title: Ischemic brain damage after ketamine and xylazine treatment in a young laboratory monkey (Macaca fascicularis).
abstract: After a 4-year-old female laboratory cynomolgus monkey manifested neurological abnormalities, including tetanic spasm, after intramuscular injection of 20 mg/kg ketamine, we administered 2 mg/kg xylazine in an attempt to control the seizure. However, the animal continued to display opisthotonus, nystagmus, and symptomatic epilepsia. Analysis of blood chemistry revealed a dramatically increased creatine phosphokinase level. Abnormal histopathological findings included acute neuronal necrosis or glial reaction or both in the cerebral cortex, nucleus lentiformis, hippocampus, cerebellar cortex and nucleus, and medulla oblongata; severe myocardial hemorrhagic necrosis; and hepatic subcapsular hematoma. Although the mechanism of this neuronal damage has not been clarified, it may be attributable to an ischemic condition in the brain, probably due to temporal cardiac arrest or hemorrhagic change in the liver and heart, with subsequent decreased blood pressure, after ketamine and/or xylazine treatment. Because both drugs often are used as general anesthetics in veterinary medicine, attention should be paid to this rare case with neural damage.
authors.affiliation: Drug Safety Research Laboratories, Astellas Pharma Inc., Osaka, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yoshizawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Oishi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Abraham
authors.initials: A
authors.lastname: Nyska
mesh_terms: D000758:Anesthesia / Q000009:adverse effects / Q000662:veterinary*; D000818:Animals; D002545:Brain Ischemia / Q000139:chemically induced* / Q000150:complications / Q000473:pathology; D002525:Cerebellar Cortex / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology; D003342:Corpus Striatum / Q000473:pathology; D005260:Female; D006624:Hippocampus / Q000473:pathology; D007273:Injections, Intramuscular; D007649:Ketamine / Q000008:administration & dosage / Q000009:adverse effects*; D008252:Macaca fascicularis; D014991:Xylazine / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D014991:Xylazine; D007649:Ketamine