Sharon Campbell, DVM, MS, DACVIM

The confusion between pain and behavioral problems was a hot topic at the recent International Veterinary Behavior Meeting (IVBM). Overlooking pain as a cause of the behavioral condition can delay treatment and prolong the patient’s suffering. Below are some things to consider when ruling out pain as the possible underling cause of a behavioral problem.

The Relationship between Fear, Anxiety, and Stress (FAS) and Pain

1. Pain, stress, anxiety, and fear are intimately related:

• Pain is stressful and can exacerbate fear and anxiety.
• Fear can be an initial response to pain and severe or constant pain can lead to chronic stress and anxiety. ^{1, 2,3}
• The behavioral responses to fear and anxiety, such as trembling, muscle tension, and hypervigilance, can then exacerbate pain. An example of this is the recently published association between noise aversion and musculoskeletal pain.⁴ (See Study: Exploring Pain & Noise Aversion to learn more.)
• The vicious cycle of pain, fear, anxiety, and stress can only be stopped by identifying and treating the underlying causes.

2. Pain and fear share common characteristics:

• Acute pain and fear are adaptive and are requirements for survival.
• Chronic pain and fear are maladaptive and serve no beneficial purpose.

3. Generalization in Dogs is Common:

• Dogs are very good at generalizing if the event causes a strong emotional response. For example, a dog with hip dysplasia that has an exacerbation of that pain when playing with another dog, may now become aggressive to that dog and other dogs in anticipation of pain.

Pain that Masquerades as Behavioral Problems

Behaviors that can be associated with pain include:

• Pica⁵
• Aggression^3,6,7
• Resource guarding⁸
• Attention seeking behavior⁸
• Repetitive behavior such as tail chasing or licking (self or surface)⁸
• Changes in sleep behaviors³
• Development or worsening of other anxieties (separation anxiety, noise aversion)^3,4,8

Indicators of Chronic Pain

Indicators of chronic pain from the history, physical examination or workup include:

• Reluctance to move or decreased tolerance of exercise
• Difficulty sitting up, lying down, jumping, or going up and down stairs
• Inappropriate elimination
• Lameness, gait abnormalities
• Sitting abnormally
• Muscle atrophy
• Pain on palpation of the spine or manipulation of the joints
• Radiographic evidence of joint disease, IVDD, etc.

In cases where a painful condition was diagnosed, an analgesic trial was initiated. In most cases, the behavioral signs resolved without the need for behavior modification. When the pain medication was discontinued, the behavioral signs recurred; behavioral signs resolved when the analgesics were readministered. ^3,5,6,9

Summary

Clinically significant pain can be overlooked in dogs presented for behavioral problems. Lack of response to anxiolytic medication, may be an additional indication that some painful or other medical conditions is the cause. Including pain as a differential diagnosis for behavioral problems could allow early intervention and relief, therefore diminishing the suffering of the patient, improving the quality of life of both the patient and owner and preserving the human animal bond.

This article was reviewed/edited by board-certified veterinary behaviorist Dr. Kenneth Martin and/or veterinary technician specialist in behavior Debbie Martin, LVT.

References

1. Asmundson GJG, Katz JK. Understanding the co-occurrence of anxiety disorders and chronic pain: State of the art. Depression and Anxiety 2009; 26: 888-901.
2. Hannibal KE, Bishop MD. Chronic Stress, cortisol dysfunction, and pain: A psychoneuroendocrine rational for stress management in pain rehabilitation. Physical Therapy 2014; 94: 1816-1825.
3. Lindley S. The effects on pain and behavior and behavioural problems Part 3: Aggression and compulsion. Companion Animal 2012; 17: 50-54.
4. Lopes-Fagundes AL,Hewison L, McPeake KJ et al. Noise sensitivities in dogs: An exploration of signs in dogs with and without musculoskeletal pain using qualitative content analysis. Frontiers in Vet Science 2018; doi: 10.3389/fvets.2018.00017
5. McPeake KJ, Mills DS. “Daisy swallowed another stone… Musculoskeletal pain as a differential for pica – a case report. Proceedings 12^th International Veterinary Behavior Meeting. 2019: 79-84.
6. Barcelos AM, Mills DS, Zulch H. Clinical indicators of occult musculoskeletal pain in aggressive dogs. Vet Rec. 2015; 176: 465.
7. Camps T, Amat M, Mariotti VM, et al. Pain-related aggression in dogs:12 clinical cases. J Vet Behav 20102; 7: 99-102.
8. Mills DS, Hewison L, Van Haevermaet H et al. Observations concerning potential adjunctive behaviours as proxy indicators of chronic pain in dogs referred to a behaviour referral clinic.
9. Lindley S. The effects of pain on behaviour and behavioural problems Part 2: Fear and Anxiety. Companion Animal 17: 55-58.