Evaluation of Amantadine in a Multimodal Analgesic Regimen for Alleviation of Osteoarthritis in Multiple Captive Zoo Species
A variety of captive zoo species with chronic pain from osteoarthritis were prescribed amantadine hydrochloride as part of a multimodal pain therapy. Animals that received this drug included an adult female California sea lion (Zalophus californianus), an adult male hybrid orangutan (Pongo spp.), two adult female rockhopper penguins (Eudyptes chrysocome), an adult Kangal dog (Canis lupus familiaris kangal), and an adult female American bald eagle (Haliaeetus leucocephalus). Each animal had a history of decreased mobility and activity, and some had decreased appetite and interaction with trainers and/or other animals in the enclosure. Previous radiographs confirmed osteoarthritis in various joints of each animal. Nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and gabapentin had previously been prescribed to the animals; however, recurrent signs of pain were observed even at higher dosages of each medication. The N-methyl-D-aspartate receptor (NDMA) antagonist, amantadine, was trialed with each animal at dosages ranging from 1.1–3 mg/kg PO, SID. Prior to and after administration of amantadine, animals were assessed for pain and mobility and scored for each on a scale of 1–5. After 3–7 days of administration, mobility and pain improved in each animal. Amantadine was prescribed to an adult great plated lizard (Gerrhosaurus major). The dose was increased to 4 mg/kg, but results were not consistent. NSAIDs have been discontinued in one animal, and opioids discontinued in two. Currently, animals being maintained on amantadine have had no further increase in dose required, the need for additional analgesics, or further relapses of arthritic pain seen.
The authors would like to thank the Polly Horton Hix veterinary health care staff and the Indianapolis Zoo animal care staff for their assistance in the care of these animals.