New insights into bog asphodel poisoning of ruminants

Bog asphodel poisoning produces two different diseases. The first of these is elf fire, which affects lambs that graze on bog asphodel. These lambs incur liver damage leading to the accumulation in the blood of substances that make the animals overly sensitive to sunlight.

Some flocks in the west of Norway have been known to lose up to 30 – 50% of their lambs to this condition. Steroidal saponins, one of the toxic groups of the bog asphodel, are thought to be the source of the liver injuries seen in elf fire. The second form of bog asphodel poisoning is acute kidney failure, which is seen sporadically in cattle and moose.

Wisløff's work primarily addressed the disease of acute kidney failure. Lambs with elf fire suffer transient kidney damage of the same type seen in cattle and moose that graze on bog asphodel.

The short-lived kidney injuries seen in lambs are, however, milder and are thought to be caused by a furanone (3-methoxy-2(5H)-furanone). Testing of this substance on kidney cells produced, however, unclear results. Helene Wisløff described therefore other toxins from the bog asphodel and discovered that steroidal saponins had the greatest toxic effect on the kidney cells. Another furanone (5-hydroxy-4-methoxy-2(5H)-furanone) produced more moderate damage.

In one experiment in which lambs received a commercial dietary supplement containing the same saponins as those of bog asphodel, several of the lambs developed acute kidney failure. Saponins were found in the kidney and liver tissues from these lambs.

It was previously thought that saponins from the plants were almost completely converted to sapogenines and sugars in the rumen (one of the stomachs). However, the saponins found in the lamb kidneys were of the same type as those of the plant, that is, they had not been modified. At present it is not known whether the saponins from the bog asphodel can cause kidney damage in ruminants under natural conditions.

Helene Wisløff defended her thesis entitled “Toxic effects of Narthecium ossifragum with emphasis on kidney lesions”, for the degree of Dr. med. vet. at the Norwegian School of Veterinary Science, on March 13, 2008.