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Veterinarian Technician March 2009 (Vol 30, No 3)

No Pain, Plenty of Gain

by Alison Gottlieb, BS, RVT, VTS (ECC)

    CETEST This course is approved for 1.0 CE credits

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    Veterinary professionals have come a long way in treating pain. Today, debates about whether animals feel pain are rare,1 and guidelines for treating pain have been created by the American Animal Hospital Association and American Association of Feline Practitioners, entire books have been written on the subject,2 and the International Veterinary Academy of Pain Management offers advanced certification in pain management. Pain control in animal research is even mandated by federal legislation.3 Therefore, there is now consensus that pain is detrimental to healing, and procedures referred to as routine can generate pain that requires appropriate analgesia.1 Enormous strides have been made in some aspects of pain management in veterinary medicine, whereas work is still needed in other areas. Management of chronic pain in cats is one of these areas.

    There are several reasons that feline chronic pain has not been emphasized. Medicating cats has traditionally been associated with fear and anxiety.4 In addition, unlike the obvious acute pain that accompanies trauma, chronic pain in cats can be difficult to recognize by both owners and veterinary professionals. Furthermore, sparse scientific data on chronic pain in cats are available. Whereas canine chronic pain has been well documented, studied, and publicized over the past 10 years,5,6 few studies have been conducted in cats,4 although one retrospective study7 found that 90% of cats older than 12 years of age showed radiographic evidence of joint disease. Ironically, in the United States there are 10 million more pet cats than pet dogs, with 32.4% of all US households having at least one cat.8 Cats also are living longer.9 Despite their greater numbers and long lives, cats with chronic pain remain neglected in veterinary medicine.

    Identifying Pain — a Multifaceted Hurdle

    Chronic pain in cats is typically associated with osteoarthritis, chronic dermatitis, interstitial cystitis, dental and periodontal disease, and neoplasia. Chronic pain is defined as pain lasting 3 months or longer.4,10 Other types of pain include neuropathic pain11(e.g., a shooting or burning pain that develops as a complication from onychectomy), which often fails to respond to traditional analgesia alone.

    The first step in alleviating feline pain is recognizing it, which can be difficult because cats often try to hide pain, especially in the presence of humans and other animals,12 similar to survival in the wild.13

    Unfortunately, because cats are often reluctant to even be in the exam room, veterinary staff can find it difficult to discern subtle changes in cats in a clinic setting.14 Therefore, the cat owner is the first line in recognizing chronic pain,15 making client education imperative. Because cats exhibit more "normal" behavior at home, owners need to understand what signs to look for (see the handout  Feline Acute Pain Scale developed at Colorado State University). Even with education, it is more difficult for owners to recognize pain in cats than in dogs. Dogs like to please their owners, and if any of their pleasing behaviors are disrupted, they typically alert the owners immediately. The same cannot be said for cats — traditionally, they sleep for hours and do not care if the owner goes out, the doorbell rings, or a ball is tossed toward them. Therefore, recognizing pain in cats becomes a multifaceted hurdle that both veterinary professionals and owners need to overcome by opening dialogues on feline pain.

    Changes associated with chronic pain can be subtle and are often mistakenly attributed to age.16 In addition, lameness is not a common clinical characteristic of feline osteoarthritis,16 primarily because of bilateral joint involvement.10,16 But cats may display behavior changes that owners could inadvertently attribute to osteoarthritis or age rather than to chronic pain from a different source. Decreased grooming resulting in a greasy, clumped, or matted hair coat may be a sign of chronic pain,14 and its counterpart, obsessive grooming, likewise can signify pain. Reluctance to jump onto furniture or countertops could be a sign of chronic pain, and inappropriate urination or defecation is not an affliction solely attributed to age.4 Oral pain can result in weight loss or reluctance to eat dry food.15 Less obvious signs of pain include changes in sleep patterns, hiding, and objecting to being brushed or stroked.14

    Treating Pain Involves Multimodal Intervention

    Because cats are private about displaying chronic pain, sometimes initiating treatment measures can solidify a diagnosis. Profound improvement after treatment has been initiated can confirm that pain had been present.15

    Treatment of chronic pain in cats should be multimodal17 and can consist of environmental and lifestyle changes, pharmacologic interventions, and alternative therapies. Because so few pain medications are labeled for cats, experts and studies vary in their off-label dosing for these drugs. Therefore, the table is a consolidation of expert opinion gathered by Donald C. Plumb, PharmD,18 and may differ from some of the off-label doses cited in this article.

