17 Apr 2025
Researchers say they are encouraged by the findings of a newly published study, but say other methods are still likely to be needed.
Chris Simpson
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Image (expanded) © Justin / Adobe Stock
A common drug used to treat horses with pituitary pars intermedia dysfunction (PPID) could also reduce the risk of them developing laminitis, a new study has suggested.
Researchers have described the findings, published in the Equine Veterinary Journal, as “encouraging”, although they acknowledge other measures are still likely to be necessary.
The study, led by academics from the University of Melbourne, compared the effects of pergolide mesylate on horses with both PPID and insulin dysregulation (ID) and those just with ID.
PPID typically affects older horses and ponies and can cause the animals to have an increased risk of laminitis, particularly if they also have ID.
It is also thought the most prevalent form of laminitis in the UK is associated with an elevated concentration of insulin in the blood.
The research, conducted in collaboration with Mars Horsecare’s Spillers brand, showed that while in horses with ID only pergolide had no effect on blood insulin levels after eating, it did lower them to equivalent levels in horses with both PPID and ID.
Mars Horsecare product manager Sarah Nelson said: “The results suggest that pergolide may reduce the amount of insulin produced in response to eating in horses and ponies that have PPID together with ID but not back to normal.
“However, it is also important to note that sugar and starch can still raise insulin to abnormally high levels even when the horses and ponies are on pergolide, meaning that a low sugar and starch diet remains crucial for horses with PPID and/or ID.
“Finally, given that horses with ID only did not respond to pergolide we must ensure that PPID and ID are tested for separately – managing one will not necessarily manage the other.”
The research was conducted at sites in the state of Victoria by administering high-starch meals to 16 horses aged 15-32, half of which had both PPID and ID, while the other half had ID only.
Blood insulin levels were taken before and after the meals, with the tests conducted on each horse twice – once after four weeks with pergolide treatment and once after four weeks without.
The paper concluded: “The potential for pergolide to reduce the postprandial insulin response in horses and ponies with PPID is encouraging and may provide a mechanism by which pergolide could help to reduce the risk of laminitis in equids with PPID; although dietary management and other measures are likely to still be important.
“Further work to explore the effect of dopamine and dopamine agonist drugs on insulin secretion is warranted.”
