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The VMTH offers a full range of breeding management services to
provide horse owners the most current technology for artificial
insemination with fresh, shipped or frozen semen. These services are
provided at the farm or in the hospital, both on an inpatient or
outpatient (trailer-in) basis.
General procedures involved in
artificial insemination
Rectal palpation and ultrasound are performed daily or every other
day during estrus to determine the optimal time for insemination.
The day after insemination, rectal exams are repeated to confirm
ovulation and evaluate uterine health. Presence of free intrauterine
fluid > 24 h after insemination indicates the presence of
endometritis. Mares with endometritis receive intrauterine
treatments (uterine lavage, infusion with antibiotics) to ensure the
uterine environment is optimal to support embryonic development. A
pregnancy exam is performed 14 days after ovulation.
Hormones are administered as
necessary to bring the mares into estrus (prostaglandin), induce
ovulation (human chorionic gonadotropin or deslorelin) or help clear
the uterus from free fluid (oxytocin). Semen quality (sperm count,
motility and morphology) is evaluated with each artificial
insemination.
Artificial insemination with
fresh semen
Artificial insemination is performed with fresh semen when the mare
and the stallion are held at the same location. Once the mare is
ready for insemination, the stallion is collected at the farm or at
the VMTH. A complete semen evaluation is performed, and semen is
deposited into the mare within 30 minutes of collection.
Artificial insemination with
shipped semen
Artificial insemination with shipped cooled semen allows the mare to
be maintained at home while being inseminated to stallions from
other locations. Semen is diluted with an extender, maintained at 4°C
to 6°C and transported throughout the
country to be used within 12 to 36 h of collection. The stallion’s
owner or manager is contacted by the Theriogenology Service during
the mare’s initial visit to obtain information on semen collection
and shipping schedule and requirements. Once the mare is ready for
insemination, semen is ordered. Semen is shipped overnight via
commercial carrier, or on the same day of collection
counter-to-counter via commercial airline. The VMTH receives semen
shipped in both ways, including Saturday Delivery service from most
commercial carriers. A complete semen evaluation is performed upon
arrival of the semen before insemination.
Artificial insemination with
frozen semen
Frozen semen is kept in liquid nitrogen at -196°C
and can be used years after collection. This allows transportation
of semen overseas and insemination of mares to stallions that are
already dead. However, because freezing and thawing induce changes
in the spermatozoa that decrease their half-life, frozen semen need
to be deposited into the mare within 12 hours before to 6 hours
after ovulation. Because of this, mares are either ultrasounded
every 6 h and inseminated with a full dose of semen as soon as
ovulation is detected, or they are timed-inseminated 24 and 40 h
after administration of an ovulation-inducing agent with half a dose
of semen each time. Frozen semen can be temporarily stored in the
VMTH’s liquid nitrogen tanks until insemination.
Equine Viral Arteritis
Equine Viral Arteritis is a contagious, primarily respiratory viral
disease. It is of special concern because it can result in abortion
in pregnant mares, illness and death in young foals, and
establishment of the carrier state in stallions. EVA can be
transmitted through respiratory and venereal routes. EVA can be
spread during teasing, mating or insemination through contact with
semen or reproductive tract secretions of acutely infected stallions
and mares. In addition, chronically infected carrier stallions also
shed the virus in their semen. The virus is resistant to cooling or
freezing and transmission can occur after insemination with infected
fresh, cooled or frozen semen. Because of its contagious nature, the
VMTH requests that semen shipped to our premises be accompanied by
results of blood tests and proof of vaccination of the stallion. A
seropositive result will not impede breeding the mare or accepting
the semen into the VMTH, but it will indicate the need for specific
isolation protocols to prevent spreading the virus.
To obtain acceptable pregnancy rates after traditional artificial
insemination, the minimum insemination doses are 500 x 106 motile
spermatozoa for fresh or cooled semen, and 240 x 106 motile sperm
for frozen semen. Low dose insemination allows for a drastic
reduction in the number of spermatozoa required to achieve
pregnancy. Insemination doses typically range from 1 to 25 x 106
motile spermatozoa in volumes from 0.2 to 1 mL. Low dose
insemination makes more efficient use of frozen-thawed semen or of
ejaculates of heavily booked stallions. Two non-surgical low-dose
insemination techniques are available, hysteroscopic and deep horn
insemination.
