By Margaret A. Wissman, DVM, DABVP, Avian Practice
Q: I have chickens on my Washington farm, along with around two dozen pet birds (Bourke’s parakets, parrotlets, button quails, Gouldian finches and zebra finches, sun conures and an Amazon parrot). What steps can I take to ward off worms in my flock? Can the medications ivermectin or piperazine be used on parrots and finches? The vets I consult say not to worry about worms, but I’m concerned.
Courtesy Mary Cory, North Carolina
Infested wild birds may pass droppings that land in outside bird cages, on their food or in their water bowl, and breeder birds can become infested if they ingest any eggs.
A: You are right to worry about the possibility of internal parasites. There is a real chance that pet birds could harbor them.
This is an overlooked area of avian medicine because the standard test usually employed to detect internal worms in other animals – the fecal flotation – is unpredictable in detecting worm eggs in birds. With this test, fecal material is placed in a vial with a special solution causing most eggs to rise to the surface. A slide is placed on the top of the vial, and the eggs float up and collect on the slide. This slide is then examined under the microscope for the presence of eggs.
Other tests use special solutions and a centrifuge to spin eggs or parasites to the bottom of a test tube, then examine this material under a microscope. Dogs and cats may have one or two bowel movements per day, and eggs can collect in the fecal material. Birds pass droppings much more frequently, so there are proportionally fewer eggs found per dropping; it is likely that a fecal flotation test will come up negative even if a bird harbors worms. One way to increase the chance of finding parasite eggs would be to collect droppings for one to three days, and then perform the fecal parasite examination.
Older literature suggests that the only birds at risk for worms are those with access to the ground. This is not so. Birds that have lived their entire lives in suspended flight cages have harbored roundworms. When I did a necropsy (animal autopsy) on one Amazon parrot, her intestines were loaded with roundworms. Not only that, but there was evidence of larval roundworms migrating through her tissues.
The Truth About Cats & Dogs
Unlike the common roundworms of dogs and cats, rounds in birds have a direct life-cycle, meaning the eggs can directly infest other birds. Mammalian roundworms require an intermediate host, meaning that the animal must ingest a rodent, lizard, frog, insect, etc. that harbors the larval stage of the worm. Once the host eats the intermediate host, the larvae are released and end up in the intestines of the host.
Some birds bred outdoors in suspended flight cages are exposed to the droppings of wild birds, and bird roundworm eggs can directly infest other birds. Infested wild birds may pass droppings that land in bird cages, on their food or in their water bowl (another reason to convert birds to water bottles), and breeder birds can become infested if they ingest any eggs.
I recently performed an aviary evaluation in Chicago, where the breeder birds were all purchased from other aviculturists and housed in suspended flight cages in the basement. Vets had checked all of the birds and performed fecal flotation examinations. Some vets may disagree with me, but it is my policy that all birds seen for the first time are routinely dewormed with a safe dewormer, which I used on these birds; it kills the rounds, which are then passed in bird droppings. While examining the newspapers beneath the cages the next morning, the owner discovered a pile of spaghetti-looking worms under one of them, once again disproving the effectiveness of fecal flotations for birds, as a rule.
My practice is in Florida, the land of bugs and parasites. I have had many owners call me the day after the initial visit, telling me that their bird had passed some nasty-looking pinkish worms. If a bird does pass worms, it should be dewormed periodically for the rest of its life, due to the risk of encysted larvae in the tissues and because they have the ability to reinfest themselves through eggs passed in the droppings. I also routinely deworm aviary birds during yearly examination of breeding pairs.
Poultry and waterfowl also may become infested with worms. They forage on the ground, and are more likely to come in contact with worm eggs, resulting in parasitic infestation. Set up a deworming program with an avicultural vet familiar with parasitology. If you cannot locate such a vet, ask your avian vet to set up a consultation with an avian specialist, available through the diagnostic lab that your vet uses. Most large veterinary diagnostic labs offer this as a complimentary service for the vets using the lab.
I don’t recommend that any bird owners deworm their birds without the supervision of an experienced avian vet.
If you are concerned about worms, contact your avian vet. Parasitology labs can do special stains and tests to increase the chance of identifying internal parasites on pooled samples collected over several days. Worms can cause obstruction, they compete for nutrients and can cause tissue damage, weight loss and diarrhea so they are best not ignored.
While worms may be underdiagnosed, there are birds out there harboring them. Talk to your vet about your bird’s risk and a possible diagnostic and treatment plan. Testing is available, and treatment is very safe in the hands of a professional.
Parasites & Treatment
Note: Some FDA-approved mammalian de-wormers offer safe treatment of pet birds. Anecdotal evidence suggests that others may be dangerous to birds, so talk to your avian vet about the effects and potential hazards of each option.
Ascarids, aka Roundworms: Most common in pet birds. Juvenile worms, called larvae, can encyst in bird tissues and be released during stress or possibly through hormonal activation from breeding season. Often safely treated with pyrantel pamoate, this medication will not remove encysted larvae in the tissues, which ivermectin is more efficacious in killing.
Cestodes, aka Tapeworms: Unlike ascarids, tapes require an intermediate host (perhaps the cockroach or grain beetle). Tapeworms are unlikely to be diagnosed via fecal flotation and may be found only if a tapeworm segment is passed in droppings or an egg is identified in the feces. Given by precise injection or orally, praziquantel can safely eradicate tapeworms. It often kills the worm, which is then digested and removed from the intestinal tract. There may be no evidence in the droppings.