Bleeders. Nothing ruins a good run like seeing blood at your horse’s nostrils. This week we’re gonna chat about Exercise Induced Pulmonary Hemorrhage, or EIPH. That’s the fancy acronym doctors use to describe bleeders. EIPH is complicated! Hang on for a wild ride with some really good prevention stuff at the end.

Bleeding while running seems like a bad plan

It seems like a theme to life here at the Clinic. Horses have some serious design flaws, and bleeding from your lungs because you ran too fast certainly seems like one of them. As an apex predator, I do have to run down the occasional mouse out in the shed, but I’ve never encountered bleeding from my lungs. When I asked my Docs about this, I was blown away by the explanation (total airway pun there. I do crack myself up). 

Fast-running horses move air out of their lungs so quickly, they literally suck the air across the blood vessel wall. What the what?!? That’s just crazy. When horses are running fast (cats too, just in case you didn’t think we were athletes), the guts are a huge component of breathing and heart rate. As the inside front foot hits the ground, the guts push forward on the diaphragm, pushing the air out of the lungs, and causing the heart to contract. As the hind feet push off to propel the horse forward, the opposite happens. The guts move back in the abdomen and pull air into the lungs, and give the heart room to expand. This means horses aren’t moving air in and out with their muscles alone, that massive GI tract is throwing its weight around. This all works in a very delicate balance. Anything messes that balance up, and poof you’ve got blood cells on the wrong side of a blood vessel wall.

Small bleeds

A cat could lose himself in Google Scholar for days looking at EIPH research. You don’t think I spend all my time just sleeping on the keyboard, do you?? Anyway I spent a long weekend with no humans around diving deep into EIPH. The literature is kind of scattered on the early stages of EIPH. This is not because no one is looking! Completely shameless plug here for supporting basic level science research. This is how curious cats find the answers to life’s questions! 

Anyway, a pretty decent association has been made between inflammation and EIPH. Fungus in the airways plays a role, and Winter/Fall seems to, as well. Oddly, bacteria don’t seem to matter. The research also shows that lots of these horses start out with tiny bleeds, the lungs scar and develop more inflammation, and they bleed worse. It is well documented that age is a huge factor in EIPH with older racehorses being way more prone to having career-limiting episodes. 

What’s it all mean??

Great, you say, but what does this mean for horses? Never fear, I have wisdom to drop. Many of you have heard of giving furosemide (Lasix) to bleeders. It works, but it only works OK, not spectacularly. Furosemide makes the blood thicker so it’s harder for it to cross those blood vessel walls. It does this by dehydrating your horse a little bit. If you’re going to use it, make sure you talk to my Docs about managing this dehydration, and the potassium loss that goes with it. 

The way, way more important thing to do is prevention! Those fungi I talked about earlier? Those come from the air. Keeping horses in really well-ventilated spaces is a huge preventative measure for not just EIPH, but also all kinds of respiratory challenges. Think about hay bags on the trailer, stabling at equine events, arenas (especially those indoor ones). All of these are great ways to put your horse in an area with massive amounts of fungus traveling through the air. 

What’s a human to do? Wet your hay down, especially if you’re feeding it from anywhere higher than the ground. Keep your stall meticulously clean and dust free. This goes for anytime, really, but in particular those indoor stalls at horse shows can get NASTY. Think about the ammonia smell that knocks you down as you walk in the doors. All that ammonia is murder (literally murder) on lung cells! Finally, encourage show management to keep arenas appropriately watered down to keep dust in the air to a minimum.

Confounding factors

EIPH rarely shows up all by itself in older horses, and by older, I mean horses over 4 years. It’s really, really important to do what’s called a Bronchoalveolar Lavage (BAL) on these horses to make sure all the lung things are taken care of. In one study nearly half (!!!!!) of all the barrel horses tested had asthma and EIPH. You can give that horse all the Lasix you want; it’s not going to run any better because it still can’t breathe! Lameness is also strongly associated with EIPH. What I’m saying is don’t go all cowboy tough on this one. Talk to my Docs!!!! This is complicated and you need help to keep your horse performing at their best.

EIPH is way more than a little blood from the nose. Manage your horse well, and they’ll have years of performance ahead of them. You know where to go for help with that. My awesome Docs are just a phone call, email, or even a text away.  

Until next week,
~Tony

P.S. The humans have a great podcast on this topic called Airway Issues. You can find it over on the Podcast Page if you’re not already subscribed to the podcast. If you want to step up your game on this stuff, that’s a great resource. Trust me. I’m a cat.