6 minute read
ENDOCRINOLOGY
PPID Treatment Improves Quality of Life
Client satisfaction was also high
Marie Rosenthal, MS
Equids with pituitary pars intermedia dysfunction (PPID) treated with pergolide (Prascend, Boehringer Ingelheim Animal Health) may not need progressively increased doses for long-term treatment, according to Harold C. Schott II, DVM, PhD, DACVIM, who with his colleagues at Michigan State University performed a multi-year study looking at long-term PPID treatment.
They found that although the treatment improved the quality of life of the equids, as well as saw high client satisfaction, it did not necessarily prolong life, according to Dr. Schott, who spoke at the AAEP Annual Convention 2022.
“We all know that PPID is increasingly being recognized and treated,” said Dr. Schott, a professor in equine internal medicine at Michigan State University. However, without long-term data it is difficult for clients to weigh the benefits of what could end up be-
ing life-long treatment for some diseases, especially when considering the possible financial implications of such treatment.
Dr. Schott and his colleagues had the opportunity to answer some of these questions after the pivotal FDA trial for Prascend, when Boehringer Ingelheim agreed to fund a truly long-term study—>10 years looking at some of the horses that were enrolled in the original study done for FDA approval.
Horses with the typical hair coat of PPID.
Image courtesy of Dr. Harold C. Schott II
The questions he was interested in were:
• Will we have to progressively increase the dose of pergolide to control the clinical signs and possibly endocrine test results in equids affected with PPID?
• Does pergolide treatment really improve quality of life?
• Does it potentially prolong the life of the horses?
• Are our clients satisfied with treatment outcomes?
During the original trial, they managed 40 horses and asked their owners if they would be willing to participate in the longer trial. They enrolled 30 equids (28 horses and 2 ponies) from that original 6-month trial, and the second trial began in 2009. BI had a different endpoint. BI wanted to know about the longterm safety of the medication, which was also measured.
The researchers conducted follow up interviews by telephone every 3 months asking about any medical problems the equids were seeing, and the equids were examined every couple of years throughout the study, which lasted 12.5 years. One of the participants was Dr. Schott’s daughter’s pony, Rusty, who is still alive.
When the original study was performed, they did not have the adrenocorticotropic hormone (ACTH) assays that are used today, so the ACTH values were often lower in the older assays, he explained. They based on the original results on the classic overnight dexamethasone suppression test, so that was the endocrine test they continue to use as they monitored the animals over time.
“In the FDA open field trial, there were 113 equids and 86 of those or 76% were considered treatment successes. Our cohort was again, a subgroup of that, and 18 of 30 were considered treatment successes. So, they were easily representative of the overall 113 horse cohort with possibly maybe a little bit more advanced PPID,” Dr. Schott explained.
In the original study, the average 500-kg horse received 2 µg/ kg/d and were reevaluated with clinical scores and endocrine tests after 3 and 6 months. If they passed their endocrine tests after 3 months (plasma cortisol <1 µg /dL 18 hours to 19 hours after dexamethasone administration) they stayed at the 2 µg/kg/d dose.
If they failed, the dose was increased to 4 µg/kg/d.
In the follow-up study, 7 of 15 equids saw an increase in dose to 4 µg/kg/d within 5 years of the study.
“Overall, what we can see here is for the next 4 to 5 years, most of these horses did well and continued to have a normal endocrine test results despite remaining on just 1 mg of pergolide per day,” he said.
By now, all but Rusty, Dr. Schott’s pony, has died or was euthanized.
“The median survival of these equids was 3.3 years over this period of time,” Dr. Schott said. “Now, to date, we've lost 29 of the 30 horses. Rusty's the only one that is still alive. Five of these were euthanized because of laminitis, so that we could say was associated with their PPID; 24 had other age-related disorders, arthritis, strangulating lipomas, a couple of fractures, and just things that we did not think were associated with PPID.”
At the 5.5-year follow-up, owners of 13 equids that were still alive said they continued to see clinical improvement in the horses, and 75% had normal endocrine test results.
However, normal endocrine tests were only seen in 2 of 6 surviving equids at 9.5 years.
“After about 10 years, we did a client satisfaction survey. We sent the survey out, and we had an 86% completion rate,” Dr. Schott said.
Most clients said they were satisfied with the animal’s treatment:
• 44% strongly agreed they would provide lifelong treatment if they had another equid with PPID; and
• 44% agreed they would provide treatment if they had another equid with PPID.
• 71% strongly agreed the treatment improved their equids quality of life; and
• 25% agreed the treatment improved their equids quality of life.
Specifically:
• 77% said the horse had more energy;
• 71% saw improvements in haircoat and shedding; and
• 41% saw a reduction in abnormal sweating.
They were also asked what they were willing to pay for medication:
• 26% said $500;
• 56% said $1,000;
• 10% said $1,500;
• 4% said $2,000; and
• 4% said $2,500.
Dr. Harold C. Schott's daughter's pony, Rusty, which had PPID and was part of the study, with his daughter through the years.
“The sweet spot was right about 1,000 dollars, and once the price got over that we started to see a decline—they would think about it a little bit more. So that's important information to know what your clients may be willing to do in the future,” he said.
“Our equids with PPID might not need a progressive increase in drug dose over time. The endocrine test results can improve over a prolonged period even if they were abnormal for the first year.
“So, you might want to do a case-by-case base assessment. Treatment appears to improve quality of life, but it doesn't appear to prolong life,” he said.
Rusty, he said was still doing well. “He's a happy little boy,” MeV
Boehringer Ingelheim has been very generous in supporting this study over the years, as well as providing funding for the large animal clinical sciences department of MSU. Dr. Schott is a consultant for Boehringer Ingelheim on projects.
