Advanced pain management protocols in veterinary hospice and palliative care

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Palliative care and hospice cases present unique challenges to veterinary professionals. When it comes to treating these patients, some of our most used medications in hospice and palliative care plans may be less frequently used in general practice, as the risk-benefit analysis changes significantly in the end-of-life stage. Because uncontrolled pain and mobility difficulties are among the most common causes of euthanasia, understanding these medications and their proper usage can significantly enhance the quality of life for patients in their final weeks.

Acetaminophen: An effective adjunctive pain medication for dogs

Although acetaminophen is toxic in cats, it can be a very valuable adjunct pain medication for dogs. Its mechanisms of action are not fully understood, but it can complement other analgesic medications in a multimodal approach for chronic pain. Because it lacks significant anti-inflammatory properties, it is most beneficial when used alongside nonsteroidal anti-inflammatory drugs (NSAIDs) or steroids. Acetaminophen is commonly used during washout periods between transitioning between NSAIDs to steroids. The standard accepted dosing is 10 to 15 mg/kg twice daily to 3 times a day, although some studies suggest that dosing up to 33 mg/kg is safe and potentially more effective in dogs.¹ It is recommended to monitor liver and kidney function every 6 months during its use, although testing is often waived in the hospice and palliative care settings.

Acetaminophen and hydrocodone: A useful combination for pain palliation

Acetaminophen combined with the opioid hydrocodone can effectively palliate more pronounced or breakthrough pain in dogs. Hydrocodone, with an oral bioavailability of 40% to 80%, is a better choice than codeine, which has poor bioavailability in dogs (approximately 4%).² The dosing is based on the acetaminophen component, with 5 mg, 7.5 mg, or 10 mg of hydrocodone per 325-mg acetaminophen tablet. Often, a pet is prescribed a plain acetaminophen treatment plan with acetaminophen/ hydrocodone tablets on hand that can be swapped at the pet’s normal medication time when breakthrough pain is present.

Pregabalin: A promising alternative to gabapentin for pain and anxiety

Pregabalin offers a similar mechanism of action as gabapentin. Unlike gabapentin, pregabalin exhibits linear absorption with a bioavailability greater than 90% regardless of mg/kg dosage. Dosing recommendations are 2 to 5 mg/kg by mouth every 12 hours. It is generally associated with less sedation and ataxia than gabapentin, but these adverse effects are often still present.

It is generally recommended to start at night and with a lower dose to titrate to effect, much like gabapentin. The recent availability of a generic version makes it a more affordable alternative than it has been in past years.³

Subanesthetic subcutaneous ketamine: An innovative pain relief approach

Ketamine, an NMDA receptor antagonist, can effectively reduce the volume of pain signals in the nervous system. Veterinary professionals have observed success with subanesthetic subcutaneous dosing, administered every 3 to 4 weeks, and titrated based on the patient’s response. Starting at 0.5 mg/kg, the dose and frequency of administration can be increased to daily as required. Although most research has focused on subanesthetic dosing via continuous rate infusion, anecdotal reports support its efficacy in intermittent subcutaneous administration with minimal adverse effects.⁴

Emergency kits: Ensuring comfort in critical moments

Emergency medication kits play a crucial role in hospice care, providing comfort and relief in critical moments when patients experience drastic changes in their condition. These kits are prescribed to families to offer peace of mind, as they can provide comfort to their beloved pets until they can seek veterinary assistance or death occurs. The kits can contain prefilled syringes with medications such as opioids for pain and anxiety, intranasal midazolam for seizures, furosemide for congestive heart failure, and oxymetazoline for epistaxis; these kits are tailored to each patient’s anticipated crisis. Childproof packaging, consent forms, and detailed instructions are provided to the caretakers, including reassurance that the medications in these kits will not hasten their pet’s death but simply relieve pain and anxiety throughout the active dying process. Most caretakers describe the peace of mind provided by this tool as priceless to them.⁵

Incorporating palliative pain management tools into veterinary practice can significantly enhance the well-being of patients during their final stages of life. Strong communication between the family’s primary veterinary practice and their hospice and palliative care veterinary team can be invaluable to families caring for their terminally ill or aging pet in the best way they know how. As veterinary professionals, understanding and implementing these tools can improve the quality of life for pets and their families, which creates a compassionate and supportive environment during this sensitive time.

Tyler Carmack, DVM, CVA, CVFT, CHPV, CTPEP, is the director of hospice and palliative care at Caring Pathways, a national at-home end-of-life veterinary practice. She founded Hampton Roads Veterinary Hospice in 2011 and has developed a special interest in integrative approaches to palliative pain management.

References

1. Monteiro BP, Lascelles BDX, Murrell J, Robertson S, Steagall PVM, Wright B. 2022 WSAVA guidelines for the recognition, assessment and treatment of pain. J Small Anim Pract. 2023;64(4):177-254. doi:10.1111/jsap.13566

2. KuKanich B. Pharmacokinetics of acetaminophen, codeine, and the codeine metabolites morphine and codeine-6-glucuronide in healthy Greyhound dogs. J Vet Pharmacol Ther. 2010;33(1):15-21. doi:10.1111/j.1365-2885.2009.01098.x

3. Ben-Menachem E. Pregabalin pharmacology and its relevance to clinical practice. Epilepsia. 2004;45(suppl 6):13-18. doi:10.1111/j.0013-9580.2004.455003.x

4. Subcutaneous ketamine for analgesia. Zero Pain Philosophy. Accessed October 12, 2023. https://www.zeropainphilosophy.com/post/ subcutaneous-ketamine-for-analgesia

5. Bailey FA, Williams BR, Goode PS, et al. Impact of a hospice emergency kit for veterans and their caregivers: a prospective cohort study. J Palliat Med. 2014;17(8):931- 938. doi:10.1089/jpm.2013.0395