Some Key Points from Dr. Bellone:

• R/R isn’t a guarantee of future SCC, but it is an increased risk. Knowing a horse is R/R gives you the ability to make management decisions to help lower that risk.
• R/R and N/R horses should be bred to N/N to decrease risk of SCC, but we DON’T want to avoid breeding these horses altogether. We don’t know what else is tied to that DNA string that we could also be breeding out!
• Watch the video for more!

So that we can help as many people and Haflingers as possible, we ask that you please plan to use your discount code within six months, or wait to request your code until you’re ready to purchase testing.

About SSC & DNA Testing

What is SCC?
Ocular squamous cell carcinoma (SCC) is a condition characterized by tumors of the limbus (junction of the cornea and sclera), third eyelid, and/or upper and lower eyelids.

What does DNA have to do with it?
Researchers at the Veterinary Genetics Laboratory and the University of California, Davis School of Veterinary Medicine investigated ocular squamous cell carcinoma (SCC) in the Haflinger and discovered a recessively inherited DNA marker that identifies horses at higher risk for this cancer occurring on the limbus (junction of the cornea and the sclera) and/or third eyelid. With this mutation, damage to DNA from the sun cannot be repaired, and the accumulation of DNA damage may lead to cancer.

What does this have to do with Haflingers?
The frequency of the risk allele is approximately 20% in Haflingers. Horses homozygous (R/R) for the risk variant factor are 5.6 times more likely to develop ocular SCC than those with one copy (R/N) or no copies (N/N) of the risk factor. This risk factor does not explain all cases of ocular SCC, but it appears to be a major contributor. 75% of horses with ocular squamous cell carcinoma (SCC) have the R/R genotype.

Why should I test?
Testing for this SCC risk variant can help owners identify horses at higher risk for developing ocular SCC and help assist breeders with mate selection.
Homozygous horses (R/R) are advised to have routine eye exams performed by a veterinary ophthalmologist for early detection and better prognosis, and to wear a UV protecting fly mask when out during the daylight hours.
Breeding homozygotes (R/R) and heterozygous (R/N) among or to each other should be avoided to reduce the chances of producing horses that have a high risk of developing this cancer. The ideal mate in either case (R/R or R/N) is a horse with no copies of the risk factor (N/N).

What do the results mean?
Each horse will have a pair of alleles listed in their test results, which will be labeled as N = Normal or non-risk or R = Risk for SCC

• Horses with N/N genotype do not carry this risk variant for SCC and cannot transmit this SCC risk variant to their offspring.
• Horses with N/R genotype are not at elevated risk of developing SCC, but are carriers. They may transmit this SCC risk variant to 50% of their offspring. Matings between two carriers result in a 25% chance of producing a foal that will be at elevated risk of developing SCC.
• Horses with R/R genotype are more likely to develop ocular SCC than horses that genotype as N/R and N/N. They will transmit this SCC risk variant to all of their offspring.

For additional information, please visit UC Davis Veterinary Genetics Laboratory