The Silent Threat: Understanding Placentitis in Pregnant Mares

Amidst the excitement and anticipation of equine pregnancy, a silent threat looms – placentitis. Unlike more overt ailments, placentitis operates surreptitiously, often without conspicuous symptoms. This condition involves inflammation of the placenta, the essential organ that facilitates the exchange of nutrients and oxygen between the mare and the developing foal. Placentitis poses a considerable risk to the health of both the mare and the unborn foal, yet its silent nature makes early detection a formidable challenge. In this blog, we delve into the nuances of placentitis, exploring its causes, and subtle signs, and emphasizing the imperative need for proactive measures to safeguard the health of pregnant mares and their precious offspring.

Placentitis can result from various factors, and understanding these common causes is essential for proactive management:

• Infections: Bacterial or fungal infections can ascend from the mare’s reproductive tract into the uterus, causing inflammation in the placenta. Common pathogens involved include Streptococcus species and E. coli.
• Ascending Infections: In some cases, bacteria can ascend through the cervix and reach the uterus, leading to placentitis. This often occurs when there are anatomical abnormalities or after multiple breedings.
• Environmental Factors: Poor stable hygiene, exposure to contaminated bedding, and unsanitary conditions can contribute to the development of placentitis.
• Endocrine Disorders: Hormonal imbalances or underlying endocrine disorders in the mare may increase the risk of placentitis. Recognizing these potential causes allows for targeted preventive measures and early intervention, emphasizing the need for vigilant monitoring during pregnancy.

While outward, obvious symptoms may be lacking, there are subtle signs that vigilant caretakers can observe, suggesting the presence of placentitis:

• Vaginal Discharge: A persistent, abnormal discharge from the mare’s vagina can be a sign of placentitis. This discharge may vary in color and consistency.
• Changes in Udder: Premature udder development or changes in udder consistency may be observed, indicating hormonal fluctuations associated with placentitis.
• Behavioral Changes: Mares affected by placentitis might exhibit changes in behavior, such as increased restlessness, discomfort, or a reluctance to move.
• Abnormal Fetal Movement: Changes in the pattern of fetal movement or a decrease in fetal activity may be noticed.
• Reduced Appetite: Mares may show a decrease in appetite, and in some cases, weight loss may occur.
• Enlarged Vulva: Swelling or enlargement of the vulva can be a subtle indicator of underlying reproductive issues, including placentitis.

Placentitis can be influenced by a combination of environmental, mare-related, and other factors. Understanding these risk factors is crucial for implementing preventive measures and early detection strategies:

• Previous History of Placentitis: Mares with a history of placentitis in previous pregnancies are at an increased risk. Prior occurrences may indicate underlying predisposing factors that need careful management.
• Age of the Mare: Younger and older mares may be more susceptible to placentitis. Older mares, in particular, may have compromised uterine function, while younger mares may not have fully developed immune responses.
• Multiparous Mares: Mares that have had multiple pregnancies (multiparous) may be at a higher risk. Repetitive cycles of pregnancy and parturition can contribute to uterine changes that increase vulnerability.
• Uterine Anomalies: Structural abnormalities in the mare’s reproductive tract, such as a malformed cervix or uterus, can create conditions conducive to bacterial ascent, increasing the risk of placentitis.
• Twin Pregnancies: Mares carrying twins are more prone to placentitis due to the increased strain on the placenta and heightened risk of complications.

• Hygiene and Sanitation: Poor stable hygiene and unsanitary conditions increase the likelihood of bacterial contamination. Regular cleaning of stables, proper disposal of manure, and maintaining clean bedding are essential preventive measures.
• Geographic Location: Certain geographical regions may have environmental factors, such as climate and soil conditions, that contribute to the prevalence of bacterial agents associated with placentitis.
• Seasonal Influences: Environmental factors, including changes in temperature and humidity, can impact the risk of placentitis. Certain seasons may be more conducive to the growth of bacteria associated with placentitis.
• Overcrowding: Mares housed in crowded conditions are at a higher risk of exposure to pathogens. Overcrowding can lead to increased stress, making the mare more susceptible to infections.

