IN people, pain is what the patient says it is. In animals pain is what the attending veterinary surgeon says it is. Simple behavioural changes and postural changes can be used to help us recognise pain in our patients.
Introduction
Veterinarians consider surgical procedures in dogs and cats to be equally painful and carry out as many procedures in cats as in dogs, yet they treat cats for peri-operative pain less frequently than dogs. This is partly a result of difficulties in recognising and assessing pain in cats.
Pain scoring systems which measure physiologic data (objective) and/or behaviour (subjective) do exist for the cat, but none is yet validated.
The Visual Analogue Scale (VAS) is a widely used subjective scoring system. It consists of a continuous line anchored at either end with a description of the scale limits. For example, “no pain” may be at one end of the scale and “severe pain” at the other end. The observer places a mark on this line at the point which he or she believes correlates with the animal’s degree of pain. This mark is converted to a number by measuring the distance from zero (see Example 1).
A practice should choose a scoring system that meets its own needs, is user-friendly for veterinary surgeons and nurses and can be used in every postoperative situation to assess a cat’s level of pain. The system needs to become an integral part of every post-operative assessment. Assessment of pain in the cat should rely on both behavioural changes and postural indicators, which will be covered in this article.
Behaviours related to pain
Loss of normal behaviour
Assuming the animal is not heavily sedated or still recovering from anaesthesia, the absence of normal behaviour (for example grooming, or moving to the litter box to urinate or defecate) in a cat should prompt a veterinarian to question whether the cat is in pain.
Each cat’s behaviour in a clinic setting is unique and those that are fearful or stressed may stay at the back of the cage or hide under a blanket. Therefore, careful observation of their normal behaviour before surgery is essential to detect the subtle changes in behaviour after surgery.
For example, a cat which was friendly and interactive before surgery, and is hunched and hiding at the back of the cage after surgery, should be assessed to determine whether its level of analgesia is adequate.
Fear and stress can worsen pain and are themselves unpleasant feelings, therefore blankets and toys from home, and the provision of boxes or blankets to hide in or under, and the use of synthetic facial pheromones (Feliway, Ceva) to make the cat as comfortable as possible while in the clinic should be considered.
The subtle signs of pain which are described in this article may be missed if an observer is only looking for active and overt signs of pain such as vocalisation and agitation.
Response to palpation
Wound palpation is an important part of pain assessment. Other than in feral cats, a veterinarian should be able to apply gentle pressure to, and around, a wound site in a cat that has received adequate pain control, without the cat flinching or attempting to bite. It is important to have assessed the cat’s temperament before surgery as these could just be the reactions of a bad-tempered cat!
Shaking of a limb which is bandaged or excessive licking of a bandaged site may reflect dislike of a bandage, an overly tight bandage or it may reflect poorly controlled pain. Excessive licking of a wound may reflect irritation with sutures, or it may reflect poorly controlled pain.
Careful examination of the cat’s behaviour, posture and facial expressions may help to differentiate which is the most likely cause of a cat’s distress in a post-operative situation.
Orientation in the cage
A cat with post-operative pain will often sit at the back of its cage and will not interact with veterinary or nursing staff. Again, it is important to have assessed the cat’s temperament before surgery.
Postural changes related to pain
Hunching
A cat which adopts a hunched posture, with a low head position, is likely to be experiencing pain. A hunched or tucked-up posture has been correlated to acute pain after abdominal surgery (Waran et al,2007). This observation has been correlated by preliminary work at the University of Glasgow (Robertson, S. A., College of Veterinary Medicine, University of Florida, unpublished data 2007).
Compare and contrast the posture of the cat in Figure 2 with that of a cat with adequately controlled pain in Figure 1.
Facial expressions
A head-down posture with angled and half shut “squinty” eyes and drooping ears may correlate with pain.
Compare and contrast the eye position and ear position of the cats in Figures 2 and 3, with that of a cat with adequately controlled pain in Figure 1.
Body position
A cat which is lying flat out and unresponsive or uninterested in its surroundings may be in severe pain.
Compare and contrast the body position and facial expression of the cat in Figure 4, which was taken taken pre-surgery, to the same cat with poorly controlled post-operative pain in Figure 5.
The cat in Figure 1 demonstrates the posture of a comfortable cat; the front legs are curled under and resemble a croissant, pretzel or bagel.
How often should pain be assessed?
Concurrent illness, the extent of the surgery or injury and the anticipated duration of the analgesics administered all determine the frequency with which a cat should be re-evaluated for pain.
For example, a cat which is resting comfortably and has a normal facial expression after post-operative administration of an NSAID and buprenorphine may not need reevaluation for two to four hours.
Animals should be allowed to sleep as much as possible following surgery and administration of analgesic therapy. Vital signs can be checked without unduly disturbing the animal; however, the cat should still be given the analgesics “on schedule” and periodically more interactive observations (such as gently palpating the wound) should be carried out to determine if the level of analgesia is sufficient.
We don’t want to wait till the cat is showing very obvious signs before we re-treat – animals should not have to “earn their analgesia”.
The more closely the cat is observed pre-surgery and the more frequent the observations post-surgery, the more likely that subtle signs of pain will be detected.
Pain does not disappear when the cats are discharged; therefore, the owner should be asked to monitor the cat’s appetite and demeanour at home to determine the response to the analgesics prescribed for post-operative home care.
Conclusions
Every cat should be carefully observed before and regularly after surgery to detect the behavioural and postural changes which may reflect poorly controlled pain.
If the observer is unsure whether a cat has adequately controlled pain or not, he or she should administer appropriate analgesics and reassess the response to therapy.
Reference
- Waran, N.,Best,L.,Williams, V. M., Salinsky, J.,Dale,A. and Clarke, N. A. (2007) Preliminary study of behaviour-based indicators of pain in cats. Animal Welfare 16(S): 105-108.
