Research In Action: Finding Better Treatments For Placentitis

by Natalie Voss


Placentitis is the sneaky foe of many a breeder or broodmare manager. The condition can arrive with no calling card, or such mild symptoms that they’re easily missed. By the time a pregnant mare’s caretakers are aware of it, it’s often too late to save the foal.

It’s been the leading cause of pregnancy loss, especially late pregnancy loss, in horses for years.

Dr. Margo Macpherson, professor emeritus at the University of Florida’s College of Veterinary Medicine, has been one of many researchers trying to figure out how to stop it in its tracks.

FREE Webinar presented by LTBA: Pregnancy basics in the mare, when it goes right and when it goes wrong!

FREE Webinar presented by LTBA
Pregnancy basics in the mare, when it goes right
and when it goes wrong!
Tuesday, March 14⋅2:00 – 3:00 pm

Presentation by Jenny L. Sones, DVM, PhD
Diplomate, ACT
Associate Professor of Theriogenology
School of Veterinary Medicine
Louisiana State University

Jenny L. Sones, DVM, PhD is an Associate Professor of Theriogenology (Reproductive Medicine) at Louisiana State University School of Veterinary Medicine. She received my Bachelor of Science and Doctor of Veterinary Medicine degrees from Louisiana State University in 2004 and 2008, respectively. Following a year in private veterinary practice at Delta Equine Center (Vinton, LA), she pursued advanced training in reproductive physiology as a PhD student and Theriogenology resident at Cornell University from 2010-2015. Her current appointment in the department of Veterinary Clinical Sciences, December 2015-present, includes clinical service, biomedical research, and instruction of undergraduate, graduate, veterinary students and residents.

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Ask Your Veterinarian: Putting Broodmares Under Lights

by Paulick Report Staff


Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock.

Question: When it comes to putting broodmares under lights for cycling are overhead lights or mask lights better? And why does it work?

Dr. Peter Sheerin, Rood and Riddle Equine Hospital: In many breeds, Jan. 1 is considered the birthdate for all horses in the breed, no matter when they are born. This can put late-born foals at a disadvantage when competing or at yearling sales. Because of this, many breeders want their mares to foal as early as possible.

The horse is considered a long day breeder, meaning they are cycling when the days are longer. Mares left at natural conditions in the Northern Hemisphere will typically start cycling late March to early April. Mares further north will start cycling later than mares closer to the equator. Researchers determined that by artificially increasing the day length and the amount of light that mares were exposed to, one could get mares to cycle earlier. Mares did not begin to cycle for 60 to 75 days after the beginning of exposure to longer days. So, for a breeding season that starts Feb. 15, one would start lights Dec. 1 at the latest.


Read Paulick Report Article

Mare and Foal Workshop available now online

Horse owners can gain insight on care, foaling process


Horse owners and managers can learn about important topics related to managing the broodmare and foal by attending the online Mare and Foals Workshop, presented by Texas A&M AgriLife Extension Service on AgriLife Learn.

A foal looks away as its mother grazes on lush green grass below a tree
A mare grazes on lush green grass with her foal by her side. (Texas A&M AgriLife photo by Tamara Garza)

Horse owners and breeding managers who might need extra guidance in the foaling process, along with some practical guidelines, are invited to access the course. The course cost is $75, and is available at

The content was developed by industry experts and is presented by instructors Jennifer Zoller, Ph.D., and Chelsie Huseman, Ph.D., AgriLife Extension horse specialists in the College of Agriculture and Life Science’s Department of Animal Science, Bryan-College Station.

Those taking the course will learn about the foaling process, including predicting and preparing for foal arrival, postpartum placental evaluation, proper nutrition for a pregnant mare and foal, and vaccination programs for the broodmare and foal. There will also be information on vaccination administration guidelines.

Instructors provide multiple trainings

Huseman conducts education across the state for adults and youth through seminars, short courses and other educational programs. Her research interests are in the areas of skeletal adaptation to exercise and equine reproduction management. Her most recent work includes testing whole-body vibration and its effect on the skeleton and new technologies for semen analysis.

Zoller provides statewide leadership for planning, implementing, conducting and evaluating AgriLife Extension education programs in equine sciences. She provides leadership with the State 4-H Horse Show, Texas Horse Help mobile application and horse judging competitions across the state. Her research interests include energy balance, manipulating the body condition of the exercising horse to maximize nutrition programs, and the health benefits of participating in equine activities.

Equine reproductive short course

Huseman and Zoller also conduct the annual Texas A&M Equine Reproductive Management Short Course designed for owners and breeding managers who want to learn the most efficient methods for ensuring the success of their breeding programs.

This interactive, three-day short course will be held Jan. 12-14 at the Texas A&M University Thomas G. Hildebrand Equine Complex, 3240 F&B Road, College Station. The in-person course is limited to 12 people, and the fee is $700. However, this course is also available online for $300 at

For more information, email or or call 979-845-5264.


