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Squamous Cell Carcinoma


→ A malignant tissue formation (tumor) that develops from the superficial layers of the skin and mucous membranes.

Instructions for ordering:

  1. Enter the information of the first horse for which you want to order the test
  2. Add to cart
  3. Go to cart to check out, or
  4. Enter the information for a second horse
  5. For sample collection follow the instructions here.
  6. You can use this template to send in hair samples.
  7. Please also send the completed order form together with the samples.

For a breeder or veterinarian discount please contact us before ordering.

Any information you include here is optional, but will be included on the certificate of results (except “Additional Info”).

Enter the name of your animal
Enter your animal's date/year of birth
Enter the breed name
Enter the registration number if known
Enter the microchip number
Is there anything else you would like to tell us about your horse? Reason for testing, symptoms etc.?

General Information

  • Most common type of eye cancer in horses.
  • This test identifies a gene mutation that increases the risk of developing an SCC. → Risk Test
  • Due to this mutation in the DNA, the DDB2 protein, which is responsible for DNA repair in UV light damage, is not correctly formed.
  • SCC is particularly common in Haflinger Horses due to the frequent occurrence of this mutation in the breed.
  • It has also been described in Belgian draft horses and Pecherons.


  • Slowly growing malignant skin neoplasms.
  • Especially mucous membranes are affected.
  • Development of eye cancer.
  • Impairment or loss of the eye.

General Information:

Inheritance and Genotypes

Inheritance: autosomal recessive

→ The risk of developing SCC is increased if both copies of the gene (scc/scc) are affected by the mutation. Animals with only one copy (N/scc) are clinically normal carriers.

Possible Genotypes:

Genotype: The horse is/has:
N/N normal. The horse has no copies of the genetic variant causative for SCC and therefore cannot pass it on to its offspring.
N/scc a carrier. The horse is clinically healthy. The genetic variant causative for CSS will be passed on to its offspring with a probability of 50%.
scc/scc a risk. The horse has an increased risk of developing SCC. The mutation will be passed on to its offspring with a probability of 100%.



  • Carriers may be bred to normal animals (N/scc x N/N) without any risk of producing at risk offspring. The offspring should also be tested before breeding to determine if they are carriers or normal.
  • When breeding two carriers (N/scc x N/scc), there is a probability of 25% for each foal to inherit two copies of the mutation (scc/scc) and therefore having an increased risk of developing SCC. This should be taken into consideration when planning breedings.


Bellone, R.R., Liu, J., Petersen, J.L., Mack, M., Singer-Berk, M., Drögemüller, C., Malvick, J., Wallner, B., Brem, G., Penedo, M.C., Lassaline, M. : A missense mutation in damage-specific DNA binding protein 2 is a genetic risk factor for limbal squamous cell carcinoma in horses. Int J Cancer :, 2017. Pubmed reference: 28425625. DOI: 10.1002/ijc.30744.

Singer-Berk, M., Knickelbein, K.E., Vig, S., Liu, J., Bentley, E., Nunnery, C., Reilly, C., Dwyer, A., Drögemüller, C., Unger, L., Gerber, V., Lassaline, M., Bellone, R.R. : Genetic risk for squamous cell carcinoma of the nictitating membrane parallels that of the limbus in Haflinger horses. Anim Genet :, 2018. Pubmed reference: 29999543. DOI: 10.1111/age.12695.

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