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Botulism in Swans and other Water Birds

Veterinary Record – September 23 1995 – Letters (p32g)

Sir

The unusually hot dry summer this year has led to a very high incidence of avian botulism over the late month. The Swan Sanctuary has been assisting casualties from outbreaks over the South of England including those in west and northeast London and in Oxfordshire. Several hundred deaths have occurred among water birds such as the Mute swan, Canada goose, tufted duck, grebe, moorhen and seagull.

For the affected birds paralysed by the botulism toxin, a high level of intensive support therapy has been found to be successful in many cases, particularly with the injection (Hoechst) and three-day administration of vitamin B12 injection (the latter to stimulate appetite). Intravenous Hartmann’s solution together with an amino acid and vitamin supplement (Duphalyte, Duphar) can be administered though the medial tarsal vein. This is only practical for larger species and only necessary for the more depressed patients. Caution is necessary when offering bowls of food and water, as it is possible for the birds to drown in them. A cool, quiet environment is important as the birds are unable to show fear. Recovery can task several weeks.

More birds are likely to suffer botulism over the next few weeks, or until rainfall increases appreciably. Until then, the site of an outbreak must be cleared of carcasses, as maggots feeding on them concentrate the toxin and are a further source of intoxication (Friend and Lock 1987).

Despite the high fatality this year in birds, the last outbreak of botulism is humans was in 1989 when 26 people suffered as a result of eating hazelnut yoghurt (Communicable Disease Surveillance Centre, personal communication).

Sally Goulden

The Swan Sanctuary

Felix Lane, Shepperton

TW17 8NN

Reference

FIREND, M & LOCK L.N(1987) Field Guide to Wildlife Disease, Vol.1 US Department of Interior Fish and Wildlife Service Resource Publication 167, Washington DC.

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