    In many instances, enormous commitment from owners and the veterinary staff is necessary, but the benefits far outweigh the effort.4

    As with humans and dogs, the first step in alleviating chronic musculoskeletal or arthritic pain in cats may be weight loss,15 which not only reduces stress on joints but can improve the cat's mobility.13 Controlling caloric intake may involve offering fewer high-calorie treats, eliminating table scraps from the diet, and changing the cat's diet to a reduced-calorie product.15

    Small amounts of controlled activity also can help keep muscles and joints active and moving.17 Playing with laser pointers, feathers, and toys on strings can strengthen joints and muscles while improving the bond between the owner and the patient. Treat balls, which are plastic devices with a hole that allows food to fall out when the cat plays with them, also can help in increasing exercise and controlling weight.19

    Environmental changes should be geared toward improving comfort and accessibility. Keeping cats from jumping up or down can alleviate some stress on the joints. Adding steps or ramps can help the cat get to its favorite places without having to jump.15 Placing food and water dishes on the floor also helps discourage jumping.14 Because chronic pain may prevent the cat from using its scratching post, the cat owner may need to trim the cat's nails more frequently.

    Inappropriate elimination can be managed by using a larger litter pan that has low sides, making it easier for the cat to use the pan.16 Adding well-padded bedding to the cat's favorite sleeping spots helps cushion pain, and heated beds can quickly become a new favorite sleeping place.15

    Massage therapy, passive joint manipulation and stretching, and underwater treadmill activity can help alleviate pain, depending on the cat's temperament and willingness to be involved in these activities.20 In addition, alternative therapies, such as acupuncture and homeopathic remedies, may be helpful in lessening chronic pain as long as the therapy does not cause undue stress.17,21

    Nutraceuticals have recently gained popularity in veterinary medicine, and glucosamine and chondroitin sulfate have been shown to help alleviate chronic pain associated with osteoarthritis in humans.22 Glycosaminoglycan (GAG) plays an important role in balancing the water content in cartilage, which is crucial to normal function; glucosamine is a precursor to GAG, and chondroitin sulfate is a GAG found in articular cartilage.23 Adding an omega-3 fatty acid has been shown to have antiinflammatory benefits,24 but studies in cats have not been conducted. In addition, nutraceuticals may help when used with other pharmacologic interventions,16 although owners should be advised that they may not notice improvement for 6 weeks and nutraceuticals are not appropriate as a sole treatment for severe pain.

    Injectable chondroprotectants also may help. However, there is no labeling for cats.15 In canine studies,25,26 Adequan (Novartis Animal Health) helped increase the range of motion.

    NSAIDs continue to be a controversial treatment for feline chronic pain because of the susceptibility of cats to toxicosis.10 This class of drugs should be avoided in cats with preexisting hepatic or renal disease, cats receiving steroids, or when hypovolemia is present; obtaining baseline blood values is recommended before starting any NSAID.4 However, quality of life also is important to consider, as severe unrelenting pain may take precedence over potential adverse events.

    Injectable meloxicam (Metacam, Boehringer Ingelheim Vetmedica) has been approved for cats in the United States as a single-dose administration.4 The oral form of meloxicam is off-label and formulated as a sweet elixir that can be added to food. A recent study conducted in Australia27 found no differences in blood values of cats receiving oral meloxicam at a dose of 0.01 to 0.03 mg/kg q24h and cats in the placebo group. The study also found that 85% of cat owners were pleased with the efficacy and palatability of the drug.27` Daily administration of the oral formulation is approved in other countries, but its use remains off-label in the United States.15 Carprofen (Rimadyl, Pfizer Animal Health) also is labeled for cats in Europe and other countries and has been used off-label in the United States.4 Its half-life is 9 to 48 hours, so repeat dosing may be questionable.15

    Tricyclic antidepressants, such as amitriptyline, have been used at doses lower than those used for depression in humans with chronic pain,28 have few side effects, and are readily available. The off-label dose that a veterinarian might prescribe ranges from 0.5 to 2.5 mg/kg PO q24h.29

    Anticonvulsants are showing some promise in treating chronic pain.4 Gabapentin is a human drug that is widely available and inexpensive. The mechanism of action is not completely understood; however, veterinary practitioners using gabapentin are citing positive results.30 These practitioners are using a starting dose of 2 to 5 mg/kg PO q12h, which can be increased or decreased depending on the response. Gabapentin comes in a liquid elixir that may be difficult to administer to cats, and some human formulations contain xylitol, which can be toxic to cats.

