10. AZALEA, RHODODENDRON

(Rhododendron spp.)

(heath family)

TOXICITY RATING: Moderate. These plants grow wild in the East and cause significant problems there, the danger from these plants in Indiana is much less.

ANIMALS AFFECTED: All animals may be affected.

DANGEROUS PARTS OF PLANT: all parts, especially leaves.

CLASS OF SIGNS: Stomach irritation, abdominal pain, abnormal heart rate and rhythm, convulsions, coma, death.

PLANT DESCRIPTION: These perennial shrubs have tough, glossy, smooth-margined evergreen leaves. The large, showy flowers are in terminal clusters and have five white, pink, or red petals (fig. 10). Some horticultural varieties have yellow or orange petals. Common and local names for these plants include "lambkill" and "calfkill". These plants have been used by people to commit suicide.

SIGNS: These plants, as well as mountain laurel (Kalmia spp.) contain grayanotoxins (glycosides) which affect the gastroenteric (stomach and intestines) and cardiovascular systems. The older name for this toxin was andromedotoxin.

In order for toxic signs to manifest, 0.2% by weight of green leaves needs to be ingested. Gastroenteric signs develop first, generally within 6 hours of ingestion, including salivating, vomiting (in capable species), diarrhea, abdominal pain, and tremors. Disturbances in cardiac rate and rhythm may then be noted. If sufficient quantites were consumed, convulsions may occur, followed by coma and death. Not all affected animals will die, and livestock may recover without treatment, depending upon amount ingested.

FIRST AID: Prevent further ingestion and provide supportive care. Veterinary attention is needed if ingestion was recent, or if clinical signs are present.

SAFETY IN PREPARED FEEDS: These plants are not safe in hay nor in any other prepared feed.

PREVENTION: Animals should not be allowed to graze these plants. Keep hungry livestock away from areas where these plants grow. Pets may nibble or taste the leaves out of curiosity or boredom, and this is not advised, but seldom leads to clinical toxicosis. Honey made from the nectar of these flowers is also toxic and should not be consumed, so exercise caution when placing beehives.