A pilot study:sodium urate synovitis as an acute model of inflammatory response using objective and subjective criteria to evaluate arthritic pain in cats

Abstract

Sodium urate (SU) synovitis was evaluated as a model for feline arthritic pain using a placebo- and positive-controlled (meloxicam) randomized blinded controlled single crossover design. Monosodium urate crystals [20 mg (1 mL) rod-shaped] were injected into alternate stifles of trained anesthetized cats (n = 3) with a 28 day washout. During the first trial phase, two cats received meloxicam (0.1 mg/kg, PO), a nonsteroidal anti-inflammatory drug (NSAID), for three days before and on the day of SU injection; the third cat received placebo. Treatments and stifles were switched for the second trial. Total force, contact pressure and area of the fore and hind limbs were measured using a pressure mat one day and 0.5 h before, and 2, 4, 6, 8, 10, 24, and 30 h post-SU injection. Skin temperature, joint circumference, analgesia, lameness, and visual analogue scale (VAS) pain scores, were measured at the same times. Comparisons were made for each time and for areas under the curve (AUC) using original and change from baseline; P < 0.05 was significant. Significant differences in force mat data and subjective data were found for the hind limb data (total force and total contact pressure at 6, 10, and 30 h; analgesia and VAS for pain at 4 h; lameness at 10, 24, and 30 h) and for AUC(0)-->(24h) and AUC(0)-->(30 h) (total force, total contact pressure, and mean lameness score) and for differences from BL AUC(0)-->(10h) (total contact area) and AUC(0)-->(24h) (total contact area and mean lameness score) and AUC(0)-->(30 h) (total force, total contact area, and mean lameness). No cats required rescue analgesia. Injection of 1 mL of monosodium urate into the stifle of a cat causes moderate transitory pain and was suitable for assessing analgesic efficacy of an NSAID with a pressure mat and subjective criteria.

Dose range finding study for the efficacy of meloxicam administered prior to sodium urate-induced synovitis in cats

“…The efficacy of the investigated meloxicam doses was evaluated based on the objective (contact area, contact pressure and total force) and subjective (AS, LS, and VAS, Carroll et al. 2008) outcome measures for pain assessment.…”

“…2008) outcome measures for pain assessment. At any observation, if an AS score of 5 (very painful; Carroll et al. 2008) was assigned, butorphanol (0.4 mg kg −1 IV, subcutaneously, or IM) was to be administered.…”

“…1998). The results of subjective behavioral pain scale scores (i.e., Analgesia Scale [AS], Lameness Scale [LS], Visual Analog Scale [VAS]) used in an OA placebo‐controlled sodium urate (SU) model were consistent with objective pressure mat data (Carroll et al. 2008) and are used in this study.…”

“…The SU tonic model in cats originally proposed by Okuda et al. (1984) and validated by Carroll et al. (2008) was used to test the analgesic and anti‐inflammatory effects of meloxicam, an NSAID approved for perioperative use in cats in the United States, among others, and for OA in the European Union and other countries.…”

“…1984). The SU model caused mild transitory pain suitable for evaluating an NSAID (Carroll et al. 2008).…”