11/13/2024
Did you know that 80-90% of laminitis is caused by endocrine disease?
The two most common endocrine issues we come across in laminitic cases are 1) PPID (formerly known as Cushings) and 2) metabolic disease most commonly insulin resistance/dysregulation with hyperinsulinemia. We hear a lot of people group these as one BUT they are two very different issues.
Pituitary pars intermedia dysfunction (PPID) in short is a dopamine dysregulation (with or without tumor formation in the pituitary) that results in increased secretion of POMC and ACTH, which in turn increases cortisol. ACTH will naturally start to rise mid- July to late November with the peak in mid to late September. The additional increased circulating cortisol and adrenaline are the responsible parties for clinical signs associated with the disease. One of these signs is the classic long hair coat that fails to shed, but contrary to popular belief, this is a sign of late stage PPID and much more subtle signs should be taken into consideration when deciding to test for the disease (muscle wasting and loss of topline, increased water intake/urination, and lethargy to name some). This often happens in older horses and 20% of horses 15 or older will test positive for PPID. In addition, 30% of the horses positive for PPID will ALSO have insulin dysregulation. It should be noted that while it is common for horses with PPID to also have insulin dysregulation, not all horses with insulin dysregulation will have PPID (slightly confusing, I know). Chronic infections, dental disease, and laminitis are common complications.
Horses with Insulin dysregulation/resistance have abnormal glucose (sugar) and fat metabolism and increased circulating insulin (hyperinsulinemia). Insulin does naturally elevate in December, January, and February. These horses often, but not always, present with a very specific look with large cresty necks, large fat pockets especially on top of the butt/tail head, behind the shoulder, and near mammary glands and sheath. There is no age preset and a horse of any age, breed, look, etc can have insulin dysregulation/resistance. These horses do require a very specific diet to reduce circulating insulin and the detrimental effects, most commonly laminitis. This diet will consist of low sugar/starch content (below 10% with starch below 4%) which includes all hay, feed, and treats and most importantly, significant owner compliance.
Both are easily tested for and if you are concerned, feel free to ask Dr. Laura for a consultation and/or testing.
(Please enjoy a picture of Dr. Laura's metabolic/laminitic pony who wishes she didn't have this knowledge so she could have sugar again no matter the consequences)
