#27 Gabapentin-The Underappreciated Anxiolytic

I invite you to peruse and use any of the information from this and past nmvetlist missives. You will find the entire archive on the For Veterinarians page of my website, drjeffnichol.com/

Historically, gabapentin has been valuable for neuropathic pain and as an adjunct in many other analgesia protocols. It can also be a helpful add-on for anticonvulsant therapy. In the behavior specialty we often employ gabapentin in cases of anxiety. It can be especially helpful for dogs and cats with anxiety-related aggression. Adding it an SSRI like fluoxetine, sertraline, or paroxetine, gabapentin can reduce the “explosive” nature of reactive behavior.

Gabapentin can also be used as a sole agent in cases of mild to moderate anxiety. I recently prescribed it for a dog who needs to learn to respect the boundaries of his people and their visitors.  This big, young, active dog is more than his elderly owners bargained for. Rather than struggling with his rambunctious nature, adding more exercise (he already gets a lot), or rehoming (a huge source of anxiety –think separation-related behaviors) this big knucklehead needs to be set up to succeed.

If Big Goofy can just relax a bit better his owner will be able to employ differential reinforcement. This will mean preventing the dog from jumping up by standing on the drag line (leash he drags around the house) while ignoring until he earns quiet reinforcement for not jumping up. We will then add targeting and clicking as a response substitution. Punishment will have no place because it is easily misinterpreted by the dog as play or, in some cases, can lead to an even greater loss of impulse control like reactive biting.

Here is more information on this very safe drug.

  • Dosage guidelines are below but there may be no upper limit for dosing.
    • If a pet gets sedated the dose can be reduced.
    • When the gabapentin capsule is opened and added to food, cats readily consume it.
    • This makes gabapentin an excellent pre-veterinary visit pharmaceutical for cats who become fear-aggressive in the clinic.
    • Have the client mix the contents of one 100 mg gabapentin capsule in a small amount of food about one hour prior to leaving home.
    • Remove the top of the cat carrier and quietly/gently handle the cat.
  • May be useful in self-mutilation disorders.
  • Pet has time to think before reacting.
    • Can be good with SSRI for explosive aggression.
    • Often good for dogs with amygdalar hyperreactivity.
  • Cats with hyperesthesia-use as a secondary agent
  • Used to treat chronic neuropathic pain.
  • Gabapentin + Cerenia (for car sickness).
  • The mechanism of action for gabapentin and pregabalin is uncertain, but both drugs have high binding affinities to the α2δ-1 subunit of presynaptic voltage-gated calcium channels in the CNS
    • Their analgesic effects may be related to calcium influx inhibition as well as inhibition of the release of excitatory neurotransmitters in spinal and supraspinal pathways.
    • It is hypothesized that conditions such as neuropathic pain and epilepsy may involve excessive formation of excitatory synapses. A recent study showed that by binding to this α2δ-1 subunit, gabapentin prevents the binding of thrombospondin, a synaptogenic protein secreted by astrocytes, thereby impeding synapse formation between neurons.
  • Urinary incontinence can occur with doses above 5mg/kg
  • Eliminated by the kidneys
  • Gabapentin can change urination patterns.
    • Anecdotally, it has always been in overnight urinations where the dog suddenly starts waking the owner.
    • When the dose was reduced the effect went away within the week.
  • A good general analgesic in geriatric dogs. Start low (5mg/kg q8-12h) and titrate to effect balancing analgesia with sedation.
  • Dose:
    • Dogs: 25-60 mg/kg divided q 6-8h.
      • Dose can be gradually increased.
      • Fear/reactive to specific contexts: 20-30 mg/kg
    • Cats: 12.5 mg/cat BID.
      • When dosing 25 mg BID.
      • For travel anxiety and reactive behavior at the veterinary clinic:
        • 100mg per cat unless they were petite of geriatric
        • Small cats 50mg.
        • Big huge cats or very difficult cats give 150-200 mg per cat.
        • Dose them 2 hours before appointment time.
        • Expect cats to act sedated up to 12 hours but don’t count on it being effective for handling more than 3-4 hours after dosing.
        • Remember to warn owners about ataxia and sedation (don’t let fall off counter etc).
      • Cats eat it readily on some favored food followed by regular food.
      • Duration of sedation depends on lean mass of the cat.
  • Available in 100, 300, & 400mg capsules; 600 & 800 mg. tablets.
  • Liquid (Neurontin) has xylitol and is not recommended for dogs and cats.

 

I invite you to peruse and use any of the information from this and past nmvetlist missives. You will find the entire archive on the For Veterinarians page of my website, drjeffnichol.com/

 

All the best,

Jeff