This past Saturday night was the 35th Anniversary Gala for the Philadelphia Women’s Rugby Club
, a team I was proudly a member of from 2002-2006 while living in Philly during vet school. Rugby is a rough sport (yes girls can play too, and yes we play by the same rules as the boys, no helmets, no pads, just knee socks and a mouth guard) and during my time with the Philly Women, in addition to making it to Nationals twice and being named to a few all-star teams, I also dislocated my right shoulder, broke my nose (for the 3rd and 4th time) and had more than one black eye that made my boyfriend afraid to be seen in public with me. Ruggers know about pain, and pain management. And the one thing I was thinking about on Sunday morning, after a long night of reminiscing with old friends, dancing in 4” BCBG metallic blue stilettoes (a far cry from my old brown clogs) and one too many Yeungling lagers (you can’t get it in Indiana) was pain management.
When you look at the Pain Relief aisle of your local Walgreens or CVS, for pills containing the anti-inflammatory drug ibuprofen there are a million and one choices: joint & muscle pain, back pain, childrens’ pain, arthritis pain, menstrual pain, migraine pain and oral pain. And I’ve always wondered; How do the drugs in this ibuprofen pill treat just my back pain? What makes that ibuprofen pill just go to my headache? But when you read the fine print on the label, many of these pill contain the same concentration of the same drug, no magic road map to your pain, its just that they are marketed for certain ailments (and usually the arthritis pills have an easy to open cap and the childrens’ pills have a child-saftey cap). And while we tend to use them interchangeably, most of us understand that ibuprofen is not the same as aspirin, which is not the same as naproxen (Aleve®), making the choice even more confusing. Luckily in the horse world we don’t have so many choice. Pretty much just two dominate the field: phenylbutazone (Bute) and flunixin meglumine (Banamine®).
Their innovative marketing techniques aside, the most misleading part of the previous paragraph is how the section in the pharmacy is labeled: Pain Relief. I think that it is very important to understand how these drugs work and why we prescribe them. Yes, they do relieve pain, but that is a secondary benefit of their main focus: control of inflammation. This is why we call them Non-Steroidal Anti-Inflammatory drugs, or NSAIDs, which include phenylbuazone, flunixin meglumine, firocoxib (Equioxx®), ketoprofen and carprofen (Rimadyl® for our dogs). They are “non-steroidal” because this group does not contain corticosteroids (dexamethasone) which also stop inflammation but also affect the immune system. They are anti-inflammatory because they stop the affects of inflammation by blocking the production of prostaglandins, one of the final products of the inflammatory pathway. Prostaglandins are produced by many tissues in the body as part of normal functions like blood flow to the stomach and colon lining and the kidneys (remember this point, it’ll come up again later).
So are Bute and Banamine® the same? Not exactly… Banamine® has been shown to be more effective in relieving gastrointestinal, soft tissue and systemic inflammation and pain. Think colic, eye pain, sepsis. Bute on the other hand is more commonly used for musculoskeletal inflammation and pain (muscle pain, arthritis, tendon/ligament injury).
So now that you have an idea of which drug to give when, the next questions are: How do I give it? How much? and How often?
Both Bute and Banamine® are prescription medications and should be obtained from your veterinarian to treat a specific problem on a specific horse. That being said, we all know it lives in every medicine chest of every farm out there. Bute comes in an injectable solution that should only be given intravenously (IV) by an experienced person, namely your veterinarian. It is very irritating and if it gets outside of the vein or in the muscle it can cause severe inflammation, necrosis and sloughing of the tissue.
The safer formulations for laypeople to use are the oral forms, powder or paste. Make sure you read the label to know how many grams are in one scoop of powder or one turn of the dial on the paste tubes (its usually 1g). Banamine® also comes in injectable and oral formulations. The injectable form can be given IV (again make sure you have an experienced hand giving the injection) or intramuscularly (IM). I tend to discourage people from giving Banamine® IM because it has been closely associated with Clostridial myositis, a severe and often life threatening bacterial infection in the muscle. You can also give the injectable formulation orally! Yes, draw the same amount from the bottle that you would have giving IV or IM and squirt it in their mouth! It has similar oral bioavailability, which means its absorbed just as well. NB Injectable Banamine® is VERY bitter (trust me, I’ve accidentally gotten some sprayed in my face) and your horses will appreciate it if you mix it with applesauce or molasses before giving it orally. Banamine® also comes in a paste and granules to be given orally.
The label dose of Banamine® is 1.1mg/kg BID which is a fancy way of saying that a 1000lbs horse should get ~500mg (10cc or a 1000bls dose of paste) no more than once, every 12 hours. Bute’s label dose is 4.4-8.8mg/kg BID. Translation: a 1000lbs horse should get between 2 and 4 grams no more than once every 12 hours. It is very important to note that these volumes are based on body weight and are for a ONE THOUSAND POUND horse!!! If your horse weighs more or less than 1,000lbs, then these doses are not right for you! Example, a 500lbs pony is half the weight of a 1,000lbs horse (get out your calculator and check if you don’t believe me, but my mother will tell you I did very well in math as a child), therefore a 500lbs pony should receive HALF the dose of a full sized horse. I know, I know “But human medicine gives every adult the same amount of pills whether you’re a 90lbs gymnast or a 300lbs sumo-wrestler.” This doesn’t make sense to me, and I hope someday an MD will give me a good explanation as to why. And notice how I say “no more than once every 12 hours?” I didn’t say “twice in a day” because to some people that means, once, and then if it doesn’t work, another dose 20min later. And giving your 1000lbs horse 10cc of Banamine® and then another 10cc an hour later is the same as giving them 20cc at once, and you have overdosed your horse.
So why is it that I’m so crazed with appropriate dosing? Because, being an internist, I get to deal with the sickest, most critical cases and I hate seeing ones that could have been prevented. While Bute and Banamine® are wonderful drugs that help us keep our horses comfortable and inflammation free, they are not without side effects. Remember how I said that there were “normal” functions of prostaglandins and how that fact would be important later? Well the time is now. Prostaglandins regulate blood flow to the kidneys and to the lining of the stomach and colon (specifically the Right Dorsal Colon). When NSAIDs are given, they block all prostaglandins, both normal and inflammatory, so you get decreased heat, swelling and pain but you also get decreased blood flow to your kidneys and gut lining. Now in a well-hydrated horse that is getting an appropriate dose for a short period of time, this usually won’t be a problem. If your horse is dehydrated, getting excessive doses or even normal doses but for long periods of time, you will see the harmful side effects. Gastric ulcers, colonic ulcers and renal failure. These can lead to colic, diarrhea, excessive drinking/urination and many other signs associated with NSAID-toxicity. This is a treatable condition but it can become so severe that no amount of treatment can repair the damage.
It’s not that we should never use these medications; we just need to know the appropriate doses and dosing intervals to make their use as safe and effective as possible.
Believe me, Sunday will not be the last time I reach for the ibuprofen (only at the labeled dose and I’ll keep hydrated with plenty of water) but I do so cautiously (and swear to myself I will never run down Walnut St in 4” heels in freezing temperatures again!). And the safest, most cautious way to administer NSAIDs to your horses is to do so under the direction of your veterinarian. Only he or she knows the right type and the right dose of NSAID for your horse based on the specific problem at the time.