    Tramadol, another human drug, is a nonopioid that seems to be gaining popularity in veterinary medicine.30 It is inexpensive, is not controlled, and has been used to treat pain in humans without having many of the side effects associated with opioids.10 Tramadol does have a bitter taste that may make it difficult to administer to cats, and compounding often does not mask the severe bitterness. Studies have shown that tramadol works best when given with other analgesic drugs.10 There are no published studies on the effects of tramadol in cats. Veterinarians may use an off-label dose of 1 to 2 mg/kg PO q24h.30

    Amantadine is a centrally acting drug that is thought to decrease pain sensitization.4 It has been widely used as adjunct therapy in humans dealing with chronic pain and has more recently been used in dogs and found to be well tolerated.10 Because veterinarians tend to use an off-label dose of 3 to 5 mg/kg PO q24h in cats, they reformulate the 100-mg capsules.4 There are no published studies conducted in cats.

    Opioids can be another option when dealing with severe pain in cats.17 Buprenorphine has been found to have better analgesic properties than morphine does in cats.15 Because this drug can be given subcutaneously, the owner can administer it at home.29 Transmucosal administration in cats also has been found to be as effective as any other route.30 Owners simply need to get a small amount of liquid into the cat's mouth, which can be done with a syringe. Buprenorphine rarely causes dysphoria or vomiting in cats and can provide analgesia for up to 6 hours.15 Buprenorphine has been recommended for breakthrough pain or when osteoarthritis is first diagnosed. However, chronic daily use is only recommended for severe or neoplastic pain.17

    The transdermal fentanyl patch was developed to provide continuous analgesia to people with chronic pain.30 Using a transdermal patch may be an effective way to deliver fentanyl to cats because it is a well-tolerated, longer-lasting delivery method.31,32 One feline study compared intravenous with transdermal administration of fentanyl.32 Although the study was small — only six cats — the research suggested that plasma concentrations were sustained throughout a 5-day period in cats that received the transdermal fentanyl vs. those that received the product through IV administration.32

    Several studies show that the product does provide analgesic effects in feline patients.31,33 In one randomized, controlled clinical trial of 45 client-owned cats undergoing onychectomy, onychectomy and ovariohysterectomy, or onychectomy and castration, researchers found that cats treated with fentanyl a minimum of 4 hours before surgery had better recovery scores, lower sedation scores, and lower pain scores compared with cats treated with butorphanol.33

    Glucocorticoids can have significant systemic side effects,23 and evidence has shown that long-term use for neoplastic or uncontrollable pain may promote cartilage degeneration, thereby exacerbating arthritis.23 However, because quality of life needs to be considered in some severe cases, chronic pain may be improved by administering these drugs.

    The Role of Veterinary Technicians

    Veterinary technicians need to be aware of all the options that the veterinarian may discuss with an owner so they can reinforce that information and better educate the client on following the recommended multimodal approach to feline chronic pain. Because most of the pain medications are used off-label in cats, clients need to be reminded to look for adverse events and to immediately report any to the veterinarian.

    Sometimes chronic pain does not become obvious until the cat has become so debilitated that no treatment can restore an acceptable quality of life. When that happens, it is necessary to discuss euthanasia for humane reasons. As recommended by the ethicist Dr. Bernard Rollin, "letting them [cats] live in unalleviated pain is the worst thing we can do to them."3 Therefore, if chronic pain interferes with quality of life, the staff needs to serve as the patient's guardian and bring up this difficult topic.

    1. Flecknell PA, Waterman-Pearson A. Pain Management in Animals. London: Harcourt; 2000:2-3.

    2. Gaynor JS, Muir WW. Handbook of Veterinary Pain Management. St. Louis, Mo.: Mosby; 2002.

    3. Rollin BE. Science and Ethics. New York: Cambridge; 2006:215.

    4. Gaynor JS, Muir WW. Handbook of Veterinary Pain Management. St. Louis, Mo.: Mosby; 2002:415-435.

    5. Hanson PD, Brooks KC, Case J, et al. Efficacy and safety of firocoxib in the management of canine osteoarthritis under field conditions. Veterinary Therapeutics 2006;7:127-140.

    6. Aragon CL, Hofmeister EH, Budsberg SC. Systematic review of clinical trial of treatments for osteoarthritis in dogs. JAVMA 2007;230: 514-521.

    7. Hardie EM, Roe SC, Martin FR. Radiographic evidence of degenerative joint disease in geriatric cats: 100 cases (1994-1997). JAVMA 2002;220:628-632.

