Pain – an overview
What is pain?
Pain is an unpleasant sensory and emotional experience. Different animals (like different people) will have very different experiences of the same pain. Acute, sudden pain is necessary in terms of survival and signals a threat to the animal. However, pain that is ongoing does not usually have any beneficial effect and needs to be treated.
The longer our pets live and the more we can do for their medical care, the more important it becomes for us to recognise and treat any pain that they may experience.
Different types of pain
All tissue injury, including that from any surgery, may cause pain.
In general, there are three types of pain, based on where in the body the pain is felt:
- Somatic pain (from limbs and skin)
- Visceral pain (from internal organs)
- Neuropathic pain (from nerves and the spinal cord)
The three pain types can be felt at the same time depending on the type of injury, and the different types of pain respond differently to the various pain medications which are available.
Pain of all three types can be either ‘acute’ or ‘chronic’.
This is instantaneous pain that is usually the outcome of a physical trauma e.g. a fall, a broken bone, inflammation or an infection. This is emergency pain and it is trying to warn the sufferer that the body is being damaged in some way. Acute pain is short lasting and usually manifests in ways that can be easily described and observed. It can be extremely uncomfortable for your pet and it may limit his/her mobility. Acute pain normally goes away with time and treatment.
Chronic pain is defined as pain lasting more than three months. It is much more subjective and not as easily described as acute pain. Chronic pain, unlike acute pain, will not simply go away and continues even after healing has occurred. The role of chronic pain in the body is difficult to understand. Many conditions produce chronic pain – these include arthritis, rheumatic disorders and cancer.
Somatic pain is the result of an injury to part of the body such as a muscle or a bone. When one of these tissues is damaged, pain sensors send pain messages to the brain and the spinal cord (the nerves in the spine running to and from the brain). Somatic pain is caused by inflammation, repetitive trauma, excessive activity and vigorous stretching. The pain feels as if it is in one place, it is constant and often aches or throbs. Generally speaking, somatic pain is usually aggravated by activity and relieved by rest. Examples of somatic pain include: broken bones, burns, bumps, bruises and post-surgical pain from the surgical incision.
Visceral pain results when the internal organs are damaged or injured, and is by far the most common form of pain. It is caused by the activation of pain receptors in the chest, abdomen (tummy) or pelvic areas. Visceral pain is vague and not well localised and is usually dull or diffuse, and can described as pressure-like or deep squeezing in character. Visceral pain is caused by problems with internal organs, such as the stomach, kidney, gall bladder, urinary bladder, and intestines. These problems include distension, perforation, inflammation, and impaction or constipation. There may be other symptoms associated with the pain, such as nausea, fever, and malaise.
Neuropathic pain is the result of a problem with the nerves themselves and is often caused by an injury or an operation. Any event that can cause an injury to your pet’s body has the potential to damage the nerves at the same time. For example, if a muscle is crushed, then the nerves within the muscle may also be crushed. Nerves can also be damaged or squeezed by tumours and scar tissue, or irritated by an infection.
Neuropathic pain feels like burning, stabbing, ‘pins and needles’ sensation or an electric shock. Strong pain resulting from only a light touch is also common. Neuropathic pain may last for months or years – long after the injury appears to have healed.
Examples of neuropathic pain include: nerve damage, certain cancer pain, phantom limb pain (after amputation), a trapped nerve due to e.g. a slipped disc, and peripheral neuropathy (widespread nerve damage).
How do we know when an animal is in pain?
Pain management in animals is obviously challenging because our pets cannot tell us what they are feeling. Instead, we have to interpret changes in their behaviour and use our own experiences to decide that a pet is in pain. It is very likely that cats and dogs feel pain in a very similar way to us, and this allows us to anticipate to some extent what may prove to be painful for a dog or a cat.
As an owner, you may see changes in your pet’s sleeping patterns, the development of lameness and other behavioural changes, depending on what area is affected and also on the nature of the discomfort. It is important to consult with your veterinary surgeon, as sometimes it is difficult to distinguish the behavioural changes associated with pain from some medical conditions.
For more information on the recognition of pain, see our helpful information sheet ‘Is my pet in pain?’
Why do we have to treat pain?
Ongoing pain does not generally have any benefits to a patient, and in fact it has many disadvantages. For example, if we do not control such pain, a pet which has undergone surgery may take longer to recover from the operation and will have a greater risk of complications.
How do we treat pain?
The drugs that we use to treat pain depend on the type and severity of the pain your pet is experiencing. For example we will administer morphine type drugs when your pet undergoes surgery, but these may not be necessary for a disease such as arthritis. There is no doubt that, as a disease progresses, we may have to alter the medication your pet is on and possibly add more tablets.
There are other things that can be used to help decrease the level of pain your pet is experiencing, such as:
- Comfortable bedding
- Exercise regulation, as discussed with your veterinary surgeon
- Physiotherapy appropriate to your pet’s condition
- Complementary therapy such as acupuncture
One of the most important things is to realise that pain management, especially in chronic conditions, requires a team approach between the owners and the veterinary surgeon. The pain management plan may well need to be regularly reassessed as your pet’s condition changes.
In addition, it is very important to take advice from your vet and never to use any pain killers used for treating humans unless this is recommended by your veterinary surgeon – human painkillers can be fatal to dogs and cats! For more information on this, see our information sheet ‘Can I give human painkillers to my pet?’.
If you have any queries or concerns about your pet’s pain management, please contact us.