Category Archives: ultrasound

Estimate Fetal Age

Posted: | October 15, 2023

A New Method to Estimate Fetal Age in the Mare Sometimes there arises a need to estimate fetal age in the mare, for which a breeding date perhaps is unknown. Several methods have been previously identified, such as measurement of the fetal eye[1][2], or biparietal diameter, eye approximated volume, fetal aortic diameter and femur length[3], among others. These… Read More »

Steroidal Secretion Effects on Uterine Ultrasound Characteristics

Posted: | October 27, 2021

Ultrasound Characteristics of the Uterus in the Cycling Mare and their Correlation with Steroid Hormones and Timing of Ovulation – By Jonathan Pycock, BVetMed, PhD, DESM, MRCVS, RCVS Specialist in Equine Reproduction – Steroid Effects on Uterine Ultrasound in the Mare By Jonathan F Pycock, BVetMed, PhD, DESM, MRCVS, RCVS Specialist in Equine Reproduction The introduction of transrectal… Read More »

Double Trouble – The Twin Dilemma

Posted: | February 3, 2021

Managing Twinning in the Mare – While most equine pregnancies are simple, twinning when it happens is an issue. Here we discuss managing twinning in the mare. By Jos Mottershead and Kathy St. Martin You’ve read all the articles at, your mare was in heat, you jumped through all the various hoops you needed to in order… Read More »

The Oxytocin Protocol!

Posted: | February 1, 2021

Oxytocin use in the mare during breeding – Delayed Uterine Clearance and Breeding-Induced Endometritis problems can be helped by Oxytocin use when breeding a mare! By Jos Mottershead Oxytocin acts on smooth muscle in the body, causing it to contract. One such area of tissue, which is of tremendous importance relative to breeding, is the mare’s uterus and… Read More »

Anovulatory Hemorrhagic Follicles (AHF)

Posted: | January 23, 2021

Persistent Anovulatory Follicles – Anovulatory Hemorrhagic Follicles, Luteinized Unruptured Follicles, PAFs, AHFs, LUFs – all follicular headaches in the mare! By Jos Mottershead You’re following a mare’s follicular development using ultrasound prior to breeding and are relieved to see a good sized follicle developing. Unusually, the follicle continues to develop beyond the size at which you normally see… Read More »

Predicting Ovulation

Posted: | January 16, 2021

Indications of Impending Ovulation in the Mare – Predicting ovulation in the mare can be a challenge with mares displaying different characteristics. Here we describe some common signs. By Jos Mottershead Predicting ovulation in the mare can be difficult, as they have the capacity to be notoriously unpredictable in their timing! This can lead to frustration, aggravation and… Read More »

Mare Management with Cooled-Shipped or Frozen Semen

Posted: | December 17, 2020

Protocols for Mare Management with Cooled-Shipped or Frozen Semen – methods to time breeding of mares both with and without use of pharmacological manipulation. By Jos Mottershead Mare management with cooled-shipped or frozen semen can often seem daunting but is a key element for success or failure. One can use or forgo pharmacological manipulation, and we discuss here… Read More »

Early Embryonic Death (EED) – what it is and why it may happen

Posted: | December 3, 2020

Early Embryonic Death – Noted reproductive veterinarian Dr. Jon Pycock explores early embryonic death in the mare and some possible resolutions to the problem. By Jonathan F Pycock, BVetMed, PhD, DESM, MRCVS, RCVS Specialist in Equine Reproduction For all horse breeders, it is important to realize that not every mare will give birth to a live foal. Failure… Read More »

Dealing with the Older Maiden Mare Syndrome

Posted: | November 16, 2020

Breeding the Old Maiden Mare – Older maiden mares present problems of their own in achieving pregnancy. Noted reproductive expert Dr Jon Pycock explores some solutions. By Dr. Jonathan F Pycock, B.Vet.Med., Ph.D., D.E.S.M., M.R.C.V.S. Equine Reproductive Services, Messenger Farm, Ryton, Yorkshire Breeding OR inseminating a mare induces an immediate inflammatory response in the uterus. This is a… Read More »