Abstract

The robust advances in pain management for companion animals underlie the decision of AAHA and AAFP to supplement and expand on the information provided in the 2007 AAHA/AAFP Pain Management Guidelines for Dogs and Cats. The 2015 guidelines summarize and offer a discriminating review of much of this new knowledge. Pain management is central to veterinary practice, alleviating pain, improving patient outcomes, and enhancing both quality of life and the veterinarian-client-patient relationship. The management of pain requires a continuum of care that includes anticipation, early intervention, and evaluation of response on an individual-patient basis. The guidelines include both pharmacologic and nonpharmacologic modalities to manage pain; they are evidence-based insofar as possible and otherwise represent a consensus of expert opinion. Behavioral changes are currently the principal indicator of pain and its course of improvement or progression, and the basis for recently validated pain scores. A team-oriented approach, including the owner, is essential for maximizing the recognition, prevention, and treatment of pain in animals. Postsurgical pain is eminently predictable but a strong body of evidence exists supporting strategies to mitigate adaptive as well as maladaptive forms. Degenerative joint disease is one of the most significant and underdiagnosed diseases of cats and dogs. Degenerative joint disease is ubiquitous, found in pets of all ages, and inevitably progresses over time; evidence-based strategies for management are established in dogs, and emerging in cats. These guidelines support veterinarians in incorporating pain management into practice, improving patient care. (J Am Anim Hosp Assoc 2015; 51:65–82. DOI 10.5326/JAAHA-MS-7331)

Introduction

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. These guidelines continue the trend in all branches of medicine toward evidence-based consensus statements that address key issues in clinical practice. Although not a review article, this compilation is a force multiplier for the busy practitioner, consolidating in a single place current recommendations and insights from experts in pain management. These guidelines are the product of a collaborative effort by the American Animal Hospital Association (AAHA) and the American Association of Feline Practitioners (AAFP). The recommendations of the guidelines task force are evidence based insofar as possible and otherwise represent a consensus of expert opinion.

These guidelines are designed to expand on the information contained in the 2007 AAHA/AAFP Pain Management Guidelines for Dogs and Cats.^1,2 The 2015 guidelines differ from the earlier version in several ways. The first sections are general concepts designed to ‘‘set the stage’’ for the remaining, more specific content. The 2015 guidelines also discuss the importance of an integrated approach to managing pain that does not rely strictly on analgesic drugs. Because pain assessment in animals has become more scientifically grounded in recent years, various clinically validated instruments for scoring pain in both dogs and cats are described. The extensive list of published references includes numerous studies published within the past 3 yr, reflecting the rapid pace of advances in managing pain for companion animals. The 2015 guidelines summarize and offer a discriminating review of much of this new knowledge.

Types of pain

All types of tissue injury can be generators of pain. Occasionally, pain may occur in the absence of such causative factors. Understanding the mechanisms of pain is the key to its successful prevention and treatment. The pain response is unique to each individual and involves two components: (1) the sensory component is nociception, which is the neural processing of noxious stimuli, and (2) the affective component is pain perception, which is the unpleasant sensory and emotional experience associated with either actual or potential tissue damage. Pain is the endpoint of nociceptive input and can only occur in a conscious animal; however, there is also involvement of autonomic pathways and deeper centers of the brain involved with emotion and memory. Hence pain is a multi-dimensional experience; it is not just what you feel but also how it makes you feel.³ 

Acute pain has been defined as pain that exists during the expected time of inflammation and healing after injury (up to 3 mo), and chronic pain is defined as that which exists beyond the expected duration associated with acute pain. Therapy should be focused on the underlying cause of pain, (nociceptive, inflammatory, or pathological) rather than on arbitrary labels based on duration.⁴ 

Nociceptive pain occurs when peripheral neural receptors are activated by noxious stimuli (e.g., surgical incisions, trauma, heat, or cold). Inflammatory pain results gradually from activation of the immune system in response to injury or infection, and pathological pain, also called maladaptive pain, occurs when pain is amplified and sustained by molecular, cellular, and microanatomic changes, collectively termed peripheral and central hypersensitization. Pathological pain is characterized by hyperalgesia (exaggerated response to noxious stimulus), allodynia (painful response to nonnoxious stimuli, such as touch or pressure), expansion of the painful field beyond its original boundaries, and pain protracted beyond the expected time of inflammation and healing. Under some conditions, genomic, phenotypic changes occur that create the condition known as neuropathic pain, whereby pain can be considered a disease of the central nervous system. Those changes are not necessarily chronologic. Maladaptive pain, or the risk for it, can occur within a matter of minutes of certain acute pain conditions (e.g., nerve injury, severe tissue trauma, or presence of pre-existing inflammation).

