Hudec CP, Griffin CE. Changes in the stress markers cortisol and glucose before and during intradermal testing in cats after single administration of pre-appointment gabapentin. J Feline Med Surg. 2019 Apr 14;:1098612X19830501. doi: 10.1177/1098612X19830501
Gabapentin is a commonly used drug in veterinary medicine. Traditionally an anti-epileptic, it has seen extensive use for neuropathic pain control. Gabapentin is commonly used in a single pre-appointment dose for sedation and anxiolysis in cats to facilitate handling and examination, especially in high stress or “fractious” animals. Despite their use for this purpose and apparent clinical efficacy, there is little data on the effects of gabapentin on “stress” markers in cats.
Intradermal skin testing is widely considered the gold standard for the diagnosis of environmental allergies. Presentation to a clinic, shaving, injection, and interpretation of results is notoriously a stressful situation for many cats, and increase in stress hormones may confound the interpretation of results. Cortisol and glucose are traditionally viewed as “stress” markers in cats, and so are often used as surrogates of a stress response.
The purpose of this study was to determine if pre-appointment gabapentin was effective in reducing the stress markers cortisol and glucose in domestic cats in an intradermal skin testing (ITD) model. The study was performed in conjunction with a study determining if gabapentin has an effect on ITD results. 16 cats were enrolled in the study which was designed as a prospective, investigatory blinded crossover trial. Group 1 cats received gabapentin at the first visit and nothing at the second, while group 2 cats received nothing at the first visit and gabapentin at the second. 10 male neutered and 6 female spayed cats were enrolled. Cats were 1-14 years old (median 4 years)
Cats received a dose of gabapentin based on their weight which varied between 25-37.5mg/kg. Capsules were opened and the dose of gabapentin mixed into food after an overnight fast. A blood sample was collected on arrival at the clinic, the patients were sedated with dexmedetomidine, a second sample was collected, and then IDT performed and a third sample collected.
Patients were assigned an “ease of catheterization” score, owners filled out a questionnaire on overall experience, and the investigator logged whether or not they believed the patient received gabapentin. Serum cortisol and gabapentin levels were assayed on each blood sample.
There was no significant difference between blood glucose or cortisol concentrations based on whether or not the patient received gabapentin. Increasing number of venipuncture attempts, time to first blood sample, and time to catheter placement lead to increased cortisol in the group that did not receive gabapentin but not he group that did.
Owner assessment of stress levels were lower in most cats on the gabapentin visits, however these were, not blinded. Ease of catheter placement did not significantly differ between groups.
The authors conclude that gabapentin may provide a sedative effect to cats but does not reduce physiologic markers of stress. They further suggest that, as the cats who received gabapentin did not elevate their cortisol levels with increased handling, gabapentin may allow for longer periods of handling without proportionate increase in stress markers.
A potential limitation to this study is that glucose and cortisol are surrogate markers of physiologic stress, but may not be the only indicators of a patient’s mental status. While it may be concluded that gabapentin does not affect the pituitary-adrenal axis in cats, this does not give information on the entirely of the stress response. The small sample size and lack of complete blinding also limit the ability to interpret results. Despite these limitations, this study suggests that while gabapentin limits outward signs of stress, it does not affect some of the more common biomarkers of physiologic stress in cats. MRK
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