Originally published in the November 2014 issue of Veterinary Practice News The cat is the off-label species. About 80 percent of all drugs we use in cats are used off label. That includes lactated Ringer’s solution and prednisolone. Managing chronic pain is an off-label event in the cat as no products are FDA-approved for long-term management of feline pain. The situation is somewhat better for acute or post-op pain, but several very widely used options are also off label. Neither cat owners nor their veterinarians are happy to see a cat in pain. However, finding agents that relieve feline pain can be problematic. Some have side effects, and some work better as part of a multimodal approach. None is effective for all patients so a trial-and-error approach may be needed. How to Recognize Pain In the wild, sick cats are targets for predators, so cats have become experts at masking pain. Therefore, with the aid of cat owners supplying careful observations, veterinarians must ask the right questions to uncover the signs of pain. Important questions include: Unwillingness to jump/play Decreased appetite Inappropriate elimination Repeatedly over-grooming the same location Change in mood Treatment of Acute Pain Acute pain is usually due to trauma (falls, blunt trauma, vehicular accidents, etc.), organ insult (stomach, small bowel, ureter, urinary bladder, etc.), or surgical or medical procedures (fracture repair, laparotomy, bone marrow aspiration, etc.). Regardless of the source, the pain should be addressed. If there is an underlying cause, it should be treated properly, but often the cat will still be uncomfortable during the treatment before the problem is resolved. Here are some of the drugs that we use in our practice: Buprenorphine is an opioid that is very effective for treating pain in cats. Buprenorphine comes in a form that may be injected or placed in the oral cavity. The drug lasts about 8 to 12 hours so repeated hospital or home treatments are required. A compounded formulation exists that provides analgesia for three days after an injection.a Potential side effects include sedation and constipation, both of which resolve when therapy is terminated. This drug is widely used. Meloxicam (Metacam) is a nonsteroidal anti-inflammatory (NSAID) that is currently approved for a one-time injection prior to elective surgery in well-hydrated cats. Although oral forms are not approved in the United States, they are used widely here as well as Canada, the U.K., Europe and Australia. It is available as a very palatable liquid that can be put in food or given orally. Recently, the FDA black boxed the warning against oral use in cats. If one chooses to use this drug orally, informed consent by the owner is strongly recommended. It is an effective short-term pain medication. Robenacoxib (Onsior) is a new NSAID that is available for cats and is approved for a three-day course. Studies have shown that when given preoperatively, Onsior significantly decreases post-surgical inflammation and its resulting pain. Onsior comes in a tasty chewable tablet that is appealing to most cats. A potential side effect of all NSAIDs is gastrointestinal upset, but this occurs only rarely. Treatment of Chronic Pain Chronic pain can also have many causes, but the most frequent indication for treatment is arthritis, a disease that is common but often hidden by the cat. The most frequently reported clinical signs are reluctance to jump, guarding of joints and lameness. However, if it is bilateral (both knees, for example), a noticeable limp is usually not present. Management of chronic pain caused by arthritis is complicated because limited options exist. Some of the best options include: Onsior: Use of Onsior past three days is considered off-label in the U.S. It is approved for six-day use in many other countries around the world. However, it is increasingly being used for chronic feline pain, most notably that caused by arthritis. To date, side-effect have not been reported other than mild GI upset. We have used it very successfully in older cats with arthritis. It is prescribed for daily use, but after a period of stabilization, some cats do well with treatment every 48 hours. Informed consent in writing is also recommended. Meloxicam: Meloxicam is not approved for long-term use in cats in the U.S., although it is approved in Canada, the U.K., Europe, New Zealand and Australia. Meloxicam has a history of causing acute renal failure after just one or two doses, but it has also been shown to be beneficial to renal function in older cats.1 Informed consent is strongly recommended because of the black box recently imposed by the FDA. We often dispense Onsior for nine days to check response then give the client the option of continued Onsior or a change to Metacam. Glucosamine/chondroitin: This combination product is a nutritional supplement and not subject to FDA efficacy or safety testing. It is combined with an avocado extract to make a product called Dasuquin.b Glucosamine/chondroitin is thought to lubricate joints and improves cartilage health. Dasuquin is a capsule that can be opened and sprinkled on food once daily. The powder is tuna flavored to appeal to the cat. Treating with glucosamine/chondroitin can take up to four weeks for beneficial effects to be obvious to the owner. Polysulfated glycosaminoglycan (Adequan): This injectable chondro-protective drug is designed to decrease the viscosity of joint fluid. Because feline use is off label, there is no approved dosing scheme. We give 0.25 ml SC or IM q7d for four weeks then every four to six weeks thereafter. In some cases, we dispense the drug for owners to give. It can be very effective in managing arthritis in cats. Laser: Therapy lasers are used to reduce inflammation and encourage healing or regeneration of tissue. They are non-invasive and produce results in many patients. They appeal to a subset of our patients who are opposed to chemical control of pain. Sedation is not needed unless the cat is aggressive, so there are literally no risks taken with this form of therapy as long as the operator is trained to use the proper settings. Treatments are given several times per week for two to three weeks then on a “booster” basis every few weeks. As with every drug listed, there are some failures and some successes. The Multimodal Approach Often, no single approach is successful for treating chronic pain in cats. We frequently combine an NSAID and a glucosamine/chondroitin supplement with laser therapy. Every cat is different; what works for one cat might not work for others. Trial-and-error is the key to achieving pain relief for the most cats. Footnotes a. Buprenorphine SR, ZooPharm (www.zoopharm.net) b. Nutramax Laboratory Veterinary Sciences, Inc. Edgewood, Md. References 1. Gowan RA, Lingard AE, Johnson L, et. al. Retrospective case control study of the effects of long-term dosing with meloxicam on renal function in aged cats with degenerative joint disease. J Fel Med Surg. 2011:13;752-761
