ridecamp@endurance.net: Calf Manna, tying up

Calf Manna, tying up

RALSTON@AESOP.RUTGERS.EDU
Thu, 04 Dec 1997 10:12:25 -0400 (EDT)

Calf Manna, though originally designed for calves
has been used extensively as a horse supplement for
years. Palatable, 25% protein, with added minerals and
vitamins it is a good supplement (though pricey) for horses
that need some extra protein or minerals HOWEVER-do not feed more
than the recommended amounts (no more than 1 lb or two of the
cardboard scoops provided in the bag) per day. It has high levels of
Vitamin A and D that are potentially toxic if fed in excess. If
protein is all you are feeding it for, Soybean meal would be
a more economical choice!

Tying up: yes there are two distinct syndromes, though both
involve disruption of muscle fibers, pain and potential kidney
damage if severe enpough:
Classic Monday morning disease, wherein the horse ties up soon after the
onset of exercise. These horses are not dehydrated or tired, but tend to have a
low blood pH (ergo often treated with bicarbonate). There is a lot
of debate whether it is due to lactate accumulation or other factors such as
electrolyte deficits, glycogen accumulation etc. It
probably is multifactorial but is classically seen in horses fed large amounts
of grain, laid off work then started back into work without adeqwuate warm up.
Nervous fillies in race training also are reported to be more susceptible. In
chronic recurrent cases, it has been documented that there exists a genetic
defect in which excessive glycogen is stored in the muscle (Don't attack me
ti-this has been well-documented in the veterinary literature by Stephanie
Valberg). These horses have been documented by researchers at Cornell (the
group includes Dr. Harold Hintz) to improve (elimination of the problem)
when fed a high fat, high complex carbohydrate (read:forage) ration with
little or no grain. Breeds documented to date to have this problem include
Standardbred race horses, Quarterhorses and draft horses. This does NOT
however, imply that every horse that ties up early in exercise has a glycogen
storage problem.
The Late in exercise syndrome we see more in endurance occurs after the
horse has worked hard for hours-these are dehydrated, usually in electrolyte
imbalance, tired and have a high blood pH. The treatments used in Monday
Morning Disease (bicarb, tranquilizers, painkillers) are Completely wrong
for these-indeed several horses in the 70's were killed before the vets figured
it out. They primarily need gallons of fluids with electrolytes. Bicarb is out
because blood pH is already high. Banamine, tranquilizers which lower blood
pressure by expanding blood vessels and Bute are out until the horses
are rehydrated. The cause is thought to be a combination of overexertion with
excessive water and electrolyte losses. Glycogen and blood glucose are not a
factor. High calcium (re:alfalfa) training rations have been
implicated in some cases but obviously not all- this seems to be highly
idiosyncratic.
Vitamin E may help in some cases, especially if horses are on high fat
rations (Fat iny increase the need for Vitamin E and other antioxidants). Selenium
may help if in truly selenium deficient areas, but use caution-it is
potentially toxic.

Sarah Ralston, VMD, PhD, dipACVN
Ralston@aesop.rutgers.edu

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