• Immunosuppression: Any condition that compromises the mare’s immune system, such as concurrent illness or certain medications, increases the risk of placentitis.
• Endocrine Disorders: Hormonal imbalances, such as those associated with metabolic disorders like equine metabolic syndrome (EMS) or Cushing’s disease, can contribute to an increased risk of placentitis.
• Poor Body Condition: Mares that enter pregnancy in poor body condition may be more vulnerable to systemic issues that can affect the placenta. Maintaining optimal body condition through proper nutrition is crucial.
• Reproductive Tract Infections: Pre-existing infections in the mare’s reproductive tract can serve as a source for ascending bacterial infections, leading to placentitis.

Understanding these risk factors allows equine caretakers and veterinarians to tailor management practices and monitoring protocols, reducing the likelihood of placentitis and enhancing the overall health and well-being of pregnant mares.

• Clinical Examination: A thorough clinical examination by a veterinarian is an essential first step. This includes assessing the mare’s overall health, observing any behavioral changes, and checking for physical signs such as abnormal vaginal discharge or changes in udder development.
• Rectal Palpation: Veterinary professionals may perform rectal palpation to assess the size, shape, and consistency of the uterus. This allows them to detect any abnormalities or signs of inflammation.
• Blood Tests: Bloodwork can be instrumental in identifying signs of systemic inflammation or infection. Elevated white blood cell counts and changes in acute-phase proteins may indicate the presence of placentitis.
• Hormonal Assays: Measurement of hormone levels, including progesterone, can provide insights into the mare’s reproductive health. Disturbances in hormonal balance may be indicative of placentitis.
• Endometrial Biopsy: In some cases, a biopsy of the endometrial lining may be performed. This involves taking a small tissue sample for microscopic examination, helping to diagnose inflammation or infection.

• Transabdominal Ultrasound: Ultrasound is a crucial diagnostic tool for assessing the health of the placenta and monitoring the developing fetus. Transabdominal ultrasound involves placing the ultrasound probe on the mare’s abdomen to visualize the uterus and placenta.
• Measurement of Placental Thickness: An important aspect of ultrasound diagnosis is measuring the thickness of the placenta. Increased thickness may indicate inflammation.
• Assessment of Fetal Well-being: Ultrasound allows veterinarians to monitor the fetus’s heartbeat, movement, and position, providing valuable information about its well-being.
• Detection of Placental Separation: Ultrasound can help identify placental separation, a serious complication of placentitis that can lead to abortion.

• Early Detection and Intervention: Regular veterinary check-ups throughout the pregnancy are critical for early detection of any potential issues, including placentitis. Early intervention can significantly improve the chances of a positive outcome.
• Monitoring Fetal Development: Regular ultrasounds allow veterinarians to monitor the growth and development of the fetus, ensuring it is on track for a healthy birth.
• Adjustment of Management Practices: Regular check-ups provide an opportunity to adjust management practices based on the mare’s evolving needs. This includes nutrition, exercise, and environmental considerations.
• Preventive Measures: Routine veterinary visits enable the implementation of preventive measures, such as vaccinations and hygiene protocols, to minimize the risk of infections that can lead to placentitis.
• Client Education: Regular check-ups also offer the opportunity for veterinarians to educate horse caretakers on signs to watch for and best practices for maintaining a healthy pregnancy.

In summary, a combination of clinical examinations, advanced diagnostic tests, and regular veterinary check-ups, especially involving ultrasound, is crucial for monitoring the health of pregnant mares and detecting placentitis at its earliest stages. Early intervention based on these diagnostics is key to ensuring a successful and healthy pregnancy outcome.

Untreated placentitis can have profound effects on the health of the mare, extending beyond the reproductive system:

• Systemic Infection: As placentitis progresses, the risk of a systemic infection increases. Bacteria can enter the bloodstream, leading to conditions such as metritis or septicemia, posing a severe threat to the overall health of the mare.
• Uterine Damage: Chronic inflammation associated with untreated placentitis can cause damage to the uterus, compromising its future reproductive capacity. This can lead to difficulties in conceiving or carrying subsequent pregnancies.
• Increased Risk of Laminitis: Mares with placentitis are at a higher risk of developing laminitis, a painful and debilitating condition affecting the hooves. Laminitis can have long-term consequences on the mare’s mobility and well-being.

