Gabapentin is a drug that was formally approved in 1993 for the treatment of epilepsy. It is still commonly used as an anticonvulsant drug, generally as an adjunct. Roughly a decade later, the drug was approved for the treatment of neuropathic pain. It is considered to function via modulation of GABA (gamma-aminobutyric acid) in the brain.
The drug has a relatively vague mechanism of action that produces anticonvulsant, analgesic, and anxiolytic effects. Some have compared the drug to various benzodiazepines like Valium (Diazepam) in that it reduces physiological arousal. It is also frequently prescribed as an off-label treatment for restless leg syndrome, hot flashes, and refractory cases of anxiety.
Due to the fact that many dogs (canines) can experience epilepsy and neuropathic pain, Gabapentin has been researched as a potential pharmaceutical treatment. It is believed to elicit similar effects in canines as humans, has a high bioavailability, and appears to be well-tolerated. Just because a drug is well-tolerated does not make it automatically effective.
Gabapentin For Dogs: The Research
It is important to avoid wrongfully assuming that a medication that’s effective for humans is automatically effective for canines and vice-versa. Although Gabapentin has been approved for the treatment of various human conditions, there is little research that has been conducted investigating its efficacy in dogs.
Absorption: A paper published in 1986 suggested that Gabapentin is well-absorbed by canines and maximum blood levels are reached within 1 to 3 hours of administration. This paper highlighted the fact that Gabapentin transitions into “N-methyl-gabapentin” in canines; a biotransformation that does not occur in humans. The peak blood levels occur in dogs and humans both within 1 to 3 hours after ingestion. The elimination half-life of Gabapentin in dogs is 3 to 4 hours, whereas in humans it is 5 to 6 hours.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/3730018
Bioavailability: Research published in 1995 indicates that Gabapentin has favorable bioavailability in canines. One report highlighted the oral bioavailability of Gabapentin in dogs when administered at 50 mg/kg was approximately 80%. Maximum blood concentrations were attained within just 2 hours of oral administration in this study. Furthermore, 34% of the dose was metabolized into N-methyl-gabapentin; a biotransformation that does not occur in humans.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/7600909
Gabapentin for Dogs: Potential Uses
Below is some research analyzing the potential therapeutic uses for Gabapentin in dogs. Due to the fact that most studies are small-scale, it is difficult to suggest Gabapentin’s clinical efficacy for any condition. Some evidence suggests that it may be an effective adjunct when used for the treatment of epilepsy.
Anticonvulsant effects: There is some evidence to suggest that Gabapentin may be an effective adjunct for the treatment of epilepsy in canines – particularly those with refractory idiopathic epilepsy. Though the drug does not appear to reduce seizure intensity, evidence suggests that it may reduce both the number of seizures experienced and the number of days on which seizures occur (per week). It may also increase the time between seizures (interictal period).
Some dogs appear to have more favorable responses to others to Gabapentin when used as an anticonvulsant. In fact, one study found that some dogs went from having severe frequent seizures to no seizures once Gabapentin was added to their treatment regimen. Like humans, responses to Gabapentin are likely subject to significant individual variation.
2005: Due to the fact that Gabapentin is an effective adjunct for the treatment of epilepsy in humans means that it could have similar therapeutic effects in canines. In 2005, researchers tested the efficacy of Gabapentin as an adjunct treatment for dogs with refractory epilepsy. A total of 17 canines were included in the study; 16 of which were diagnosed with idiopathic epilepsy.
All canines included in the study were treated with phenobarbitone and/or potassium bromide for stabilization of seizures. After the dogs were stabilized (as determined by serum concentrations), 35 to 50 mg/kg of Gabapentin was administered. This dosage was given 2 or 3 times per day over the course of 4 months.
The dog owners were instructed to document all seizure activity and side effects in a journal. The dogs had undergone physical examinations and blood sample extractions each month to assess concentrations of the pharmaceutical agents. The results suggested that there was no significant reduction in the number of seizures experienced during the 4 months with Gabapentin administration.
That said, researchers reported that 3 dogs completely stopped seizing and the interictal period (time between seizures) significantly increased. The most notable side effect of Gabapentin administration was sedation and loss of muscle control. Over the long-term, it was reported that 2 of the dogs were seizure free and 10 owners reported benefit from the Gabapentin.
