Originally published in the August 2015 issue of Veterinary Practice News. Subscribe today!
American Animal Hospital Association (AAHA) and the American Association of Feline Practitioners (AAFP) have recently published the "2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats." The entire article is easily found online (for free) to any interested reader.
Full disclosure: What follows is not a summary of the AAHA and AAFP article, but a review of a few key points made by the authors as they relate to perioperative pain control. In addition, we interviewed the lead author, Dr. Mark Epstein.
NSAIDs are a mainstay for chronic-pain management, as well as for perioperative use. However, "preexisting elevated liver enzymes are not a risk factor." The guidelines state that "the importance of maintaining a normotensive state during anesthesia is considered paramount when utilizing preoperative NSAIDs."
Studies have shown that NSAIDs are more effective when given prior to surgery (concept of preemptive analgesia), but if IV access is not possible or intraop normotension is not certain, the NSAID should be given after surgery, once blood pressure has normalized.
"Also critical is patient selection," says Dr. Mark Epstein, lead author of the guidelines and medical director and senior partner at TotalBond Veterinary Hospitals near Charlotte, N.C.
"Question the owner: What other medications is the patient taking (specifically other NSAIDs or steroids)? What is their appetite, water intake, GI signs? Educate clients about recognizing side-effects. Instruct when to stop the NSAID and call their vet."
Ample information is provided in the guidelines to increase the safety of NSAID administration. In particular, blood work should be performed regularly. "The frequency will depend on the risk factor of the patient." In low-risk patients, blood work can be done within the first month of initiating therapy, then every six months. For at-risk patients, monitoring is recommended every two to four months.
The guidelines don't provide much information on constant rate infusions (CRIs), but list them as one of the options for dealing with surgical pain. They do encourage the use of ketamine and lidocaine as being safe and beneficial in a CRI.
Butorphanol only provides limited somatic analgesia and very short duration of visceral analgesia. When compared to buprenorphine, pain control with butorphanol is limited, while buprenorphine may last up to six hours.
Alpha-2 adrenergic receptors are located with opioid receptors. Therefore, giving these drugs together improves sedation and analgesia synergistically. In addition, the combination reduces the dose of each drug, thereby minimizing their side effects, such as bradycardia.
Phil Zeltzman, DVM, DACVS, CVJ
The 2015 AAHA/AAFP Pain Management Guidelines say that an epidural "should be strongly considered."
Ideally, the same person would assess the patient's behavior and pain throughout the hospital stay. The guidelines recommend using a pain scale, such as the Colorado State University Acute Pain Scale (Canine vs. Feline), or the University of Glasgow Short Form Composite Pain Score, in order to reduce subjectivity and variability between observers. The article provides links to the pain scales, available to any interested reader for free.
Such scales are based on simple criteria including:
- Observing the patient without interaction (e.g. the patient's orientation in the cage).
- Observing the patient while interacting with a caregiver (e.g., what happens when the cage door is opened).
- Observing the patient's response to palpation of the surgical site.
A numerical score is then assigned to the patient at that point in time.
The guidelines clearly state that, "Because of their safety and significant benefits, local anesthetics should be utilized, insofar as possible, with every surgical procedure." Further, "most of those blocks can be readily learned by clinicians."
We asked Dr. Mark Epstein how useful tramadol, gabapentin and amantadine are in pets.
"There is a lack of safety, toxicity, efficacy and dose-titration data regarding oral tramadol in dogs," he says. "However, there is evidence that parenteral tramadol in dogs, and oral tramadol in cats, has some pain-modifying activity. In other words, oral tramadol deserves skepticism…
There is a reasonable kinetic and safety data for utilizing gabapentin for chronic pain in dogs and cats, especially if it involves a neuropathic component. This includes osteo-arthritis in cats.
The task force took a neutral approach for its use for surgical pain." However, a study out of Brazil has been published since (www.ncbi.nlm.nih.gov/pubmed/25816802 ).
As for amantadine, the Lascelles study (www.ncbi.nlm.nih.gov/pubmed/18289289) demonstrates the utility of amantadine as an adjunct medication to NSAIDs in the management of canine osteoarthritis.
We also asked Mark Epstein whether NSAIDs should be used in abdominal surgery.
"Since surgical pain is mostly inflammatory in origin, it can be argued that use of NSAID is indicated anytime a blade is laid to skin, including for laparotomy. However, since tissue healing is dependent in part on COX enzymes (especially COX2), and human studies demonstrate higher levels of leakage at anastomotic sites when NSAIDs are administered, special consideration may be given when gastrotomy or enterotomy is performed."
The "right" answer to this question is not really known, and the guidelines do not take a position, but "you could use a more-balanced NSAID (i.e. less COX2-selective), and limit the use of NSAID i.e. to the first 24 to 48 hours postop only."
There are also multiple non-pharmacologic modalities to manage pain, including:
- Weight loss, not only because of excessive pressure but also because of circulating cytokines that exacerbate pain
- Omega-3 fatty acids to help with degenerative joint disease.
- Cold compression
- Environmental modification, both in the hospital and at home
- Gentle handling techniques
- Interestingly, "This Task Force has not found sufficient, reliable, non-contradictory evidence for the use of chiropractic care for pain management in veterinary medicine at this time."
- Similarly, "Evidence that homeopathy is effective in either human or veterinary medicine for the treatment of pain is lacking."
We would like to conclude with the excellent introduction to the guidelines: "Pain management is central to veterinary practice, not adjunctive. Alleviating pain is not only a professional obligation (recall the veterinarians pledge to 'the relief of animal pain and suffering') but also a key contributor to successful case outcomes and enhancement of the veterinarian-client-patient relationship. A commitment to pain management identifies a practice as one that is committed to compassionate care; optimum recovery from illness, injury or surgery; and enhanced quality of life."
Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling practice takes him all over eastern Pennsylvania and western New Jersey. You can visit his website at www.DrPhilZeltzman.com, and follow him at www.facebook.com/DrZeltzman.
Kelly Serfas, a certified veterinary technician in Bethlehem, Pa., contributed to this article.