A reproductive or breeding soundness exam (BSE) is a series of
diagnostic procedures performed on a mare to identify the cause of
subfertility, elaborate a treatment plan and/or give a prognosis for
future fertility. Routinely, a mare BSE includes a reproductive
history, physical exam, rectal palpation and ultrasound, vaginoscopy,
vaginal palpation, and endometrial culture, cytology and biopsy. In
addition, uterine endoscopy, hormonal and cytogenetic tests, or
exploratory laparoscopy or laparotomy may be required to identify
the cause of subfertility. BSEs are performed in the fall or early
spring to determine the cause of barrenness and initiate treatment
before the breeding season starts, as part of a pre-purchase exam of
any broodmare, after a pregnancy loss to identify its cause and any
time a diagnosis for subfertility and prognosis for fertility are
required.
There are many infectious and non-infectious causes of infertility
in mares, including endometritis, ovarian tumors, ovulatory failure
and embryonic death. A complete reproductive exam is performed
initially to identify the cause of infertility. Based on the results
of the exam, a treatment and/or management plan is elaborated. The
Theriogenology Service offers intensive diagnostic, treatment and
management plans to get your problem mare pregnant. In addition, the
latest reproductive biotechnologies (embryo transfer, oocyte
transfer) are available for the treatment of mare infertility.
Pregnancy diagnosis is an
essential part of a breeding program and it is routinely performed
by ultrasonography 12 to 16 days after ovulation. Early diagnosis
allows us to identify mares that are not pregnant and breed them
again before their next ovulation, and to detect mares carrying
twins. Twins are a serious problem in horses and early detection
before day 16 is essential to reduce these pregnancies to singleton
pregnancies. Mares that lose their pregnancy later than 35 days
after ovulation will generally not return to estrus that season
because of the formation of endometrial cups. For this reason,
pregnancy is re-evaluated 24 to 30 days after ovulation to confirm
the presence of a heart beat in a normal looking embryo. Any
abnormalities noted in the embryo may indicate the need to terminate
that pregnancy before endometrial cups are formed so that the mare
can be re-bred on the same season. Most pregnancy losses occur
before day 60 of gestation, so pregnancies are reconfirmed again at
60 days. Ideally, a final confirmation of pregnancy is made at 120
days before vaccination, nutritional and management schedules
specific for the pregnant mare are initiated.
Mares that are diagnosed with
twins, placentitis, uterine torsion, colic and laminitis, among
other diseases, are considered to have a high-risk pregnancy. Oxygen
and nutrient supply to the fetus, as well as wastage removal by the
placenta are usually impaired in these mares. This can result in
pregnancy loss or birth of a compromised foal. The VMTH offers an
intensive pregnancy monitoring program and elaborates treatment
plans tailored to your mare’s and foal’s specific needs. In
addition, mares with high-risk pregnancies can be foaled at the VMTH
to ensure immediate neonatal support is available for the
compromised foal.
The VMTH foals out pregnant
mares and provides routine neonatal care. Foaling services include
24-hour monitoring, milk calcium testing to predict impending
foaling, Foal Alert® foaling
monitoring system to detect onset of foaling, veterinarian present
during foaling, umbilical cord care, antibody level measured in the
foal’s blood, and mare and newborn post-partum examinations.
Additional services include supplementation of colostrum or plasma,
treatment of unexpected events such as dystocia or retained placenta
and foal heat breeding.
The VMTH provides assistance
during complicated foalings (dystocia). Dystocias are true
emergencies and have devastating consequences for mare and foal. The
staff of equine theriogenologists, internists and surgeons works in
concert to maximize the chances of having a live foal with minimum
trauma to the mare in the event of a dystocia. Assisted and
controlled vaginal delivery, fetotomy and Cesarean section are
available for resolution of mare dystocias. In addition, intensive
post-partum care of mare and foal are provided.
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