Front Matter

488 Canine Sports Medicine and Rehabilitation

See Figure 19.3 for cautions regarding possi-
ble serotoninergic drug interactions.

Gabapentin

Gabapentin is labeled as an anticonvulsant
drug, yet has become popular in human medi-
cine for many chronic and neuropathic pain
conditions (Backonja & Glanzman, 2003). While
structurally similar to GABA, it is not a direct
agonist; it appears to exert its effect mostly by
downregulating voltage‐gated calcium chan-
nels (Longmire et al., 2006). Its utility in the
transoperative setting is supported by a num-
ber of systematic reviews (Clivatti et al., 2009;
Dauri et al., 2009). Pharmacokinetic studies in
dogs reveal that it has a half‐life of 3–4 hours
(Vollmer et al., 1986), suggesting t.i.d. adminis-
tration. The primary adverse effect in dogs and
humans appears to be somnolescence.
There is no literature to support gabapentin
as an adjunctive treatment for OA in dogs or
humans, but such literature does exist in
rodents. There are a number of case reports
describing the successful use of gabapentin in
dogs experiencing neuropathic pain (Plessas
et  al., 2015), and a hypersensitization compo-

nent appears to be present in at least 25% of

humans with OA (de Luca et al., 2016). This may

explain the increasingly widespread and anec-

dotally successful use of gabapentin for OA in

dogs. Interestingly, a gabapentin analog reduced

the development of experimental OA in rodents

(Boileau et al., 2005). Gabapentin should be con-

sidered for other maladaptive and neuropathic

pain states encountered in veterinary medicine.

Tips for use

To avoid drowsiness, a starting dose of 3–5 mg/

kg b.i.d. or t.i.d. is recommended for chronic

pain. As the patient acclimates, the dose is

increased gradually to a target of 10–20 mg/kg

b.i.d.. For surgical pain, starting doses are

higher (e.g., 10 mg/kg), with one dose adminis-

tered preoperatively and one to three doses

administered in the postoperative period; slight

drowsiness does not seem to impede appetite

or other daily functions.

Other drugs in class

● Pregabalin (Lyrica®), a gabapentin‐like

compound, is labeled in humans for pain

associated with diabetic neuropathy and

Potential serotoninergic, monoamine drug Interactions

Analgesics:

• tramadol


• tapentadol
  Other dopaminergic:


• amantadine


• metaclopramide

Tetracyclic

antidepressant:

• mirtazapine

Selective serotonin/norepinephrine

reuptake inhibitors:

• duloxetine


• fluoxetine

Supplements:

• S-adenosylmethionine (SAMe)

Tricyclic antidepressant:

• amitriptyline


• clomipramine

Monoamine oxidase

inhibitors:

• selegiline/I-deprenyl


• amtiraz

Figure 19.3 Many compounds and chemicals may involve serotoninergic or monoaminergic (especially dopamine)
mechanisms, and caution and/or judicious use should be exercised when using them in combination.