Collaborative Care Saves Mare During Unsuccessful Pregnancy

Thanks to the team approach to patient care at the UC Davis William R. Pritchard Veterinary Medical Teaching Hospital (VMTH), Lucy survived a rare pregnancy complication. The 18-year-old American Quarter Horse mare was discovered to have a non-viable fetus and was treated for a potentially fatal infection and escaped development of life-threatening complications.

“Unfortunately, not all horse pregnancies result in successful births of healthy foals,” stated Dr. Catherine Renaudin, chief of the VMTH’s Equine Reproduction Service. “Lucy’s case was extremely rare – I have only seen one other in my entire career.”

Dr. Renaudin, a world leader in fetal ultrasonography in horses, and equine reproduction resident Dr. Flavia Vieira, treated Lucy when she was brought to the VMTH’s Large Animal Hospital after her owner noticed things were not right as Lucy approached her due date.

“Horses start to bloom in their belly and udder later in pregnancy,” said owner Barbara Wilson. “But I noticed Lucy wasn’t developing ‘milk veins’ in her belly and udder toward her due date.”

It was difficult for Wilson to determine if something was wrong simply based on Lucy’s size. Lucy was previously diagnosed with pituitary pars intermedia dysfunction (PPID), a common, slowly progressive endocrine disorder in older horses, formerly known as Equine Cushing’s Disease. This metabolic disease caused Lucy to be overweight regardless of her pregnancy.

Wilson contacted Lucy’s primary veterinarian who performed an ultrasound that showed a non-moving, small fetus for such a late stage in the pregnancy. She referred Lucy to UC Davis immediately.

A transrectal ultrasound examination by Drs. Renaudin and Vieira confirmed a non-viable fetus.

“Based on femur length, we were able to determine that the fetus died in utero at around 100 days of gestation,” said Dr. Renaudin.

A full-term pregnancy in a horse is 340 days. Lucy presented to UC Davis at 353 days.

Dr. Renaudin was able to determine age of the fetus based on her prominent research that is known for pioneering and detailing advanced methods for equine fetal ultrasonography, particularly focusing on fetal gender determination, fetal bone development, and gestational age.

Through this extensive research, Dr. Renaudin has established measurements for the sizes of different parts of a fetus (head, femur, eyes, etc.) throughout pregnancy. She has completed tables of these expected measurements for the American Quarter Horse, Warmblood, and light breed horses. These tables have become useful for veterinarians to determine gestational age when unknown and to track proper growth pace when gestational age is known.

Following extraction of the non-viable fetus, Lucy developed metritis, an infection of the uterine wall. Her bloodwork revealed systemic signs of inflammation and infection, prompting the use of systemic antibiotics and anti-inflammatory medications. Having already been diagnosed with PPID, Drs. Renaudin and Vieira feared the possible onset of endotoxemia-associated laminitis secondary to the metritis, so they started Lucy on preventive treatments for laminitis and supportive care.

Due to these potential complications, Lucy was transferred to the Equine Internal Medicine Service where Dr. Rana Bozorgmanesh, Dr. Gary Magdesian, and equine internal medicine resident Dr. Mathilde Fournier continued her care.

“One of the many advantages of having an animal treated at UC Davis is the collaborative care environment at the hospital,” said Dr. Renaudin. “Various specialty services routinely work together to cover every aspect of a patient’s case, all under one roof. Lucy’s case showed the importance of working together with internal medicine specialists and having the unique ability to seamlessly transfer a case in-house for the best continuity of care and safety of the mare.”

Lucy responded well to treatment, showing significant improvement within 48 hours. Drs. Renaudin and Vieira complemented internal medicine’s care by continuing to flush Lucy’s uterus daily until the volume of intrauterine fluid decreased and the fluid collected during each lavage became progressively clearer.

After six days in the hospital, Lucy’s care team determined she was well enough to return home. At her two-week recheck appointment, Lucy’s primary veterinarian reported that she is recovering well. She never developed laminitis.

"Even with dedicated owners and appropriate prenatal care, unexpected complications can still occur," said Dr. Renaudin. "Routine examinations throughout pregnancy, particularly during the last month before term, give us an opportunity to assess fetal presentation and positioning and, when possible, prepare owners for any additional care that may be needed during delivery."

The Equine Reproduction Service can assist horse owners with any concerns during their mare’s pregnancy or to help owners plan the best approach to welcoming the next generation of their horse’s lineage. 

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