- Distinguishing features
- Halogeton is an annual weed (3-24 inches) with small, round, fleshy weiner-shaped leaves (0.5 inches) that grow in clusters along reddish or purplish stems. The basal curvature of each branch is characteristic. In late fall, the leaves are hidden by dense clusters of fruits, each fruit enclosed in five wing-like bracts.
- Halogeton is an annual herb with horizontally spreading branches that curve upward to 2 feet. Mature plants have red stems with blue-green leaves that end in a single hair. Plants have small, inconspicuous yellow flowers.
- Geographic range
- Found in rangelands of the western United States and thrives on arid alkaline soils and clays.
- Toxic principle
- Soluble sodium oxalate can be lethal to sheep and cattle. The toxin is found in fresh and dried plant. Soluble oxalate levels vary with environmental conditions.
- The toxic dose is 0.3 to 0.5% of the animal's body weight when consumed over a short period of time. Sheep are able to adjust to slowly increasing amounts of soluble oxalates in their diet as the ruminal microflora adapts.
- Mechanism of toxicologic damage
- Soluble oxalates cause disturbance to calcium homeostasis, altering blood calcium levels, blood coagulation, and nerve and muscle function. Metabolic disturbances may occur due to inactivation of the enzymes lactate dehydrogenase and succinyl dehydrogenase.
- Clinical signs
- Disease is acute and highly lethal in sheep with initial signs evident four hours post-ingestion and death occuring within 24 hours. Disease in cattle may be acute and lethal or may present as subacute locomotor difficulties.
- Laboratory Diagnosis
- Blood calcium levels is 1.4 mg/dL and blood magnesium and phosphate levels double. A 2-3 fold increase in serum lactate dehydrogenase and a 2 fold increase in blood urea nitrogen may be seen.
- Increased free fluid is found in abdominal and thoracic cavities. Splotchy hemorrhages on the heart, rumen, and other viscera. Pale and swollen kidneys. Microscopically, proteinaceous casts and calcium oxalate crystals are found in renal tubules. Renal epithelium is flattened and necrotic.
- Parenteral calcium is moderately effective in cattle but its effectiveness in sheep is questionable.
- Proper feed and water management is highly important because the problem is greatest when large amounts of Halogeton are present around watering areas.