Twenty birds in an aviary were prophylactically treated with a single dose of ivermectin. The following morning, one adult Nenday parakeet (Nandayus nenday) was found on the floor of the cage, prostrate with some wing movement and with signs of bradypnea, hypothermia, ataxia, and depression. The animal was placed in a warm place and was treated with intraosseous fluid therapy and a single high dose of corticosteroids. The parakeet did not recover and died 10 hours after the onset of the treatment. No necropsy was performed. The death was supposed to be an adverse reaction to ivermectin.
Ivermectin is an antiparasitic drug effective for some nematodes, mites and lice, and is commonly used in avian practice.4,10 It has a wide safety margin in a variety of birds,7,8,10 but increased sensitivity to ivermectin has been described in some species.1,3,10 Toxic reactions occurred following IM administration in finches and budgerigars,9 oral and topical administration in psittacine birds,3 and topical administration in finches.9 Toxicity due to the propylene glycol used to dilute ivermectin has also been described.5,9 The purpose of this poster is to describe a suspected ivermectin intoxication in a Nenday parakeet.
Twenty birds in an aviary were prophylactically treated with a single dose of ivermectin (Ivomec, Merial, Spain). The drug was not diluted with propylene glycol and was given in the pectoral muscles at a dose of 0.2 mg/kg. The flock was predominantly macaws, cockatoos, lories, parakeets, and toucans. The following morning (10 hours after injection), one of the two adult Nanday parakeets (Nandayus nenday) was found on the floor of the cage, prostrate, with half-closed eyes and some wing movement, and showing signs of bradypnea, hypothermia, ataxia and depression. The animal was immediately hospitalized and placed in a warm place, with intraosseous fluid therapy. A single high dose of corticosteroids (methylprednisolone [Solu-Moderin, Pharmacia & Upjohn, Spain] 1 mg/kg IM) was administered. The animal did not recover and died 10 hours after the onset of the treatment. No necropsy was performed. No other bird in the aviary (not even the other specimen of the same species) showed any kind of symptom.
In the present report, this parakeet showed similar signs as chickens treated at doses of 15 mg/kg7 and falcons treated at 11 mg/kg.8 These doses are 55–75 times higher than the recommended dose for birds (0.2 mg/kg).9 This fact suggests an individual increased sensitivity to the toxic effects of ivermectin, rather than toxic effects due to the wrong dosage or to toxicity to other components of the vehicle. This kind of adverse reaction involving neurologic signs after correct ivermectin dosage has been described in collie dogs, Old English sheepdogs, and Murray Grey cattle.6 The cause is probably due to some characteristics that allow ivermectin to penetrate the blood-brain barrier more readily than would normally be expected.6 In this Nenday parakeet, as in mammals, individual sensitivity could have allowed ivermectin to enter the CNS and stimulate the GABA-ergic neurons, producing prolonged and potentially irreversible toxic effects.2
As a result of the potential for adverse reactions to ivermectin in some avian species, it is recommended to use this antiparasitic drug in those species in which it has been demonstrated to be safe. Administration into the crop or via SC is recommended due to toxic episodes when administered IM, PO or topically.
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2. Bennett. D.G. 1986. Clinical pharmacology of ivermectin. J. Am. Vet. Med. Assoc. 189(1):100–104.
3. Bloomfield, R.B., M.E. Fowler, and L. Lowenstine. 1995. Necrotizing tracheitis after oral administration of ivermectin. Proc. Assoc. Avian Vet. Pp. 521–522.
4. Clyde, V.L. and S. Patton. 1996. Diagnosis, treatment, and control of common parasites in companion and aviary birds. Semin. Avian Exotic Pet Med. 5(2): 75–84.
5. Dumonceaux, G. and G.J. Harrison. 1994. Toxins. In: Ritchie, B.W., G.J. Harrison, and L.R. Harrison (eds). Avian Medicine: Principles and Application. Lake Worth, FL: Wingers Publishing. Pp. 1030–1052.
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7. Kim, J.S. and E.C. Cricklow. 1995. Clinical signs of ivermectin toxicity and the efficacy of antigabaergic convulsants as antidotes for ivermectin poisoning in epileptic chickens. Vet. Human Toxicol. 37(2): 122–126.
8. Lierz, M. 2001. Evaluation of the dosage of ivermectin in falcons. Vet. Rec. 148: 596–600.
9. Ritchie, B.W. and G.J. Harison. 1994. Formulary. In: Ritchie, B.W., G.J. Harrison, and L.R. Harison (eds). Avian Medicine: Principles and Application. Lake Worth, FL: Wingers Publishing. Pp. 457–479.
10. Sikarskie, J.G. 1986. The use of ivermectin in birds, reptiles and small mammals. In: Kirk, R.W. (ed). Current Veterinary Therapy IX—Small Animal Practice. Philadelphia, PA. Saunders. Pp. 743–745.