AQHA Magazine July August 2019 AQHA July-Aug 2019 Final | Page 26

HORSE HEALTH
R
TYING-U SE
P?
PG.24
The signs of acute ‘tying-up’ are usually readily
recognisable and easily confirmed with blood tests that
measure the muscle enzymes (AST, CK and LDH) released
when muscle cells become damaged. Your veterinarian
may measure blood selenium and do an exercise test (15
minutes trotting on the lunge with blood collection and
muscle enzyme analysis 4 hours later – 80% of PSSM
horses fail this test); a urinalysis to detect electrolyte
imbalances and the presence of myoglobin which leaks out
of damaged muscle cells and is toxic to kidneys; a muscle
biopsy to identify abnormal sugar storage, and genetic
testing to determine whether the GSY1 gene is abnormal.
With the amazing advances in science and technology, we
can now do the genetic testing using blood or hair with
roots attached. Approximately 30 hairs from the mane or
tail are required and testing is available at the Practical
Horse Genetics Laboratory (practicalhorsegenetics.com.
au).
When any exercise-induced tying-up episode occurs, the
activity should be immediately stopped and the horse
evaluated. Mild cases can be handled by an experienced
horseperson, but some episodes require immediate
veterinary attention. Tying-up is a veterinary emergency
if the horse is exhibiting profuse sweating, reluctance to
move and dark urine.
Depending on the cause of the tying-up episode,
treatments may vary and include: rehydration, correct
electrolyte replacement, pain management, muscle
relaxation, regular monitoring of blood and urine,
prevention of further muscle damage, promotion of blood
flow and muscle movement. In severe episodes stall rest
and complete confinement are advised for the first 24–72
hours until horses move willingly, there is no muscle pain
and urine is normal. Horses must be kept warm, dry and
rugged if required.
Prevention and management are essential as a lack of
routine daily exercise and a diet high in starch increase the
risk of a tying-up episode. Dietary change must include
weight loss if required. If the horse is not too forward in
condition, feeding 1.5-2% of body weight as good quality
(i.e. low mould and dust) hay plus a balanced, low starch/
sugar/NSC (<12%), high oil vitamin-mineral-amino acid
supplement is the place to start. For horses with ER and
PSSM, hay is preferable to haylage or silage. Lucerne can
be provided at up to 0.5% of bodyweight (around 2.5kg
for a 500kg horse). Soaking hay once or twice can help
reduce the starch/sugar content.
Adding oil to the diet (start with 60 ml/day and add 60
ml every 2 to 3 days until feeding 400-800ml) can help
reduce muscle dysfunction. Olive, canola, coconut and
linseed oils are preferred due to their higher omega 3
content. Oils high in omega 6 should be avoided (corn,
sunflower, safflower and peanut oils). Other positive
changes of increased oil intake include better way of
going, energy efficiency, exercise tolerance, attitude
and body condition — alleviation of back pain has been
reported in many horses. A significant decrease in post
exercise serum CK and AST levels, indicative of reduced
exercise-induced muscle injury, has also been reported.
A wide variety of feedstuffs could be combined to produce
a low starch, high oil diet, but diets must be balanced
to provide adequate amino acids, protein, vitamin and
minerals. A balanced diet can also prevent electrolyte
AUSTRALIAN QUARTER HORSE ASSOCIATION