Todayโs path rounds are on ๐ฒ๐๐ฅ๐ฅ๐จ๐ฐ ๐ฌ๐ญ๐๐ซ ๐ญ๐ก๐ข๐ฌ๐ญ๐ฅ๐ toxicity!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
The ๐ฒ๐๐ฅ๐ฅ๐จ๐ฐ ๐ฌ๐ญ๐๐ซ ๐ญ๐ก๐ข๐ฌ๐ญ๐ฅ๐ is a common weed that likes to grow in dry summer pastures. In some cases, this plant may be the only green thing left for animals to eat in the pasture!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This toxicity affects horses who graze on the plant.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
The yellow star thistle contains a toxic called ๐ซ๐๐ฉ๐ข๐ง, which causes damage to neurons in the brain. Repin specifically targets two areas of the brain called the ๐ ๐ฅ๐จ๐๐ฎ๐ฌ ๐ฉ๐๐ฅ๐ฅ๐ข๐๐ฎ๐ฌ and the ๐ฌ๐ฎ๐๐ฌ๐ญ๐๐ง๐ญ๐ข๐ ๐ง๐ข๐ ๐ซ๐, causing death of the neurons in these areas. This presents as ๐ฆ๐๐ฅ๐๐๐ข๐ (softening) of the brain in these areas, and in some cases may even form cystic structures.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
The globus pallidus controls ๐ฉ๐ซ๐จ๐ฉ๐ซ๐ข๐จ๐๐๐ฉ๐ญ๐ข๐ฏ๐ movements, or movements the horse makes to establish itself in its environment. The substantia nigra controls the production of ๐๐จ๐ฉ๐๐ฆ๐ข๐ง๐, which is the main neurochemical that helps an animal control movement. Put together, damage to these areas often leads to persistent chewing movements and difficulty picking up feed due to incoordination of the mouth and tongue. Ultimately, these animals will die of starvation or dehydration, since they are unable to properly eat or drink.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Unfortunately, this disease is typically only diagnosed on necropsy of the animal. In the affected areas of the brain, the pathologist will see distinct areas of malacia or cysts, and be able to make the diagnosis when combined with the history of persistent chewing movements.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
There is no known treatment for this disease, other than euthanasia to prevent the animal from starving to death 
๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) Photos of yellow star thistle so you can keep an eye out for it in your pasture!
3-5) Examples of the ๐ง๐ข๐ ๐ซ๐จ๐ฉ๐๐ฅ๐ฅ๐๐๐ข๐๐ฅ ๐๐ง๐๐๐ฉ๐ก๐๐ฅ๐จ๐ฆ๐๐ฅ๐๐๐ข๐ that is characteristic of this toxicity.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 1. Sixth Edition.
Photos 1-5 ยฉ Noahโs Arkive contributor Saunders, Ward, Harrington, Jakowski licensed under CC BY-SA 4.0.
