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VetBooks.ir Chapter 67

Mushroom Toxins

Birgit Puschner

INTRODUCTION toxicokinetics, and diagnostic and therapeutic approaches,
with a focus on veterinary medicine.
Management of mushroom poisonings of humans and
animals can demand extensive effort from clinicians and
toxicologists and often involves emotion and publicity. HEPATOTOXIC CYCLOPEPTIDES
The public expects the toxicology profession to provide
guidance and a coherent approach regarding these cases. Worldwide, most fatalities are caused by exposure to
Although it is estimated that very few species are lethal, cyclopeptides. Three genera—Amanita, Galerina, and
it is not clear how many of the mushrooms worldwide Lepiota (Lincoff and Mitchel, 1977a)—are known to con-
contain potentially toxic compounds. New species are tain hepatotoxic cyclopeptides, with Amanita phalloides,
being discovered continuously, and for many species, tox- the ubiquitous death cap or death angel, and Galerina
icity data are unavailable. It is very difficult to establish a sulpices being considered the most toxic worldwide.
confirmed diagnosis of mushroom poisoning in animals; A. phalloides (Fig. 67.1) is found throughout North
thus, clinical reports of mushroom poisoning are uncom- America, commonly in association with oaks, birch, and
mon. In fact, because animals are at much greater risk of pine, and it is the species most frequently resulting in
exposure to toxic mushrooms than are humans, mushroom fatalities in humans (Mitchel, 1980; Barbato, 1993) and
poisonings in animals are most likely underreported. probably dogs. It can also be found in open pastures.
A. phalloides is particularly common in the San Francisco
Bay area, the Pacific Northwest, and the Northeast, and it
BACKGROUND is most abundant in warm, wet years. The large fruiting

The reported frequency of mushroom poisonings in veteri- bodies appear in the late summer and fall, and they have
nary medicine is low because routine diagnostic methods
to confirm exposure are lacking. Most cases are diagnosed
by positive identification of the suspect mushroom along
with the occurrence of consistent clinical signs and clinico-
pathological changes. Animals are often left unattended,
and a history of mushroom ingestion is not available. An
estimated 200 300 calls related to mushroom ingestions
have been registered each year by animal poison control
centers in the United States. California accounts for more
than 10% of these cases, the highest among all states.
California also leads the United States in the number of
reported cases of mushroom ingestions in humans; 894
cases were reported in 2008. Many factors influence the
toxicity of mushroom toxins, such as genus and species of
mushroom, the season and geographic location, preparation
of mushroom prior to ingestion, and the individual’s sus-
ceptibility. Although not inclusive of all mushroom toxins,
this chapter is organized by the various types of toxins, FIGURE 67.1 Amanita phalloides. Courtesy of Dr. R. Michael Davis,
providing detailed information on their toxic mechanisms, University of California at Davis.

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