This mushroom is found exclusively in eucalyptus woods in North America, Australia, Brazil, and Uruguay. It is reported to be poisonous to ruminants (cattle and sheep). The toxin is an unknown, volatile compound or compounds found throughout the plant that is reported to interfere with sulfur-containing amino acid incorporation. Drying decreases toxicity.
Signs may appear as early as 3 days but up to 6 days following exposure and include anorexia, diarrhea, salivation, hyperthermia, depression, hyperemic coronary band, hemorrhage (anterior chamber of eyes), oral ulceration, altered keratinization (hair/hoof loss, similar to selenium poisoning) and recumbency. Death or recovery may be expected in 3–15 days.
These mushrooms grow exclusively among eucalyptus plants, so history of exposure to eucalyptus is key. Selenium exposure and toxicity causes similar signs. The duration and outcome of the clinical expression helps to confirm diagnosis.
Treatment involves removing the affected animal from the source and offering supportive care. Recovery requires time.
This mushroom has a dry or slimy, brownish cap with in-rolled margin and yellowish gills descending a short distance on the brown, smooth stalk. The spore print is clay-brown. P involutus is widely distributed in North America. It may appear singly or in groups of several near or on wood in mixed woods in the spring/autumn. The toxin is unknown but may cause hypersensitivity over time, leading to kidney failure.
Vomiting, diarrhea, cardiovascular irregularity, and RBC destruction may be noted 1–3 hr following ingestion. Recovery generally takes 2–4 days but could be longer. Acquired sensitivity develops over time.
Diagnosis and Treatment
A diagnosis can be made based on mushroom identification, consistent clinical signs, and response to supportive care. Treatment involves symptomatic and supportive measures.
Last full review/revision March 2012 by Cecil F. Brownie, DVM, PhD, DABVT, DABFE, DABFM, FACFEI