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General Breeding Information
The single most prevalent reason for reduced fertility today is lack of cleanliness or sanitation.
by Dickson D. Varner, DVM, MS, Diplomate ACT
Charles C. Love, DVM, Ph.D., Diplomate ACT
Terry L. Blanchard, DVM, MS, Diplomate ACT
Steven P. Brinsko, DVM, MS, Diplomate ACT
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University
Although the upcoming breeding season is 3 months away, a successful year for 2005 begins with preparation
of mares and evaluation of stallions right now.
by B. W. Pickett, Ph.D. Professor Emeritus, Colorado State University
Although some of you may feel that the prior breeding season has just ended, it is time to
begin thinking about the upcoming breading season.
By Patrick M. McCue, DVM, PhD,
Diplomate American College of Theriogenologists
A uterine biopsy may be collected from a mare by a veterinarian to evaluate the histology or
microscopic anatomy of the uterine lining or endometrium
By Patrick M. McCue, DVM, PhD,
Diplomate American College of Theriogenologists
Culture of the uterus to determine if one or more microorganisms are present or if the mare is 'clean'
(i.e. free of organisms) is an important diagnostic test.
Stallions and Stallion Management
By Patrick M. McCue, DVM, PhD,
Diplomate American College of Theriogenologists
The 2019 equine breeding season is almost here. One way to help ensure a successful start is to have a
reproductive evaluation performed on your stallion(s) prior to the onset of the season. The goals of the
reproductive evaluation would be...
A hemacytometer, originally designed to count blood cells, has been used for many years to count other types
of cells. Toward the end of World War II, with the advent of artificial insemination in cattle, it became painfully
obvious that other methods of counting spermatozoa had to be developed, because of the length of time it
required for an accurate count to be obtained with the hemacytometer.
When the stallion manager and the mare owner have confidence in one another and a spirit of cooperation,
shipped semen has many fewer disadvantages and a much greater chance of success.
Extenders by B. W. Pickett, Ph.D. Professor Emeritus, Colorado State University
To quote Dr. R.H. Foote, one of the most noted reproductive physiologists of our era, "Artificial insemination
(AI) was the first great biotechnology applied to improve reproduction and genetics of farm animals."
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
The birth of the first foal conceived using frozen semen occurred almost 50 years ago. Use of frozen semen was
approved by the AQHA in 2001 and in 200_ the rule was adjusted/an amendment was passed to allow for the
use of frozen semen from a given stallion even after he has died.
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
Artificial insemination of mares with cooled-transported semen has become a routine procedure in the equine
breeding industry. The ability to cool semen makes it feasible to ship semen from one location to another...
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
Management techniques to control Urospermia in a stallion.
Mares and Mare Management
By Patrick M. McCue, DVM, PhD,
Diplomate American College of Theriogenologists
A reproductive evaluation is recommended for all broodmares before they are turned out in a pasture breeding
program, before they go to the breeding shed in a live-cover program, or before they are inseminated or semen
is ordered in an artificial insemination program. It is common sense to make sure that the mare is cycling and
does not have any reproductive issues that would potentially limit her fertility before the breeding season starts...
by E.L. Squires, M.S., Ph.D., hon, ACT, Colorado State University
Dr. Squires outlines a strategy for assuring that mares are ready for the next breeding season, with
considerations for different categories of mares.
by Dickson D. Varner, DVM, MS, Diplomate ACT
Charles C. Love, DVM, Ph.D., Diplomate ACT
Terry L. Blanchard, DVM, MS, Diplomate ACT
Steven P. Brinsko, DVM, MS, Diplomate ACT
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University
Many advances have been made in assisted reproduction for horses in recent years, and several breed
registries in the United States have adopted many of these newly-found techniques.
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
Mares can continue to produce foals well into their late teens or early to mid 20's. However, mare owners should
realize that the prognosis for fertility of an older mare decreases each year.
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
Cytologic evaluation of the uterus involves the collection and interpretation of cells lining the uterus
(endometrium) and within the uterine lumen. Cytology is used in conjunction with culture and biopsy
in the diagnosis of endometritis
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
Events of reproduction in the mare are fairly similar to that of other domestic animal species. Typically one
dominant follicle develops and produces estrogen that causes the mare to come into estrus or heat. The
dominant follicle ovulates toward the end of estrus and a corpus luteum forms from the site of the former
follicle...
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Economic pressures of the equine breeding industry result in a demand for accurate early pregnancy diagnosis.
