Hi there! Curious to find out if anyone, other then me lol, has experienced unusual side effects in their flock after having used a fenbendazole based dewormer. I have small bantam chickens. I started using Fenbendazole earlier in 2015 and stopped using it in May of this year. I experienced unusual mortality in my flock along with feathering deformities in some of my birds. I have attached a picture of one of me hens that had such feathering deformity. It was in May of this year I learned not to use Fenbendazole during molt, but I even did more research and found this information... "Ten African white-backed vultures (Gyps africanus), 3 lappet-faced vultures (Torgos tracheliotus), and 6 marabou storks (Leptoptilos crumeniferus) were routinely treated for gastrointestinal parasitism with fenbendazole administered in the feed at dosages of 47–60 mg/kg for 3 days. Subsequently, all birds became depressed and anorectic. Results of hematologic testing of severely affected birds revealed profound leukopenia. Six white-backed vultures, 1 lappet-faced vulture, and 1 marabou stork died. Gross necropsy findings were minimal other than enlarged livers and spleens. On histologic examination, severe necrotizing enteritis, bacterial hepatitis, and evidence of septicemia were found. The clinical signs and necropsy findings in these birds were consistent with fenbendazole toxicosis. Fenbendazole at published doses can cause immunosuppression and secondary septicemia in some birds. Therefore, benzimidazole anthelmintics should be used with caution in certain avian species, and appropriate, broad-spectrum antibiotic therapy is indicated in suspected cases of benzimidazole toxicosis." http://www.bioone.org/doi/abs/10.1647/1082-6742(2003)017[0016:SFTIVS]2.0.CO;2 I find it peculiarly odd that gross necropsy findings only found enlarged liver & spleens - stunningly similar to what I've been through with my flock. I have since adopted the attitude not to use any fenbendazole products unless a fecal float reveals it's necessary - I do have a veterinarian thank god, but of course I found one after the mortalities, we were stumped - but now we know better Meanwhile, I'm curious to find out if anyone else has experienced unusual side effects from using fenbendazole on their flock - or am I alone in my woes lol.