caecum, colon and sometimes the rectum undergo a
large dilation and fill with faecal mass. Associated with
homozygosis of the Overo Lethal White gene it results
in incomplete migration of nerve cells to the large
intestine during embryonic development. Affected foals
may die within seventy-two (72) hours of birth;
19.5 Autosomal Recessive Genetic Disorders:
a) Horses applying for registration that have lineage to
Poco Bueno/Miss Taylor must be tested for HERDA;
b) Where both parents have been tested for HERDA/
OLWS and both parents have a negative result on file
for that genetic disorder, the horse applying for
registration is not required to be tested for that
particular genetic disorder;
c) Horses applying for registration that display excessive
white markings beyond the limits described in Rule 11.4
a), unless the horse applying for registration is out of
two (2) negative parents, must be tested for OLWS;
Exception: Horses applying for Foundation Recording
that display excessive white markings beyond the limits
described in Rule 11.4 a) will not be accepted for
Foundation Recording;
d) Horses applying for Foundation Recording will be
required to complete an OLWS test and must return a
negative result to be considered for recording;
e) Any horse that does not carry lineage for HERDA will not
be required to be tested for that disease;
Exception: All ASH registered horses applying for
Foundation Recording must complete a HERDA test
and return a negative result to be considered for
recording;
f) Horses that return a positive (Homozygous/Afflicted)
result to HERDA/OLWS will not be accepted for
registration;
g) Horses that return a positive (Heterozygous/Carrier)
result to HERDA/OLWS will be considered for
registration;
Exception: Foundation Mares and Foundation Stallions
will not be accepted unless they return a negative result
to HERDA and OLWS.
h) Horses that return a negative result to HERDA/OLWS
will be considered for registration;
i) Geldings that display excessive white markings are not
required to be OLWS tested if parent validated to two
(2) registered Quarter Horses;
j) Geldings who are by or out of a HERDA carrier are not
required to be HERDA tested;
k) Geldings whose parents are both HERDA carriers will
be required to be tested, and if they return an Hr/Hr
result will not be eligible for registration;
l) All horses tested for HERDA/OLWS will have their
papers marked with the test result.
19.6 Stallions and Mares
a) All breeding stallions and mares with lineage to Poco
Bueno/Miss Taylor and no HERDA results on file with
the Association will be suspended and no paperwork
will be processed for the stallion or mare;
b) All breeding mares who cannot prove that they do not
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