Abstract
Racemic carprofen (Rimadyl™ Pfizer) is a veterinary non-steroidal anti-inflammatory drug (NSAID) of the propionic acid class that includes ibuprofen, naproxen, ketoprofen, and vedaprofen.9 It is licensed in the United States for use in dogs to help control inflammation and pain associated with surgery and osteoarthritis.5,12 Forms of the drug have been used in other domestic species, including cattle,7 horses,6 cats,11 and rats10. Ketoprofen has been used to good effect in Asian elephants (Elephas maximus),4 llamas,8 and camels1. There is a growing precedent for the off-label use of carprofen in California sea lions (Zalophus californianus; W. Van Bonn, personal communication),2 and sea otters (Enhydra lutris)3. However, little is known about the use of carprofen in California sea lions and no controlled study that describes the pharmacokinetics or clinical effectiveness of analgesics and/or NSAIDs in pinnipeds has been performed to date. Understanding the pharmacokinetics of a drug can improve the likelihood of establishing dose parameters that will allow the practitioner to alleviate pain and reduce inflammation, while minimizing untoward side effects. Improved pain control is necessary as we continue to develop and improve the comprehensive medical and surgical care of sea lions in rehabilitation and display facilities.
California sea lions (n=10) with traumatic injuries, osteoarthritis, pneumonia, or keratitis resulting in blepharospasm that were eating on their own, appeared to be of normal hydration status, and that during rehabilitation would have received analgesic/anti-inflammatory therapy for their disease, were entered into the study. Study animals received an admit examination including a comprehensive physical exam, complete blood count (CBC) and serum chemistry analysis, and a pre-drug heparinized plasma sample. Those animals were then started on a treatment course of carprofen at the recommended canine dose of 3–4 mg/kg orally once daily for 5 days. Study animals were randomly assigned to two of ten possible time points (0.25 and 0.5, 1, 1.5, 2, 3, 4, 5, 8, 12 h) for post-drug heparinized plasma collection on the first day of carprofen treatment. These time points were then summarized to reconstruct a drug elimination curve. Heparinized plasma, a CBC and serum chemistries were also collected on day five of treatment and again five days later. Plasma concentrations of carprofen were determined by high-performance liquid chromatography. Hematology and serum chemistries were assessed for significant changes during and after treatment. Daily clinical assessments (SOAPs) were made to document any improvement (or lack thereof) in the animals’ condition. Specific attention was paid to lameness exams, mobility and activity, appetite, and interaction with pen mates, to subjectively determine analgesic efficacy.
The maximum plasma concentration, elimination half-life, and systemic availability of carprofen were determined. No adverse changes that could be correlated with carprofen administration were found on hematology or serum chemistries. There were no documented clinical deleterious side effects associated with drug administration. All study animals continued to eat and interact with pen mates. Animals with trauma or osteoarthritis-associated lameness showed improved mobility and there was documented reduction in blepharospasm in those study animals with corneal disease.
These data suggest that racemic carprofen is an acceptable drug to use for the alleviation of pain and inflammation associated with trauma, osteoarthritis, and corneal disease in California sea lions. The authors caution that the use of this drug in sea lions is considered “off-label”, and while there were no deleterious side effects seen in this study, some have been reported in other species.11
Acknowledgments
The authors wish to thank the staff and volunteers of The Marine Mammal Center for their skill and support in the care of stranded marine mammals, and the veterinary pharmacology departments of UC Davis and NCSU for their help and advice.
Literature Cited
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