    8. The American Veterinary Medical Association. US Pet Ownership & Demographics Sourcebook. Schaumburg, Ill.: AVMA; 2007.

    9. Wise JK, Heathcott BL, Gonzalez ML. Results of the AVMA survey on companion animal ownership in US pet-owning households. JAVMA 2002;221(11):1572-1573.

    10. Robertson SA. Chronic pain in dogs and cats. Proceedings of the Southern European Veterinary Conference & Congreso Nacional AVEPA, 2007; Barcelona, Spain.

    11. Gaynor JS. Complications — feline onychectomy. Proceedings of the North American Veterinary Conference, 2005; Orlando, Fla.

    12. Gaynor JS, Muir WW. Handbook of Veterinary Pain Management. St. Louis, Mo.: Mosby; 2002:62-72.

    13. Wolf AM. The practitioner's guide to evaluating cats for osteoarthritis and chronic pain. Proceedings of the North American Veterinary Conference, 2006; Orlando, Fla.

    14. Wolf AM. Degenerative joint disease in cats. Proceedings of The Latin American Veterinary Conference, 2007; Lima, Peru.

    15. Robertson SA. Assessment and treatment of chronic pain in cats. Proceedings of the North American Veterinary Conference, 2006; Orlando, Fla.

    16. Bennett D. Cats do not suffer arthritis, do they? Proceedings of the World Small Animal Congress, 2008; Dublin, Ireland.

    17. Lascelles BD. Long term pain management in dogs and cats. Proceedings of the European Society of Veterinary Orthopaedics and Traumatology, 2004; Munich, Germany.

    18. Plumb DC. Plumb's Veterinary Drug Handbook, ed 6. Stockholm, Wis.: PharmaVet Inc; 2008.

    19. Yin S. Making weight loss easy. Veterinary Forum 2008;25:28-32.

    20. Hudson SL. Rehabilitation modalities and techniques for pain management in the cat. Proceedings of the North American Veterinary Conference, 2007; Orlando, Fla.

    21. Wynn SG. Ten herbs and nutraceuticals you can't live without. Proceedings of the North American Veterinary Conference, 2006; Orlando, Fla.

    22. Beal BS. Nutraceutical treatment in dogs and cats. Proceedings of the North American Veterinary Conference, 2005; Orlando, Fla.

    23. Scott H. Current medical therapies for canine and feline osteoarthritis. Veterinary Focus 2007;17:18-23.

    24. Innes JF. Osteoarthritis multimodal management plan. Proceedings of the Southern European Veterinary Conference, 2007; Barcelona, Spain.

    25. Fox SM. The power of multimodal management for K-9 osteoarthritis. Proceedings of the North American Veterinary Conference, 2007; Orlando, Fla.

    26. Wynn SG. Feed my hips: nutraceutical and herbal adjuncts for treatment of osteoarthritis; the veterinary institute for integrated medicine; www.viim.org/research/articles/osteoarthritis.asp: Accessed Feb. 5, 2009.

    27. Gunew MN, Menrath VH, Marshall RD. Long term safety, efficacy and palatability of oral meloxicam at 0.01-0.03 mg/kg for treatment of osteoarthritic pain in cats. J Feline Med Surg 2008;10:235-241.

    28. Morello CM, Leckband SG, Stoner CP, et al. Randomized double-blind study comparing the efficacy of gabapentin with amitriptyline on diabetic peripheral neuropathy pain. Arch Intern Med 1999;159(16):1931-1937.

    29. Lascelles BD. Feline osteoarthritis: what we need to know about the disease, diagnosis, and treatment. Proceedings of the North American Veterinary Conference, 2007; Orlando, Fla.

    30. Posner LP. New approaches to the treatment of chronic pain in dogs and cats. Proceedings of the North American Veterinary Conference, 2007; Orlando, Fla.

    31. Scherk-Nixon M. A study of the use of a transdermal fentanyl patch in cats. JAAHA 1996;32:19-24.

    32. Lee DD, Papich MG, Hardie EM. Comparison of pharmacokinetics of fentanyl after intravenous and transdermal administration in cats. Am J Vet Res 2000;61:672-677.

    33. Franks JN, Booth HW, Taylor L, et al. Evaluation of transdermal fentanyl patches for analgesia in cats undergoing onychectomy. JAVMA 2000;217:1013-1020.

    References »

    NEXT: Nutrition Know-How — The Benefits of Using Nutrition in the Management of Critical Care Cases

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