Vespa vulgaris (wasp); Vespa crabo (hornet).

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Animals most affected
Birds, horses, dogs, cattle.

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Etiology

• direct ingestion of the insect (through eating food attractive to wasps, e.g. fruit, upon which the insects may be found);
• an insect may attack if surprised by abrupt movements or loud noises, and even without provocation.

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Toxicity
The venom contains

• vasoactive components: histamine, serotonin;
• enzymes: phospholipase A, hyaluronidase;

It elicits an immediate immune response once injected into an animal. The toxic effects vary according to the type of insect, the age of the animal and its immune status.

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Clinical features and lesions
At the site of the sting

• acute pain, redness (appearing within 30 seconds);
• oedema, which may increase in area during the first 24-48 hours, but often not visible due to the thickness of the coat or fur of the animal;
• pruritus.

General effects

• sweating, vomiting, diarrhoea, tachycardia;
• occasionally collapse, coma and death.

If the sting is in or near the oropharynx

• oedema of the glottis;
• possibly asphyxia.

Allergic reactions may occur in animals that are sufficiently sensitive to the venom. In cases where there has been multiple stinging, the allergic response may progress rapidly to anaphylactic shock.

In birds

• extreme pain, paralysis;
• death in 5-7 hours according to the amount of venom injected.

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Treatment
Locally

• tincture of iodine, arnica;
• corticosteroids or antihistamine creams.

In cases of an allergic reaction

• sc adrenaline, 0.1-1 ml of a 1:1000 solution;
• im antihistamines e.g. promethazine (Phenergan®);
• corticosteroids;
• emergency tracheostomy in cases where the throat is involved, and where there is swelling and obstruction of the airways.

Some animals may be successfully desensitized by administration of total extracts of wasp venom by subcutaneous injection over several years.