Over-the-counter availability of drugs in developing countries poses the risk of their abuse and overdosing in animals by the owners themselves. This report describes ivermectin toxicosis and its treatment with neostigmine methylsulfate in two kittens and an adult cat that had been massively overdosed by their owners. Of the two 4-wk-old 300g kittens, one (case-2) injected with 1.5ml (15mg; corresponding to 250 times that of general therapeutic dose) ivermectin by the owner became comatose, started salivation and died after two and a half hours. The other kitten (case-1) treated with about 0.75ml (7.5mg; corresponding to 125 times that of general therapeutic dose) of ivermectin by the same owner developed ataxia and salivation after two hours but went into coma next morning and was presented for treatment. Clinical examination of this kitten revealed mydriasis, coma, slight fever (102.4 °F), tachypnea (respiration rate 48/min) and severe tachycardia. This kitten treated twice at half hourly interval with a mixture of neostigmine methylsulfate (25µg) and 5% dextrose (20ml) IV showed a transient improvement but died twelve hours later. A 2-y-old, 4.5kg male cat (case-3) was similarly treated with 1.5ml (15mg; corresponding to 16.6 times that of general therapeutic dose) of ivermectin by its owner. The clinical examination of this cat revealed a slight salivation, lacrimation, mydriasis, protrusion of third eye-lid, tachypnea (42 breaths/min), tachycardia (128 beats /min) and ataxia. The patient was treated with a mixture of neostigmine methylsulfate (150µg) and 5% dextrose (100ml) IV, followed by intravenous administration of 200ml of Heartmann's solution. The treatment was repeated after 6hrs. Follow up treatment over next two days comprised daily IV administration of neostigmine and dextrose. The patient completely recovered after 5day of initiation of treatment.