Case based chronic pain management: Creating hope (Proceedings)

There are two major dynamics driving the expanding need for effective chronic pain management; pets are living much longer and they are now frequently considered full members of the family. Chronic pain may result from a variety of causes including osteoarthritis, intervertebral disc disease, cancer pain, and past injuries and surgeries.

The longer pain exists and the greater its severity, the more difficult it is to control. The pain related pathways are subject to major alterations in receptor sensitivity as well as actual neural structural change. The summation of these changes leads to two basic realities: what should only hurt a little hurts a lot and what shouldn't hurt at all may be perceived as markedly unpleasant. Chronic pain affects patient quality of life as well as their functional capabilities.

Ultimately, declines in quality of life and functional capabilities invariably lead an owner to thoughts of euthanasia. By effectively controlling chronic pain we can achieve two superb outcomes: patients that feel better and live longer. Patients that feel better and live longer are a joy to work with as well as a boon to their family and, invariably, a benefit to your practice.

Ideal pain management requires the most accurate diagnosis possible given the limitations of any given case. Our foundational assessments are based upon a detailed history and physical examination with thorough neurologic evaluation. Often advanced imaging is required to achieve an accurate diagnosis.

Chronic pain is best addressed in a multidisciplinary fashion. In many cases you will need to network with a surgeon, neurologist, or physical rehabilitation therapist to achieve the best possible diagnosis and patient outcome. Medications alone cannot fix all pain related ills. They can be a critical aspect of initial pain control and they do perform a crucial role during early physical rehabilitation as a tool to help minimize discomfort from the therapy. Physical rehabilitation therapy (PRT) builds on the foundational relief gain from medications. Medications decrease pain pathway sensitivities while PRT gains patient function. PRT can improve joint range of motion, muscle strength and flexibility, and increase positional awareness and balance. Medications and PRT combine to make the patient feel better, perform better, and they improve resistance to injury.

Acupuncture is an additional discipline that can figure quite prominently in the management of chronic pain. There are many patients that are either poorly tolerant of or poorly responsive to conventional analgesic medications and some may not be cooperative for physical rehabilitation therapy. In addition, there are certain clients that are disinclined to accept conventional pain medication and surgical advice. Acupuncture can help address the needs of these clients and patients.

Chronic arthritic pain: There are many dogs and cats that fit this general category. Conservative estimates suggest that no less than 20% of the canine population suffers from OA. It is also suggested that 90% of cats over 12 years of age have evidence of degenerative joint disease. Arthritic pain can develop at any joint including the dorsal facets along the spine. Chronic joint pain is often the most critical limitation to longevity for large breed dogs. The likelihood of clinically significant arthritic development is minimized through intelligent weight management and appropriate surgical interventions. Once established, its progression and its painful consequence can be minimized through a variety of measures.

Weight control is the most cost effective management step. The newer therapeutic agent, Slentrol®, has been a welcome addition to our canine battle of the bulge. Slentrol® is capable of curbing the patient's appetite which increases the chances of owner diet control compliance substantially. For feline weight control challenges, a low carbohydrate diet may well help facilitate patient weight loss.

The Injectable polysulfated glycosaminoglycans are a well tolerated option for feline and canine arthritic management. PSGAGs are capable of influencing the inflammatory and structural health of an arthritic joint. Injectable PSGAG therapy is most convenient when given by the owners at home. Omega 3 fatty acids have anti-inflammatory properties beneficial to feline and canine arthritic patients. Supplements may be added to the patient's normal diet or a diet with added omega 3 fatty acids may be selected.

Many oral medications are available for arthritic disease management. NSAID are consistently effective against arthritic pain. Patients often exhibit marked individual variation as to which NSAID best serves their needs. Long term NSAID use is usually well tolerated by canine patients while alternative drugs would be preferable to long term NSAID use for feline arthritic management. While patients on any long term pain medication should have periodic hepatic and renal evaluations to minimize adverse consequences, this is especially true with long term NSAID therapy.

Tramadol is a medication with both weak mu opioid activity and, to some degree, a monoamine reuptake analgesic benefit. Tramadol is much better suited to long term use in dogs as its bitter taste is poorly tolerated by cats. Amantadine is an oral NMDA antagonist, an antihyperalgesic, that targets the central sensitization process tightly associated with chronic pain. In a way, amantadine turns down the pain "volume" helping the practitioner gain pain control. Gabapentin targets the alpha2-delta1 subunit on the voltage-gated calcium-channel. Initially thought to be a neuropathic pain specific medication, gabapentin has demonstrated versatility across many pain related conditions including arthritis. There is evidence that gabapentin helps to attenuate arthritic decline through the inhibition of metalloproteinases. In most chronic pain cases, best patient benefit is derived from the multimodal coordination of several of these oral medications.

Acupuncture and physical rehabilitation therapy (PRT), as noted above, have become essential patient management tools for arthritic disease management. Often a patient can be weaned off of the majority of their medications after completing a course of physical rehabilitation therapy. PRT can be the difference between a patient feeling less painful and a patient not only feeling less pain, but a patient resuming many of its favored recreational activities further enhancing patient quality of life. Acupuncture and PRT are especially attractive for patient less tolerant of many medications, such as patients with preexisting gastrointestinal, renal or hepatic disease.

Spinal Pain: Neuropathic pain can be one of the most intense pain entities. Neuropathic pain is generally poorly responsive to NSAIDs. Gabapentin, on the other hand, is particularly well suited to neuropathic pain. Amantadine and tramadol can also be useful medications. Recent studies have shown a significant patient benefit when acupuncture is added to conventional therapy for intervertebral disc disease. Cold therapy and low level laser therapy are PRT modality considerations.

Cancer pain: Pain associated with cancer disease is often the most critical factor determining patient longevity. This is especially true of bone cancer pain. A combination of analgesic strategies can be coordinated to produce impressive patient responses. We have been very successful at controlling bone cancer pain with patients recovering near normal, if not a fully normal, clinical function. Many patients have shown sustained control with some in excess of 13 months. The aminobisphosphonate, pamidronate, is used to moderate the osteoclastic destructive process reducing pain and the risk of pathologic fractures. Palliative radiation, if available, is an excellent tool also capable of enhancing pain relief and reducing pathologic fracture risk.

NSAIDs can help alleviate pain and they can also exert an anticancer effect. Tramadol, amantadine, and gabapentin all are potentially effective analgesic tools for cancer pain with gabapentin, perhaps, having the greatest overall capability.

Gaining control of pain: It may be necessary, at the outset, to hospitalize intensely painful patients for epidural Injections, analgesic constant rate infusions, or regional anesthetic/analgesic blocks. These more intense analgesic applications can help ramp down the sensitization process.

Expectations: A study of human pain management shows that the more difficult pain problems do not always have a predictable management pattern. It is not unusual for a given treatment to benefit a minority of patient within any given patient group. The practitioner and the client need to be aware that it may take more than one strategy to accomplish reasonable pain control.