A continuum of care

Appropriate pain management requires a continuum of care based on a well-thought-out plan that includes anticipation, early intervention, and evaluation of response on an individual-patient basis. It should be noted that response to therapy is a legitimate pain assessment tool. Continuous management is required for chronically painful conditions, and for acute conditions until pain is resolved. The acronym PLATTER has been devised to describe the continuum of care loop for managing pain (Figure 1). The components of the PLATTER algorithm for pain management are PLan, Anticipate, TreaT, Evaluate, and Return.

It's not just about drugs

Classic veterinary medical education places a strong emphasis on treatment of disease through pharmacology and surgery, the esoteric skills that are the domain of the trained clinician. Increasingly, evidence-based data and empirical experience justify a strong role for nonpharmacologic modalities for pain management. A number of those should be considered mainstream options and an integral part of a balanced, individualized treatment plan. 

Examples of nonpharmacologic treatments supported by strong evidence include, but are not limited to, cold compression, weight optimization, and therapeutic exercise. Other treatment options gaining increasing acceptance include acupuncture, physical rehabilitation, myofascial trigger point therapy, therapeutic laser, and other modalities, which are discussed in these guidelines. In addition, nonpharmacologic adjunctive treatment includes an appreciation of improved nursing care, gentle handling, caregiver involvement, improved home environment, and hospice care. Those methods have the critical advantages of increased caregiverclinician interaction and a strengthening of the human-pet bond. That shared responsibility promotes a team approach and leads to a more complete and rational basis for pain management decisions.⁵ 

Recognition and assessment of pain

The patient's behavior is the key

Because animals are nonverbal and cannot self-report the presence of pain, the burden of pain assumption, recognition, and assessment lies with veterinary professionals. It is now accepted that the most accurate method for evaluating pain in animals is not by physiological parameters but by observations of behavior. Pain assessment should be a routine component of every physical examination, and a pain score is considered the ‘‘fourth vital sign,’’ after temperature, pulse, and respiration.^1,2,6 Obtaining a thorough patient history from the owner can help determine abnormal behavior patterns that may be pain related. [See page 18 of this toolkit for forms pet owners can complete in the exam room or at home.] Pet owners should be educated in observing any problematic behavioral changes in their pet and to contact their veterinarian in such cases.

As shown in Figure 2, pet owners and practitioners should have an awareness of behavior types that are relevant to pain assessment. Those include the animal’s ability to maintain normal behavior, loss of normal behavior, and development of new behaviors that emerge either as an adaption to pain or a response to pain relief. Because behavioral signs of pain are either often overlooked or mistaken for other problems, the healthcare team must be vigilant in recognizing those anomalies in the total patient assessment. 

Pain scoring tools

Although there is currently no gold standard for assessing pain in dogs and cats, the guidelines task force strongly recommends utilizing pain-scoring tools both for acute and chronic pain. It should be noted that those tools have varying degrees of validation, acute and chronic pain scales are not interchangeable, and canine and feline scales are not interchangeable. The use of pain scoring tools can decrease subjectivity and bias by observers, resulting in more effective pain management, which ultimately leads to better patient care.

Pharmacological intervention of pain

Effective pain management generally involves a balanced or multimodal strategy using several classes of pain-modifying medications. The rationale behind this approach is that it addresses targeting multiple sites in pain pathways, potentially allowing lower doses of each drug and minimizing the potential for side effects associated with any single drug. The choice of medication should be based on anticipated pain levels and individual patient needs. Anticipatory analgesia provided prior to pain onset is more effective than analgesia provided once pain has occurred, contributing to both a dose- and anesthetic-sparing effect. Pharmacological interventions discussed in the guidelines include:

• Opioids
• Nonsteroidal anti-inflammatory drugs
• Local anesthetics
• a-2 adrenergic agonists
• Ketamine
• Systemic lidocaine
• Tramadol
• Gabapentin
• Amantadine
• Tricyclic antidepressants (tcas)
• Selective serotonin (norepinephrine) reuptake inhibitors [ss(n)ris]
• Acetaminophen
• Maropitant
• Bisphosphonates
• Corticosteroids
• Polysulfated glycosaminoglycans (psgags)
• Nutraceuticals and other oral supplements

Nonpharmacologic modalities

Weight optimization for pain management

Adipose tissue secretes a mixture of cytokines that circulate throughout the body, contributing to the pathology of many diseases, including degenerative joint disease (DJD), and to the hypersensitization process in general. Either maintaining or regaining a lean body condition score is central to the treatment of chronic pain. 

