As discussed in the last post, the new anti-inflammatories are a great tool to use in managing arthritis.
They are only part of the medication story, though.
Medication: Multi-modal Pain Control
Pain perception is a pathway. We have:
- The source of the pain. In the case of arthritis, this is the joint, which is composed of cartilage, the bone under and around the cartilage, the joint capsule (called the synovium) and the supportive tissues around the joint such as ligaments.
- The “phone cable” – the spinal cord is the means of transmitting the signal from the site of pain to the brain. It is not just a passive conduit, though. It has “relays” that have their own signalling chemicals and receptors.
- The brain – this is where the perception of pain takes place. Without the brain to read a signal and say “hey, that hurts!”, there is no pain.
So, what do these components of the pain pathway imply for pain control?
At the source:
- decreasing the inflammation in the joint will decrease the production of pain signals. Anti-inflammatories (NSAIDs) and suppplements (see next section!) help with this.
- Injections right into the joint of a long-acting, slow release cortisone-type drug can be good for relieving severe pain, but because of the cartilage degrading effects of steroid, you don’t want to do this lightly or often.
- In some severe cases, nerve blocks have been used to relieve joint pain (even permanent destruction of the pain-sensing nerve by injecting around it with an alcohol-type chemical).
In the Spinal cord:
- In dogs, we are starting to use a drug called Tramadol a lot. While it is not a narcotic, it binds to some of the same receptors as a narcotic (Mu receptors) – this damps down the transmission of pain signals up the spinal cord.
- A medication called Gabapentin also dials back pain transmission. It messes up the nerve cells’ ability to secrete the transmitters that amplify a pain signal.
- A medication called Amantadine blocks a receptor (called NMDA) on the nerve cells, that tells them to keep the volume turned up on a pain signal. So, while it does not block pain directly, it does work well along with the other medications to decrease the overall pain signal.
- The NSAID medications also do have some effect up at the level of the spine. Some of the chemical signals that NSAIDs decrease are ones involved in amplifying and transmitting a pain signal.
In The Brain:
This is the level where narcotics have their main effect. Narcotics are fine in an in-hospital situation, where patients are monitored for any depressed breathing, and where the sedating effects don’t matter. But in day-to-day life, the side effects of narcotics, plus their potential for dependence (ie it takes more and more drug to do what a small dose did before, plus the body starts not to feel right without them) make their regular use impractical. Narcotics are generally reserved for use in cases of severe pain, and only for a short while.
There is one narcotic you may encounter being used on an at-home basis though. Cats do not tolerate many of the other medications well, but they do well with the narcotic called Buprenorphine. It has less side effects than other narcotics, and lasts long enough (6-8 hours) to be worthwhile. This is only used for severe and short-duration pain though, not for management of ongoing conditions such as arthritis.
Next up: Supplements