Horses with Cushing’s disease (also called pituitary pars intermedia dysfunction, PPID) tend to have higher fecal egg counts (FECs) than healthy horses and might benefit from more aggressive parasite control measures, reported researchers from Oklahoma State University.

"While it has long been suggested that horses with PPID are more susceptible to internal parasites than healthy horses, until now, there was no published data to support this hypothesis," explained lead researcher Dianne McFarlane, DVM, PhD, Dipl. ACVIM, from the Department of Physiological Sciences at Oklahoma State’s Center for Veterinary Health Sciences.

To determine whether FECs returned more quickly after deworming horses with PPID compared to healthy horses living in similar environments, McFarlane and colleagues dewormed 29 healthy horses and 13 horses with PPID with ivermectin. Small strongyle FECs were then calculated at two-week intervals.

"Horses with PPID had higher FECs than the healthy horses both before being dewormed and again at eight, 10, and 12 weeks after deworming," said McFarlane