The results from this study suggest that using Gabapentin as an adjunct for the treatment of epilepsy in canines may increase the interictal period with minimal side effects. Researchers report that the drug may help prevent seizures entirely in certain dogs. It should be noted that this is a very small scale study, but does show some benefit – even if it’s just lengthening the time between seizures.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/16255282
2006: Another study was published in 2006 analyzing the effects of oral Gabapentin administration on 11 dogs diagnosed with refractory idiopathic epilepsy. They were administered Gabapentin at a starting dose of 100 mg/kg every 8 hours for at least 90 days (3 months). All dogs included in this study had been experiencing generalized “tonic-clonic” seizures and were regularly treated with both phenobarbital and/or potassium bromide.
Prior to administration of Gabapentin, researchers measured: number of seizures, duration of seizures, and number of days on which seizures occurred. These baseline measures were then compared to the same measures taken after 3 months treatment. Researchers interpreted efficacy of Gabapentin based on whether it reduced the number of seizures per week by 50%.
Results suggested that 6 dogs showed marked improvement on Gabapentin treatment. Gabapentin as an adjunct in dogs reduced the number of seizures per week and number of days with seizures during the week. Though the drug didn’t appear to reduce the severity of seizures, reducing the number of seizures per week is significant.
Some side effects were noted including both sedation and loss of muscle control, but these were not considered severe. Though this study was extremely small-scale, it provides more positive evidence for the usage of Gabapentin in canines with refractory epilepsy.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/17189599
2009: A newer drug called Pregabalin (brand name “Lyrica”) is considered the successor to Gabapentin. It is more potent and is classified as a “Schedule V” controlled-substance whereas Gabapentin is not. Researchers designed a study in 11 canines with idiopathic epilepsy to test both the safety and efficacy of Pregabalin when administered as an adjunct.
Dogs were already being treated with phenobarbital, potassium bromide, and/or a combination of both substances. All dogs in the study were regarded as having “poorly controlled” epilepsy. The 11 dogs were evaluated at baseline for the number of generalized seizures in 3 months before treatment, and again in the 3 months during which Pregabalin was added as an adjunct.
Results suggested that Pregabalin significantly reduced seizures after Pregabalin in the 9 dogs that followed through with the study. Of these dogs, 7 were regarded as “responders” with major seizure reductions. Some adverse effects were reported in 10 of the dogs, but like in previous Gabapentin studies, they were considered “mild.”
While Pregabalin is certainly not the same drug as Gabapentin, it is considered very similar. Most individuals report very similar anticonvulsant effects regardless of which specific drug is administered. Results from this study may support preexisting evidence suggesting the efficacy of Gabapentin for the treatment of seizures in canines.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/20001779/
Analgesic effects: Several studies have been conducted to analyze the effect of Gabapentin as a potential analgesic in dogs. Although most studies were small scale, none of them found a significant benefit associated with using Gabapentin as an adjunct treatment for pain. In one study, postoperative morphine requirements were reduced in dogs administered Gabapentin, but postoperative pain scores did not significantly differ in the Gabapentin group compared to the placebo group.
2010: There is evidence to suggest that Gabapentin may be an effective adjunct analgesic treatment for dogs undergoing amputation of a frontal-limb. To study the effect of Gabapentin as an analgesic, researchers recruited 30 client-owned dogs undergoing amputations. They performed multiple pain assessments prior to the procedure.
Some of the dogs were administered Gabapentin (10 mg/kg) followed by 5 mg/kg, while others received a placebo. Administration of Gabapentin was continued for three additional days following the amputation of the frontal-limb. Every 18 hours post-surgery, in-patient pain evaluations were conducted.
In addition, owners were also asked to assess their dog’s activity level, appetite, and overall soreness within 3 days of being discharged from the hospital. Results suggested that pain evaluation scores did not significantly differ between the dogs receiving Gabapentin compared to those receiving a placebo. Although the study was considered small-scale and other analgesics were administered to both groups, there wasn’t significant evidence to suggest Gabapentin’s efficacy for perioperative pain reduction.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/20367041
2012: In a randomized, controlled, clinical trial, researchers analyzed the analgesic effect of Gabapentin when administered as an adjunct on 63 client-owned dogs undergoing a hemilaminectomy. A hemilaminectomy is a surgical procedure conducted to reduce pain caused by an irritated nerve and/or impingement of the spine. The 63 dogs were divided into 2 treatment groups: one receiving 10 mg/kg Gabapentin orally every 12 hours prior to anesthesia and the other receiving a placebo (gelatin) prior to anesthesia.
