This is a continuation of First Event of the Season Preparation: Part I.
As you recall, Herin has just tied up during our cross country lesson, and the vet has arrived to examine him. What is tying up? Tying up is considered a mild version of azoturia. This occurs in horses that are “…normally exercised heavily and well fed, then rested for a few days while still being fed a high energy ration. Soon after renewal of exercise after the rest period, the horse beings to exhibit muscle tremors and hesitates to move. If the horse is forced to continue working, the symptoms worsen and the animal may go down. The horse will sweat heavily, and may pass dark, coffee-colored urine. The color results from myoglobin released by the breakdown of muscle tissue. The femoral, gluteal, and iliopsoas muscles become hard, swollen, and painful.” (Adams and Chalkley 218)
As textbook as that explanation is, it is exactly what Herin experienced. Herin is quickly started on two bags of fluids to flush the myoglobin out of his system. If this is not done, the myoglobin will continue to break down in the body and could cause damage to his kidneys. The equivalent to this in humans is called rhabdomyolysis. It is rare, but has the same cause, symptoms, and treatment as we see for horses. The vet returns two days later to test Herin’s blood. Luckily, his kidney levels are normal and were not affected, which is the main concern when a horse ties up. However, his muscle enzymes are still too high for the machine to even read. This means that his muscle enzymes are at a level of ~50,000 when they should be in the realm of 200-400. The vet explained to me, over the phone, that the enzymes usually go down about 50 every 24 hours, so this is not something to be worried about; Herin needs time and rest.
Cause and Prevention
According to the textbook definition, the cause for Herin’s episode is most likely his long period of mild work, due to his puncture wound and my travel, followed by heavy work. Though it is not out of the ordinary for me to bring him back into work when he is sound, it is just something that can happen. In order to prevent this from happening again, he will need to be brought back into work slower after lameness or travel. Additionally, he requires a change in his diet. Horses that are prone to tying up may benefit from a high fat diet versus a high carbohydrate diet. There are also supplements, such as Tie Free, that contain a dose of magnesium, vitamin E, selenium, and calcium, which can prevent horses from tying up. Alternatively, the vet could inject some of these vitamins intramuscularly to help prevent tying up or azoturia.
The life of a horse person is filled with ups and downs. This week has certainly been an emotional roller coaster. As we all know, that comes with the love of our sport and our equine partners. The bright side is simple; Herin will be okay in time, there are other shows, and I can work on preventing this from happening again. I am thankful it happened in the presence of my trainer and at home instead of at the show this weekend, which would have made dealing with this for the first time even more stressful than it was.
Onward and upward!
From one horse crazed human to another – Maria Holman
References Adams and Chalkley. Veterinary Treatments and Medications for Horsemen. Equine Research Inc., Tyler, Texas, 2003