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By: G.D. Butcher, D.V.M., Ph.D.
Trichomoniasis (pigeon canker) is the most common disease of
pigeons. Approximately 80 percent of pigeons are infected with
this organism. The organism is a microscopic flagellate
classified as a protozoan. Different strains, Trichomonas
gallinae or Trichomonas columbae , vary greatly in their ability
to cause disease. The disease occurs worldwide in warm climates
or during warm weather. It may occur at any time of the year in
commercial squab operations. Adult pigeons frequently carry the
trichomonads without showing signs of disease. When the adult
pigeon is stressed, however, the organisms may multiply
profusely. A mild infection can then turn into a serious
condition. Stresses include other diseases, parasitic
infestations, or overbreeding.
Affected pigeons in a loft may cease to feed, become listless and
ruffled in appearance, and lose weight before death. Pigeons
often have difficulty when closing their mouths because of
lesions in the oral cavity. They drool and make repeated
swallowing movements. Watery eyes may be apparent in birds with
lesions located in the sinuses or tissues around the eyes.
Diarrhea, increased water intake, and respiratory distress may be
noted. Birds may die suddenly due to suffocation if the lesion
blocks the opening of the trachea. The disease becomes more
severe in birds that are noticeably emaciated. The thin weakened
bird loses the inclination to fly and will "take to the wing"
Pigeons that are carriers often transmit trichomonads to their
young during feeding. The disease is common in 10- to 24-day-old
squabs. As a method of feeding their young, pigeons regurgitate
the sloughed, fat laden cells lining the crop (crop milk) into
the oral cavity of the squabs. If squabs are infected with only
small numbers of the protozoan, they may develop immunity which
is maintained by constant low-level exposure. If squabs are
infected with large numbers, a severe outbreak may occur and
endanger the entire young generation.
Lesions of canker are usually most extensive in the mouth,
pharynx, or esophagus but may occur at other sites including the
crop, proventriculus, or sinuses. The infection is promoted by
minor injuries to these tissues. The spelts and awns from grains
can easily cause small lesions. The lesions first appear as
small, circumscribed, and elevated areas on the surface of the
oral mucosa. They may be surrounded by a thin red zone. The
lesions may increase in size and coalesce. The build-up of white
to yellow/tan caseous material may be sufficiently extensive to
partially or completely block the lumen of the esophagus.
Organisms may also enter the body through the unhealed navel of
squabs. In this form, necrotic tumor-like swellings occur under
the skin adjacent to the navel. Lesions can spread to various
internal organs, particularly the liver. Large, well-defined, and
yellowish areas of hepatic necrosis may be found on necropsy
Typical signs and lesions are very suggestive of the disease.
Demonstration of large numbers of organisms in the oral fluids is
usually considered enough evidence for diagnosis. The small
plaques in the mucosa should be differentiated from pox,
vitamin-A deficiency, or candidiasis.
Since the organism is transmitted from parent to squab, every
effort should be made to treat or remove infected birds from the
flock. If possible, depopulate at regular intervals and
thoroughly clean and disinfect the premises.
In addition, the following preventive measures should help:
practice a high standard of sanitation at all times; do not add
birds to an established flock since they may be carriers (if
birds are added, quarantine for 30 days); and provide a source of
clean, fresh water eliminating all sources of stagnant water.
The antiprotozoal drugs which were used successfully in treating
this disease, such as dimetridazole and metronidazole, have been
removed from the market. Experimentally, a number of drugs are
active against trichomonas infection. Use of 0.1% copper sulfate
(100 mg per 100 ml of drinking water), 0.5% hydrochloric acid or
0.02% mercuric chloride (sublimate) is worth investigating. The
optimum time to treat breeding pairs is at the initiation of egg
G.D. Butcher, D.V.M., Ph.D., professor and avian veterinarian,
Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida, Gainesville, 32611.
This document is copyrighted by the University of Florida,
Institute of Food and Agricultural Sciences (UF/IFAS) for the
people of the State of Florida. UF/IFAS retains all rights under
all conventions, but permits free reproduction by all agents and
offices of the Cooperative Extension Service and the people of
the State of Florida. Permission is granted to others to use
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provided that full credit is given to the UF/IFAS, citing the
publication, its source, and date of publication.