Canaries particularly in an outdoor aviary are much more susceptible to internal parasites or worms, which can be passed from wild birds, insects, and from bird to bird when in a single colony.
Worms including: Thread Worm, Tapeworm, Roundworm, Caecal Worm, and Hook Worm.
Birds get worms by eating an insect that is infested or by ingesting a worm egg passed by another bird.
If your canary is losing weight, ("going light"), it would be a good idea to have an avian veterinarian look at the droppings. Under a microscope eggs will be clearly evident if your bird has worms.
The damage to your bird varies by the type of worm.
It is recommended that you treat your birds particularly if housed outside, with a bird wormer. This should be done according to instructions (which is sometimes an over kill), and at least annually.
Notes: Soluble bird wormer.
Oxfendazole and Praziquantel are the actives in Wormout Gel. They are recognised as two of the safest wormers available and their combination covers all the major worm species found in birds includingThread Worm, Tapeworm, Roundworm, Caecal Worm, and Hook Worm.