Pain – an overview

Pain is an unpleasant sensory and emotional experience. In animals the sensory component of pain is easier for us to evaluate but the emotional component (suffering) is more difficult. Different animals will have different experiences of the same pain (as do humans) and this is down to how it is processed and perceived.

Acute (sudden / short-term) pain is adaptive (biologically useful) and signals actual or potential tissue damage e.g touching something hot, and allows an individual to take measures to protect itself from further pain. It is important for our survival and signals a threat. It still needs need to be treated for the individuals comfort and to prevent it progressing to chronic pain. Acute pain normally goes away with time and treatment.

Chronic pain is on-going (> 3months) and is much more subjective. It has no beneficial effect (maladaptive) and needs to be treated. It has the same deleterious effect on the body as chronic stress. Pain left untreated can result in abnormal processing within the spinal cord and brain, making the pain feel worse (central sensitisation). Chronic pain must be recognised as a disease in its own right, regardless of the initiating cause (which may no longer be present). This constant state of pain can be difficult to treat and requires a systematic approach to try and bring it under control. It will not simply go away and can continue even after healing has occurred. One of the commonest causes of chronic pain in dogs is osteoarthritis.

Chronic pain has no benefit and is difficult and complex to treat – the best way to avoid it is not to ignore any signs that your animal might be in pain and intervene at the earliest opportunity.

Different types of Pain

Pain can be classified according to its source and all can be felt at the same time depending on the nature of the injury / disease and these types of pain can be both acute and chronic

Chronic Pain can be further classified by type (i.e. the type of processes that are causing that pain)

Intense pain in internal organs may set up myofascial pain in the local muscles (somatovisceral pain). This is due to the nerves from that organ converging on the same nerves in the spinal cord as the local muscle where the pain is felt (so called referred pain). We can use this phenomenon in reverse by applying acupuncture to muscles along the spinal cord that are innervated by the same spinal segment as the internal structure we are trying to treat ( see acupuncture – segmental)

What is meant by central sensitisation?

The term is used interchangeably with pain “wind-up” but wind up is a normal physiological mechanism that occurs after injury and protects the injured area from further damage and promotes healing.

After an injury occurs there is a change in nerve excitability in the spinal cord. This in turn leads to an increase in receptive fields of nerves involved and recruiting other nerves that do not usually transmit pain signals. This means that receptors that usually respond to non- harmful stimuli, such as touch, now respond to touch as if it were pain. This manifests as:

This wind up process will wind down over time as the injury heals.

Central sensitisation is a pathological process and does not occur in all individuals. It can be thought of as wind up that has not wound down although it is more complicated than this as more processes are brought into play. It is the process whereby pain, from even a relatively minor lesion can spread and increase in severity to the point that there is no correlation at all with the severity of the disease process and the severity of the pain and suffering that is being experienced by an individual. There may not even be a lesion or disease process anymore (a difficult concept to get your head around!)

Central sensitization represent significant suffering and is the mechanism by which the pain itself can become the disease.

How do we treat pain?

The drugs that are used will depend on the type and severity of the pain. Pain relieving drugs are the main-stay of any pain management program but using other therapies and taking measures at home to make your pet more comfortable, alongside these, may reduce an animals requirement for medication and / or give a better level of pain control.

Please do not give your pet any pain medication that is used in humans unless it has been specifically recommended by your vet. Some can be fatal to dogs and cats and others need to be used with caution.

NEVER GIVE YOUR CAT PARACETAMOL

And finally………….

It is a team effort – owner and vet!

It is important to understand that pain management for many conditions is an on-going process and your pets pain is likely to change over time as will their pain management requirements. Most conditions that we are treating are likely to be progressive so we need to take steps to slow down this progression and make modifications to their lifestyle and their pain plan to ensure that they remain as pain free as possible and enjoy more quality time with us.