The parentage verification was qualified by the compatibility of 12
microsatellite markers according to Mendelian fashion.
Discussion
Typical methods employed to perform parentage verification apply
molecular technology to test simple Mendelian inheritance principles
between offspring, paternal and maternal candidates (Jones et al. 2010).
This concept of molecular based parentage verification is currently
applied within a range of diploid species including the equine species
and perform as a key powerful tool to ensure integrity of pedigree
recording, when testing offspring against nominated sires and dams
(Marklund et al. 1994, Binns et al. 1995, ISAG 2012).
The Horse Genetic Committee of the last virtual international society of
Animal Genetics (ISAG) Conference (2021) presented 12 microsatellite
markers (AHT4, AHT5, ASB2, ASB17, ASB23, HMS2, HMS3, HMS6, HMS7, HTG4,
HTG10 and VHL20) as international minimum standard microsatellite marker
system. Our result in this case agreed that microsatellite DNA typing of
the aborted fetus and another live foal are compatible with the 12
microsatellite markers of the dam and sire according to Mendelian
fashion (Myres et al., 2009). The data presented in our study is
providing the effective tool for confirming parentage.
This article presents a record of abortion of a single co-twin fetus in
a pregnant mare and the other fetus completed the gestation period until
full term followed by normal birth. As aforementioned the results of
genetic analysis for parentage confirmed that the two feti are co-twin
from the same sire and dam. The most important cause of abortion in
Thoroughbreds is twin as described by Acland (1987, 1993). Twins also
lead to dystocia, harmful effect on reproductive tract and intrauterine
growth retardation (McKinnon, 2011), While in this case discussed in the
article, the abortion taken place for a single fetus in an age smaller
than the other co-twin (single abortion) and continuity of the other
fetus till birth. In our opinion, the most reliable explanation is
embryonic diapause to the singleton for a time period that may reach few
months, especially this phenomenon is recorded in some mammals such as
marsupials (Renfree and Calaby 1981, Renfree and Shaw 2000 and Flint et
al , 1981), in which the embryo reaches blastocyst stage then enters a
dormant stage, moreover, the blastocyst capsule which is tough and
elastic in nature almost provides mechanical protection inside the
uterus (Stout and Allen, 2001).
CONFLICT OF INTEREST
No conflicts of interest have been declared.
ETHICS STATEMENT
Not applicable to this case report.