Some horse owners presume that a mare that fails to come back into heat within 3 weeks after breeding is
pregnant. That is not necessarily true. Up to 10 % of bred mares that fail to return to heat are not pregnant.
Reasons for a nonpregnant mare not coming back into heat include persistence of the corpus luteum
(pseudopregnancy), seasonal effects on ovarian function, and some ovarian disorders. The most reliable test
for pregnancy is ultrasonography. Pregnancy tests based on hormone levels in blood or urine are generally
used only when palpation and ultrasonography per rectum is not possible.
By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists
A vaginal speculum examination is a routine component of a mare reproductive evaluation. The goals of a
speculum examination are to evaluate anatomic characteristics of the cervix relative to stage of the estrous
cycle and to detect abnormal conditions of the vagina and cervix...
Foals and Foaling
by Patrick M. McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Retention of the placenta is one of the most common problems of the mare in the early postpartum period. A
placenta is considered to be retained if it has not passed within 3 hours after foaling. The incidence increases
following abortion, dystocia, obstetrical manipulations, cesarean surgery, induction of labor, placental
infections, fescue toxicity and other factors.
by Patrick M. McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
A majority of foals will exhibit diarrhea at some time within the first 2 months of life. In most cases, the
diarrhea is mild, transient, not contagious to other foals and not life threatening. However, in some
instances, diarrhea can be contagious, severe and possibly even fatal.
by Patrick M. McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Rejection of a foal by its dam can take several forms. The mare may avoid the foal, prevent the foal from
nursing, or may become aggressive toward the foal. Mares in the latter category may assume a threatening
posture, pin their ears back when the foal approaches, charge or chase the foal, squeal at the foal, or in more
serious cases, may kick at or bite the foal. Mares have, on rare occasions, seriously injured or killed their foals
in the first few days after giving birth.
by Patrick M. McCue, DVM, Ph.D., Diplomat American College of Theriogenologists
Patrick M. McCue presents an informative array of facts and tips that will be of interest to beginning and
experienced equine breeders alike.
By Patrick M. McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Newborn foals enter the world without antibody protection. Foals are entirely dependent on antibodies
absorbed following ingestion of mare's colostrum in the first few hours of life for protection against infectious
diseases.
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Colostrum is the thick, sticky yellow fluid produced by the mammary gland of the mare during the last few weeks
of pregnancy. It is comprised of carbohydrates, fats, proteins and electrolytes. Colostrum is rich in antibodies
or immunoglobulins that are critically important for immune protection of the newborn foal.
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Meconium is comprised of digested amnionic fluid, gastrointestinal secretions, bile, and cellular debris that
accumulate in the intestinal tract of the late-term fetus.1 It is usually dark greenish brown or black in color, firm
pellets to pasty in consistency and is generally passed within the first 3 to 4 hours after birth.
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
An owner or farm manager generally does not know in advance which foal will need supplemental colostrum.
An on-site supply of frozen colostrum can be critical for the health of a valuable neonate.
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
The placenta is the connection between the developing fetus and the mare and provides the means for btaining
nutrition and for gas exchange. Examination of the placenta can offer valuable insight into the health of the
newborn foal. Consequently, it is recommended that owners, farm managers or foaling attendants perform an
evaluation of each placenta.
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Neonatal isoerythrolysis (NI) or Jaundice Foal Syndrome is an uncommon but potentially life-threatening
condition of newborn foals. It has been estimated to occur in 1-2 % of equine births. The condition occurs when
a foal ingests colostrum containing antibodies directed against its red blood cells (RBC’s). Destruction of
RBC’s leads to release of a pigment called bilirubin that may cause the gums, white parts of the eye and feces
to become yellow or jaundiced...
by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Colostrum is the thick, sticky yellow fluid produced by the mammary gland of the mare during the last few weeks
of pregnancy. It is comprised of carbohydrates, fats, proteins and electrolytes. Colostrum is rich in antibodies
that are critically important for immune protection of the newborn foal. The process by which foals acquire
antibodies from the colostrum of their dam is called ‘passive transfer of immunity’.
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by Patrick McCue, DVM, Ph.D., Diplomate American College of Theriogenologists
Late-term pregnant mares should be monitored closely and ideally the foaling should be attended by a
nowledgeable and responsible person who can intervene appropriately if something goes awry. The last few
days prior to foaling can be especially tedious for an owner, farm manager or the foaling staff.
