Acute endocrine responses to snouted cobra (Naja annulifera) and African puffadder (Bitis arietans) envenomation in dogs

Abstract

BACKGROUND : The endocrine response to snake envenomation in dogs remains unexplored. HYPOTHESIS/OBJECTIVES : To compare the endocrine response in dogs envenomated by snouted cobra (Naja annulifera) and African puffadder (Bitis arietans) with healthy control dogs, to evaluate the change over time of specific hormones, and to investigate the correlation of these changes with C-reactive protein (CRP). ANIMALS : This study included 17 client-owned dogs naturally envenomed by either a snouted cobra (N annulifera) (n = 9) or a puffadder (B arietans) (n = 8). Two control groups (n = 10 and n = 12) consisted of client-owned dogs in good health. METHODS : In this prospective longitudinal observational study, serum samples were collected at admission, and at 12, 24, and 36 h after envenomation. At each time point, the serum total thyroxine (TT4), thyrotropin, total cortisol, and CRP concentrations were measured. RESULTS : The median serum TT4 concentrations of all the cases were significantly lower than those of controls at all time points (P < .05). The cases had a median (Q1-Q3) serum TT4 of 20.8 nmol/L (15.2-25) at admission, and 7.71 (6.4-19.7), 11.50 (6.4-18.5), and 12.3 (6.4-16.6) nmol/L at 12, 24, and 36 h after envenomation, respectively. The puffadder and neurological cobra subgroup TT4 remained significantly suppressed until 36 h after envenomation and had nadirs of 9.15 (6.4-14.65) and 6.4 (6.1-7.45) nmol/L, respectively. The non-neurological cobra subgroup had a nadir of 14.6 (9.4-21.45) nmol/L and recovered within 24 h. Serum TT4 concentration was negatively correlated with CRP (P < .05, ρ = −0.326). The total serum cortisol concentration in the neurological cobra subgroup at admission was 483.0 (153-549) nmol/L. CONCLUSIONS AND CLINICAL IMPORTANCE : Puffadder and snouted cobra envenomation are associated with profound suppression of serum TT4 concentrations, correlated with systemic inflammatory activation as measured by serum CRP concentrations.