When veterinarians increasingly prescribe a medication, it's essential to examine not just its current use, but its history, scientific evidence, and real-world effects. Gabapentin for dogs has become commonplace for managing chronic pain, anxiety, and seizures, but the story behind this drug raises critical concerns that deserve careful consideration alongside the experiences of veterinarians who use it daily.

Understanding What Gabapentin Is

Gabapentin is a medication FDA-approved for human use that veterinarians prescribe "off-label" for dogs. This means it's being used for purposes and in species not originally approved by the FDA.

Veterinarians most commonly recommend gabapentin to treat chronic pain in dogs, particularly neuropathic pain that arises from nerve damage or dysfunction. It may be prescribed alone or combined with other pain medications, and is also used to manage seizures (typically with other anti-convulsant medications) and anxiety.

The medication comes in various forms: 100 mg, 300 mg, and 400 mg capsules; 300 mg, 600 mg, and 800 mg tablets; and liquid formulations sometimes used for very small dogs. Dogs typically take gabapentin every 8 to 12 hours, though veterinarians may start with once-daily dosing at bedtime to help dogs adjust to the medication.

The Troubling History Behind Gabapentin

The background of gabapentin raises red flags that every pet parent should know. Originally developed in 1975 to treat seizures, the FDA approved it for human epilepsy in 1993 and for postherpetic neuralgia (shingles) in 2002. Under Pfizer's brand name Neurontin, it became one of the pharmaceutical giant's best-selling drugs—but not for its approved uses.

Within a few years, Pfizer (then Warner-Lambert) faced litigation for violating federal racketeering law. The company had illegally marketed gabapentin for at least a dozen off-label uses the FDA hadn't approved.

A staggering 90% of Neurontin sales were for off-label prescriptions. In 2004, Pfizer settled the case, paying $430 million in criminal charges and civil liabilities—one of the largest pharmaceutical settlements in history at that time.

The problems continued. In 2009, pregabalin (Lyrica), a gabapentin derivative, was part of a massive $2.3 billion settlement against Pfizer. Beyond the off-label marketing concerns, the drug induced pancreatic cancer in laboratory rats and caused numerous adverse effects in humans, including dizziness, loss of coordination, fatigue, tremors, involuntary muscle jerking, suicidal thoughts, addiction, and withdrawal syndrome. The Mayo Clinic documents an extensive list of oral gabapentin side effects for humans.

Despite this troubled history, gabapentin appeared in veterinary medicine around 2008—just four years after the first major Pfizer settlement and one year before the second.

What Pet Parents Are Experiencing

Over the past several years, many dog owners have reported concerning reactions in their pets taking gabapentin. Some dogs continue experiencing significant pain despite the medication, while also developing troubling side effects. For large dogs like an 80-pound Labrador who can't get up and walk, this becomes more than an inconvenience—it can lead to heartbreaking life-or-death decisions.

Common Side Effects Reported

The three most frequently documented side effects are sedation, loss of coordination, and gastrointestinal upset. However, the range of reported adverse reactions is much broader:

Physical symptoms include:

• Diarrhea, black tarry stools, and vomiting
• Low energy, excessive drooling, and sedation
• Rolling eye movements
• Loss of coordination, unsteady gait, clumsiness, and loss of balance (ataxia)
• Loss of appetite or conversely, increased appetite and weight gain
• Gastrointestinal distress
• Fluid retention in limbs and extremities

Behavioral and neurological changes include:

• Increased anxiety or agitation (ironically, from a medication sometimes prescribed to treat anxiety)
• Behavioral changes and aggressiveness
• Mental distress
• Signs of cognitive disorder, including head pressing, getting stuck in corners, and staring into space
• Dementia-like symptoms and memory loss

Serious allergic reactions include:

• Difficulty breathing
• Swelling of the lips, tongue, or face
• Hives

The Scientific Evidence Gap

Current veterinary drug references use notably cautious language when discussing gabapentin, including phrases like "may be effective in some dogs," "evidence to support use is relatively weak" (for seizures), and "extra-label use." This uncertainty exists for good reason.

The reality is stark: there have been zero controlled research studies on gabapentin to treat pain in dogs. No double-blind, placebo-controlled studies support its use for chronic pain management in canines. The veterinary literature supporting gabapentin's use as a pain medication remains sparse, with some studies suggesting potential effectiveness while others found it did not significantly decrease pain.

