Alternative analgesics for small animals during an opioid shortage

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It's necessary for veterinary practitioners to consider what alternatives there are to opioids when treating pain in their companion animal patients. The rise in opioid use by people has led to intervention by federal agencies and subsequent redirection of opioid resources. This means fewer opportunities for veterinary professionals to use opioids in their patients. As Dawn Boothe, DVM, PhD, DACVIM (Internal Medicine), DACVCP, told attendees at Fetch dvm360 conference in Kansas City, veterinarians need to look for alternative analgesics while access to opioids is restricted to prevent patient suffering as much as possible.

Controlling pet pain pre-emptively

When considering pain in canine and feline patients, remember that “the most effective means of controlling pain is pre-emptive,” says Dr. Boothe. Acute and unrelieved chronic pain can become neuropathic pain such as hyperalgesia and allodynia. If measures are not taken to control the development of acute pain, it can lead to chronic pain.

Pain management tools

For some additional help managing pain in your patients, Dr. Boothe recommends AAHA/AAFP's Pain Management Guidelines for Dogs and Cats and the Veterinary Anesthesia and Analgesia Support Group website, which includes dose recommendations.

Take steps, when possible, to prevent the progression of pain.

Analgesic alternatives

Of the non-opioid options available, Dr. Boothe says that they should generally be considered part of a multimodal approach. Here are several options to consider.

Tramadol. The use of tramadol might be indicated for a broad array of painful conditions, including chronic pain. Its short half-life in dogs means frequent dosing: either 5 mg/kg every six hours or 2.5 mg/kg every four hours. When combining tramadol with other drugs, beware of those that impair serotonin re-uptake, such as St. John's wort. Side effects for tramadol are unusual, says Dr. Boothe, and usually reflect overdosage of the drug.

Ketamine. Most commonly associated with general anesthesia, ketamine has been noted for its analgesic effects, particularly when used in combination. One example Dr. Boothe cites is the use of ketamine in conjunction with fentanyl to control cancer pain in dogs in preoperative, intraoperative and postoperative stages.

Dextromethorphan. The use of dextromethorphan has been noted to increase the analgesic effects of opiates and nonsteroidal anti-inflammatory drugs. Its elimination half-life in dogs is approximately two hours, and it is not clear if dogs or cats produce sufficient metabolite for the drug to be effective in combination analgesic therapy, says Dr. Boothe.

Alpha2 agonists. Labeled for use in dogs for clinical procedures that require short-term restraint and analgesia, alpha2 agonists warrant special consideration because they are potent analgesics at doses that do not cause sedation, Dr. Boothe says. She notes that an older version of this drug, xylazine, has profound cardiovascular effects. However, newer alpha2 agonists are safer and should have similar opioid-sparing effects.

Gabapentin. A Schedule V drug, gabapentin has been use in dogs and cats for pain control and as a treatment for anxiety (particularly in cats). Gabapentin commonly causes sedation in animals. Dr. Boothe advises checking gabapentin products before recommending them, as some contain xylitol.

Neurokinin receptor antagonists. These are among the newer drugs that could benefit dogs and cats, such as maropitant. While part of maropitant's efficacy may simply reflect control of postoperative vomiting, Dr. Boothe says this fact alone does have one obvious advantage in that it avoids vomiting commonly associated with opioids.

These are not the only opioid alternatives available, nor the only pain management tools at your disposal, Dr. Boothe says. Keep in mind that  there are a host of nondrug therapies for control of pain.