Ryegate Small Animal Hospital

54 Moore Lane
East Ryegate, VT 05042

(802)633-3660

ryegatevet.com

Last month, we explored the unique and sometimes confusing world of cat pain.


This month we are going to delve into how pain signals are created, and how they are transmitted to the brain. Many of the pain medications we use target specific areas on these pain pathways.





The pain response starts with a painful event, like touching something hot, being injured in an accident, or even pain from arthritic bones and joints.



When the painful event occurs, pain receptors release chemicals to signal that an injury has occurred. A local inflammatory response begins which is the body’s way of starting the healing process. Sometimes, the inflammation itself is also painful as blood and fluid flow into the injured area, to try and heal it.

PAIN RELIEF TARGET 1: Inflammation at the site of the injury. Anti-inflammatories such as Deracoxib, Carprofen (Rimadyl) and Meloxicam are all of a class called Non-Steroidal Anti Inflammatory Drugs or NSAIDS. They work by inhibiting or blocking the chemicals that signal inflammation at the site of the injury. When the signals are blocked, there is less pain.


In addition to chemicals
, an electrical signal is also produced as a result of the painful stimuli. This signal is immediately transmitted up a nerve called a pain fiber towards the brain. The purpose is to let the brain know that:

  1. An injury has occurred
  2. Where the injury is located
  3. How serious the injury is

The electrical signal travels up the pain sensing nerve to the spinal cord. The spinal cords job is to transmit this information as quickly as possible to the brain. Check out this pain transmission video with some excellent animation of pain signaling.



PAIN RELIEF TARGET 2:
  The spinal cord. Pain relieving drugs can be used to interfere with this electrical messaging system. By slowing the speed of the signal at the level of the spinal cord, drugs like gabapentin and amantadine can keep the message from getting to the brain. The painful stimuli can still be present, but if the brain isn’t aware of it, then pain perception is decreased.  These drugs are particularly good for chronic pain like arthritis.



Once in the brain, the pain signal is delivered to the brainstem where it is categorized and interpreted. Once the pain is perceived the brain can take steps to stop or avoid the pain. For example, if your cat jumps on a hot stove, his brain will tell him to move FAST to get away!



PAIN RELIEF TARGET 3: The Brain. Pain relief drugs can also target the end pathways in the brain through the use of opioid pain receptors. Opioid receptors are there to help our bodies deal with pain.

Drugs like Tramadol are used in the veterinary field whereas human doctors have many more opiates at their disposal. Here is a short video which shows how opioids work at the nerve endings in your brain:





As you can see, there are many points along the pain transmission pathway which can be targeted for pain relief.  In some cases, only one type of pain medication is needed. In others we bring in two or three different medications to relieve the pain. By targeting multiple points along the pain pathway, we get more pain relief than we would get with the any of the drugs used alone.

We also have other intriguing therapies we can offer such as acupuncture, chiropractic and herbal therapies. Nutritional supplements can also be helpful for treating chronic pain.

Next time, we will end our series on pain with a special feature on acupuncture and chiropractic care.