Research in human medicine adds to the concerns. A 2018 review found gabapentin provided no benefit for sciatica or lower back pain in humans. Perhaps most troubling, a 2009 study discovered that gabapentin influences a receptor responsible for creating new synapses in the brain. The medication can block the specific receptor that helps the brain grow, develop, and repair itself. This means gabapentin may actually inhibit new neural connections from forming, potentially preventing the nervous system from healing itself.

Understanding the Side Effects

Sedation and Drowsiness

Especially initially, gabapentin can cause dogs to be noticeably more sedate and sleepy than normal. You may notice your dog isn't as excited about walks or playtime, prefers to keep sleeping rather than interacting, or has slower reaction times.

Sedation becomes even more common when gabapentin is combined with other sedating medications like antihistamines (Benadryl), opioids (tramadol), or CBD supplements.

The severity matters. If your dog is only slightly more subdued, giving them a few days to adjust may be all that's needed. For more significant sedation, veterinarians may suggest giving gabapentin only at bedtime initially, allowing the dog to sleep through the sedative effects. Alternatively, starting with a lower dose and gradually increasing may help. Both approaches have the disadvantage of providing less pain control initially.

Loss of Coordination (Ataxia)

Gabapentin can cause dogs to have an unsteady gait or loss of coordination—the veterinary term is "ataxia." Dogs may appear wobbly and off balance, have trouble with stairs or jumping on furniture, occasionally stumble, or even fall over when walking. In some cases, a dog's back legs may appear to be collapsing.

This can be particularly distressing to witness. If ataxia wasn't present before starting gabapentin, the medication is the likely culprit. However, for dogs with pre-existing neurological conditions like intervertebral disc disease (IVDD), worsening of the underlying condition could also be responsible. Veterinary guidance is essential to distinguish between these possibilities.

Gastrointestinal Issues

Like many medications, gabapentin can occasionally cause GI upset, including decreased appetite, mild vomiting, or diarrhea. Giving the medication with meals or feeding a bland diet while waiting a few days for adjustment may help manage mild symptoms. Severe vomiting, diarrhea, or complete loss of appetite warrants immediate veterinary attention.

Less Common but Concerning Effects

Increased Appetite and Weight Gain: Some dogs develop increased appetite on gabapentin, leading to counter-surfing, begging, and increased caloric intake with subsequent weight gain.

Behavioral Changes: Rarely, dogs experience paradoxical reactions—becoming agitated or excited rather than sedate. Studies have reported similar reactions in children taking gabapentin, suggesting this could occur in dogs as well, though the connection isn't yet clear.

Urinary Changes: Gabapentin might slightly increase urine retention in dogs, though this hasn't been well studied. Some cases of urinary incontinence have improved on gabapentin, but whether this can be attributed to the medication or other factors remains unclear.

Additional Medical Concerns

Nutritional Deficiencies: Gabapentin works on calcium channels and can cause deficiencies in calcium, vitamin D, vitamin B1, and folate—nutrients that ironically help with nerve repair.

Organ Function: The kidneys primarily excrete gabapentin via urine, so dogs with severe kidney failure may need dose adjustments. The liver only minimally metabolizes gabapentin, so dogs with liver disease typically don't require significant dose changes.

Drug Interactions and Special Populations: Veterinarians generally avoid using gabapentin in pregnant dogs unless absolutely necessary, as its effects on the fetus haven't been fully characterized in dogs. Dogs taking antacids, hydrocodone, or morphine require careful monitoring for potential interactions.

Critical Warning About Liquid Formulations: The liquid form of gabapentin often prescribed for humans (trade name Neurontin®) can contain xylitol, an artificial sweetener that is toxic—and potentially fatal—to dogs. Veterinarians must verify with pharmacists that any liquid gabapentin formulation does not contain xylitol. If a xylitol-free version isn't available from human pharmacies, compounding pharmacies may be needed.

The Tolerance and Withdrawal Problem

Most dogs develop tolerance to gabapentin over time when using it for chronic pain relief, requiring increasingly higher doses to achieve the same effect. Higher doses increase both the risk and severity of side effects, creating a dangerous escalating cycle that also raises overdose risk.

Stopping gabapentin requires caution. Rapidly discontinuing the medication can cause increased seizure activity in dogs taking it as an anti-seizure medication. Abrupt withdrawal can also cause rebound pain in dogs using it for pain control.