Levomethadone and Fentanyl patches were administered to help reduce pain. Pain was measured with the Glasgow Composite Measure Pain Score (CMPS-SF) and via a Visual Analogue Scale (VAS). Although pain scores as measured by the CMPS-SF were of a lower “median” in the Gabapentin group, the average differences in pain scores in comparison to the placebo group weren’t of clinical significance.
Researchers suggested that the insignificant differences may be a result of the other opioid / analgesic agents administered to both groups. They also highlight the fact that Gabapentin dosing may have been inadequate to provide additional pain relief. This research suggests that Gabapentin is not an effective analgesic adjunct when administered for surgery.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/22882632
2015: Yet another study analyzed the analgesic effect of Gabapentin as an adjunct in canines. This study specifically focused on postoperative pain management following a mastectomy. A mastectomy is a surgical procedure in which breast tissue is removed.
A total of 20 dogs were included in this study, all of which were undergoing a mastectomy. The dogs were divided into 2 groups: one group received perioperative oral placebo or Gabapentin (10 mg/kg). All dogs were administered intramuscular acepromazine and morphine for pain relief, while anesthesia was achieved with propofol (4 mg/kg) and isoflurane.
Postoperative analgesic effects were evaluated for 72 hours. Dogs in significant pain were administered intramuscular morphine following surgery. The results of this study documented no significant differences in pain scores among dogs receiving Gabapentin compared to those receiving a placebo.
Gabapentin administration did provide some benefit in that it reduced postoperative need for morphine. This suggests that the dogs administered the Gabapentin may have been getting a subtle analgesic effect, but not significant enough to differ with the placebo group. This study adds to the existing literature suggesting no significant benefit associated with Gabapentin for the purposes of pain relief in dogs.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/25816802
Cancer pain: There is some evidence to suggest that Gabapentin may be an effective alternative treatment for pain associated with various types of cancers in canines. Although traditional opioids may be preferred for cancer pain management, Gabapentin may be a viable alternative with less pronounced side effects. Although its analgesic effect may be less noticeable than standard opioids, it may provide mild or moderate relief for canines coping with pain-inducing cancers.
- Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704117/
Neuropathic pain: There appears to be only one, extremely small-scale report of Gabapentin benefiting dogs diagnosed with refractory neuropathic pain. Various traditional analgesic treatments were administered, but symptoms did not improve. Administration of either Gabapentin or Amitriptyline seemed to completely alleviate symptoms.
2009: A report published in 2009 discussed the case of 3 dogs that had chronic behavioral and locomotor disorders associated with pain. All 3 dogs found no relief with traditional analgesic options including NSAIDs (non-steroidal anti-inflammatory drugs), glucocorticoids, and opioid agonists. All dogs had undergone neurological testing and various diagnostic protocols to rule out other causes of pain.
Each of the dogs was diagnosed with “neuropathic pain” and alternative treatments were considered, one of which was Gabapentin. Researchers found that by administering either Gabapentin or Amitriptyline (a tricyclic antidepressant), the neuropathic pain significantly improved in all cases. While this study is small-scale, it highlights the fact that dogs with neuropathic pain may benefit from Gabapentin – particularly those that have poor responses to traditional treatments.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/19178477
Conditions Gabapentin May Treat in Dogs
There are several conditions that may improve with administration of Gabapentin in dogs. Most of the aforementioned evidence is too small-scale to make any definitive conclusions suggesting the drug’s efficacy versus its inefficacy. That said, most research concludes that the drug may help dogs with epilepsy, but not with pain reduction.
Anxiety: While the research has not specifically studied Gabapentin for anxiety in dogs, there is reason to believe that it may elicit an anxiolytic effect. This is due to the fact that the drug causes drowsiness likely via modulation of GABA. This hypothesized GABAergic modulation suggests that (just like in humans) the drug could reduce anxiety.
