Is Gabapentin an Option for Treating OA Pain in Cats?
Gabapentin has been proposed for the treatment of neuropathic pain and was recently investigated as a treatment option for osteoarthritis pain in cats.
Geriatric cats that suffer from osteoarthritis (OA) have limited pain management options. OA pain is complex and includes a neuropathic component that is nonresponsive to nonsteroidal anti-inflammatory drugs. Gabapentin is used for neuropathic pain treatment in humans and has been suggested for the treatment of pain in cats.
A recent randomized, placebo-controlled, crossover study evaluated the effects of gabapentin in cats with OA using client-specific outcome measures (CSOMs), owner-perceived quality of life (QOL) assessments, and accelerometer-based activity assessments.
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Cats age 10 and older with owner-perceived mobility impairment underwent complete physical examination, complete blood cell count, serum chemistry panel, and radiographs of affected joints (defined by identification of pain during examination or presence of muscle atrophy) prior to enrollment in the study.
Inclusion parameters included radiographic evidence of OA in 1 or more appendicular joints, an exclusively indoor lifestyle, and an owner with a stable routine during the study period. Cats were excluded if they:
- Had a systemic disease or clinically significant laboratory abnormalities
- Received anti-inflammatory drugs or joint supplements at time of enrollment
- Missed more than 2 treatment doses (gabapentin or placebo) during the study
- Experienced severe adverse events
Cats were assigned randomly to consecutive 2-week treatment windows of twice-daily gabapentin (10 mg/kg) or placebo (sucrose capsules) with no washout period between treatments. Activity levels were assessed using an accelerometer attached to the collar. Mean daily activity counts were calculated for each 2-week treatment period.
CSOMs were defined as “place- and time-specific activities for which the owner considered the pet to have signs of impairment prior to the start of the study.” Three CSOMs were identified for each cat, and ratings were obtained by phone at the end of the week preceding and during each week of the study. CSOMs were rated on a scale of 1 (worsened) to 5 (very improved), with a score of 2 being no change. Weekly scores were summed for each cat and ranged from 3 (worse in all areas) to 15 (greatly improved in all areas).
At the conclusion of the study, owners assessed QOL as improved, the same, or worse during the study period compared with the week prior and between the 2-week treatment windows. Differences in activity level, CSOMs, and QOL assessments between the placebo and gabapentin treatment periods were analyzed for statistical significance.
Twenty cats were enrolled in the study (spayed female, n=11; neutered male, n=9); the mean age was 14 years (range, 11 to 18 years) and mean body weight 5.3 kg (range, 2.7 to 8.1 kg). One cat was withdrawn from the study due to noncompliance and another for severe muscle tremors and ataxia.
The following results were statistically significant:
- Mean daily activity counts were higher during placebo treatment.
- The proportion of owners reporting improved CSOMs was higher during gabapentin treatment.
- Cats were more likely to have decreased CSOMs when moving from gabapentin to placebo treatment than when moving in the opposite direction.
Thirteen owners indicated improved QOL during the study when compared with the week immediately preceding the study. Four owners reported no change in QOL, and 1 reported a decrease. Nine of 18 owners reported adverse events during gabapentin treatment, with sedation (n=7) and ataxia (n=3) being most common.
In this study, cats treated with gabapentin at a twice-daily dose of 10 mg/kg showed an improvement in CSOMs, suggesting that gabapentin may be a useful component in treating OA pain in cats. Sedation was a common side effect, and activity was decreased during gabapentin treatment when compared with placebo. More studies are needed to evaluate the ideal dose of gabapentin to minimize adverse events and maximize quality of life.
Dr. Boatright, a 2013 graduate of the University of Pennsylvania, is an associate veterinarian in western Pennsylvania. She is actively involved in her state and local veterinary medical associations and is a former national officer of the Veterinary Business Management Association.