gene becomes a problem only when both parents are carriers and produce a foal with two copies — and even then, only with a 25% probability.

What being a carrier does mean:

• The horse should not be bred to another carrier without genetic counselling
• The horse's market value as a breeding prospect is reduced by ~15–25%
• The horse's market value as a riding or sport prospect is not affected — they will live a normal, healthy life

We have placed several carrier Friesians over the years to riding homes where the buyer was fully informed and the price reflected the carrier status. There is nothing wrong with the horse. There is only something to plan around if you want to breed them.

The KFPS angle

KFPS — the Royal Dutch Friesian Studbook — has made dwarfism and hydrocephalus testing mandatory for any horse seeking a predicate (Ster, Kroon, Model, etc.) since 2014. Megaesophagus testing was added to the requirement around 2023. As a result, any KFPS-predicated Friesian sold today comes with the results already on file.

Non-predicated Friesians, Sport Horses, and crosses are not automatically tested. The breeder may have done it voluntarily; many do. But it's the buyer's responsibility to ask.

What our records look like

Every horse we have ever bred or sold at the estate is tested before it leaves the property. Five-panel reports go to the buyer at closing along with the rest of the vet records — KFPS papers, microchip number, full radiographs, dental and farrier history, vaccination records. Nothing is held back.

This is one of the commitments that stands through the closure: a horse leaves us with everything we know about it, in writing.

If you take one thing away

Ask for the test results in writing before you wire money. A clear N/N result on all three conditions is the baseline you should expect from any Friesian over $20,000. If the seller can't or won't produce it, that is your answer about who you are buying from.