Summer poisoning hazards

Abstract

There is a seasonal risk with some poisons and in the summer, when stinging insects and adders are more active, there is a risk of envenomation. Diagnosis of an adder bite may be missed in horses, as the biting event is rarely witnessed. Envenomation may result in local swelling and occasionally, systemic effects. Multiple bee stings are particularly hazardous as this can result in multi-organ involvement, which may be fatal. Grazing on some plants, such as ragwort or bracken, for a prolonged period can also result in poisoning as ragwort contains pyrrolizidine alkaloids which cause liver failure and bracken contains an enzyme that has an anti-thiamine effect, inducing thiamine deficiency. Photosensitisation following exposure to plants containing phototoxins and bright sunlight is also a risk in summer. Treatment of plant poisoning in horses is generally supportive and involves removing the plant, providing good quality food and supportive care. Thiamine supplementation may be required in severe cases of bracken poisoning. Animals should be protected from sunlight following exposure to a phototoxin, with supportive management of skin lesions. Management of adder bite is supportive with administration of adder antivenom. Multiple bee stings require aggressive supportive care.