Todayโs path rounds are on ๐๐ฅ๐ฌ๐ข๐ค๐ ๐๐ฅ๐จ๐ฏ๐๐ซ ๐ญ๐จ๐ฑ๐ข๐๐ข๐ญ๐ฒ! In honour of St. Patrickโs Day, even though itโs a little late 
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ฅ๐ฌ๐ข๐ค๐ ๐๐ฅ๐จ๐ฏ๐๐ซ is a common type of clover found throughout North America, that is associated with liver disease in horses. Alsike cloverโs scientific name is ๐๐ซ๐ข๐๐จ๐ฅ๐ข๐ฎ๐ฆ ๐ก๐ฒ๐๐ซ๐ข๐๐ฎ๐ฆ.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
As mentioned, this toxicity typically affects horses. In some cases, an affected pasture or hay source can lead to โoutbreaksโ of this toxicity, with numerous animals having signs of the disease.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
The toxin within alsike clover has not been identified, however we do know that it affects the liver. In particular, alsike clover toxicity causes proliferation of the ๐๐ข๐ฅ๐ ๐๐ฎ๐๐ญ๐ฌ, which remove waste products from the liver and empty them into the gastrointestinal tract. This proliferation suggests that the toxin within alsike clover might be damaging to the bile ducts, causing them to try and compensate for the damage by proliferating. This damage frequently causes ๐๐ข๐๐ซ๐จ๐ฌ๐ข๐ฌ (scarring) of the liver tissue as well.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
With the proliferating bile ducts and associated fibrosis, the liver is not able to properly excrete several waste products, including ๐๐ฆ๐ฆ๐จ๐ง๐ข๐. Ammonia begins to accumulate within the animal, where it affects the nervous system, causing ๐ง๐๐ฎ๐ซ๐จ๐ฅ๐จ๐ ๐ข๐ ๐ฌ๐ข๐ ๐ง๐ฌ like significant depression, wandering, โhead pressingโ against objects and difficulty walking.
The liver is also unable to excrete ๐ฉ๐ก๐ฒ๐ฅ๐ฅ๐จ๐๐ซ๐ฒ๐ญ๐ก๐ซ๐ข๐ง, which is derived from break down of chlorophyll in the intestines. This compound accumulates in the skin and absorbs UV radiation from the sun. It then releases this energy into the surrounding tissue, causing significant damage to the skin. This process is called ๐ฉ๐ก๐จ๐ญ๐จ๐ฌ๐๐ง๐ฌ๐ข๐ญ๐ข๐ณ๐๐ญ๐ข๐จ๐ง, and is often seen in animals with alsike clover toxicity.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Typically, alsike clover toxicity is diagnosed based on a history of exposure to the plant, combined with signs of photosensitization or liver disease. If needed, a ๐ฅ๐ข๐ฏ๐๐ซ ๐๐ข๐จ๐ฉ๐ฌ๐ฒ (sample of tissue) can be taken to identify the proliferating bile ducts and fibrosis, to help support the diagnosis.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
The best treatment is simply to remove the source of alsike clover, whether that be moving to a new pasture or changing hay sources. Animals with photosensitization lesions should also be kept indoors until their lesions have healed, to prevent further skin damage. Thankfully, these animals recover quite quickly!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) The plant in question, alsike clover!
2-3) Horses with signs of photosensitization, causing skin damage on their noses.
4-6) Livers with biliary hyperplasia and fibrosis. On the close up section, you can see nice distinct lines of scar tissue.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 2. Sixth Edition.
Foreman, JH. Hepatotoxins in large animals. Merck Veterinary Manual 2016.
Photo 1 ยฉ Wikimedia Commons contributor Aiwok licensed under CC 3.0 Unported.
Photos 2-6 ยฉ Noahโs Arkive contributors King, Doster, Metro, Howard licensed under CC BY-SA 4.0.
