Pill Poppin' Pets

Posted by Aaron

Tuesday, October 6, 2009

Now that we know more about how and why pain happens and is perceived, we can talk about how to treat pain.

Different types of pain come from different places. Remember the pain starts at the receptor somewhere out in the body and is then carried upwards towards the brain with a couple of junctions along the way. Depending on the patient, nature of the pain, and duration of the pain, we may change exactly how we treat different pets with similar problems.

Classes of drugs:
Local anesthetics
Lidocaine, bupivocaine, carbocaine are all examples. These drugs work by short circuiting the nerves carrying the signal. If they can't generate an electrical charge, the signal never makes it upstream. This can be done locally (like the spray you spritz into your throat when it's sore) or injected near a nerve (like when we do ring blocks for declaw procedures) or into the spinal column itself. Anywhere the drug goes, there will be no pain sensation generated. These drugs don't last long. For instance, lidocaine only lasts a couple of hours. Bupivocaine lasts about 12 hours when injected.

Non-Steroidal Anti-Inflammatory Drugs. These are drugs like ibuprofen (for PEOPLE ONLY), carprofen (Rimadyl), meloxicam (Mobic, Metacam), and ketoprofen (Ketofen, Orudis). This is a class of drugs that is very popular because they work well and are available over the counter on the human side. NSAIDs work by blocking the enzymes that generate pain causing chemicals and decreasing the amount of pain generated. NSAIDs work out at the SITE of where the pain is starting. NSAIDs are usually our first-line pain medications for osteoarthritis, post-operative pain control, and trauma pain management. They are often used in conjunction with a narcotic.

CAUTION: NSAIDs are a class of drugs that can be fantastic in dogs and cats, however, they must be used with caution and ONLY under the advice/supervision of your veterinarian. Cats in particular are sensitive to this class of drugs. DO NOT GIVE ANYTHING OVER THE COUNTER WITHOUT FIRST TALKING TO YOUR VETERINARIAN.

Also referred to as opiates because most all of these either came from or are related to opium and its derivatives. Opiates function in large part in the spinal cord. They decrease the amount of pain signal that is allowed to jump from the nerve carrying the signal from the periphery to the nerves in the spinal cord. They work in a couple of other places as well (brain).

Opiates are fantastic for all kinds of pain, from mild to severe. Opiates also have the unfortunate side effect of being prone to addiction because of the change in brain chemistry that happens with chronic use. Because they simply block the receptors in the central nervous system, the receptors can respond by making more of themselves. This means it takes more drug to work. We refer to this as tolerance of the drug. We have to increase doses to match. Bigger doses, longer term use and we're now talking addiction. Addiction does happen in our pets. It "looks different" because your dog won't loose his job, family, house, and friends over addiction, but the underlying physiologic response is the same - the body NEEDS the drug after it has had the drug for a period of time. Long term use of opiates must only be done under the direct management of your veterinarian.

Opiates are frequently combined with NSAIDs (think Percocet, Vicoden). This accomplishes two things - first, it provides two modes of pain control in one pill. They ALWAYS work better together than either one will work alone. It also makes them hard to abuse because the more NSAID you take, the more likely you are to have problems with the NSAID. It also makes it hard to cut the drug for street sale.

Opiates are all Scheduled drugs. This means the DEA tracks each and every tablet and drop of narcotic produced in the USA from the manufacturer to the patient. Your veterinarian has to keep lots of records on controlled/scheduled drugs. The more likely a drug is to cause addiction or abuse, the more tightly the DEA is in control of it.

Tramadol (Ultram) has become a darling of veterinary medicine. It is not a narcotic, but is narcotic-like. It also has some nifty effects in the brain where it increases seratonin levels. So even if you're in pain, you don't care (sort of). Because it's cheap, effective, and not controlled we veterinarians LOVE the stuff. Rumor has it that tramadol may become a controlled drug. We'll see. We'll still use the heck out of it, but it will make our lives a bit more difficult.

Amantadine and Gabapentin
Amantadine and gabapentin are medications that are used along WITH other pain medications. Both of these (although through different actions) help to change the way the brain and spinal cord react to CHRONIC stimulation of pain pathways. Chronic pain can cause these pathways to be "turned on" all of the time. Over time, these pathways can be permanently turned on or can be so freaked out that they don't know how to tell the difference between a little pain and a lot of pain. In some cases of chronic pain, amantadine can bring huge relief where our usual arsenal of drugs isn't cutting it anymore. These drugs take time to work and aren't used in the acute "I gotta have pain control NOW" setting.

Multi-modal pain control:
This concept means that we try to attack pain from different angles. When I am doing a painful procedure to a toe, for instance, I may do a local block at the level of the toe to try and block the signal from starting. I will also use a narcotic at the time of the procedure to help block any signal that makes it past my local block. I'll also give an NSAID so that when the local block wears off, the NSAID has had time to block the inflammatory chemicals from being made and the patient is, in theory, not painful. I've now blocked the pain signal at just about every available level. By using all three, I can use less of each and have a much better effect than I would by using only one drug alone.

There are literally entire books published on this subject, so I'm not trying to cover it all. Just trying to give you more information.

One last thing:
Some veterinarians still offer pain medications as "optional" after surgical procedures. Others make it a requirement. I require it and without fail I would have a few owners get upset that they were being sent home with pain medications when the pet didn't "look painful." 99% of the time, the complaint is that they have been asked to pay for the medication. Remember that pets don't show pain the way we do. They may be in significant pain, but not show it in an obvious way. Painful animals usually rest more than usual, have trouble getting comfortable, have increased breathing and heart rates, may refuse to eat, and may be more aggressive than usual. Cats are especially bad about hiding pain. They will seem to just be sleeping more than usual, when they are actually in quite a bit of pain.

Because it's nearly impossible to predict which pets will be more painful than others, we should ALWAYS TREAT THE PET AS IF THEY ARE PAINFUL. If pain medications are optional for you - TAKE THEM!!!!!!!! If they aren't optional - TAKE THAT AS A SUGGESTION AND USE THEM AS DIRECTED! Bone pain/amputation pain is usually the worst, followed by supporting muscle pain, neurologic pain, and organ pain. Trust me, after I have removed your dog's uterus, she's painful. After a de-claw (amputation), I can GUARANTEE your cat is painful.

Well controlled pain = faster healing time (well documented that this is true!), less stress, lower stress hormones, less susceptibility to secondary infection, and a happier pet!