One of the abstracts presented at the World Small Animal Veterinary Association Congress in 2018 involved ivermectin poisoning in 19 chelonians. They developed inappetence, weakness, pronounced lethargy and paralysis. Eighteen of them survived with supportive care.
Lizards and snakes tolerate ivermectin in therapeutic doses but it is contraindicated in chelonians and crocodilians. Secondary poisoning has been reported in snakes after they were fed mice that died of ivermectin overdose (Hahn A, D’Agostino J, Cole GA. Vet Rec Case Report 2014;2:1 e000053). The individual response is variable and the signs reported above are typical of ivermectin toxicosis in reptiles. Treatment is supportive and recovery can take days or weeks.
The WSAVA abstracts are available online.
Reference: Dewi Y. Ivermectin toxicosis in chelonians. Proceedings of the 43rd World Small Animal Veterinary Association Congress and 9th FSAVA Congress, 25-28 September 2018, Singapore.