Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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  NSAID Therapy

Dave Thompson



NSAIDS remain the mainstay of therapy for chronically painful patients. Their principal mode of action is to block prostaglandin production by binding and inhibiting cyclooxygenase (COX). While the result of this effect is mainly a reduction in inflammation and peripheral nociceptor sensitization, there is some evidence that NSAID’s have a central analgesic action as well, though the exact mechanism remains unclear.

Cyclooxygenase occurs in at least 2 isoforms: COX1 (constitutive), which mediates formation of prostaglandins responsible for GI mucosal protection, hemostasis and renal blood flow, and COX2 (inducible), which catalyzes production of prostaglandins that act as inflammatory mediators. This is a bit of an oversimplification, as COX2 can play a homeostatic role in some situations (ulcer healing, maintenance of renal blood flow during stress, prostacyclin production), but in general NSAID’s that inhibit COX2>COX1 are considered the drugs of choice in this class. These are often referred to as COX2 preferential or selective agents.

A variety of selective/preferential NSAID’s are available for use in dogs, including carprofen (2.2 mg/kg BID or 4.4 mg/kg SID), etodolac (10-15 mg/kg SID), deracoxib (1-2 mg/kg SID for chronic use), meloxicam (0.2 mg/kg on day 1, then 0.1 mg/kg SID), and tepoxalin (20 mg/kg SID on day one, then 10 mg/kg SID). Though in theory they should all be equally efficacious, some patients appear to respond better to one over another; thus, failure to achieve an analgesic effect with one drug does not imply lack of response to all NSAID’s.

Caution should be exercised when employing NSAID’s in cats. Differences in hepatic biotransformation can lead to prolonged half-lives and the potential for toxicity. Additionally, very few studies have been performed examining the feline response to these compounds. One of the few NSAID’s that appears to be well tolerated in cats is meloxicam (0.1 mg/kg SQ, PO SID the first day, followed by 0.05 mg/kg SID for 1 to 4 days, then 0.025 mg/kg every 24 to 48 hours). Because tremendous variation among individual cats exists in regard to metabolism, it’s recommended they be monitored closely for adverse effects when on long-term therapy.

In all patients, NSAID’s should be avoided in the presence of renal or hepatic dysfunction, coagulopathies, GI disorders, shock, hypotension/hypovolemia, hypoalbuminemia or pregnancy. Dogs and cats on chronic therapy should be monitored periodically for alterations in hematological or biochemical parameters, and their owners should be instructed to watch for signs of GI upset, alterations in appetite and PU/PD.

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Last modified: June 1, 2011 .