Veterinarians typically recommend gradually decreasing the dose rather than stopping cold turkey, especially for dogs who have been on it for extended periods, have a history of seizures, or experience significant pain.

How Long Do Side Effects Last?

Gabapentin has a relatively short half-life—the time it takes for the body to metabolize and eliminate half the dose. In a study of Greyhound dogs, the half-life was 3.3 to 3.4 hours. This means the body breaks down and eliminates half the dose in about 3.5 hours, so side effects should wear off fairly quickly.

Additionally, most dogs' bodies adjust to gabapentin after several days. Typically, within a week or so, dogs no longer experience significant sedation or loss of coordination. This is reassuring for mild side effects but doesn't address the broader concerns about efficacy and long-term use.

Clinical Observations from Veterinary Practice

The experiences of veterinarians who work extensively with gabapentin reveal troubling patterns:

Physical adverse effects: Dogs becoming lethargic or developing vomiting, diarrhea, and tremors—effects that resolve when the medication is discontinued.

Cognitive concerns: Elderly patients developing signs of cognitive disorder, including head pressing, getting stuck in corners, and staring into space, with recovery occurring after stopping the drug.

Behavioral changes: Dogs becoming more aggressive and exhibiting signs of dementia and memory loss. Even human family members of some practitioners have experienced senility, memory loss, and confusion with this drug.

Lack of efficacy: Perhaps most significantly, many holistic veterinarians report seeing few cases where gabapentin made a meaningful difference in pain management.

The Double Standard in Evidence Requirements

A troubling inconsistency exists in how evidence standards are applied. The holistic and alternative medicine communities face constant, extraordinary pressure to provide double-blind, placebo-controlled studies proving their treatments work. Yet gabapentin—a drug with severe, sometimes life-threatening side effects and a history of massive pharmaceutical fraud—entered veterinary medicine for off-label use without such studies. Not even safety studies were required.

This pattern becomes even more concerning when examining the timeline: pharmaceutical companies unable to market drugs effectively in human medicine (often due to safety concerns, lawsuits, or patent expiration) redirect them to the veterinary market, where regulatory standards may be less stringent and scrutiny less intense.

Comparing Gabapentin to Other Medications

Gabapentin vs. NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) like carprofen are highly effective at decreasing pain and inflammation, and can dramatically improve quality of life for dogs with arthritis. However, NSAID side effects include vomiting, diarrhea, bloody stool, GI ulcers, and lack of appetite. Additionally, NSAIDs can negatively impact kidney function, requiring cautious use in dogs with kidney issues—a common concern in senior dogs who often need daily pain management.

Gabapentin presents an alternative for these cases. While dogs with kidney disease may need lower doses due to slower excretion, gabapentin doesn't appear to have the same adverse effects on kidneys that NSAIDs do. However, gabapentin lacks the anti-inflammatory effects of NSAIDs, potentially making it less effective for conditions where inflammation contributes significantly to pain.

Gabapentin vs. Trazodone

Trazodone is a popular anti-anxiety medication that shares several side effects with gabapentin, including sedation, GI upset, agitation, aggression, and increased appetite. A significant difference is that trazodone can interact dangerously with many anti-anxiety and anti-depressant medications, risking a dangerous condition called serotonin syndrome. Gabapentin can be safely combined with trazodone and most other medications, offering more flexibility.

Gabapentin vs. Tramadol

Tramadol is an oral opioid pain medication that, like gabapentin, lacks anti-inflammatory properties. Veterinarians sometimes use tramadol and gabapentin together, or combine either with an NSAID for better pain control. Tramadol's side effects include sedation, GI upset, constipation, panting, and dilated pupils—effects that are typically uncommon and mild, similar to gabapentin.

Both tramadol and gabapentin lack sufficient evidence in the veterinary literature to conclusively prove efficacy, though many veterinarians believe they help decrease pain, especially when combined with other pain relievers.

What About Overdoses?

Gabapentin has a wide margin of safety and therapeutic range, making true overdoses uncommon. In reported cases of accidental overdose, dogs typically showed more severe versions of the standard side effects: extreme ataxia (wobbly, unsteady gait), pronounced sedation or drowsiness, and vomiting.

Because of the overlap between expected side effects and overdose signs, contacting your veterinarian or a pet poison control center (such as ASPCA Animal Poison Control Center) is the safest course if you're concerned about potential overdose.

