Challenges of Perioperative Feline Pain Management

There are a number of factors that make cats different from dogs in terms of pain management, but there are more similarities than differences. The magnitude of pain experienced depends to a large extent on the type and degree of tissue injury and severity / extent of the inflammatory process. Experience has led to the generation of opinion-based tables ranking pain severity for animals, but observation of the individual patient’s response to analgesia is the only way to accurately gauge the painfulness of the condition. More severe pain means that analgesic needs will be greater, with need for stronger opioid type and higher doses, for multiple drugs classes (multimodal) therapy, and for potentially longer duration of treatment. Premedication protocols that produce sedation are advantageous in healthy non cooperative cats to reduce the stress and pain involved with handling. It is essential to realize that when opioids, ketamine, or alpha 2 agonists are used prior to or during general anesthesia, the requirement for inhalant and injectable anesthetics can be significantly lessened. If this is not taken into account by reducing anesthetic doses, extreme anesthetic depth can lead to depression of respiration and cardiac output; risking morbidity or death. Decreased blood flow to the kidney, in combination with NSAID therapy risks nephrotoxicity. For relatively minor pain, a single agent and even as few as one administered dose might be sufficient. Opioid-only, NSAID-only, or local anesthesia-only therapy may be used, depending on the situation. Many veterinary clinical pain studies have only evaluated single agent therapy and these may compare drugs of two different types (e.g. buprenorphine versus meloxicam). As the magnitude of pain increases, there is a necessity for adding a second type of analgesic. Multimodal analgesia is thus becoming widely appreciated in veterinary medicine. Some of the advantages are that drugs with longer actions (e.g. NSAIDS) may supplement during “troughs” in levels of another drug (opioid), or that if one drug is given at sub-therapeutic dose, the other may help to make up for this inefficacy. Bandages, drains or splints, full bladder and stomach, gastric and esophageal ulceration may also contribute to acute pain; adjustments and supportive measures may result in relief and so it is important to realize that the injured body part may not be the only cause of pain. When pain is of a greater magnitude or duration than expected, despite attempts to treat it, one very important consideration is that healing is not progressing normally. In the author’s experience, in cats, this is a reason to suspect one of several complications; these include wound infection or dehiscience, nerve impingement by implants, sutures, fracture, ischemia, bandage or splint associated pain, neuroma formation, gastric or esophageal ulceration, bladder atony, cystitis, or urinary retention, delayed gastric emptying and pancreatitis. When pain is greater than expected, a thorough physical exam is mandatory and may require additional diagnostic testing. Fear, anxiety and pain often make cats difficult to handle and to complicate the hospital experience. Thus pharmacologic and non-pharmacologic methods of reducing anxiety or fear may play a role in the overall amount of pain and stress. Anxiolytic medications, despite being considered devoid of analgesic properties, are arguably useful adjuncts in managing pain. Acepromazine may be given with the understanding that if significant untreated pain is present, the preferred option is to increase analgesia first. Alpha 2 agonists have both sedative and analgesic properties and are commonly used around the time of surgery or painful procedures. They can be given by infusion to those animals deemed to require both analgesia and sedation