On Saturday River and I started the Cuyama Oaks 50 mile endurance ride. Around mile 3.5, she gave three big uphill bucks and came down lame on the right hind. Long story short, by the time I was packing up to head home that afternoon, I was 95% certain she had tied up. (Read about equine exertional rhabdomyolysis.) That diagnosis was confirmed Monday with a trip to the vet and bloodwork. Her muscle enzymes are still high 48 hours later. In this post I will describe in detail River’s mysterious tying up. I’ll provide enough of her history to inform anyone who would like to offer advice or a guess at why it happened. I am stumped.
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River’s regular feed and care regime
Changes to River’s regular regime leading up to and during endurance rides
River’s fitness going into this ride
What happened the morning of River’s mysterious tying up
Back home
What’s next?
River’s regular feed and care regime
River eats daily:
One pound Purina Enrich and one pound Purina Equine Active Senior with 1 scoop KER Elevate vitamin E (1000IU; increasing now to 3 scoops or 3000IU) and 2T white salt (the cheap 25lb bag from Costco). Two or three carrots. One half small flake alfalfa (~3 lbs), small flake oat hay (~4 lbs) and all the Bermuda hay she wants. Pasture.
In summer, I give electrolytes every day, Farnam’s Apple Elite.
After a conditioning ride, my horses get a mash of beet pulp, alfalfa-timothy cubes, and oat cubes when I have them.
River will eat anything, unless she’s out on our 30+ acre pasture in spring. None of my horses will come in for feed when they can get 20 different fresh grasses.
Housing:
Most of the time, River is on about 2 acres of pasture 24/7 but because it’s spring and she gets chubby, she is currently locked up (in a big paddock, maybe 48′ x 72′, half of which is covered) at night.
Changes to River’s regular regime leading up to and during endurance rides
I start pre-loading electrolytes two days before the ride with a scoop of Endura-max two nights before, one scoop the morning before, and one scoop the evening before. I also give a beet pulp/alfalfa & timothy cube mash the morning before. On the morning of the ride I get up at 4:30AM and feed her normal feed (though she doesn’t like Enrich at rides) with another scoop of Endura-max.
At a ride, River gets free choice alfalfa hay (and free choice Bermuda, Orchard grass, and oat or whatever I have in the trailer). She can eat 15-20 pounds of alfalfa the first night because of the standard of alfalfa deprivation going on at home 😉
I offer beet pulp/alfalfa-timothy cube mash (with about half a cup of rice bran for River) at holds and after the ride. River will eat a little bit during the day, but always finishes it at night. (At home she sucks down mash, but then she doesn’t have free access to alfalfa there.)
River drinks very well at rides. She’ll typically drink 6-8 gallons the first night. She loves dipping her head in troughs and blowing bubbles and splashing (and drinking).
I haven’t been carrying elytes to give on the trail (but that’s going to change). Before setting out on the second loop I give her 60cc Cal MPK drench at the hold and about half a scoop of Endura-max. If there is a third loop or it’s hot, I do the drench and Endura-max again.
New for this ride:
She was not locked up Tuesday and Wednesday night because no one was home to do it. (We had a neighbor feeding in the morning.) I did not locked her up Thursday night because I prefer her to be eating lots of grass before a ride and we were going to Cuyama Oaks the next morning.
I do not see how an extra two nights on pasture could have led to River’s mysterious tying up though!
River was in heat (squatting) on Thursday. I don’t think it’s the first time she’s been in heat at a ride, but can’t be 100% sure.
Above: Ride camp at Cuyama Oaks. As you can see in the first picture, River is a very calm camper. She just stands and eats and produces more poop in one night than Fantazia used to do in three.
River’s fitness going into this ride
Backstory
Two weeks ago River did back-to-back 50s at Laurel Mountain with zero issues at all except trying to kick everything from horses to cacti to the gun range. The second weekend of February she did a 50 mile ride in the Eastern Mojave, and ended up a bit footsore. (We seem to have solved that issue in exchange for tying up…) In January she came back after a long lay-up with a 25-mile ride to the Trona Pinnacles at Fire Mountain.
I had given her nearly six-months off after I rider-optioned at Montana de Oro in June. She had injured herself at the Cache Creek Ridge ride and she told me LOUD AND CLEAR on the switchbacks at Montana de Oro that she was NOT OKAY. Pulled axillar muscle that has healed, but I still stretch her every day to keep it from getting sore to probing.
