Common Name
Greasewood, chico
Botanic Name
Sarcobatus vermiculatus
Plant Family
The dominant vegetation of the dry alkaline soils of the western states.
Animals Affected
Sheep, cattle most commonly affected, but all livestock are susceptable.
Toxic Principle
Sodium oxalate. (10-22% dry matter). The leaves contain the highest concentration of oxalate. Toxicity occurs when 1.5-5.0% of an animal's weight of the plant is ingested over a short period of time.
An erect, deciduous shrub with woody, spiney branches often growing to 150 cm. The plants are many branched turning gray with maturity. The leaves are alternate, bright green, fleshy, loosely round in cross section, and up to 1-1/4 inches long. The flowers are unisexual with the plants having both sexes of flower on the same plant. The femaleflowers being inconspicuous in the axils and the male flowers occurring as terminal spikes (catkins). The fruits are winged and conical in shape.
Muscle tremors, tetany, weakness, reluctance to move, depression, and recumbency resulting from hypocalcemia and hypomagnesemia. Coma and death may result within 12 hours. Animals that survive the acute effects of oxalate poisoning frequently develop kidney failure.
Calcium gluconate, magnesium sulfate, glucose, and a balanced electrolyte solution can be given intravenously to maintain kidney perfusion, and treat the effects of the low blood calcium. Giving limewater [Ca(OH)2] orally will help to prevent absorption of further soluble oxalate from the rumen. The prognosis is usually very poor because of the severe kidney damage that results.
Renal System
Animals that survive the acute effects of oxalate poisoning frequently develop kidney failure. Insoluble calcium oxalate filtered by the kidneys causes severe damage to the kidney tubules. Animals die from renal failure.
Sudden deaths, or weak,
Special Notes
Factors that predispose an animal to oxalate intoxication include the amount and rate at which the oxalate plant is eaten, the quantity of other feed diluting the oxalate in the rumen, and prior adaptation of rumen microflora to oxalates. Ruminants allowed to graze small quantities of oxalate containing plants are able to increase their tolerance for oxalate 30% or more over a few days. Sheep and cattle adapted to oxalate can make good use of range forages containing oxalate that would otherwise be toxic. Oxalate poisoning most often occurs when unadapted sheep or cattle are allowed to graze large amounts of Halogeton or Sarcobatus as they pass through, or are pastured overnight on range land containing large stands of these plants. Prevention Supplementary dicalcium phosphate in diet prior to and during high risk situations is an effective means of reducing losses. High dietary calcium binds oxalate in the rumen as insoluble, nonabsorable calcium oxalate. Calcium may be provided to the animals in a salt mix (75 lbs salt, 25 lbs dicalcium phosphate) or in pelleted alfalfa at a 5% concentration and fed at the rate of 0.5 lbs per sheep per day.
Greasewood branch detail