Approximately 40 head of Hereford cows were grazing on 12 sections of land with oil production activity present. In one particular section, four to five cows were found dead within 12-24 hours. Another cow was observed by the owner to be shaking and trembling, had fallen and gotten up, fell a second time and became laterally recumbent. This animal was euthanized, necropsied, and samples were submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station for testing. The water source for the section of land where the cows died came from two different wells. The owner noticed a loose, white mineral near one of the wells and indicated the water from the well tasted salty.
Histopathology was performed on sections of lung, liver, kidney, and brain. No microscopic lesions were observed in any of the tissues to explain the cause of death in the animal. Ocular fluid was tested for excessive nitrates but yielded negative results. Rumen content was distilled and analyzed by gas chromatography–mass spectrometry (GC-MS) for the presence of petroleum hydrocarbons, but none were detected. The brain was analyzed for sodium and a toxic level (>7,200 ppm) was detected by flame atomic absorption spectroscopy (FAAS). Water samples from multiple sources were submitted subsequently for water quality testing. A sample of water from the well nearest where the deaths occurred contained levels of Total Dissolved Salts (TDS), conductivity, and sulfates that are hazardous to livestock.
Cattle with acute salt intake may develop gastroenteritis, weakness, dehydration, tremors, and ataxia. The cattle may appear to be blind and develop seizure-like activity. Cattle can die within 24 hours of the onset of clinical signs. Measurement of TDS in water is determined by the summation of all measured ions (cations and anions). TDS levels >3,000 ppm should be avoided by lactating animals, and levels >7,000 ppm may pose significant risks to many animals. High conductivity is an indication of TDS. Sulfate levels in water >2,000 ppm can cause diarrhea in most livestock.
TVMDL employs five veterinary diagnosticians available for consultation on a variety of subjects. TVMDL recommends clients who are interested in learning more about water quality testing, metal and mineral testing, and other test offerings of assistance to livestock producers, contact a veterinary diagnostician.
For more information about TVMDL’s test offerings, visit tvmdl.tamu.edu or call 1.888.646.5623.
REFERENCES
Provin TL and Pitt JL. Description of Water Analysis Parameters. Texas A&M AgriLife Extension. 2002. SCS-2002-10.