Q.My veterinarian diagnosed my 20-year-old mare with PPID (pituitary pars intermedia dysfunction) and prescribed medication. He didn’t recommend changing her turnout arrangements, which involve time in a grassy paddock each day. But a friend said grass is bad for PPID horses. Can horses with PPID be turned out on pasture?

—Sally, via e-mail

A.The short answer: It depends!

It depends largely on the PPID horse’s endocrine status—whether or not this horse has insulin dysregulation (abnormally high blood insulin levels) or equine metabolic syndrome (EMS), as well as having PPID. Why do we care? When a horse is EMS or insulin dysregulated, they likely cannot tolerate pasture. In fact, pasture will likely exacerbate the insulin dysregulation (i.e., it causes the horse to have even higher levels of circulating insulin in the blood, which contributes to these horses developing laminitis).

But don’t assume that all PPID horses are insulin dysregulated; this often is not the case, but it can happen. Work with your veterinarian to determine whether or not your horse is insulin dysregulated; this can be done by looking at basal insulin levels or insulin levels in response to the oral sugar test.

Also consider previous episodes of laminitis as an indicator of how much pasture the horse can tolerate.

The bottom line: If your PPID horses is not insulin dysregulated and is of good body condition (i.e. not overweight), then yes, it should be safe to turn your PPID horse out onto pasture. If your PPID horse is insulin dysregulated, depending on the severity, I would recommend working with your veterinarian or an equine nutritionist to determine how much pasture turnout time your horse should or should not have.