Border Collie Health Testing: CEA, MDR1, TNS, and Complete Guide

Border Collies are a highly intelligent, working breed with a distinct genetic disease profile driven by their foundation genetics. Responsible Border Collie breeders test for a suite of conditions before breeding — including several conditions unique to the breed or disproportionately common in it.

Collie Eye Anomaly (CEA)

CEA is the most common inherited eye condition in Border Collies. It is caused by a mutation in the NHEJ1 gene and affects the development of structures at the back of the eye — particularly the choroid (which supplies blood to the retina).

Grades of CEA:

• Grade 1 (choroidal hypoplasia): Mild thinning of the choroid — the dog may have minimal or no vision impact
• Grade 2-4 (coloboma, staphyloma, retinal detachment): Progressive involvement that can lead to significant vision loss

CEA is autosomal recessive. DNA testing identifies Clear, Carrier, and Affected dogs. The CAER eye exam can also identify clinically expressed disease.

MDR1 (ABCB1) Gene Mutation

Border Collies carry the MDR1 mutation at a significant rate — approximately 15-30% of Border Collies carry at least one copy. MDR1 dogs are sensitive to certain drugs including ivermectin (at high doses), loperamide, acepromazine, and some chemotherapy agents. All Border Collie breeding dogs should be tested.

Trapped Neutrophil Syndrome (TNS)

TNS is a severe immunodeficiency disorder affecting Border Collies. Affected dogs cannot release neutrophils from the bone marrow, leaving them unable to fight infections. TNS-affected puppies are typically stunted, fail to thrive, and die in puppyhood. Carrier frequency in Border Collies is estimated at 10–15%.

DNA test results: Clear, Carrier, Affected. Never breed two carriers. Available from Animal Genetics, PawPrint Genetics, and other labs.

Neuronal Ceroid Lipofuscinosis (NCL) / CL

Neuronal Ceroid Lipofuscinosis causes progressive neurological deterioration in Border Collies, beginning at 18 months to 2 years. Affected dogs develop seizures, loss of coordination, and behavioural changes, typically progressing to euthanasia by age 3. DNA testing is available and should be performed on all Border Collie breeding dogs.

Imerslund-Gräsbeck Syndrome (IGS)

IGS is a condition causing malabsorption of Vitamin B12, resulting in failure to thrive, lethargy, and anaemia in affected puppies. DNA testing available.

Sensory Neuropathy (SN)

Sensory neuropathy causes progressive loss of sensory function — affected puppies begin showing signs at a few weeks of age with proprioceptive deficits, self-mutilation, and inability to feel pain normally. DNA testing available.

Complete Border Collie Health Testing Panel

For CHIC certification (Border Collie Society of America requirements), the following are currently required:

• Hips (OFA or PennHIP)
• CAER annual eye exam
• CEA DNA test
• TNS DNA test
• CL DNA test

Additional recommended tests: MDR1, IGS, SN, MDR1, hearing (BAER for merle or white dogs).