Epilepsy: There is evidence to suggest Gabapentin’s efficacy in reducing the frequency of seizures in dogs. Dogs with treatment-resistant forms of epilepsy may significantly benefit from adding Gabapentin as an adjunct treatment to their regimen. Though further research is warranted, the preliminary evidence is optimistic.
Pain: Upon analysis of Gabapentin’s analgesic effect, it appears to be relatively weak in dogs. One limitation associated with analgesic research is that the studies are small-scale and the fact that Gabapentin was used as an adjunct. Researchers highlight that the effect of other opioids may have essentially overpowered the effect of Gabapentin to notice a difference. Another thought was that Gabapentin may not have been administered at a high enough dosage to elicit a significant analgesic effect.
- Cancer pain: Some studies suggest that Gabapentin may provide some relief in terms of reducing pain associated with various types of cancers in dogs.
- Neuropathic pain: One study highlighted the fact that refractory neuropathic pain in dogs may be mitigated with administration of Gabapentin and/or tricyclic antidepressants.
- Surgery-related pain: When administering Gabapentin as an adjunct to traditional opioids for the reduction of perioperative surgical pain, it appears as though the drug provides no additional benefit. It may reduce the need for additional postoperative opioids (e.g. morphine), but its analgesic effect for surgery-related pain is insignificant in canines.
Limitations of Research: Gabapentin for Dogs
There are many limitations associated with the research of Gabapentin in dogs. Perhaps the biggest limitation is that nearly every study conducted was extremely small-scale and highly specific. Therefore results suggesting possible therapeutic potential (or lack thereof) may be subject to significant inaccuracies.
Dosing: In most studies related to analgesic effect, Gabapentin was administered at doses of 10 mg/kg at various time intervals. Perhaps this was too low of a dose to achieve any significant effect. It is difficult to administer more than 10 mg/kg due to the fact that there may be potential unsafe contraindications with other opioids and/or analgesics.
Researchers haven’t experimented much with the dosing and therefore may have found insignificant effect because too low of a dose was used. Other studies administered 35 to 50 mg/kg and 100 mg/kg of Gabapentin and noted therapeutic effect for the treatment of seizures. It is possible that Gabapentin may be a superior anticonvulsant than it is an analgesic – but alternative strength of dosing needs to be researched; particularly for pain reduction.
Frequency of administration: Research conducted on Greyhounds indicates that Gabapentin is likely rapidly absorbed and eliminated in dogs. Evidence from a report published in 2011 indicates that frequent dosing is necessary to maintain minimum targeted plasma concentrations of the drug. Should any of the aforementioned studies have administered Gabapentin at time intervals exceeding 8 hours, the drug may have lost efficacy and ultimately [inadvertently] clouded the results of the study.
(This is based off of the fact that therapeutic efficacy in humans is achieved at 2 μg/mL plasma concentrations of Gabapentin, and that for dogs this concentration would need to be similar to attain a therapeutic effect).
- Source: http://www.ncbi.nlm.nih.gov/pubmed/19854080
Individual variation: Some studies mentioned that there was variation in responses to Gabapentin based on the particular dog. Some dogs seemed to respond very well, while others did not. There may be specific genetic biomarkers or breed-specific characteristics associated with increased and/or decreased efficacy of Gabapentin treatment as well as adverse reactions.
Researchers should consider that there may be variation in responses between individual dogs and breeds of dogs. This remains incredibly difficult due to the already small samples of dogs available for these types of studies.
Lack of research: The research analyzing the therapeutic effects of Gabapentin in dogs is severely lacking. The studies that have been published tend to include a very small number of canine participants. Follow-up research has been relatively unfocused and does not seem to expand off of previous findings (or lack thereof). Maybe researchers have thrown in the towel on Gabapentin in canines due to availability of more proven, effective treatments.
Mechanism of action unknown: It’s more challenging to study a drug with an unknown mechanism of action, specifically in dogs. While the mechanism of action is believed to be similar in dogs as humans, this cannot be confirmed. The drug metabolizes into “N-methyl-gabapentin” in dogs – it does not do this in humans or other rodents. The drug is believed to modulate the neurotransmission of GABA – an inhibitory neurotransmitter.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/12021399
Small-scale studies: Most studies conducted using Gabapentin in dogs have been extremely small-scale. The largest study analyzing Gabapentin’s effects included 63 dogs, with most studies containing less than 20 dogs. To determine the therapeutic efficacy of any substance, a larger-scale studies need to be conducted.
