Pain. Everybody knows what it feels like, and – apart from a few determined individuals – we tend to avoid it. But what is it? The International Association for the Study of Pain (IASP) defines it as: “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” Or, in other words, when you damage yourself it hurts. And if you’re feeling down already, it hurts more. And if you’re not feeling down already, then pain may make you feel down. And then it will hurt more. The IASP mainly looks at pain in humans, but it’s a long time since we stopped trying to pretend that animals either don’t feel pain like we do, or else don’t get upset about it. They do, and their inability to communicate pain effectively (or else our inability to properly listen) means that for a lot of animals, pain is a chronic, miserable constant in their lives, despite help being close to hand. There are tiny pain receptors all over the body, inside and out, attached to nerve fibres. When a tissue is damaged, they’re triggered to send impulses up to the brain, which senses them and registers the feeling we call pain. Hard to describe, but we all understand what it is and we’ve all got experience of it. Pain receptors are usually well embedded in tissues, and usually need a fair bit of triggering – otherwise, any form of touch would be painful. When we describe pain in ourselves, we often use terms like sharp, jabbing, dull or throbbing, and they can give an indication of how bad it is. But in a more fundamental sense, we differentiate into two types: physiologic and pathologic. Physiologic pain is ‘protective’ – it’s the pain we get when picking up a hot pan. Very quickly, the body registers the ‘ouch’ and the pan is dropped, hopefully before too much damage is done. Without this kind of reflexive response, we’d just keep on holding the pan until our hands were badly damaged. Physiologic pain, more or less, is our friend. Pathologic pain, on the other hand, is the pain that comes from existing damage, such as a broken leg or a arthritis. Whilst it can initially be useful to draw our attention to the condition, it becomes debilitating quite quickly and can be a problem in its own right. It’s this kind of pain that we need to deal with in our patients: the pain that is ever-present or recurrent, at whatever level. If we don’t, the pain becomes responsible for stress, depression and a reduced quality of life. For example, the pain of arthritis can actually make the condition worse:
- being unwilling to move around makes the joints stiffen up through lack of use
- lack of exercise piles on the weight, putting more pressure on the joints
- increased pressure on the joints means more pain, so less movement, more stiffening and more weight gain
- Understanding of normal behaviour
- Reduced mobility or abnormal movement – if it hurts to move, pain is reduced by not moving. Equally, if a pet is moving in an odd way, then it’s because moving in a normal way hurts. A major, major problem that we encounter is the attitude that reduced mobility is a normal part of ageing – so pain is often not recognised in older patients. It’s amazing what a trial on painkillers can do to change minds.
- Guarding and defence – hiding away or trying to protect the bit that hurts. A common entry on clinical notes is ‘guarding the abdomen’ which usually relates to a tenseness in the belly when we’re trying to palpate.
- Inappetance – most animals will either eat less or stop eating altogether when in pain. When the pain is settled, we often see rebound eating, where intake is increased for a while. This can be a cardinal sign for assessing response to treatment.
- Adipsia or polydipsia – most animals will also drink less, although some, often as a response to stress, will drink too much. Patients with abdominal pain will often swallow great bowlfuls of water, possibly because of a temporary soothing effect.
- Altered interaction – many animals will hide away and reduce their interactions with other members of the household; others, particularly dogs, will become more needy and seek more interaction. Normally friendly relationships may explode into world war three and, rarely, vice-versa. It’s not so much how the interactions change, but that they change in the first place.
- General distress – other signs of distress include increased breathing rate, increased pulse rate, abnormal breathing (cats DON’T pant as a normal behaviour), vocalisation (howling, mewing, whimpering), a certain glassiness of the eyes, hunched body position, bubbling at the mouth (reptiles), fluffing of the feathers or over-stimulation and anxiety from normal noises and events.
- The amount of time that it’s been going on for - most of us are fairly stoic, at least at first, but sooner or later an inability to get comfortable, to sleep, to do the things we want to, all start to get us down. It’s the same for our pets.
- Having more than one painful bit – two plus two in this case tends to make five.
- Previous experience of pain. Our pets have a phenomenal memory for pain, which translates to a fear of repeating the experience. Pain at the vets can put a patient off us for life, which is why we try to make the first couple of visits as stress-free as possible.
- Being in a bad mood already. If you walk down the street on a happy day and stub your toe, it hurts. If you’re already in a bad mood, the world seems to cave in. This is where the vicious cycle of pain and depression starts to bite: being in pain causes stress and depression, and stress and depression make pain feel worse.