Fall Founder
Laminitis, commonly known as founder, can range from a
frustrating problem being controlled with management to a
life threatening condition. It is often associated with late
spring/early summer when horses are turned out onto fresh,
lush pasture. This rapid increase in forage sugar content in
pasture from the dry hay of winter can cause inflammation of
the connective tissue between the hoof wall and the bone
within. However, the spring transition is not the only period
of increased risk. As the days get shorter, the risk of Fall
Founder rises.
Whereas the spring is associated with new feed, this fall risk is due to both a surge of
new grass growth and a natural increase in hormones and can be the first warning sign
of a serious condition. As horses age, the portion of their brain that regulates many
hormones of metabolism can develop benign, but biologically active, tumors resulting in
Pituitary Pars Intermedia Dysfunction (PPID), or Equine Cushing’s Disease. Directly,
this causes a rise in the hormone ACTH, but more importantly, the indirect effect causes
a steady rise in cortisol- a steroid that regulates the immune system and metabolism of
energy. With chronic high levels of cortisol comes high blood glucose, decreased ability
to fight infection, and increased breakdown of body tissues. These, as well as the often
associated insulin resistance, place the horse at high risk of foundering. To compound
the issue, in late summer and early fall there is a normal rise of ACTH, thus a natural
increase of cortisol for this period. This natural cycle is exaggerated in older horses,
ponies, and the early stages of PPID and can cause a higher risk of laminitis.
Other early signs that your horse might be developing PPID include failure to shed its
coat properly- resulting in a distinctive shaggy appearance, muscle loss along the top
line with a rounded belly, recurrent sole abscesses, and overall weight loss with regional
fat deposits. ACTH levels can be tested with a simple blood test, though interpretation
can be difficult in the fall, as the normal elevation ranges have not been fully
established.
PPID is a treatable condition and, as with all diseases, early recognition and treatment
is crucial. Any founder event should be reported to your veterinarian, especially if
accompanied by any of the other signs listed above.
Fall is the perfect outdoor riding weather, so enjoy it while it lasts!