VN June 2021

Vetnews | June 2021 13 Having the owner explore checklists andmobility animations prior to the visit can increase the likelihood of pain being identified, as the owner’s input will provide a template for pointed pain-related, cat-specific questions. A feline-friendly musculoskeletal examination focused on joint-specific pain and mobility using gentle palpation and range of motion should be a part of any examination for patients in which pain is a potential problem and for every examination for cats >7 to 10 years of age. Detailed videos on feline-friendly, pain-focused musculoskeletal examinations in cats are available (see Education & Diagnostic Tools ) and include thorough evaluative descriptions of the patient and several joints, including the hip, stifle, tarsus, and elbow—common locations for feline OA. Asking the owner to video their cat at home can also help facilitate diagnosis, as mobility and behaviour can be more accurately assessed when the cat is in an environment it is familiar with. Radiography can provide valuable information and is recommended; however, some patients will have radiographic lesions with no pain, and some patients may have pain that is worse than the radiographic evidence. Regardless, pain should be the focus of treatment, not the radiographic changes. Education & Diagnostic Tools • Feline Examination Videos: felineOAexam.com • Feline OA Owner Checklist: catOAchecklist.com • The International Veterinary Academy of Pain Management: Animal Pain Awareness Month: ivapm.org/animal-pain-awareness-month • Role of Nerve Growth Factor in OA Pain: thenewscienceofOApain.com • Zoetis Technical Bulletin: Current & Future State of isease: felineOApain.com Treatment of Feline OA There are no research-backed, FDA-approved, easy-to-administer, long-lasting analgesic treatments for chronic pain in cats. NSAIDs are currently the most effective treatment option but can cause adverse effects, including renal dysfunction, which is a common concern in cats. NSAIDs are typically a first- line treatment option in all species but often do not control pain—especially moderate to severe pain—when used alone. Other pharmaceuticals can be used to treat OA pain in cats, but most have little to no demonstrated efficacy in cats and typically require oral administration. For advantages and disadvantages of drugs commonly used to treat chronic pain in cats, see Table 1. Non- pharmacologic treatment (e.g., acupuncture, laser and physical therapy) should be considered, although these techniques are largely unproven by research and require frequent treatment visits. Nutraceuticals and specific joint diets may be effective and could be added to the protocol asmultimodal therapy but also have little tonodemonstratedefficacy in cats. Most of these compounds are likelymost effective at slowing disease progression, whichmay potentially delay the onset of worsening pain, than they are at providing analgesia directly. The Future ofTreatingOA-Associated Pain Nerve growth factor (NGF) is a cytokine that has recently been recognised as a major factor in the generation, propagation, and sensation of pain. Once released from damaged tissue, including tissue in an osteoarthritic joint, NGF rapidly escalates pain due to its impact on multiple pain pathway components, resulting inmaladaptive pain. NGF binds to tropomyosin receptor kinase A (trkA receptors) and causes nociceptor sensitisation, which can lead to hyperalgesia and/or allodynia; this is augmented by the release of other inflammatory mediators (e.g., histamine, bradykinin) and additional NGF following NGF binding to trkA receptors on pro-inflammatory cells (e.g., mast cells). In addition, the NGF/trkA receptor complex is internalised and transported to the neuronal cell body in the dorsal root ganglion, where it promotes the expression and/or upregulation of a variety of other pronociception ion channels and receptors, including transient receptor potential vanilloid receptor 1, which is integral for development of central sensitization. Because of profound pronociceptive involvement and the ability to rapidly produce both peripheral and central sensitisation, NGF is an obvious target for the control of OApain. Monoclonal antibodies couldpotentially be an option for anti-NGF therapeutics; they can bind to specific targetmolecules, including cytokines, and block the activity of the target. Specified (felinised and caninised) anti-NGFmonoclonal antibodies for dogs and cats are in development butnotyetavailable.Inproof-of-conceptstudies,anti-NGFmonoclonalantibodies have shown promise for relief of OA-associated pain for ≈1 month following SC injection. Conclusion OA can causemaladaptive, potentially excruciating, pain in cats. Althoughowners may struggle to identify pain in their cat, educating owners on the prevalence of OA-associated pain and available treatment options may make owners more likely tobring their cat to the clinic. Education canbe provided throughnumerous resources, such as posters, questionnaires, andmobility animations. Providing education to owners through these means can also help expedite a diagnosis of OA, as pointed questions regarding changes in behaviour and vertical movement can helpmore quickly identify pain. Incorporating these tools for both the owner and the clinician can help to more readily identify and treat feline OA-associated pain, improving patient quality of life. Article TABLE 1: COMMON MEDICATIONS USED TO TREAT CHRONIC PAIN IN CATS: ADVANTAGES, DISADVANTAGES AND DOSAGES Drug & Class Dose, Frequency, & Route Advantages Disadvantages Notes Robenacoxib (NSAID) 1-2.4 mg/kg PO every 24 hours* Class is effective against OA-associated pain Oral administration, which may be difficult for owners Adverse effects are possible with NSAIDs, which can frequently be an owner concern No limit on duration of therapy Meloxicam (NSAID) 0.1 mg/kg PO first day, then 0.05 mg/kg every 24 hours thereafter* Class is effective against OA-associated pain Oral administration, which may be difficult for owners Adverse effects are possible with NSAIDs, which can frequently be an owner concern No limit on duration of therapy Doses as low as 0.01-0.03 mg/kg every 24 hours may be effective 17 >>> 14