The term multimodal analgesia describes the use of a combination of different analgesic drug classes to target different points in the pain pathway.1 When these combination regimens are prescribed, an assumption exists that the agents provide analgesia at the suggested dosages. However, when it comes to considering acute and chronic pain management in dogs, particularly for human medications used in an extralabel (off-label) manner, the optimal dosages are often unknown.
One drug combination suggested for analgesia in dogs is an oral opioid formulation plus acetaminophen.2–4 Opioids that have been combined with acetaminophen for this purpose include codeine, oxycodone, and hydrocodone.3,5 However, the clinical efficacy of these products has not been rigorously tested or supported in dogs.6 Indeed, a recent study5 yielded no data to support the use of acetaminophen-hydrocodone for the management of acute postoperative pain. Despite the lack of supportive clinical data, these products are used in small animal practice today, often to avoid administration of traditional NSAIDs when contraindicated. Additionally, AC has been used as a rescue analgesic in clinical trials to assess the success or failure of other compounds being tested for the treatment of osteoarthritis in dogs.7,8
The purpose of the study reported here was to examine the ability of AC to attenuate lameness attributable to SU-induced synovitis in the stifle joint of dogs and to compare those effects with the effects of an NSAID (carprofen) known to successfully attenuate signs of lameness in dogs that have this experimental condition.9–13 Measurement of plasma concentrations of the administered drugs was included in the protocol to ensure that the drugs had been administered in accordance with the protocol and had achieved measurable plasma drug concentrations. Intra-articular SU injection induces a consistent self-limiting lameness and provides a predictable method for detecting changes in lameness associated with transient inflammatory synovitis over a moderate period (36 to 48 hours). Our hypothesis was that AC would be as effective as the NSAID (carprofen) in the attenuation of SU-induced lameness as assessed by both subjective measurements and objective gait analysis.
No third-party funding or support was received in connection with this study. The authors declare that there were no conflicts of interest.
Craniocaudal braking impulse
Craniocaudal braking peak force
Craniocaudal propulsion impulse
Craniocaudal propulsion peak force
High-performance liquid chromatography
Peak vertical force
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