Guillot M, Moreau M, Heit M, Martel-Pelletier J, Pelletier JP and Troncy E. Characterization of osteoarthritis in cats and meloxicam efficacy using objective chronic pain evaluation tools. Vet J. 2013; 196: 360-7.
Chronic osteoarthritis (OA) in cats is estimated to be more common than previously thought, with radiographic evidence of arthritis in as many as 60-90% of older cats. This high percentage is likely an underestimate since many cats with physical symptoms consistent with osteoarthritis do not have correlating radiographic evidence of the disease.
In this study, researchers from the University of Montreal, Quebec used three different tools to evaluate pain relief efficacy for different low doses of meloxicam (i.e., 0.025 mg/kg, 10 cats; 0.04 mg/kg, 10 cats; 0.05 mg/kg, 9 cats, and placebo, 10 cats) in cats with naturally occurring OA. Evaluation tools included peak vertical ground reaction force (PVF), accelerometer-based motor activity (MA), and the von Frey anesthesiometer-induced paw withdrawal threshold. PVF has previously been objectively evaluated in OA-associated pain/disability whereby a floor mat-based system is used to measure changes in a cat’s willingness to bear weight on their paws as the cat trots over the mat. MA assessment complements PVF and provides objective quantification of changes in a cat’s physical activity related to OA-associated pain by using a collar-attached movement sensor. The von Frey probe and anesthesiometer assess tactile allodynia. Allodynia refers to sensation of pain from a stimulus that does not normally provoke pain.
This study is the first to report on the good to excellent reliability of kinetic gait analysis, accelerometer-based MA assessment, and von Frey anesthesiometer-induced paw withdrawal. Each tool reflects a distinct component of the chronic pain syndrome, and they are thus considered complementary in cat OA pain assessment.
No statistical difference in PVF or allodynia was measured between placebo and meloxicam treated cats. The authors hypothesized that muscle atrophy and weekly exercise masked the benefit from meloxicam administration regarding the PVF experiment. Non-steroidal antiiflammatory drugs like meloxicam, as expected, would not have any effect on allodynia. However, daily low-dose meloxicam administered at 0.025 and 0.05 mg/kg for 4 weeks showed a significant improvement in physical activity in cats suffering from OA suggesting meloxicam provided clinically relevant pain relief. Cats receiving the 0.04 mg/kg dosage did not show significant activity improvement and this was attributed to the high degree of allodynia present in this group. [GO]