Vent Gleet is caused by letting chickens eat rotted food, of any kind. Also it is from Some antifungal that the bird has taken in. As soon as you have confirmed the case is Vent gleet, it is time to doctor the chicken for it Treating vent gleet is with a thorough cleansing of the chickens vent area and feather there. . After you have the bird cleaned, then put on the hens vent a topical cream daily for up to 2 weeks time. The cream needs to be anti-fungal such as you use on a case of athlete's foot. Nystatin is very good but may require a veterinary prescription. You can use probiotics or garlic added to water while treating the vent gleet. Vent gleet is caused by yeast in the vent. Do not give antibiotics while treating vent gleet. If given antibiotics will make the vent gleet worse. It could be an antibiotic caused the vent gleet. . Basically to prevent Vent gleet is by keeping the coop area clean, healthy fresh food, and water. By keeping the chicken house clean, always keeping a dry environment is the only way to keeping healthy chickens. A clean dry area to live in makes the chickens safe from any yeast growth. Besure and add 2 tbsp of apple cider vinegar to a gallon of drinking water in plastic chicken waterers. The use of probiotics helps to maintain good gut bacteria thus keeping vent gleet away from the hens body.