Hands-free tools for evaluating and managing feline pain

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Both veterinarians and clients want to minimize discomfort and pain in pets. Although strategies for pain relief in veterinary patients have improved greatly in recent history, available options for diagnosing and managing feline pain remain limited. Cats are presented less commonly to the veterinarian for evaluation, show more subtle signs of pain and have fewer pharmacologic treatment options than their canine counterparts, making diagnosis and management of their pain difficult. At Fetch dvm360 conference in Baltimore, Jennifer Johnson, VMD, CVPP, president-elect of the International Veterinary Association of Pain Management (IVAPM), discussed several tools that can be used to address feline pain in practice.

Recognizing feline pain

The first hurdle in treating feline pain is to recognize its existence and localize the source, Dr. Johnson said. In a study of 100 geriatric cats presenting to the veterinarian for numerous reasons, 61% showed radiographic evidence of degenerative joint disease (DJD) in at least one joint.1 Despite its prevalence, DJD is diagnosed less often in cats than in dogs, due to differences in presentation. The most commonly affected joints in cats are the shoulders, elbows and tarsi, with hips being lower on the list. Additionally, lameness is rarely reported by cat owners. Clinical signs of pain in cats, such as changes in appetite or toileting behavior, decreased grooming or stress (e.g. increased vocalization, overgrooming), are often attributed to aging.

Cats also suffer from other chronic pain conditions such as feline idiopathic cystitis and stomatitis. It is important for veterinarians to communicate with cat owners that pain is prevalent in cats. Dr. Johnson encouraged the audience to take the time to teach cat owners how to recognize pain in their pets. She suggested utilizing resources from the IVAPM as well as painfreecats.org, a website developed by the Comparative Pain Research and Education Center at the North Carolina State University College of Veterinary Medicine.

Diagnostic tools for feline pain

Pain in animals is inherently difficult to evaluate due to the patient's inability to verbalize. Physical examination is central to pain evaluation, but patient behavior often limits the extent of the veterinarian's examination. Dr. Johnson recommended the use of gabapentin or trazodone for fractious cats, noting that trazodone may be the better option in cases where pain is suspected because this drug lacks analgesic properties that may mask pain during examination.

Dr. Johnson noted that much of the current literature on evaluating pain in feline patients focuses on acute pain, but ongoing research will help to develop better methods for evaluating chronic pain. The most recent literature suggests that pain scales that include a feline grimace scale provide the most accurate evaluation. The two most utilized feline pain scales in practice are the UNESP-Botucatu Multidimensional Composite Pain Scale and the Glasgow Composite Measure Scale: Feline.

Dr. Johnson also encouraged veterinarians to have clients complete the Feline Musculoskeletal Pain Index (FMPI)-a newly validated feline-specific pain assessment tool-prior to the cat's appointment and noted that it can be repeated over time to track response to treatments.

While pain scales are helpful tools, the results can be confounded by the person doing the evaluation, creating a need for more objective ways to measure pain. Digital thermal imaging (DTI), which detects heat gradients caused by altered blood flow, is increasingly used as a hands-free screening tool. An increased thermal gradient is seen in areas of increased blood flow due to ongoing inflammation, while a decreased thermal gradient can be seen in areas of decreased blood flow due to chronic disuse or atrophy. DTI has been used successfully in studies of both canine and feline pain conditions, most recently in the diagnosis of feline arterial thromboembolism.2 In a study comparing owner questionnaires, physical examination and DTI for detection of feline pain, DTI and palpation were found to be superior for detecting mild pain.3 As DTI offers a hands-free diagnostic tool, it is an attractive option for evaluating pain in cats, especially those that are less amenable to physical examination.

Adjunctive pain management options

Dr. Johnson closed her lecture by discussing two nonpharmacologic tools for pain management in cats: photobiomodulation (laser therapy) and pulsed electromagnetic field therapy (PEMF). Both tools offer noninvasive pain relief options and have been used with anecdotal success for many years. Ongoing research in pain management has led to a growing body of literature to support the use of these modalities in both human and veterinary patients.

Photobiomodulation, more commonly known as laser therapy, allows a noninvasive, in-clinic approach to pain control. The key to successful laser therapy is the administration of the correct wavelength, dose and application technique for the location and type of pain being treated. Laser therapy can be useful in both acute and chronic pain conditions. It has been shown to decrease the need for exogenous opioids by creating biochemical changes along the pain pathways, promote healing by improving blood flow to the target area, alter nerve signaling in acute pain and stimulate nerve healing for chronic pain conditions.

Common uses of laser therapy in many veterinary practices include chronic musculoskeletal conditions and postoperative use. Dr. Johnson encouraged practitioners to consider the use of laser in both acute feline pain conditions, such as urethral obstruction, and in more chronic conditions, including interstitial cystitis and stomatitis. She also discussed the use of laser therapy to modulate ongoing inflammation in the kidneys of cats diagnosed with both acute and chronic renal disease.

While many patients tolerate laser therapy well, they must come to the veterinary hospital for treatment by a trained professional. An alternative pain relief option is PEMF, which promotes tissue healing through pulsing, nonthermal electromagnetic fields. A recent study in canine patients showed efficacy in reducing incisional pain and improving proprioception in dogs with intervertebral disk disease,4 and a review of PEMF use in veterinary patients suggests it is an effective tool for multimodal pain relief.5 Feline patients that do not travel well to the clinic may especially benefit from PEMF, as devices such as the Assisi Loop can be prescribed for at-home use. These loops can be attached to a bandage or placed in bedding to administer treatment multiple times per day.

Conclusion: thinking outside the box for feline pain

Dr. Johnson encouraged veterinarians to be alert for signs of pain in their patients and to open the conversation with cat owners about how to recognize these signs. The tools discussed in her lecture offer attractive hands-free options for pain evaluation and treatment. Ongoing research in veterinary patients will help practitioners learn how to use these tools most effectively in the context of feline pain management.

References

1. Slingerland LI, Hazewinkel HAW, Meij BP, et al. Cross-sectional study of the prevalence and clinical features of osteoarthritis in 100 cats. Vet J 2011;187(3):304-309.

2. Pouzot-Nevoret C, Barthélemy A, Goy-Thollot IU, et al. Infrared thermography: a rapid and accurate technique to detect feline aortic thromboembolism. J Feline Med Surg 2018;20(8):780-785.

3. Vainionpää MH, Raekallio MR, Junnila JJ, et al. A comparison of thermographic imaging, physical examination and modified questionnaire as an instrument to assess painful conditions in cats. J Feline Med Surg 2013;15(2):124-131.

4. Zidan N, Fenn J, Griffith E, et al. The effect of electromagnetic fields on post-operative pain and locomotor recovery in dogs with acute, severe thoracolumbar intervertebral disc extrusion: a randomized placebo-controlled, prospective clinical trial. J Neurotrauma 2018;35(15):1726-1736.

5. Gaynor JS, Hagberg S, Gurfein BT. Veterinary applications of pulsed electromagnetic field therapy. Res Vet Sci 2018;119:1-8.