SURGERY
Article sponsored by Petcam ®
And she says it’s important for a management plan
to be individualised, based on the patient’s mobility
evaluation. “We need to figure out the disability level
to give us the baseline. Otherwise, it’s very difficult
to determine if our treatment has been successful,
or if it’s been a failure.” So, what does Dr. Edwards
use as her multimodal toolkit?
The multimodal toolkit
In a given management plan, she might include
pharmaceuticals, disease-modifying agents to slow
arthritis progression, nutrition, physical medicine
and rehabilitation, joint injections, regenerative
medicine options and surgery, if indicated. “Our
goal with multimodal pain management is to
maximize our treatment success while minimizing
side effects,” she says.
Pharmaceuticals
According to Dr. Edwards, the most commonly used
pharmaceuticals in arthritic patients are nonsteroidal
anti-inflammatory drugs (NSAIDs), gabapentin and
amantadine. NSAIDs are the drugs of choice for
initial therapy, since arthritis is an inflammatory
disease process. NSAIDs can help increase activity,
maintain muscle mass and, because the pet feels
like moving again, assist with weight loss.
What about tramadol?
Tramadol is questionable as an appropriate choice
for the management of chronic pain patients. Dr.
Edwards says, “It’s fairly insignificant from a pain
management standpoint and it’s fairly unreliable
in dogs. It has poor oral bioavailability and a very
short half-life. Dogs do not produce the ODM
metabolite, which is the metabolite with the
opioid effect.” Besides the pharmacokinetic issues,
tramadol can cause serious side effects including
nausea, anorexia, sedation and serotonin syndrome
issues. “It’s not a benign drug,” Dr. Edwards says.
“And it tastes terribly bitter, which can lead to food
aversion.”
Determining the lowest effective NSAID dose
is ideal, but it may be an unrealistic goal to
discontinue the drug in patients with maladaptive
pain. “Remember that it takes time to change all of
the central and peripheral sensitisation that occurs
with chronic pain,” says Dr. Edwards. “We know
that a longer NSAID course is more beneficial;
it’s almost cumulative. If we discontinue or taper
the drug too soon, we may not see the maximal
benefit. Continued daily dosing is much better than
intermittent dosing as needed.”
Many osteoarthritis patients benefit from the addition
of a second pharmaceutical when an NSAID is no
longer sufficient. “Gabapentin is a great choice for
chronic and neuropathic pain,” Dr. Edwards says. “It
alters the calcium channels involved in excitatory
pain synapse formation. It activates descending
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Issue 01 | MARCH 2018 | 14
inhibitory pathways, the body’s pathway to turn down
the intensity of incoming pain information. It may
affect glial cells, which are huge players in neuropathic
pain. It modulates pain signals to unwind the windup
and resets the pain thermostat.”
She notes that in human patients with chronic pain,
gabapentin administration is rarely discontinued.
Therefore, she doesn’t worry about getting her patients
off of gabapentin. She continues it while tapering the
NSAIDs.
Another drug she uses is amantadine (Symmetrol®),
an NMDA receptor antagonist, which is in the same
category as ketamine. “NMDA receptors play a key
role in inducing and maintaining central sensitisation.
So shutting down those receptors is beneficial,” she
says. “Amantadine is not an analgesic by itself, so it’s
used in conjunction with other pain medications. It
quiets the receptors and allows the other medications
that are on board to work more effectively.”With any
of these pharmaceuticals, Dr. Edwards waits 10 to 14
days to allow the patient to reach a steady state before
changing a drug dose.
Disease-modifying agents
Despite pharmaceuticals targeting inflammation,
providing pain relief and modulating neurophysiology,
they do not alter the disease progression. As stated
earlier, one goal is to slow the progression of arthritis
and try to protect the joint cartilage, which is where
dis