Laryngeal chondritis in texel sheep

Flock health survey of Irish Texel society breeders and larynx examination in Texel sheep

Background

Laryngeal chondritis is a disease of undetermined aetiology, characterised by oedema, ulceration, abscessation and necrosis of the laryngeal mucosa and cartilage. The initial aim of the study was to document flock health issues identified by Irish pedigree Texel breeders using a questionnaire survey. Additionally, given the reports of breed predisposition for laryngeal chondritis in Texels, a further aim was to identify if laryngeal problems were perceived as an issue. Work was then conducted to identify if pre-clinical laryngeal mucosal pathology was identifiable in Texel sheep showing no overt clinical signs of respiratory disease and if associations existed between laryngeal measurements and laryngeal pathology.

Thirty one larynges were collected from a Texel flock that previously had laryngeal chondritis diagnosed in fallen stock. Gross visual inspection was performed to identify and grade (0–5) laryngeal pathology. A series of measurements were then performed on larynges that had been formalin fixed. Associations between independent variables (larynx measurements) and the dependent variable (laryngeal pathology score) were examined.

Results

Respiratory disease was the most frequently identified health issue. Farmer-diagnosed ‘throat problems’ were reported by over 80% of respondents.

Laryngeal pathology was noted in Texels showing no overt clinical signs of respiratory disease. Associations between laryngeal measurements and laryngeal pathology were identified relating to the angle between the cranial point of the cricoid cartilage and the vocal process of the arytenoid cartilage.

Conclusions

Mild laryngeal pathology was noted in animals with no overt clinical signs of respiratory disease. Future research should examine whether significant associations between laryngeal measurements and laryngeal pathology identified in the current study can be measured ante mortem, and whether such ante mortem measurements will allow early identification of sheep at risk of developing laryngeal chondritis.

Anatomy and Pathology of the Texel Sheep Larynx

Laryngeal chondritis, or “Texel throat”, is a disease affecting the upper respiratory tract of sheep with breeds like the Texel appearing to be predisposed. Previous work suggests the conformation of these breeds of sheep may be predisposing these animals to laryngeal disease. This study evaluated the anatomy of the Texel sheep larynx and describes incidental pathology. Forty-three larynges from rams of the Texel and Bluefaced Leicester breeds of sheep were measured and photographed. A larynx from each breed was submitted for computed tomography (CT) and magnetic resonance imaging (MRI). Measurements, photography, CT, and MRI demonstrated a difference in the anatomy of the larynx between breeds and a higher proportion of Texel sheep had laryngeal lesions. This study supports the hypothesis that the anatomy of the Texel sheep could be pre-disposing the breed to laryngeal chondritis.