Toxic Rhododendron. What is puzzling though is why a plant would secrete insect defence toxins into nectar as this is the food reward for pollinators which in the case of rhododendron are insects and more specifically bees. Cases of rhododendron poisoning among humans who have eaten toxic honey date as far back as 400 b c.
Dx by history and finding the leaves in the vomitus feces or rumen. What is puzzling though is why a plant would secrete insect defence toxins into nectar as this is the food reward for pollinators which in the case of rhododendron are insects and more specifically bees. Rhododendron is typically not very palatable to horses unless it is the only forage available but sheep and goats may graze readily on the plant.
Toxins in this plant were discussed by casteel and wagstaff.
Rhododendron can be toxic to ruminants. Outbreaks of toxicosis have been reported when sheep were hungry and had access to the plant. Dx by history and finding the leaves in the vomitus feces or rumen. Many plants synthesise defence chemicals so it shouldn t be a surprise that rhododendrons do as well.