Trichostrongylus tenius

Wide host range, but particularly important in grouse (and geese).
Found in the intestine and caeca.
Appearance, life-cycle and epidemiology of this worm very similar to that of the Trichostrongylus species of ruminants (hypobiosis can occur in winter).
On moorland, the L3 accumulate in the heather tips eaten by grouse.
Contributes to (but probably not the main cause of) the cyclical crashes in grouse populations.
Treatment is achieved by putting out dishes of medicated grit.
Grouse are particularly vulnerable in spring (when body condition is often poor after the winter):
- infection

→ reduced appetite and hypoalbuminaemia → reduced survivability and egg-laying.