Management of Chronic Pain in Cats
Chronic pain areas in cats
Painkillers Don’t Diagnose Chronic Pain: Cats have become trendy pets worldwide, but the assessment and treatment of feline pain lag behind that of dogs. Although this knowledge gap is closing, most information on pain management in cats is limited to perioperative analgesia. In contrast, chronic pain conditions remain undiagnosed and in urgent need of treatment.
Chronic pain assessment tools have improved in recent years, but measuring chronic or long-term pain remains difficult. Veterinary assessment of chronic pain needs to catch up to assessment of acute pain. The effectiveness of analgesics in relieving pain in cats cannot be assessed due to the need for validated chronic pain assessment methods. This review details our current understanding of chronic or maladaptive pain, techniques for detecting and monitoring the condition and associated central nervous changes. It provides a comprehensive review of data on potential therapeutic agents in cats.
The concept of chronic pain does not fully apply to veterinary practice.
In human medicine, chronic pain lasts more than 3-6 months.In animals, the definition of chronic pain still becomes more complicated due to species’ shorter lifespans and different conditions (such as cancer). The challenge of clearly distinguishing the transitional stages from acute to chronic pain has led to a growing recognition that what used to be called acute pain and chronic pain are a continuum. Using new definitions will be even more important for understanding the nature and treatment of pain.
Recently, “adaptive” and “nonadaptive” have been suggested as more appropriate terms to describe pain.
What are adaptive pain and nonadaptive pain?
1. Adaptive pain includes nociceptive pain and inflammatory pain.
Nociceptive pain: Activated only by high-threshold nociceptive stimuli, including stimuli that cause tissue damage.
Inflammatory pain occurs after tissue damage and increases tissue sensitivity associated with the typical inflammatory response.
Both 2 types of pain are considered protective or adaptive to sense and avoid actual and potential tissue damage. These usually have easily identifiable causes (surgery, injury, etc.) and are reversible.
2. Nonadaptive pain includes neuropathic pain and functional pain.
Neuropathic pain: pain caused by direct damage to nerve tissue. Not only does it affect the central nervous system, it can also be caused by peripheral neuropathy. Neuropathic pain was previously thought to result from severe spinal cord injury or significant damage to peripheral nerves, such as peripheral nerve sheath tumors or surgical trauma. It is now increasingly recognized that many diseases, such as osteoarthritis (OA) and cancer, may be associated with direct damage to nerve endings in tissues or with increased innervation accompanying joint remodeling, angiogenesis, and some degree of peripheral neuropathy.
Functional pain: In the absence of nerve damage or inflammation, pain is caused by dysfunction or malfunction of the nociceptive system. Classic examples are phantom limb pain or fibromyalgia—no evidence of peripheral neuropathy or inflammation but increased sensitivity to stimuli and spontaneous pain.
Nonadaptive pain is not protective and is primarily due to plastic changes in the pain processing system.
What does chronic pain in cats include in clinical practice?
Clinical long-term pain (chronic pain) is a complex mixture of adaptive (inflammatory) pain and nonadaptive (neuropathic, functional) pain. Most pain-related chronic diseases comprise several pain components, including active, persistent inflammatory components (e.g., degenerative joint disease, gingivostomatitis, etc.) and nonadaptive pain associated with neuronal changes and sensitization. Therefore, the clinical goal is to make informed choices about analgesics based on understanding the mechanisms contributing to individual pain.
Although it is not easy to distinguish clinically between inflammatory pain and nonadaptive pain states, there is increasing recognition that many common chronic diseases are associated with central plasticity and nonadaptive pain. Common conditions associated with nonadaptive pain in cats include osteoarthritis and degenerative joint disease, interstitial cystitis, gingivostomatitis, diabetic neuropathy, cancer, and ocular pathology (including glaucoma and chronic anterior uveitis), Skin diseases (including chronic infections, burns, delayed wound healing, side effects of radiation therapy), etc.
Another critical point about chronic pain is that it can persist and be composed of multiple driving mechanisms. Some chronic pain may begin and continue with inflammatory pain, and it is easy to imagine that this pain will overlap with the pain of peripheral nerve disease. Nonsteroidal anti-inflammatory drugs (NSAIDs) are thought to play a role in these painful conditions. However, in many cases, persistent nociceptive input to the nervous system due to peripheral disease processes and damage to nerve terminals may induce changes in the central nervous system that produce nonadaptive pain. It is this nonadaptive component that makes chronic pain difficult to treat. Therefore, through data searches, we found that other drug treatments can be used in conjunction with NSAIDs or even replace NSAID treatments.