Foundering with a horse can come about simply by eating green hay that is high in sugar and protein. Alfalfa can trigger it be it still green on the vine or even after mowed and stacked. Excess eating of a grain such as oats or barley can trigger it. Consider that all horses have different levels when it comes to foundering. Some have no problems, while others can get it very easily.
Understand that I am not an expert, but recently I had my horse founder because he got into a big bag of barley. I call him Colbie Diablo (the devil) simply because if there is something to get into he will do it. He is a Morgan and Morgans are highly susceptible to foundering. They can founder easily in the spring when the grass is heavily laden with sugar. Now that I look back I believe he was having some symptoms of it prior to eating the grain.
When I first saw symptoms he had made a bee line to come see me. Not fast, but very slow, whinnied slightly and had his head hanging down. He had gotten into some barely that I was completely unaware of and over ate. It gave him a bad case of diarrhea. I also noticed his stomach was swollen and felt like a rock. I immediately loaded him in the trailer and took him to the vet who proceeded to give him an enema and then put a gallon of mineral oil down him — into his stomach and gave him a penicillin shot.
Some horses can’t take a hose put down their nose like the vet did to get the mineral oil pumped into them. It usually requires a twitch be put on their nose to hold them down. I will have to say he did fine by allowing it to be done with out a twitch. He flinched a little, but took it like a horse (should).
The next day was when the foundering started to set in. His front hooves and lower legs heated up and were 94 (hoove) to 97 degrees (F) on his legs. (I used one of those digital thermometer readers that you point and shoot like at a car radiator or engine). The temperature was way to high for a horse to have. Now, sometimes on an extremely hot day, a horse’s hoof will reach those high temperatures for a short period of time (hour or two). But, he was drooping and I could tell he was hurting. So I got two heavy duty feeding pans and filled them with iced water. I made him stand in it for about 25 minutes. After I let him get out you would have thought he was completely back to normal. His head came up, he walked around like normal. However, I treated him twice more with the iced water that day and again twice the next.
I went and saw the vet an go a product called Prinovox. It is a type of pain reliever they give to dogs (and horses). So he got a half tablet of that each day with a small amount of nutritional pellets (corn, oats, vitamin mix). On the third day he was back to normal except for the diarrhea. He was still passing barley. So that goes to show you how long it takes for food to pass through the digestive system of a horse.
I dropped over to a neighbors house and got a few pitch forks of dry hay and put it in the stall area where he was hanging out. He ate about three quarters of it and used the remaining roughage as a bed. The next day I got him a half rolled bundle of baled hay. However, now that hs is running around he doesn’t eat much of it, but again likes it for a bed to sleep on.
Colbie Diablo is a very smart horse and after you give him instructions two or three times he has it. Although he hates putting his feet in water, I left the two units of cold water in the stall area and he did go up and put his feet in. (Both buckets were dirty). The ground area of the stall (actually a calving shed) is earth, not cement or wood. So I proceeded to make a big mud puddle for him. He likes that better than the buckets. Years back a vet had told me about doing that to a horse that had foundered on us and was lame. Just make a mud puddle and make them stand in it. Try to get it above the top of the hoof onto their legs (higher the better).
Some symptoms to watch for besides lameness. If they dip over their water bucket with front feet by pawing at it. (They are trying to cool their feet.) If there front feet are hurting from heat they may stretch their front legs outward like we would when stretching our arms. You will think they are yawing, If you are riding your horse and he is on hard ground and he stops and pounds his feet on the ground that is another symptom. Move him into softer ground. Now all of these symptoms could be just that the day is extremely hot and their hooves are hot. But, watch them after and buy one of those digital read outs so you can test his feet by simply pointing and shooting. if they are hot, get water on them. Even putting water on the horse’s body with a hose helps to cool them down.