An appeals court in New Mexico has affirmed a trial court’s decision to dismiss claims that a horse rancher’s family became ill as a result of exposure to horse feed containing an antibiotic toxic to horses. Parkhill v. Alderman-Cave Milling & Grain Co., No. 29,120 (N. M. Ct. App., decided October 6, 2010). The parties settled claims that the feed sickened or killed horses from several of the plaintiffs’ horse ranches, and the trial court dismissed claims, as a sanction for discovery abuse, that the family’s personal health was affected by exposure to the feed. The appeals court did not reach the sanctions issue, finding that the lower court properly excluded the testimony of the plaintiffs’ experts.

The toxin involved was monensin, an antibiotic that is a common additive to feed for livestock, but prohibited in horse feed. The plaintiffs alleged that immediately after contact with the feed they developed skin rashes, irritated eyes, brittle nails, and diarrhea. While they did not seek treatment then, some eight weeks after the feed was no longer used on their ranches, Joey Parkhill sought treatment from his family physician for shoulder pain, and then he and the rest of the family consulted with the physician for “generalized health complaints, including dizziness and light-headedness, breathing difficulties, insomnia, decreased energy, irritability, elevated blood pressure, and weight gain.” They sought to have this physician and another testify that their health problems were caused by monensin exposure.  

The appeals court agreed with the trial court that the experts were not qualified to testify that monensin exposure caused the family’s health problems. Regarding the treating physician, a majority of the court concluded that “testimony as to external causation, or etiology, was beyond the expertise of the average treating physician and beyond the scope of a differential diagnosis conducted for the purposes of diagnosis and treatment.” A concurring judge would have held that the majority went too far “by excluding differential diagnosis testimony to establish cause in all toxic tort cases.”

According to the court, the physician who was hired for the litigation and proffered as an expert in environmental medicine and toxicology could not testify that the illnesses were caused by the family’s exposure to monensin because he had no experience with the antibiotic, did not quantify the dose they received and did not know that monensin is handled at much greater concentrations in the livestock industry with no adverse health consequences for workers. In this case, the ranch hands who worked for the family apparently experienced no ill effects from the contaminated horse feed.