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Friday, 13 April 2012

Lungworm in horses

The lifecycle of lungworms is different to other nematodes as adults settle in the lungs rather than the intestine. Eggs are laid then travel up the trachea, are swallowed and passed out in the faeces. Further development then takes place on the pasture, infective larvae are swallowed by horses or donkeys to further develop into egg laying adults.

It is extremely rare for lungworm larvae to develop to full maturity in horses as the horse is not a good host for that particular parasite.  Horses can be infected with lungworm but as they do not mature in to egg laying larvae in any numbers to sustain a population on the pastures.  Exceptions to this in horses can arise in very young or old horses and seriously depilated horses whose immune systems are impaired.

Up to 70% of donkeys carry lungworms often showing no clinical signs of infestation and it is in donkeys where the parasite reaches full maturity.  Donkeys do not always develop the symptomatic cough that is seen in horses but if horses are grazed along side donkeys then particular care must be taken to treat for lungworms accordingly with particular attention to foals as they can sustain permanent lung damage if infected.

SH Wetherald E-SQP
Animal Medicines Advisor