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Canker (trichomonosis)

Crop Canker, Frounce, Trichomoniasis, Avian Trichomoniasis

Avian trichomonosis, commonly referred to as 'canker', is a protozoan infection characterized by the onset of 'cankerous'-like, caseous plaques inside the chicken's mouth. The disease is caused by Trichomonas gallinae, a flagellate protozoa commonly found in pigeons and doves. The severity of the infection varies depending on the strain of T. gallinae, immune status of the bird, and their age. There are numerous strains of T. gallinae, ranging from some which cause no clinical signs to highly pathogenic strains. Younger birds are usually more seriously affected than older, mature birds.

Columbiformes are the most common host of T. gallinae, with most wild and almost all domestic pigeons and doves being infected. It is estimated that approximately 80-90% of adult pigeons are infected with T. gallinae, many of which may never show clinical signs of disease. Over the past several years, there has been an increasing number of T. gallinae infections reported in chickens, turkeys, raptors, and songbirds (passerines).

Clinical Signs of Canker in Chickens

Early signs of infection include the appearance of small, hard, well-defined, cream to yellowish sores that are stuck to the side and/or roof of the oral cavity, tongue, edges of the beak, and occasionally covering the glottis.
appearance of canker lesions in chickens
As the disease progresses, these sores increase in size and thickness, and become caseous ('cheese-like') in appearance. Sores are usually found inside the chicken's mouth, but can also develop on the beak exterior and near the eyes (where it might be confused with fowl pox). Other non specific signs observed include huddling, listlessness, ruffled feathers, and depression. Oral sores that develop inside the bird's mouth are usually easy to see by gently opening the bird's beak and looking inside.

Sores can develop in the chicken's esophagus or throat can potentially block air passage and impact the bird's ability to swallow. This may initially present as reduced feed and water intake and leading to weight loss. Throat sores can also potentially close off the windpipe, causing the bird to suffocate. In other cases, the disease can progress to a lethal systemic infection, spreading throughout the body. If sores invade the roof of the mouth (oropharyngeal cavity) and sinuses, they can potentially penetrate through the base of the chicken's skull and into the brain.

How Chickens get Canker

Chickens become infected with T. gallinae by drinking or eating from contaminated sources. Water or feed becomes contaminated when infected birds drink or eat from it, usually domestic or wild pigeons or doves, but an increasing number of other wild bird species have been confirmed hosts recently as well. T. gallinae can also be transmitted between adult chickens during courtship behavior. T. gallinae can remain infectious for at least 5 days in moist grains and from 20 minutes to several hours in water. Adult chickens that recover from canker may still carry the parasite, but are resistant to reinfection.

Canker Vs Thrush

Candidiasis (Thrush)Canker
Body areas affectedOral cavity, esophagus, and cropOral cavity, esophagus, and crop
Pathogen typeYeastProtozoan parasite
Pathogen speciesCandida albicansTrichomonas gallinae
Oral lesion appearancePatches of raised, whitish, dead epithelial debris. The top white pseudomembranes can be wiped off. Sticky, yellowish-white 'canker-like' masses of caseous, necrotic material.
More likely to occur followingProlonged antibiotic therapy, concurrent disease, infestation with internal or external parasites, or stressful event.Pigeons and doves sharing the same water or feed source.
TreatmentNystatin, copper sulfateMetronidazole, thyme extract

Clinical Signs

Oral 'cheesy-like' lesions
Difficulty swallowing
Bad odor from mouth
Pendulous crop
"Puffy" face
Loss of appetite
Reduced water intake
Weight loss


  • History - of pigeons and doves drinking or eating from the same sources as chickens.
  • Clinical signs
  • Physical exam
  • PCR testing


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Word of CautionRemoval of affected tissue from the chicken's mouth or throat is not recommended unless in cases where the bird can't breath or swallow, as it promotes invasion by pathogens leading to secondary bacterial infections.
MetronidazoleAdministered in drinking water at 50 mg/kg body weight for daysSeddiek ShA et al., 2014
ThymeThyme extract administered orally showed to be as effective as metronidazoleNT Nasrabadi et al., 2012
Aqueous water extract of garlicAdministered in drinking water at 200 mg/kg body weight for one weekSeddiek ShA et al., 2014
BerimaxA highly effective alkaloid nutraceutical derived from purified plant extracts by a Norwegian veterinarian.
Copper sulphateAdded to drinking water (1/2000)



  • Don't allow doves or pigeons access to the chicken feeders and waterers.
  • Don't let chickens drink from water sources that wild birds drink out of
  • Maintain sanitary conditions
  • Provide apple cedar vinegar in drinking water (1 tablespoon per gallon (15 ml per 4 L) periodically (once a month or so).
  • Where chickens are frequently visited by wild birds, add acidified copper sulfate (powdered bluestone) solution to drinking water once a month for a duration of 3 days.

Scientific References

Good Overviews


Age Range

Usually younger chickens are more susceptible to infection.

Risk Factors

  • Pigeons and doves drinking or eating from the same water or feed source.