Between January and May of 2023, River completed 255 endurance miles. Last year at Cuyama Oaks, she completed back-to-back 50s, the first in the snow.
Older backstory
Possibly relevant to understanding River’s mysterious tying up… She is an ex-racehorse. She raced 17 times and won once (two places, four shows). River was no speed demon, but her race record tells me something went on. Possibly they never figured her out, possibly bleeding. Until a few months ago I just thought she was slow.
River was–is!–very fit
Last year I purposefully undertrained River, going very slowly. This was to keep her calm, but I believe it backfired. I needed a fitter horse at the cache Creek Ridge mud bath. This year I’ve let her go faster (at home), which has meant charging up hills, cantering more, trotting fast. She has loved it. She’s a lot more difficult to ride, but that’s because she feels really good.
River loves to canter. She’s not really a trotter (though she’s learning). But she truly enjoys sprinting whenever I let her. She especially loves it in good footing. You can watch her playing by sprinting up the long side of a friend’s arena in this video.
River has a low resting heart rate, and usually self-monitors when it gets “too high.” Too high = 130 when she’s trotting, though she’ll happily charge up a hill till it’s 175. When she decides she’s tired (at 130 trotting), she stops and walks until she’s below 70. I don’t have to tell her a thing. Today at the clinic she impressed the vet by being steady at 36 bpm all the while pushing and twitching and trying to escape. (She hates the inside of the clinic, probably the smell of the operating rooms.)
I’ve stopped using a heart rate monitor on rides because she doesn’t sweat enough. It loses contact. And she’s always down before I get back to camp after a loop.
River started (look at her eagerness at the start in this video) and finished the second 50 two weeks ago with energy to spare. She was eager at the start last Saturday too!
Above: Looking over Cuyama Valley on our pre-ride the day before River’s mysterious tying up.
What happened the morning of River’s mysterious tying up
Pre-ride
Everything went as usual before the start at 7:30. I handwalked her around 6:30 for about 15 minutes, and again briefly at 7. I saddled at 7:15, and handwalked a bit more because she could see excited horses on the road. At 7:33, after the bulk of the riders had left, I started walking her down the road.
Four-tenths of a mile of leading River
As usual, I started on the ground. (I have found that riding River when she’s throwing her head around and wanting to buck is counter-productive. It becomes a test of wills and we end up going backwards.) On Saturday there was a lot of green grass, so I let her stop and eat grass multiple times.
After 7 minutes I got on. (I’m using the output from my Garmin watch to know times and distances here!) At this point I’d been hand-walking for 20 minutes, counting ambling around ride camp. River was not particularly worked up. Of course, once I was in the saddle she started slinging her head around and half-bucking. We were ner a mule that was acting very similarly. I could tell River liked the mule. Kindred spirits!
We started trotting half a mile in… and things went sideways too soon
At this point, River was worked up but not specially so. She calmed down a bit once I allowed her to trot, and she accepted a pace of 7-7.5mph without much complaint. (Going slower caused more rambunctiousness that energy saved.) We were in a nice bubble and there was enough room to pass people and be passed without issue. She didn’t try to kick anyone. (Two weeks earlier she was a kicking monster.)
Around 2.75 miles, we passed the mule, and within a minute River slowed down markedly. I did think it felt odd, but assumed she was waiting for the mule. In retrospect, I believe she started to tie up then.
At 3 miles she wanted to jump a small stream in a gulch, but I controlled her and kept it to a tiny levade with propulsion at the end. That wound her up, and she tried to charge up the other side. I restrained her, but she got off three big bucks. When we got to the top, she was lame on the right hind.
Once there was space beside the trail, I hopped off, and looked at all four feet. When I lifted her right hind, she was not a happy camper. I couldn’t lift her leg more than a bit. She was not sweating, but her heart rate was slightly over 60 (high for her after a few minutes with me on the ground).
Several riders passed by, and most concurred that she was off in the right hind. It wasn’t hard to see after a few minutes. She held it cocked and in pain. I figured she had a muscle spasm and started to make my way back to camp.