Safer, Evidence-Based Alternatives

Effective alternatives exist for managing pain in dogs without the risks and questionable efficacy associated with gabapentin:

Turmeric: A powerful anti-inflammatory with extensive research supporting its use

Acupuncture and Electroacupuncture: Particularly effective for nerve pain, with substantial evidence base

Chinese Herbal Therapies: Time-tested formulations for pain and inflammation with centuries of clinical use

Western Herbs: Numerous botanicals with demonstrated anti-inflammatory and analgesic properties

Homeopathic Remedies: Individualized treatments based on the whole patient

These approaches address pain while supporting the body's natural healing processes rather than potentially interfering with neural repair and regeneration.

Making Informed Decisions for Your Dog

The decision to use gabapentin should involve careful consideration of both potential benefits and documented risks. Before accepting a gabapentin prescription, consider discussing these questions with your veterinarian:

1. What specific evidence supports using gabapentin for my dog's particular condition?
2. What are all the potential side effects, and how will we monitor for them?
3. How will we objectively measure whether the medication is actually working?
4. What alternative treatment options exist, including both conventional and integrative approaches?
5. If my dog develops tolerance and needs higher doses, what's the long-term plan?
6. Given gabapentin's history and the lack of veterinary studies, why is this the best choice for my dog?
7. Can we try alternative approaches first, or combine them with a lower gabapentin dose?

Balancing Perspectives

It's important to acknowledge that veterinary experiences with gabapentin vary. Some veterinarians report that their clinical experience has made them believers in gabapentin's usefulness and efficacy, despite the sparse literature. They find that many dogs experience no side effects or only mild, transient ones that resolve within days. These practitioners may view gabapentin as a valuable tool, especially when combined with other pain management strategies.

However, this clinical confidence must be weighed against the documented concerns: the complete absence of controlled studies in dogs, the troubling pharmaceutical history, the mechanism that may inhibit neural repair, the pattern of tolerance requiring dose escalation, and the reports of significant adverse effects including cognitive changes.

The Bottom Line

Every dog deserves effective pain management based on solid evidence and genuine efficacy, not on pharmaceutical companies' need to find new markets for medications with troubled histories. The facts surrounding gabapentin paint a concerning picture:

• A history of massive legal settlements for illegal off-label marketing in humans
• No FDA approval for the conditions it's prescribed to treat in dogs
• Zero double-blind, placebo-controlled studies supporting its use for canine pain management
• Evidence suggesting it may prevent the nervous system from repairing itself
• A pattern of tolerance requiring dose escalation with increased side effect risks
• Reports of significant adverse effects including cognitive changes and behavioral problems
• The troubling timeline of entering veterinary medicine shortly after major pharmaceutical settlements

While some veterinarians report positive clinical experiences with gabapentin, these subjective impressions cannot replace rigorous scientific evidence—the very standard demanded of alternative and integrative medicine approaches.

Your dog's health, comfort, and quality of life deserve treatment decisions made with complete, transparent information about both potential benefits and documented risks.

When a medication's history raises as many red flags as gabapentin's does, pet parents have every right to ask hard questions and explore alternatives before their beloved companions become part of an ongoing, uncontrolled experiment in veterinary medicine.

Whether you choose to use gabapentin should be an informed decision made in partnership with a veterinarian who respects your concerns, presents all the evidence honestly, and supports exploring multiple approaches to keep your dog comfortable and thriving.

References

Di Cesare F, Negro V, Ravasio G, Villa R, Draghi S, Cagnardi P. Gabapentin: Clinical Use and Pharmacokinetics in Dogs, Cats, and Horses. Animals (Basel). 2023 Jun 20;13(12):2045. doi: 10.3390/ani13122045. PMID: 37370556; PMCID: PMC10295034.

Huang YH, Pan MH, Yang HI. The association between Gabapentin or Pregabalin use and the risk of dementia: an analysis of the National Health Insurance Research Database in Taiwan. Front Pharmacol. 2023 May 30;14:1128601. doi: 10.3389/fphar.2023.1128601. PMID: 37324474; PMCID: PMC10266423.

Peckham AM, Evoy KE, Ochs L, Covvey JR. Gabapentin for Off-Label Use: Evidence-Based or Cause for Concern? Subst Abuse. 2018 Sep 23;12:1178221818801311. doi: 10.1177/1178221818801311. PMID: 30262984; PMCID: PMC6153543.