Chronic Pain: The Wind-up Phenomenom

Chronic pain is different to acute pain.

(Chronic pain is usually classed as pain lasting more than two weeks, such as osteoarthritis, lumbosacral disease, intervertebral disc disease etc.)

Acute pain usually reflects the degree of tissue damage or inflammation. Chronic pain however, is not proportional to the degree of damage and serves no protective purpose. 

Animals in some degree of constant pain can develop something called ‘the wind-up phenomenon’.

Wind-up happens when the nociceptors (pain nerves) receive repeated and prolonged pain signals. This alters the brain’s processing of pain signals and in some cases, can lead to pain that is non-responsive to standard pain medication protocols. 

Wind-up can result in hyperalgesia, where a small pain stimulus can result in a larger, disproportionate pain response.

After hyperalgesia occurs, nerve fibres that don’t normally transmit pain signals are recruited to do so. 

Wind-up causes the nerves to be super sensitive and can mean that a non-painful stimulus, such as stroking or picking up a paw, can be interpreted as pain by the animal’s brain. This is called allodynia. This is why animals in chronic pain can be very reactive to normal stroking and touching.

We must adopt a different rehab approach when treating chronic pain compared to acute pain. We need to break through the wind-up wall! 

Vets may prescribe medications on top of NSAIDs such as gabapentin or amantadine, which reduce the sensitivity of nerves. 

When it comes to laser therapy, often chronic pain patients will have a ‘loading dose’ of 6 sessions (using high doses) over 2-3 weeks to reduce wind-up and get on top of the inflammation. After this, the animals can then usually be managed routinely. 

Chronic pain can be difficult to manage but with a holistic, multi-modal approach, we can get there!