Introduction: Response to trauma includes various endocrine, metabolic and immunological changes, that have been well documented in people but less known in veterinary patients. Objective: To determine the impact of a recent trauma on the thyroid axis and adrenal activity in dogs and to assess the usefulness of urinary cortisol to creatinine ratio (UCCR), basal serum thyroid-stimulating hormone (TSH) total thyroxine (tT4) and free thyroxine (fT4) concentrations in the prediction of outcome in dogs presented for road traffic accident (RTA).

Methods: A retrospective cohort study was conducted from a referral and emergency veterinary clinic and laboratory. The exposed group included 210 dogs involved in RTA, evaluated within 24 hours from trauma, compared with an equivalent group of dogs presented for various illnesses.

Those unexposed dogs were chosen from all dogs that presented to the clinic in the same period of time and were individually matched to a group of exposed dogs for age (±6 months), sex and sexual status, and breed.

Results: UCCR resulted significantly higher in exposed than in unexposed dogs (median 101.5 vs. 21.0; p<0.0001). Serum tT4 value showed no statistical difference between exposed and unexposed dogs, while both serum TSH and fT4 levels were significantly lower for group of exposed dogs compared to unexposed sick dogs (median=0.05 vs. 0.08 ng/mL; p<0.0001 for TSH and median=15.85 vs. 17.95 pmol/L; p=0.003 for fT4). UCCR was significantly higher for non survivors compared to survivors (median=106.7 and 47.9 respectively; p<0.04), TSH was unremarkable, and serum tT4 and fT4 were significantly lower for non survivors (median=12.70 and 17.60 pmol/L respectively; p=0.005).

Conclusions: This study offers new insights about the endocrine characteristics in emergency dogs for RTA. UCCR is significantly higher in injured dogs than in dogs affected by other conditions and is a prognostic factor for mortality. Serum tT4 in traumatized is similar to what obtained in dogs affected by other diseases, while fT4 and TSH are both significantly lower in the exposed group. Low fT4 and tT4, and increased UCCR are new prognostic factors for mortality in dogs presented for RTA.