Why should I do DNA testing?
Horse owners choose to do DNA testing on their horses for a few different reasons.
Breeders test for coat colour and health genes to increase their ability to produce healthy, desirable foals. They can also choose to do DNA profiles for parentage verification to confirm their horses’ pedigrees, adding to their value. Occasionally they might even need to confirm which stallion is the sire of a particular foal.
Horse owners who don’t intend to breed also use DNA testing, but for different reasons. The most common motivations are curiousity about their horse’s colour, or checking for disorders such as PSSM1 which can cause performance and health issues.
What can I test for?
Horse DNA tests currently fall into four categories: coat colour genes, health genes for inherited disorders, genes for movement, and DNA profiles for parentage verification.
Coat colour genes influence the colour of your horse’s coat and the patterns of white markings. It is often possible to predict foal colour from the colour genetics of the parents. Some colour genes can also have health impacts: for example, the frame overo gene is the same gene that causes Overo Lethal White Syndrome (OLWS) when a foal gets the gene from both parents.
Health genes can predict which horses may produce foals with inherited disorders, or be affected by inherited disorders themselves. Some inherited disorders have very severe impacts, such as SCID in Arabians. SCID stands for Severe Combined Immune Deficiency. When a foal gets the SCID gene from both parents it effectively has no immune system, and it will die from opportunistic infections. Breeders use health gene tests to avoid matings that have the potential of producing affected foals. Different health genes are relevant to different breeds.
There is also a gene that contributes to horse’s ability to use gaits other than the standard walk, trot, canter and gallop. Breeders that aim to produce gaited horses and can use this test as an aid in their breeding program.
Lastly there are DNA profiles. If DNA profiles are available for both parents and the foal, then the foal’s pedigree can be verified. DNA profiles can also pick up a few rare problems that affect fertility, such as sex-reversal and Turners Syndrome. They do not identify breed.
Where can I get testing done?
I run a horse DNA testing laboratory called Practical Horse Genetics, based in Sydney and Australian-owned and run. We can run most tests that are relevant to Australian horses, and we will try to help you find the right overseas laboratory if you need a test that we don’t offer. Racing Australia also carries out testing, but only for organisations rather than individuals.
There are also a number of laboratories around the world that can do your horse DNA testing. If you choose to use an overseas laboratory one tip is to ship your samples with an international courier. The COVID-19 outbreak has made normal post very slow or even impossible to some countries.
How exactly does testing work?
The first step is generally a bit of self-education. What are you hoping to achieve by testing your horse? You’ll need to pick the right tests to achieve your aim. You learn about the different tests by reading about the different tests online or speak to a testing laboratory about which tests are right for your horses. For some breeds you may be able to find a breed panel that suits your needs. Panels are groups of tests that are commonly ordered together.
Once you’ve decided what tests you want, you can place your order at a testing laboratory.
The next step is to take a sample from your horse. You will need to have clean hands. Usually you’ll be taking mane or tail hair follicles, i.e. pulling out some hair with roots attached. A good sample should have 20-40 hairs with roots attached.
If you have arthritic or injured hands, you may want to ask a friend to take the sample for you.
Samples should be dry when they are collected, and should be packed individually into paper envelopes (preferred) or plastic ziplock bags. Samples last longer when they’re packaged in paper, but many people are used to putting their samples in a ziplock bag. Whichever you are using, it’s a good idea to label your envelope or bag before you collect the sample.
Post the sample to your chosen laboratory. Make sure each sample is labelled, and if it’s heading overseas make sure you have included a copy of the laboratory’s import permit.
The laboratory will let you know as soon as your test results are available.
How expensive is DNA testing?
A single test can cost $40-50 per horse, with the cost ramping up to a couple of hundred dollars per horse if you choose a large number of tests.
How often do I need to test my horse?
DNA doesn’t change over your horse’s life, so they should only need to be tested once. The exception to this is when someone else tests your horse on your behalf – for example, an organisation like a breed society or registry. Some organisations may be unable or unwilling to provide the owner with a copy of the results of their horse’s DNA testing. If this is your experience you may need to test the horse again for your own records.
Is DNA testing perfect?
No testing is perfect. We have all seen examples of high-profile false positives in COVID-19 testing, for example. DNA testing should be substantially more accurate than many other common tests but if there is a surprise result then you should question it and ask for the test to be re-done.
In some cases you may be asked to take a fresh sample. Samples that include a little bit of DNA contamination from one or more extra horses can produce incorrect results.
Can I test for breed?
Unfortunately the answer is no. Almost all horse breeds have been created by mixing together other breeds, and there is too much overlap to be able to reliably tell the difference between the various breed mixes.
It’s important to remember that your horse’s temperament and ability to perform are far more important than its breed. If you and your horse are enjoying your chosen sport and working to improve, you’ve done well.
Visit our lab site at Practical Horse Genetics.