All Cooped Up: Candidiasis
Reading Time: 4 minutes
What is it? A fungal disease of the mouth, crop, or entire digestive tract found predominately in chickens, quail, and turkeys.
Causative Agent: Candida albicans, a yeast.
Incubation period: N/A, can develop after antibiotic use.
Disease duration: Depends on when treatment begins and intensity of infection.
Signs: Poor appetite, slow growth, listlessness, white patches of fungal growth in the mouth, bad breath, and hard or squishy crops.
Diagnosis: An assumptive diagnosis can be made based on the clinical signs.
Treatment: Antifungals, supportive therapy, and a reduction in risk factors.
Candidiasis is an infection caused by an overgrowth of Candida albicans in poultry. It is a type of yeast that is part of the normal flora of the digestive tract. In healthy birds, the yeast in present in low enough that it typically doesn’t cause problems. Other names for Candidiasis are Thrush, Sour Crop, and moniliasis.
Certain risk factors exist for the development of Candidiasis in birds. Therapeutic levels of antibiotics or antibiotic overuse are seen preceding cases of this disease, along with dirty drinking water, vitamin deficiencies, and stress. Other health conditions can increase the risk of a bird developing Candidiasis, including birds with weak immune systems. This disease most commonly affects young chicks or poults.
Delayed crop emptying is both a sign and a risk factor for Candidiasis. The growth of yeast and the presence of lesions can slow the rate that the bird’s crop empties. Alternatively, other health factors like Marek’s or unfavorable genetics can also cause delayed crop emptying, which in turn can promote an overgrowth of yeast or an infection in the crop.
Candidiasis infections are common and can be present without any obvious clinical signs. Signs start to appear after the infection spreads throughout the digestive system. One of the first signs of a Candidiasis infection are telltale white to yellowish plaque-like patches of fungal growth in the mouth and throat. These are the overgrown yeast colonies, and a sample taken would reveal an abnormal amount of growth.
Birds with advanced Candidiasis have a ‘pendulous’ or impacted crop. To check for an impacted crop, feel the crop early in the morning before the bird has had anything to eat or drink. The crop should be empty while the bird is preparing to eat and forage during the day. If the crop is not empty, separate the animal and withhold food-but not water-before checking again the following day.
If the animal’s crop is still full the next morning, it may need to be flushed. Birds do not naturally vomit, and if the crop is not moving then the bird is not getting any nutrition. This process is dangerous to the bird and should only be done by a veterinarian. Assessment is key prior to flushing because the crop may be full for other reasons such as a blockage in the intestines or gizzard.
The crop is a muscle, and it will overstretch in a condition known as a “pendulous crop” with continued delayed emptying or impaction. This common comorbidity seen in Candidiasis infections has lasting consequences even once the infection has cleared. Birds with a pendulous crop have a low, drooping crop. Food becomes stuck in the crop, as the muscles can no longer adequately contract to empty it. This can lead to increased infections, malnutrition, and death.
Many owners, when faced with a pendulous crop, have found success with “crop bras”, which are fabric bras or vet wrap fashioned around the bird’s crop to aid with emptying. The rationale behind such a garment is it will bind up the crop, not only preventing it from becoming over full, but serving to help push the food towards the gizzard. If the crop stays reasonably empty, there is a lower risk of impaction or infection.
Candidiasis is not typically life threatening to the bird unless it isn’t caught quickly enough and becomes a serious infection. Candidiasis in poultry is similar to the yeast infections or thrush that people can get, in that once treatment begins the symptoms go away fairly quickly.
Treatment of Candidiasis begins with separating the sick bird. It is not contagious; however the individual will benefit from separation. Antifungal medications such as nystatin or copper sulfate easily clear out a Candidiasis infection. The bird will likely need a few days of supportive care during its’ treatment. If the bird has further signs of malnutrition from the infection, longer care may be indicated.
Younger birds are more likely to come down with Candidiasis. Any species can contract this disease, but infections are seen most often in turkeys. The pendulous crop occurs more often in broilers and turkeys due to their habit of binging on feed.
Candidiasis can be prevented by keeping water, bedding, and feed clean and sanitized, as well as taking care to use antibiotics correctly. Overdosing, misuse, or frequent antibiotic usage can cause a Candidiasis infection since it is an opportunistic organism that thrives with the natural bacteria are reduced.
Originally published in the June/July 2021 issue of Backyard Poultry and regularly vetted for accuracy.