Acupuncture for pain control 

The guidelines task force holds that acupuncture offers a compelling and safe method for pain management in veterinary patients and should be strongly considered as a part of multimodal pain management plans.⁹⁶ It is a minimally invasive treatment that, for most animals, is not uncomfortable, often pleasant, and can be used either alone or in addition to other pain treatment modalities. Acupuncture has been recognized by the National Institutes
of Health since 1998 as having applications in human medicine, specially pain management. There is a solid and still-growing body of evidence for the use of acupuncture for the treatment of pain in veterinary medicine to the extent that it is now an accepted treatment modality for painful animals.^97–101 Other nonpharmacologic modalities discussed in the Guidelines include:

• Physical rehabilitation nutrition management
• Thermal modification (heat or cold)
• Environmental modifications
• Chiropractic care
• Homeopathy
• Gentle handling techniques

Other major topics covered in the guidelines include:

• Managing surgical pain associated with DJD for dogs and cats
• Hospice and palliative care

A team approach and client education: creating an environment for success

Primary care practices should be committed to educating the healthcare team and its clients about prevention, recognition, assessment, and treatment of pain. A team approach and consistent pain-management messages directed at clients will help ensure patient comfort during all stages of treatment. The client is often considered the most important member of the healthcare team. Each healthcare team member should be able to recognize pain-associated behavior in animals as described earlier in this document and know how to respond appropriately.

Staff training and education

Ideally, every healthcare team member should have a defined role in managing animal pain. Staff and client education should address conditions associated with pain; its prevention and treatment; and appropriate interaction, handling, and nursing care involving the patient. Medical rounds and staff meetings are effective tools in making sure that all staff members are aware of the individualized pain management needs of every hospitalized patient. Having a patient advocate for each hospitalized animal will enable a highly accurate and individualized evaluation of the patient and ensure successful treatment.

Client education and instructions

With each pain management plan, it is important that the client be given specific instructions, both verbally and in writing. Potential adverse drug effects and action to be taken should be emphasized. It is advisable to provide a hands-on demonstration on how to administer medications and handle the pet at home. To reinforce verbal information about pain assessment, provide handouts that discuss general information about animal pain and any side effects of medications. Compliance will improve if the pet owner understands the treatment schedule and a demonstration of how to administer oral medications is given. Clients should be encouraged to address their concerns about the pet’s condition and treatment plan via e-mail, phone, or follow-up consultations.

Conclusion

Effective pain management is an essential component of companion animal medicine. It reduces disease morbidity, facilitates recovery, enhances quality of life (QOL), and solidifies the relationship among the veterinarian, client, and pet. Behavioral changes are the principal indicator of pain and its resolution, for which there are now several validated, clinical scoring instruments. Pain is not an isolated event but instead exists either as a continuum of causation, progression, and resolution or as a chronic condition. Thus, treatment of pain should consist of a continuum of care in the form of anticipatory analgesia through the anticipated pain period followed by longer-term or even chronic treatment that relies on periodic reassessment of the patient’s response. 

Effective pain management is integrative in two respects. First, it does not rely solely on pharmacologic methods but also uses a variety of nonpharmacologic modalities. Not least of those is gentle handling and nursing care of the patient in the context of a stress-free physical environment. When considering either nonpharmacologic methods or hospice care that may be outside the immediate skills or services provided by the primary practice, the veterinarian should have a list of experts for referral in place. A second aspect of integrative pain management is the multimodal use of medications that either block or modify multiple pain pathways. A multimodal approach also reduces reliance on any single agent, minimizing the potential for adverse drug events. 

Pain management in clinical practice is a team effort, with the pet owner functioning as an integral part of the team. All healthcare team members should have a defined role in the practice’s approach to providing compassionate care to its patients. That enables the practice to speak with one voice and in a consistent manner in the implementation of pain management protocols. Client education is a key component that enables the pet owner to manage pain in the home setting. Direct involvement of the client in pain management efforts is consistent with the continuum of care concept and a demonstration of the practice’s commitment to the pet’s QOL. A fully integrated approach to pain management, involving recognition and systematic assessment, pharmacologic and nonpharmacologic methods, and one that includes both healthcare team members and the pet owner, ensures that everything possible has been done to relieve a patient’s pain once it enters the practice’s care.

For references (footnotes) in this document, please refer to the 2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats.

These guidelines were prepared by a task force of experts convened by the American Animal Hospital Association and the American Association of Feline Practitioners for the express purpose of producing this article. These guidelines are endorsed by the International Veterinary Academy of Pain Management. They were subjected to the same external review process as all JAAHA articles.

The Task Force acknowledges the contributions of Mark Dana of the Kanara Consulting Group, LLC, in the preparations of the 2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats.