Use of a national identification database to determine the lifetime prognosis in cattle with necrotic laryngitis and the predictive value of venous pCO2.

ABSTRACT

BACKGROUND: Necrotic laryngitis, caused by Fusobacterium necrophorum, frequently requires surgical intervention (laryngostomy) in the chronic stage. HYPOTHESIS/OBJECTIVES: To determine survival until slaughter of cattle surgically treated for necrotic laryngitis and to identify predictors of mortality. ANIMALS A total of 221 cattle diagnosed with necrotic laryngitis by laryngoscopy and surgically treated METHODS: Retrospective cohort study. Clinical records were matched with the national cattle identification, registration, and movement database. Information on possible predictors including clinical examination, biochemistry, and surgery was collected. A multivariable Cox proportional hazard model was used to identify predictors of mortality. RESULTS: The overall survival rate was 65.2% and 58.6% of the animals with a completed life cycle could be slaughtered. Animals <6 months old experienced significantly higher mortality risk (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.1-3.5). The venous partial pressure of carbon dioxide (pCO2 ; HR, 2.4; 95% CI, 1.4-4.2) at a 64.5 mm Hg cut-off was most significantly associated with mortality. Sensitivity and specificity of the final model consisting of age and pCO2 were 49.1 and 86.4%, respectively. Instead of pCO2 , total carbon dioxide (TCO2 ) could also be used, with similar diagnostic accuracy. CONCLUSIONS AND CLINICAL RELEVANCE The lifetime prognosis for chronic necrotic laryngitis in cattle with surgical intervention appears fair. Age, venous pCO2 and TCO2 are easily accessible predictors of survival to support owners and veterinarians in their decision process of whether or not to operate and to identify high risk animals that require more intensive follow-up.