Pain Is Part Of Defence: Pain is not a disease or illness. It is a pet's first line of defence. Pain is protective. Feeling pain causes a pet to avoid continuing dangers. Continued pain reduces use of damaged tissues, giving time for repair. Inactivity, as a result of pain may favour the immune system's response to body damage. Pain has two separate dimensions, intensity and unpleasantness. The sensation of pain is a constant. It is not affected by typical pain-killing drugs but the unpleasantness of pain can be reduced by drugs, conditioning, even by placebo.
Short-term pain ranges from mild to so excruciatingly unpleasant it causes a pet to go into clinical shock. Pain is the natural way a dog or cat knows it should avoid something or that something has gone wrong. Pain can have an obvious source. Nerve endings capable of receiving pain messages are everywhere but especially concentrated on the skin. Curiously, the amount of pain a pet feels is not related to the amount of damage that exists. Your pet's brain constantly monitors the inflow of all information and sets a biological priority to a fraction of that information. If your pet suffers potentially painful penetrating bite wounds from another dog or cat, its response may be not to feel the pain but to bite back. Conscious acute pain occurs only after other priorities have been met. The pet with deep puncture wounds from a bite may appear pain-free until its brain registers different priorities and pain sensation develops.
Chronic pain is relentlessly uncomfortable. Most pets suffering from chronic pain behave stoically. Owners notice changes in behaviour, for example a reluctance to play as actively as before, difficulty with stairs or jumping on furniture or irritability. The degree of pain that a pet feels varies enormously. In dogs there are breed differences. For example most bull terriers appear to be less sensitive to pain than most small spaniels. Some forms of chronic pain respond well to mild pain-killing drugs but other forms of chronic pain are more difficult to control.
How Pain Is Transmitted
Nerve receptors throughout the body, in muscles, joints but especially in the skin are stimulated by temperature, pressure or natural chemicals called prostaglandins which are released by damaged cells. Messages are relayed through nerves to the brain where they are interpreted as pain. Each pet interprets these signals in its own way that is partly learned and partly inherited. Dog breeds differ in how they feel pain and cats seem to experience less pain than dogs do . According to the 'gate control' theory, information from nerve receptors travelling to the brain has to pass through 'gates'. A number of factors determine how wide open these gates become. Emotion certainly affects the size of the gate opening, probably by altering endorphins, the body's natural pain killers. This is why during the emotional intensity of a fight, there can be serious injuries but the fighters are resistant to pain and keep fighting. A simple, routine injection by your vet, on the other hand, may be capable of inducing unpleasant pain, especially in dogs.
To alleviate short term pain, we use a variety of medications . Non-steriod anti-inflammatory drugs (NSAIDs) work by inhibiting the production of inflammatory prostaglandins. Paracetemol blocks pain impulses in the brain itself. Narcotic pain killers like pethidine and morphine mimic endorphins the body's natural pain killers, blocking pain impulses at specific body sites. Narcotics are used for severe pain associated with trauma, major surgery and some forms of cancer. NSAIDs are commonly used for mild to moderate pain. Steroids are sometimes used when pain is associated with intense inflammation.
Acupuncture May Be Beneficial
Chronic pain does not always respond well to conventional therapies. Acupuncture is thought to work by stimulating the release of endorphins and prostaglandin-suppressing cortisone. Our experience is that the insertion of needles does not appear to be resented by the great majority of dogs. The American Veterinary Medical Association and the World Health Organisation both recognise acupuncture as a treatment for joint-related pain. While studies in humans show that acupuncture is effective in relieving back pain, studies in dogs are complicated and difficult to perform. Our veterinary acupuncturist, Philippa Hanslip says that the more chronic the pain the more treatments may be necessary before pain relief is observed.