Mass envenomation of a mare and foal by bees

The clinical course of toxic envenomation of a mare and her foal after an attack by a swarm of bees in the Upper Hunter Valley of New South Wales is described. Early agitation and urticaria were followed by more severe systemic clinical signs within 18 h. There was severe, generalised angioedema, rhabdomyolysis, hypovolaemia, gastrointestinal stasis and renal injury. A particular feature in the mare was almost maniacal behaviour during the first 48 h. Clinical pathological examination showed evidence of haemoconcentration, intravascular haemolysis, thrombocytopenia, azotaemia, rhabdomyolysis and hypoproteinaemia. Symptomatic treatment was initiated using intravenous fluids, anti-inflammatory drugs, histamine antagonists, analgesia and antibiotics. The foal responded within 12 h, but management of the mare was complicated by severe pain, generalised oedema, intrauterine haemorrhage, renal injury and later, recurrent fever. The most severe, acute effects of mass envenomation lasted for 3-4 days. Neither mare nor foal suffered any known lasting systemic effects of envenomation, although localised dermal necrosis resulted in white hairs at some sting sites and deformed ear tips in the foal.

Early recognition of clinical signs and treatment of toxic envenomation with an understanding of the physiological effects of hymenoptera venom can lead to a favourable outcome in horses receiving a non-lethal dose. Further case reports of the treatment of affected horses are needed to expand knowledge of how best to approach this rare, but serious intoxication.