The images below (Figure 1-2) are of a plant known as "Rattle box". This plant is commonly found throughout Florida and the southeastern USA however is usually only found to be blooming during the spring and fall months (Figure 3) . There are several varieties of this plant that are all in the Crotalaria spp family. The plant produces a toxin known as a pyrrolizidine alkaloid which causes pulmonary hypertension and liver fibrosis. Interestingly, horses develop a taste for these plants and will consume them during the months that they are present in the pasture; however, clinical signs typically don't develop for 2-4 months.
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| Figure 1 |
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| Figure 2 |
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| Figure 3 |
The effect that the toxin has on horse's liver is remarkable. In the image below, there is a normal sample of liver (top) next to a fibrotic sample of liver (below). The fibrosis is so severe that there is minimal blood filtration through the liver, rendering the liver useless. As such, toxins that are normally detoxified by the liver accumulate within the horse and result in depression, anorexia, neurologic disease and ultimately death! Once the horse develops clinical signs for liver fibrosis, the prognosis is very poor. It is strongly recommend that all pastures and fence lines be screened for the presence of this plant species, especially during the fall and spring ( that means now!!). The plant must be removed by physically pulling the plant out of the ground. Mowing will only spread the plant by disseminating the seeds that are present within the "rattle box" pods!! If your horse has been exposed to this plant, I would recommend a simple chemistry analysis of their blood to determine if they have early signs of liver disease.
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| Figure4 |
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