EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2018


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higher brain centres, where their impulses are perceived as pain. To complicate this process, there are opportunities along this ‘pain pathway’ for intrinsic and extrinsic factors to affect the nature, degree and duration of the pain event (Zaki 2013). Pain causes measurable physiological responses that can


be identified, but these responses tend to be indicators of a stress response rather than specific for pain (Zaki 2013). Changes in behaviour as well as posture and facial expression have been postulated as indicators of pain in animals (Langford et al. 2010; Lesimple et al. 2012). Behavioural changes, abnormal or awkward posture, stiffness, positive response to palpation and reduced performance can all point toward a pain response. Pain assessment also involves quantifying how much pain an animal is experiencing. Pain scales and pain scoring systems are all used to try to identify the animal’s level of pain (Bussi


eres,


et al. 2008; Wagner 2010; Van Loon et al. 2010). Pain can be adaptive or maladaptive. Acute pain is


considered adaptive and is a response to tissue injury. Initiated by the inflammatory process, the response to the noxious stimulus is appropriate and reflects the degree of damage to the affected tissue. Pain becomes maladaptive when the painful experience continues despite the removal of the noxious stimulus. This type of pain is chronic, difficult to evaluate and difficult to treat, requiring a multifaceted approach. In horses, it is associated with conditions such as chronic laminitis and navicular disease and results in hyperalgesia, allodynia and spontaneous pain (Zaki 2013; Daglish and Mama 2016). In animals, maladaptive pain can result in behaviours difficult for the veterinarian to assess or understand. Bucking under saddle, aggression while being girthed and ‘cold-backed’ behaviour are often considered training or behavioural issues (Holmes and Jeffcott 2010; Jeffcott 2010), but evaluation for pain is essential to rule out chronic or maladaptive pain responses.


Clinical diagnosis of back pain


Horses with TL spine issues tend to present to the veterinarian for evaluation of poor performance rather than for palpably painful backs (Jeffcott 1980a, 1999, 2010; Jeffcott et al. 1982; Denoix 1999). Performance problems due to TL conditions have been evaluated in many sport horses including Thoroughbreds and Standardbreds (Thomson et al. 2014), Warmbloods (Gorgas et al. 2007) and endurance horses (Fraipont et al. 2011). There is a large variation in the severity of the responses between individuals, regardless of the degree of underlying pathology (Cauvin 1997). The technique of manual palpation, widely used and described in the literature (Allen et al. 2010; Cauvin 1997) has been correlated to pressure algometry in horses with sacroiliac dysfunction (Varcoe-Cocks et al. 2006), but algometry has not been adopted by the general practitioner as a way to evaluate equine TL pain. Thoracolumbar pain in the horse may arise as a primary


condition, or may be secondary to another problem in the appendicular skeleton such as lameness (Jeffcott 2010). Changes in patterns of movement because of distal limb osteoarthritis can cause tightening and pain in the epaxial muscles. Also, many normal horses show quite dramatic reactions to manual palpation of the muscles of the back such as skin twitching or muscle fasciculation through to


Patient history and signalment As in any case presented to the veterinarian, a thorough history is required. Lameness is not a definitive finding in horses with TL spine pathology (Landman et al. 2004; Haussler and Jeffcott 2014) and any horse with lameness as a primary presenting problem should be examined for joint and limb pathology. It is also important that any evaluation of the horse with a back problem should include a thorough examination of limbs and feet. The history will need to consider general information as


well as more targeted questions (Table 1). The horse’s use and athletic performance are important. For example, a vaulting horse has a different training and working life than a


TABLE 1: Questions to ask when assessing the history of a horse with TL pain


General information Owner information


Age Breed Gender Management – diet, housing, herd mates


Prepurchase examination information Length of time with current owner Rider’s experience and level of ability Personality towards pain as per owner (stoic vs. sensitive)


Career of horse


Type of performance or use Level of training Frequency and duration of exercise per week and per session Frequency and level of competition Type and fit of saddle


Current problem


Character and onset of clinical signs Duration of clinical signs Any particular exercises or ridden work horse is having trouble with Any known trauma Previous occurrence of condition Any other physical problems or abnormalities Any current or previous lameness Problems grooming or tacking up Problems rolling or lying down Reluctance to lift one or more legs or problems with the farrier


Treatment


Any veterinary examinations or treatment undertaken and response Any alternative care treatment and response Any rest periods undertaken


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dipping of the spine (Jeffcott 2010)). The concept of clinically significant back pain in the horse is also complicated by the fact that some horses with palpable back pain continue to perform at a high level. A third category of back problems must also be considered: that of the ‘apparent’ painful back. These horses display what appears to be back pain, but this is a behavioural response related to their temperament or from a lack of fitness or ability (Jeffcott 2010). Finally, there are some horses that roach or dip their backs when being girthed or when first mounted. These horses are often referred to as ‘cold-backed’ horses. This syndrome affects many young horses, particularly Thoroughbreds and Arabians and is characterised by transient muscle spasm and back stiffness during saddling or mounting. There has been little research into this condition, but clinically it does not seem to be related to TL pathology (Jeffcott 2010).


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