Backtracking towards ride camp
I started moseying back, in no hurry to have nothing to do but go home. I got on to be safer when riders pass (River kicks so I have to be way off trail). Many people suggested she could walk it off but I thought no. Yes, I agreed it was probably a muscle cramp, but River had never had one.
After everyone I assumed was behind us had passed, I got off to lead. At this point we’d only gone about 300 feet back. River was still favoring the right hind. She lagged behind me for about half a mile, but then was at my side. Soon she was pulling and making it hard for me to relax. (watch this video of me leading her) I figure she knew we were heading back, and mounted. She started jigging and was NOT lame.
I turned around to see if she was lame the other way (this is a horse that when she hurts she won’t go anywhere, but I wanted to test). Nope not lame. I passed more riders who thought she looked great, but I still didn’t really believe in lameness being “walked off.” I kept going, but I did get adventurous about our way back. At the very least I’d have a good ride.
River started being a handful. She was trotting fine. At less than a half mile from camp, I decided maybe I could do the LD loop instead of the 50. I called Annie to see if that was ok (she said yes). I wasn’t sure I’d do the second loop (for one thing, I’d probably be overtime, as I wasn’t going to hurry), but just in case I wanted to make sure it’d be all right.
At this point I’d gone about 5 miles. Average moving speed was 4.4 mph.
Completing Loop 1 of the LD
I started my watch again, so I know we did 15.25 more miles. I hadn’t downloaded the LD tracks to my watch, but the trail was well-marked. (And was the same as for the 50s, minus an extra keyhole loop.) My goal was to average 5.0 mph, as long as River remained sound.
At first everything went well. River was not lame, and she was relaxed and happy. We met a lot of people already heading back, first 25s, and then 50s. River did fine until the 50s started catching us up, because they came behind us. Then she started wanting to go a lot faster.
River shows clear signs of having tied up
A few miles from ride camp (as the crow flies or the horse goes by the fastest route) she turned into a raving lunatic, sweating and dancing. This is not normal. Yes, River gets ornery and slings her head and bucks all the time. But she never gets nervous and has never built up an anxious sweat. All this she did as soon as we were close to camp, even though we then looped around. I I had to turn around and stand several times. In the end, I got off and led her. (I was aiming for 5mph max because I wasn’t convinced she was fine.)
At this point I was thinking she had tied up slightly or would by the time we are back. I’ve ridden lunatic mares who have tied up. Sweating and extreme anxiety are typical. And River was sweating like she NEVER sweats. Not lame and trotting freely but that’s adrenaline.
Above: River is anxious and pulling (though you cannot really tell from the video) as we are near Ride Camp and she knows the way back. I believe her anxiety was also due to pain. She was sweating unusually for her.
Coming into the hold
I had led her at least a mile, so despite her unusually worked up state, River’s pulse was down when we walked in. I then let her drink while waiting for a delicious egg salad sandwich made by Annie. River had drunk very little during the ride. That wasn’t particularly surprising, because it was cool and she had not worked that hard. (The craziness when we got close to ride camp excepted.)
River had been jigging as we approached camp, so I knew she was not noticeably lame. Given her state though, I was pretty sure that she would cool down into lameness, or at least extreme stiffness.
Back at the trailer
Although she drank well, River was even less interested in her mash than usual, only picked at her hay, and refused carrots. I knew something was Not Right. She also had tell-tail patches of sweat on her rump. She did pee copiously and medium yellow (normal), which was a relief.
Above: The sweat patches on her rump convinced me that River had definitely tied up. At this point I knew we wouldn’t be riding a second loop.
After giving River 15 minutes to eat and rest, I took her to the vet. At this point she was stiff on both sides but worse on the right, though still not regularly lame as she had been earlier, when I first pulled up. As soon as we’d vetted out, I took River back to the trailer and gave her 1g of bute. She’d have an hour to rest while I packed. Before leaving, I asked Rebecca to draw me a vial of blood.
I thought about staying the night!
I could have helped Kent and Juan cook steaks and drink some more tequila 😉 But I knew River would be more comfortable at home where she could move around. And honestly, I had a lot of work to do. When I go to a ride, I end up working late into the night when I get home. A silver lining was that I’d get far more sleep.
Above: Pictures from Friday evening. I helped the cooking (Kent and Juan) and serving (the girls from Love this Horse Rescue) crew with the tacos. In the last photo you can see Dave getting ready to talk about the trail for Sunday. Notice the sign in back of him!
