You don’t need to be a rocket scientist to work out that lungworms hang out in the respiratory tract.
They’re actually a major parasite that affects donkeys.
Horses can host them, too, but they are highly unlikely to reproduce. That, however, does not stop them causing in infected horse some grief.
That said, unless your horses enjoy the company of donkeys they are unlikely to be a problem.
Lungworms, or Dictyocaulus arnfieldi, are quite a large parasite, able to grow to about 8cm in length. It is therefore hardly surprising that they’re able to cause some problems in the lungs.
Horses eat infective larvae in pasture. The larvae migrates to the lungs in less than a week and will be laying eggs within a month.
The irritating cough they generate helps the eggs up the windpipe. They’re not looking for an exit out the mouth, however.
From the throat, they aim to get swallowed and take a quick tour of the intestinal tract before exiting on to pasture. They’re able to re-infect horses in as little as five days if conditions are right.
As with most parasites, serious problems are possible once the burden gets heavy, but this would be very rare in horses.
A horse suffering from a recurring cough or chest problem could be suffering from any one of a number of problems. If you can establish a link with donkeys, a lungworm infestation is worth exploring by your veterinarian.
However, you could list two dozen causes of a cough in your horse that would far more likely a lungworm problem.
Lungworms easily fall victim to the macrocyclic lactones, which include ivermectin and moxidectin.
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First published on Horsetalk.co.nz in February, 2009