What Medications Are Safe for Mares?

Giving medications to pregnant mares is never without risk and should always be discussed with your veterinarian.

Which drugs are safe for use in pregnant mares? 

My pregnant mare is colicking … can I give her Banamine? She needs a laceration sutured … is it safe for her to get a sedative? What about her fall vaccines?

Which common drugs and medications are safe for use in pregnant mares is a huge topic with more questions than answers, says Margo Macpherson, DVM, MS, Dipl. ACT, professor of large animal reproduction at the University of Florida’s College of Veterinary Medicine, in Gainesville. This is primarily because very few drugs have been thoroughly evaluated and validated for use in this population.

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Pregnancy Problems: How to Increase Your Chances of Delivering a Healthy Foal

By Jen Roytz

What could be that difficult about breeding? You select a stallion that suits the mare and your goals, breed your mare, then keep her fed and watered for 11 months until you’re rewarded with a healthy foal.

If only it were that simple.

There are many reasons a mare can prove difficult to get into foal, or to stay in foal. It could be as simple function of age. It could be results from a complicated delivery. Or, it could be a multitude of other reasons.

Regardless, now is the time breeders should be paying special attention to preparing their breeding stock for the upcoming season, and for those with known issues there are added safeguards and steps breeders can take she gave themselves and their horses the best chance at a successful pregnancy.

Issues that Can Impact Conception

There are many reasons a horse may have issues getting impregnated, the most basic of which are her age, not breeding her at the appropriate time during her cycle, or poor reproductive health of the mare or stallion.

A typical mare’s ovum, or egg, begins to lose viability within just five to six hours post-ovulation, and typically loses all viability within 24 hours. While a stallion’s semen typically remains viable for 48 hours, a reduced number and quality of a stallion’s semen can limit its viability to just a few hours. Age can negatively impact these timeframes for both sexes.

The mare’s body condition can also play into her chances of becoming pregnant. Most veterinarians recommend mares to rank around a 5 or a 6 on the Henneke Body Condition Score (BCS). When a mare’s weight and overall health decline, so too does their reproductive efficiency.

Outside of age and general health-related issues, endometritis is the most common reason for infertility in mares. This condition, which is an infection or inflammation of the lining of the uterus caused by foreign contaminants such as bacteria or spermatozoa, can either be acute as a result of breeding (both artificial and natural), reproductive examination or as a result of poor conformation.

“There are simple, but important steps one can take to improve the chances of conception, including a physical examination of both the mare and the stallion, a careful and thorough reproductive exam of the mare prior to the breeding season and during the estrous cycle during which breeding is to occur and to optimize the overall health of the horse,” said Kristina Lu, VMD, an equine reproductive specialist with Hagyard Equine Medical Institute.

Early vs. Late Term Pregnancy Loss

Just as there are a number of reasons a mare can be difficult to impregnate, the same can hold true for keeping her in foal. Most pregnancy losses occur in the initial weeks and months of pregnancy.

Again, age can play a role. As mares age, they may experience uterine fibrosis, which can lead to a placenta that is less-efficient in getting nutrition to the growing fetus.

Other causes for early-term pregnancy loss can be unavoidable complications, such as genetic defects or embryonic abnormalities. They can also be due to uterine infections that may have been low-grade and undetectable at the time of breeding/conception but proliferate in the subsequent weeks and months.

Late-term losses can have their own set of culprits.

“Placentitis, umbilical cord torsion, systemic illness can all cause late, and in some cases mid-term abortion in mares,” said Lu. “Diseases such as leptospirosis, equine herpesvirus 1 or 4 and equine viral arteritis are threats to a healthy gestation as well, some of which can spread quickly through a herd and may not generate obvious clinical signs other than abortion.”

Then there are also those mares that have little trouble carrying a foal to term, only to be prone to dystocias (difficulty giving birth), which can be caused by congenital abnormalities, such as contracted limbs that prevent the foal from properly fitting through the birth canal. This, in turn, can lead to oxygen deprivation in foals.

Safeguards to Protect Both Mare and Foal

While some complications are simply unavoidable, there are safeguards and protocols that can be implemented to support the gestation and delivery of a healthy foal.

“Some simple things horsemen and women can do to protect their mares and future foals are to maintain good general health of a mare, conduct thorough reproductive examinations, monitor the mare’s reproductive tract before and after breeding, ensure regular core vaccinations, consider screening for placentitis if the mare has a previous history and consider vaccinating for herpes or leptospirosis if appropriate,” said Lu. “Breeding as close to ovulation as possible can also be of benefit. On the other hand, repeated breeding during an estrous cycle (average 21 days) may increase opportunity for endometritis in some mares.”

Above all else, staying in regular communication with your veterinarian is one of the best forms of protection one can afford their mares.