Back home
It’s a three hour drive home, and River was still a bit stiff coming off the trailer but not too bad. You can see her trot up the hill in her pasture in this video. I let her graze for an hour and then confined her to the smaller paddock as usual for the night.
Above: River hanging out at the trailer at Pacific Crest Equine while I waited for bloodwork. She never passes up an opportunity to eat alfalfa.
At the veterinary clinic
Monday morning I called the vet as soon as they opened, and took River into the clinic at 9. Pacific Crest Equine has been my vet since I moved back to California, and my mother’s vet since they opened shop. However, they had a new lameness vet whom I had not met. (Having not had a lame horse since last June, yay!)
Our new vet
Dr. Jill Marquez practiced on racetracks in Australia and Singapore before somehow making her way to Exeter, CA. She is great. Really knows her stuff but was quick to admit she knew nothing about endurance. She had dozens of questions for me about training, criteria for vet checks, comparisons with FEI, and so forth. We’d probably still be chatting if she hadn’t had more clients.
Confirmation of River’s mysterious tying up
Dr. Marquez started by taking River’s vitals and listening carefully to my explanation of why we were there. Despite being very worked up and dancing around, River’s heart rate was 36bpm. Several vials of blood were drawn for CBC and selenium assays. (I also took advantage of being there to get River’s rabies vaccine. It’s the only one I cannot get myself.) We then went out into the rainy morning to watch River move. Dr. Marquez commented that she had a nice walk and trot, but that yes, it looked like she’d tied up.
I waited long enough for the first muscle enzyme results to come out. Unfortunately the blood I’d brought from the ride was no good, but there was still no doubt. River’s CK (creatine kinase) was at 2,773 U/L. That’s more than seven times higher than normal. Dr. Marquez counseled pre-loading electrolytes for longer if not giving them every day, increasing omega 3s and fat, and doing more bloodwork in one week. She offered to give River liquids, but I thought it was a bit late to be very effective. We agreed I needed to travel with supplies in the trailer in case River tied up again. (Liquids are most effective if given as soon as possible.)
Why did River tie up?
We don’t know. Dr. Marquez believes it could be not enough electrolyte pre-loading, possibly in conjunction with warmer weather. I will address the pre-loading, but I don’t think it was that warm. (Although it’s true that last time we were at Cuyama it was snowing, so…)
We also discussed more lengthy warm-ups before rides. I tend to believe this is the best explanation, because River is not excitable. Fantazia starts warming up around midnight at rides, by dancing around all night. River stands still all night, only shifting to reach more food or poop in a different place. True, I did a lot of hand-walking, if you count minutes. But if you count distance or energy, I did very little. River moseys. She didn’t put much energy into moving until we were on Foothill road (about a quarter of a mile into the ride).
What about River being in heat?
Dr. Marquez does not believe it is related to hormones. I’m not completely convinced though, and am considering trying to control River’s cycles. We did discuss alternatives to Regu-mate, which I cannot give because I am gone half the week. After having received feedback on Facebook and read this page, I am going to talk to Dr. Marquez again, or perhaps to my breeding vet, Dr. Taryn Holliday. I like the idea of an injection that lasts a while. Maybe it will stop her from kicking so much too.
What’s next?
I didn’t wait for the rest of the bloodwork, but the clinic emailed the labs (above). Her AST levels (another muscle enzyme, aspartate aminotransferase, released during muscle damage) were also high (1207 U/L), as were her Chloride levels (114 mmole/L). everything else was normal. (It takes four days for selenium and vitamin E assay results to come back.)
Additions to River’s diet
I am adding KER’s EO-3 as a source of omega 3 acids. River is also getting a full scoop of Endura-max every day this week to encourage drinking. I will give half a scoop daily after that. Everything else is staying the same.
Conditioning and future rides
If River’s bloodwork is back to normal on Monday, we’ll plan on heading to Huasna for the Treasure of the Sierra Madre ride on the 18th. I’ll ride her the 10th-14th, and check bloodwork again the 15th.
If we successfully complete 50s at Treasure of the Sierra Madre, I will do more bloodwork the following Monday. That will tells us what we need to know about the effects of River’s mysterious tying up and whether I need to worry about it in the future.
Above: Trotting in the first few miles, before River tied up.