Molecule of the Month: Gabapentin
Gabapentin was developed in the 1970s by scientists at Parke-Davis. Researchers were trying to design a molecule similar (structural analog) to GABA, the principal inhibitory neurotransmitter in the central nervous system, hoping it would help control seizures i.e. epilepsy treatment.
Although gabapentin was made to mimic GABA, it did not work directly on GABA receptors as expected. Later studies in the 1980’s showed that it acts by binding to the α2δ subunit of voltage-gated calcium channels, which reduces the release of excitatory neurotransmitters. This mechanism differentiated gabapentin from traditional GABA agonists and offered a novel approach to treating seizures and neuropathic pain and also contributes to its analgesic, anticonvulsant, and anxiolytic effects.
The molecule was developed through preclinical studies demonstrating anticonvulsant efficacy in animal seizure models. Based on these data, gabapentin was approved by the USFDA in 1993 under the brand name Neurontin for the adjunctive treatment of partial seizures in adults. Over the following years, its clinical use expanded to include management of neuropathic pain, postherpetic neuralgia, and other off-label indications.
While approved for human use, gabapentin is widely employed off-label in veterinary medicine, particularly for managing chronic and neuropathic pain, seizures, and anxiety in companion animals.
It should be noted that gabapentin use in food-producing animals such as cattle, sheep, Goats and Poultry, where its administration requires careful consideration of appropriate withdrawal time to prevent drug residues in animal-derived food products such as meat or milk.
Gabapentin, is a structural analog of γ-aminobutyric acid (GABA) used for the treatment of epilepsy. It primarily acts by binding to α2δ subunit of voltage-gated calcium channels, reducing the release of excitatory neurotransmitters such as glutamate. This mechanism contributes to its analgesic, anticonvulsant, and anxiolytic effects. While approved for human use, gabapentin is widely employed off-label in veterinary medicine, particularly for managing chronic and neuropathic pain, seizures, and anxiety in companion animals.
In veterinary practice, gabapentin has gained prominence for its versatility in multimodal therapy protocols. It is most commonly used in dogs and cats, with emerging applications in horses. Its favorable safety profile, even at high doses, and minimal cardiovascular impact make it a valuable adjunctive agent. However, Gabapentin is hygroscopic and pH dependent stability (under highly acidic or alkaline conditions) which may affect storage and compounding of certain formulations. Additionally, some human oral solutions currently available in the market contain xylitol as a sweetener, which can cause severe hypoglycemia in dogs, and therefore such formulations should be avoided in veterinary practice.
Veterinary Applications and Evidence
Small Animals (Dogs and Cats)
Dogs
Gabapentin serves as an adjunct for refractory epilepsy, chronic maladaptive pain (e.g., osteoarthritis, intervertebral disc disease), neuropathic pain in lameness, and behavioral disorders. Starting doses are 10 mg/kg PO every 12 hours, often titrated higher (up to 30–50 mg/kg every 8–12 hours) for refractory cases with good tolerance. Although dosing is generally calculated on a mg/kg basis, fixed per-animal doses are preferred in cats in clinical practice for convenience. A 2024 retrospective study reported owner-perceived improvements in behavioral disorders, with minimal side effects in most dogs.
Cats
Gabapentin effectively reduces situational anxiety (e.g., veterinary visits, transport) and manages chronic pain, including osteoarthritis and postoperative recovery. Doses of 20–30 mg/kg (or 100–150 mg/cat) 1–3 hours prior to events significantly lower stress scores. A 2025 systematic review of 20 studies confirmed consistent sedative, behavioral calming, and mild-to-moderate analgesic effects, with favorable cardiovascular safety. However, a 2026 study in shelter cats found limited evidence for stress reduction or perioperative analgesia in some contexts.
Horses
Gabapentin shows variable efficacy, with benefits in chronic laminitis and neuropathic pain reported in case studies, but limited as monotherapy for lameness. Recent pharmacokinetic data (2025) indicate rapid absorption and elimination, suggesting need for higher/frequent dosing.
Cattle
Gabapentin gains use off-label for preemptive analgesia in procedures like dehorning/disbudding and lameness management. Oral doses of 10–20 mg/kg, given 8 hours prior and combined with meloxicam, provide synergistic pain control with minimal adverse effects and good oral bioavailability.
Formulations and Comparative Efficacy
Oral Formulations → Tablets, capsules, or compounded liquids/suspensions are the gold standard due to high bioavailability (near 90–100% in small animals and ruminants). They achieve reliable therapeutic levels for analgesia, anxiolysis, and seizure control. Every 8–12-hour dosing with titration is optimal for chronic pain in small animals; preoperative single doses excel in cattle multimodal protocols.
Transdermal Formulations → Less reliable in cats due to variable, lower bioavailability; oral remains superior.
Most Efficient Results: Oral administration consistently delivers the best pharmacokinetics and outcomes across species. Multimodal protocols (e.g., with NSAIDs) and higher/titrated doses in chronic cases or preoperative timing in cattle provide strongest evidence-based benefits.
Side Effects and Safety
Dose-dependent mild sedation and ataxia are common and transient. Gabapentin has an excellent safety profile, even at high doses, with minimal impacts on cardiovascular or organ function. Recent reviews confirm low adverse events in cats and good tolerance in dogs.
Conclusion
Gabapentin is a versatile, safe cornerstone in veterinary medicine for pain, anxiety, and seizure management. Recent evidence (2024–2026) reinforces oral formulations in multimodal therapy as most efficient, particularly for feline anxiolysis/sedation and canine behavioral/chronic pain support, while advancing applications in large animals. However, there is continued need for research to refine dosing regimens and expand evidence-based applications in bovine medicine.
Its integration into veterinary protocols represents an important advancement in pain management, promoting better welfare outcomes in food-producing animals.
Reference
Population pharmacokinetics of a single oral dose of gabapentin... AJVR. 2025 (advance online Sep 2025).
Pain Management in Small Animals with Lameness. MSD Veterinary Manual. Reviewed/Revised Jun 2021; Modified May 2025. Available at: https://www.msdvetmanual.com/musculoskeletal-system/lameness-in-small-animals/pain-management-in-small-animals-with-lameness
Fadel C, Sartini I, Giorgi M. Gabapentin in Cattle (Bos taurus): State-of-the-Art and Therapeutic Perspectives. American Journal of Animal and Veterinary Sciences. 2022;17(3):187-197. DOI: 10.3844/ajavsp.2022.187.197.
De Cesare F, et al. Gabapentin: Clinical Use and Pharmacokinetics in Dogs, Cats, and Horses. Animals. 2023;13(12):2045. PMC10295034.
Kirby-Madden T, et al. Effects of Gabapentin on the Treatment of Behavioral Disorders in Dogs: A Retrospective Evaluation. Animals. 2024;14(10):1462.
Various Authors. A Systematic Review of the Sedative, Behavioral, Analgesic and Cardiovascular Effects of Gabapentin in Cats. Vet Sci. 2025;12(10):938. PMC12568128.
Evaluation of the effects of gabapentin on stress and pain in shelter cats. JAVMA. 2026 (advance online Jan 2026).