signs (Hardie et al. 2002; Clarke and Bennett 2006). Overt lameness is much less common in cats than dogs (Clarke and Bennett 2006). In addition, while palpation may be effective at determining when and where dogs experience pain, cats often resist palpation under normal circumstances; therefore, response to palpation is unlikely to be diagnostic for pain or discomfort. Osteoarthritis is not the only cause of chronic pain in the cat; pain secondary to cancer and dental disease (e.g., feline orofacial pain syndrome [FOPS]) should also be of concern.
4.5.2 Neuropathic Pain
When evaluating dogs and cats for pain, it is also important to be aware that there are different kinds of pain and altered sensation. Neuropathic pain has been defined as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system” (Shilo and Pascoe 2014). It is considered a chronic pain state that results from peripheral or central nerve injury and can be due to acute events such as amputation or systemic disease such as diabetes. As opposed to functional pain, neuropathic pain is believed to serve no purpose. Nociceptors are not involved, and the mechanisms underlying the syndrome are unclear. The relief of neuropathic pain is generally considered extremely challenging.
The possibility of phantom limb pain, where the patient perceives pain in a limb that is no longer present, should also be considered as a possible outcome of amputation (Shilo and Pascoe 2014). Since animals cannot report what they are experiencing verbally, and limited diagnostic capabilities may prevent us from being able to clearly recognize these conditions in animals, it will be even more incumbent upon the caretaker to be extremely observant for signs of pain in animals.
Table 4.2 Behavioral signs of pain in dogs and cats (Mills et al. 2020; Bacon et al. 2019; Godfrey 2005; Bennett and Morton 2009; Slingerland et al. 2011).
| Dogs | Cats |
|---|---|
| More common | General signs |
| Anorexia Avoidance behaviors Hiding Aggression Hunched body posture Whining or howling Decreased social interactions Changes in activity level Changes in temperament or mood Reluctance to move or change position when recumbent or Increased restlessness and frequent changes in position Tense facial muscles with ears pulled back from the face and a grimace May attempt to bite at or lick a painful area May rub painful areas against walls, doors, or other objects Increased heart rate, respiratory rate, and/or blood pressure | Avoidance or flight behavior Restlessness or agitation Hunched posture Squinting eyes Reluctance to move Vocalization (including purring) Gait changes Decreased appetite Changes in grooming behavior Tail flicking Changes in interactions with people Decreased tolerance to handling Aggression when certain body parts are manipulated Aggression when attempting to move or lift |
| Less common | Signs of pain associated with degenerative joint disease |
| Pica Housesoiling Noise sensitivity Clinginess Excessive licking | Decreased walking, running, jumping, or climbing Increased sleep Decreased play Stiff movement or a shuffling gait Appearance of weakness Difficulty jumping Altered temperament Inappropriate elimination |
4.6 Common Medical Conditions Resulting in Behavioral Signs
4.6.1 Anxiety Disorders
Anxiety is the emotional response that occurs when there is the anticipation of future danger. What is critical for animal caretakers to be aware of is that the danger does not have to be real; it may be unknown or imagined. Equally important is that when animals perceive something to be dangerous or threatening, that is what they will respond to emotionally. The physiological responses to feelings of anxiety are similar to the responses that are seen with fear (see Box 4.2). Many of these behaviors can also be seen associated with particular medical conditions, further complicating some diagnoses.
In addition, it appears that some individuals have behavioral dysfunction due to pathological anxiety, and this results in maladaptive behavior. A definition for pathological anxiety has been proposed: “Pathological anxiety is a persistent, uncontrollable, excessive, inappropriate and generalized dysfunctional and aversive emotion, triggering physiological and behavioural responses lacking adaptive value. Pathological anxiety‐related behaviour is a response to the exaggerated anticipation or perception of threats, which is incommensurate with the actual situation” (Ohl et al. 2008).
Box 4.2 Behavioral Signs of Anxiety
Panting
Pacing
Trembling
Salivating
Increased blood pressure
Increased heart rate
Increased respiratory rate
Dilated pupils
Avoidance behaviors such as hiding
Hypervigilance
General behavioral arousal
Irritability
Restlessness
Freezing or tonic immobility response
Increased aggression or threatening behaviors
Sleep‐wake cycle disturbances
Lowered body posture (crouching)
Lowered ears
Tucked tail
Repeated lip or snout licking
Yawning
Differentiating pathological anxiety from the situational anxiety that might be expected in an animal that has recently been introduced into a shelter situation will not be easy as the line between normal and abnormal is often vague. However, caretakers should remain aware that some animals will not adapt well to the shelter environment due to preexisting behavioral pathology. In addition, the behavioral pathology may predispose these animals to illness and poor welfare due to the chronic stimulation of the HPA axis and the animal’s inability to adapt to the changing environment. Lastly, anxiety can occur as a result of any disease process, pain, or discomfort, especially if it remains unidentified by caretakers and thus untreated.
4.6.2 Neurological Disorders
A variety of different neurological disorders have the capability of affecting behavior in a variety of different ways. While many neurological disorders are steadily progressive and, thus, will eventually present additional non‐behavioral signs, in many cases, behavioral changes will precede the appearance of other more severe neurological signs by weeks or even months. Storage diseases, neoplasia, inflammatory conditions, degenerative conditions, toxicosis, malformations, ischemia, and infections can all lead to changes in behavior.
