Limbal squamous cell carcinoma in Haflinger horses

Area of Science:

• Equine genetics
• Veterinary ophthalmology
• Animal breeding

Background:

• Laryngeal squamous cell carcinoma (LSCC) is a significant concern in horses.
• Haflinger horses may be disproportionately affected by LSCC.
• Understanding the genetic underpinnings of LSCC is crucial for breed management.

Purpose of the Study:

• To determine the prevalence of LSCC in Haflinger horses.
• To investigate the genetic mode of inheritance for LSCC in this breed.
• To identify potential genetic risk factors within Haflinger pedigrees.

Main Methods:

• Retrospective review of 19 Haflinger horses diagnosed with LSCC.
• Analysis of four-generation pedigrees for 15 affected horses.
• Clinical examination of potential carrier stallions.

Main Results:

• The average age of diagnosis for LSCC in Haflingers was 8.7 years.
• Thirteen of 15 analyzed horses shared a common ancestor within five generations.
• A common sire was identified for two affected males, with no clinical signs, suggesting recessive inheritance.

Conclusions:

• Haflingers may have an increased susceptibility to LSCC, with earlier age of onset.
• Close relatedness among affected Haflingers indicates a probable heritable component.
• Further investigation using Genome-Wide Association Studies (GWAS) is warranted to elucidate the genetic basis of LSCC in Haflingers.