Thinking Twice Before Using Gabapentin in Dogs…
In most cases, Gabapentin isn’t considered a first-line treatment option for health conditions in canines. It may be prescribed as an adjunct medication to help control seizures and/or pain, but there isn’t significant evidence to suggest that it helps. Based on the current body of research analyzing Gabapentin administration in canines, the potential detriment may outweigh the speculative benefits.
- Adverse reactions: As with any medication, there’s always a potential for adverse reactions. Most research suggests that adverse reactions are mild and that the drug is well-tolerated. However, since every dog is different and the presented studies were small, more serious adverse effects may occur including coma and possibly death.
- Balance / coordination problems: A common adverse effect experienced by dogs upon administration of Gabapentin is that of “ataxia.” Ataxia is characterized by loss of control of bodily movements. This may result in balance problems and other coordination problems. While the ataxia may be relatively benign for most, some dogs may experience functional impairment and/or be increasingly prone to injury as a result.
- Drowsiness: Perhaps the most common side effect associated with Gabapentin in dogs and humans is that of drowsiness. This drowsiness stems from Gabapentin’s modulation of GABAergic activity, which decreases physiological arousal. Should your dog experience drowsiness, he or she may appear more fatigued, less energetic, and sleepy.
- Interactions: It is possible that Gabapentin may interact with other drugs that your dog is taking. For this reason, it is important to talk to your vet to determine any potential contraindications. Interactions with other drugs may result in serious side effects and could be fatal.
- Lack of efficacy: Most literature suggests that Gabapentin is ineffective for the treatment of most conditions in dogs. While the drug may be of benefit to certain dogs that fail to respond to traditional, first-line options, there isn’t significant evidence to justify its administration for most conditions.
- Superior options: It is thought that there are likely superior medicinal options to Gabapentin for the treatment of seizures and pain. While Gabapentin may be a helpful adjunct in refractory cases of epilepsy and/or various types of pain, it isn’t usually considered a first-line treatment.
Should Gabapentin be used in dogs?
It is difficult to determine whether Gabapentin should be utilized in canine populations. The drug appears to be safe with minimal side effects. However, it remains difficult to justify the drug’s use when most studies suggest that it produces no significant therapeutic effect when compared to a placebo.
Certain veterinarians may prescribe Gabapentin if your dog fails to derive therapeutic benefit from traditional first-line treatments for a condition like epilepsy or neuropathic pain. As evidenced by certain studies, some dogs may experience marked symptomatic improvement once Gabapentin is added to their treatment regimen. Therefore the drug may be beneficial to test on an experimental basis with potential therapeutic upside – especially for dogs with epilepsy.
Further research is warranted in order to confirm hypothesized therapeutic efficacy of Gabapentin in canines, particularly as an adjunct treatment for refractory idiopathic epilepsy. The drug may also prove to be effective in dogs with neuropathic pain. Potential therapeutic benefit associated with Gabapentin administration in dogs may be limited to cases of epilepsy and neuropathic pain; similar to humans.
How do the effects of Gabapentin differ between dogs and humans?
Difficult to determine whether the drug is as effective in dogs as it is for humans. Due to neuropsychological differences between dogs and humans, it is difficult to suggest that all effects are the same. Gabapentin is thought to reach peak blood levels within 1 to 3 hours in both dogs and humans.
It has an elimination half-life that is slightly quicker in dogs (3 to 4 hours) compared to humans (5 to 6 hours). Some believe that the effects may be similar in dogs as humans. It is important to highlight the fact that 34% of the Gabapentin is metabolized by dogs into “N-methyl-gabapentin,” whereas this does not occur in humans. Preliminary evidence suggests that the drug may treat epilepsy and neuropathic pain in dogs (just like humans).
Does your dog take Gabapentin?
If your vet has prescribed your dog Gabapentin to help with a condition such as epilepsy or neuropathic pain, do you believe that it has been therapeutic? Has it significantly improved your dog’s ability to function (e.g. reduced seizure activity)? If you’ve noticed any adverse effects or unwanted side effects such as increased drowsiness or lack of coordination, feel free to share a comment below. Do you think Gabapentin is an effective pharmaceutical treatment option for certain canines with minimal side effects?