Todayโs path rounds are on ๐ญ๐ฒ๐ข๐ง๐ ๐ฎ๐ฉ! This was a request 
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ฒ๐ข๐ง๐ ๐ฎ๐ฉ is more properly known as ๐๐ฑ๐๐ซ๐ญ๐ข๐จ๐ง๐๐ฅ ๐ซ๐ก๐๐๐๐จ๐ฆ๐ฒ๐จ๐ฅ๐ฒ๐ฌ๐ข๐ฌ. In this condition, exercise causes rapid degeneration of the muscle fibers, which can be extremely painful!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
We most commonly see this condition in horses!
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
The causes of tying up are ๐ฆ๐ฎ๐ฅ๐ญ๐ข๐๐๐๐ญ๐จ๐ซ๐ข๐๐ฅ, meaning there are many possible issues that may lead to this condition. Classically, we think of this disease as occurring on Monday mornings, after the horse had the weekend off. This is called ๐ฌ๐ฉ๐จ๐ซ๐๐๐ข๐ exertional rhabdomyolysis, and is caused by overworking the muscles. It is thought that inadequate vitamin E or selenium may contribute to this type of rhabdomyolysis.
Some horses have ๐๐ก๐ซ๐จ๐ง๐ข๐ exertional rhabdomyolysis, meaning they have multiple episodes that may occur even with minimal exercise. These horses typically have a genetic disorder that leads to abnormal function of the muscle fibers, causing the repeated tying up episodes.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
As mentioned, tying up leads to rapid degeneration of the muscle. These horses present with severe muscle cramping and stiffness, which can be extremely painful. When the muscle begins to degenerate, it releases ๐ฆ๐ฒ๐จ๐ ๐ฅ๐จ๐๐ข๐ง, a very large protein, into the bloodstream. This myoglobin gets trapped in the kidneys and can damage the tissue, leading to renal failure. In some cases, this myoglobin will leak into the urine, staining it dark red.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Diagnosis can usually be made based on the clinical signs, and can be confirmed by a blood test for ๐๐ซ๐๐๐ญ๐ข๐ง๐ข๐ง๐ ๐ค๐ข๐ง๐๐ฌ๐, another protein released by damaged muscle fibers. In chronic cases, genetic testing may be warranted to identify the underlying problem with the muscle, so the horse can be managed appropriately.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
Once the cramping is noticed, the horse should be immediately moved to a small area to restrict their movement. From there, fluid therapy is important to rehydrate the horse and flush the myoglobin out of the kidneys. In some cases, muscle relaxants may be given to help reduce the muscle cramping and pain. Most horses recover from tying up completely within 24 hours.
๐๐ก๐จ๐ญ๐จ๐ฌ
1-3) Pale, degenerated muscle from tying up.
4) What the muscle looks like under the microscope! Normally a muscle fibre has a very long profile with nice even streaks along its length. The one in the middle is fat and doesnโt have nice streaks!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 1. Sixth Edition.
Valberg SJ. Exertional myopathies in horses. Merck Veterinary Manual 2016.
Photos 1-4 ยฉ Noahโs Arkive contributors Crowell, Ramos, Harmon and Howerth licensed under CC BY-SA 4.0.
