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Thrush, Avian Candidiasis, Moniliasis

Candidiasis is a fungal disease that usually occurs secondary in susceptible ducks. It is primarily caused by Candida albicans, a yeast-like, opportunistic pathogen that is a normal inhabitant of the crop in healthy birds. Ducks with beak abnormalities, impacted food, tongue injuries, immunocompromised, receiving prolonged antibiotic therapy, heavy parasite loads, highly stressed, or affected by a primary illness are particularly vulnerable to developing candidiasis.

Clinical signs
Characteristic of candidiasis is the presence of white to cream, cheesy patches or plaques (oral lesions) found in the duck's tongue, mouth, crop and esophagus tissue. Often, lesions may appear as necrotic patches that can be easily peeled back from the eroded mucosal surface. When the crop is involved, Candida cause white curd-like plaques and reddening of the surrounding tissue. Affected ducks may appear listless, dehydrated, little to no appetite, loss of condition and 'yeasty or sour-like' breath. Some ducks may also show signs of mild conjunctivitis.

Ducks with candidiasis can sometimes be concurrently infected with other diseases, which can complicate or confuse clinical signs observed. A case of concurrent infection in a backyard flock of chickens occurred in 2016 where the birds were concurrently infected with fowlpox and candidiasis.


Oral lesions (white patches or plaques)
Delayed crop emptying (crop stasis)
Loss of appetite
Stunted growth
Ruffled feathers


  • History
  • Clinical signs
  • Physical exam
  • Fungal culture -presence of numerous narrowly based budding yeast.
  • Histopathology


MethodMethod Summary
Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own duck "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Nystatin300,000–600,000 U/kg PO q8–12h
Itraconazole5–10 mg/kg PO q12h
Apple cider vinegarMay help with mild cases.

Reported Cases

  • Case 1: Pulmonary candidiasis in a Sun conure An adult male sun conure was evaluated because of lethargy, ruffled feathers, and decreased appetite. Physical examination revealed hypothermia, dehydration, dyspnea, and crop distention. Results of a complete blood cell count revealed a marked inflammatory leukogram, and cytologic examination of a crop swab sample identified gram-negative bacilli and occasional yeast organisms. Radiographs demonstrated an opaque, ill-defined, soft tissue structure in the caudal coelom just cranial to the renogonadal silhouette, loss of serosal detail, and splenomegaly. Endoscopic examination revealed a pale, granuloma-like structure within the caudal aspect of the left lung, splenomegaly, and an enlarged proventriculus. Intraoperative cytologic examination of a biopsy sample of the lesion demonstrated yeast organisms, and a subsequent culture of the biopsy sample revealed Candida albicans. The bird was treated intraoperatively with intralesional amphotericin B. Postoperative treatment consisted of meloxicam, trimethoprim sulfa, amphotericin B by nebulization, and systemic itraconazole and fluconazole. The bird made a complete recovery, was discontinued from all medications, and has remained asymptomatic for 6 months. Although rare, pulmonary candidiasis should be on the list of differential diagnoses for any respiratory infection in birds. Endoscopic biopsy, cytology, and fungal culture were valuable in making the diagnosis. Ref


  • Do not administer antibiotics in ducks unless specifically prescribed to by a veterinarian.
  • Maintain good sanitary conditions for ducks
  • Feed a balanced diet that is intended for waterfowl


Risk Factors

  • History of long term antimicrobial therapy (antibiotics)
  • Ducks living in poor sanitary conditions
  • Older ducks or young ducklings are more susceptible to candidiasis
  • Ducks with weakened immune systems, such as when recovering from an illness or chronic injury.