Bruno H. Pypendop, DrMedVet, DrVetSci, DACVAA, University of California, Davis
Gabapentin is often used in dogs and cats to prevent seizures and treat neuropathic pain.
Mechanism of Action
Although gabapentin is a structural analog of the neurotransmitter gamma-aminobutyric acid (GABA), it appears not to interact with GABA receptors.
Its mechanism of action is not entirely clear but is likely related to inhibition of calcium and, possibly, sodium channels.1
Gabapentin is excreted unchanged in humans but is metabolized to N-methyl-gabapentin in dogs.
Results in faster elimination and ability for shorter dose intervals in dogs as compared with humans2
The metabolism of gabapentin has not been studied in cats, but pharmacokinetics demonstrates faster elimination than in humans, with similar implications for dose intervals as in dogs.3
Gabapentin has been used as an adjunct treatment for seizures in dogs and cats and as treatment for neuropathic pain.4-9
Gabapentin may be effective as an adjunct treatment for acute pain in humans (eg, pain following some surgeries, including spinal surgery and hysterectomy) and, to a lesser extent, in dogs and cats.10-16
However, meta-analyses of human studies have failed to show strong benefits.17,18
A single case report described the successful use of gabapentin in the management of neuropathic pain in a horse.19
Most evidence showing efficacy of gabapentin in pain management in animals is anecdotal and not based on controlled studies.
The recommended dose is variable, ranging from 10-20 mg/kg q8-12h in dogs4,7-9,20 and 3-20 mg/kg q6-24h in cats.7,14-16,20
A dose of 2.5 mg/kg q12h has been used in a horse to treat neuropathic pain.19
Gabapentin has anecdotally been used in cats as a sedative to facilitate veterinary visits and procedures (eg, physical examination).
Doses of 50 mg/cat and 100 mg/cat have been shown to attenuate fear response in cats treated as part of a trap-neuter-return program.21
Sedation and ataxia are the most common adverse effects.8,9,20
Usually observed when doses at the higher end of the dose range are administered or when combined with other drugs that cause sedation
May decrease after a few days of administration9,20
Some liquid formulations of gabapentin contain xylitol, which is toxic in dogs; other formulations are xylitol free.
The xylitol-containing formulation may result in hypoglycemia in dogs when administered at the higher end of the dose range.
However, more severe toxicity (ie, liver failure) is unlikely unless extremely high doses (ie, >80 mg/kg) are used.20