The consequences of untreated placentitis extend to the developing foal, impacting various aspects of its health and viability:

• Inadequate Nutrient Supply: Placentitis can disrupt the normal exchange of nutrients between the mare and the foal. Insufficient nutrient supply can lead to intrauterine growth restriction (IUGR), affecting the foal’s overall size and development.
• Preterm Birth or Stillbirth: Severe cases of placentitis can result in premature separation of the placenta, leading to preterm birth or stillbirth. The foal may be born underdeveloped and face significant challenges in survival.
• Respiratory Distress: Foals born to mares with placentitis may experience respiratory distress syndrome due to underdeveloped lungs. This condition can pose a life-threatening risk to the foal.

• Dystocia (Difficult Birth): Placentitis can lead to changes in the mare’s cervix and birth canal, increasing the risk of dystocia during labor. Difficulties in the birthing process can be dangerous for both the mare and the foal.
• Increased Vulnerability to Infections: Foals born to mares with untreated placentitis are more susceptible to infections, as their immune systems may be compromised. This vulnerability can lead to various health complications during the neonatal period.
• Neonatal Sepsis: The risk of neonatal sepsis, a systemic infection in the newborn foal, is heightened when placentitis is left untreated. This condition can be life-threatening and requires immediate veterinary intervention.
• Long-term Health Issues: Foals that survive placentitis-related complications may face long-term health issues, including developmental abnormalities, musculoskeletal problems, and an increased susceptibility to infections.

Understanding the severe repercussions of untreated placentitis emphasizes the critical need for early detection and prompt veterinary intervention. Timely management not only mitigates the immediate risks to the mare and foal but also plays a crucial role in ensuring their long-term health and well-being.

• Regular Veterinary Check-ups: Implementing a comprehensive management plan begins with regular veterinary check-ups throughout the mare’s pregnancy. These check-ups enable early detection of potential issues, including signs of placentitis, allowing for timely intervention.
• Nutritional Support: Providing a well-balanced and nutritionally appropriate diet for pregnant mares is essential. Adequate nutrition supports the mare’s overall health and ensures proper fetal development, reducing the risk of complications such as placentitis.
• Stress Management: Minimizing stress is crucial for maintaining the health of pregnant mares. Stress can contribute to hormonal imbalances and compromise the immune system, increasing the susceptibility to infections associated with placentitis.
• Hygiene and Cleanliness: Maintaining a clean and hygienic environment is paramount. Regular stall cleaning, proper disposal of manure, and routine disinfection of facilities help reduce the risk of bacterial contamination, a key contributor to placentitis. We completely disinfected every stable after a mare foaled, we would move her into a new stables and disinfect the stable she foaled in before another mare came into it to foal.
• Isolation of High-Risk Mares: Mares with a history of placentitis or those identified as high-risk individuals may benefit from isolation. Separating them from the general population reduces the likelihood of exposure to pathogens that could trigger placentitis. If a mare loses her foal in a paddock with other mares it is very important to remove them from that paddock so they do not catch any infections from sniffing the aborted foal.

• Rhodococcus equi Vaccine: Rhodococcus equi is a bacterium associated with placentitis. Vaccination against Rhodococcus equi can be considered, especially in areas where this bacterium is prevalent. Consultation with a veterinarian is essential to determine the appropriateness of this vaccination for individual cases.
• Influenza and Herpesvirus Vaccination: Vaccination against equine influenza and herpesviruses is crucial for preventing respiratory infections that can potentially lead to systemic issues, including placentitis. Discussing an appropriate vaccination schedule with a veterinarian is key.
• Tetanus Toxoid: Tetanus vaccination is a standard practice for all pregnant mares to prevent this potentially deadly bacterial infection. Ensuring that mares are up-to-date on tetanus vaccination is essential for overall herd health.

• Proper Bedding and Stall Management: Ensuring clean and dry bedding in stalls is essential. Wet or soiled bedding can harbor bacteria, increasing the risk of ascending infections. Regular cleaning and appropriate bedding materials contribute to a healthier environment.
• Paddock Rotation: If possible, rotate pastures to minimize exposure to potentially contaminated areas. This practice helps reduce the overall bacterial load in the environment and lowers the risk of placentitis.
• Quarantine and Biosecurity Measures: Implementing quarantine measures for new additions to the herd and practicing biosecurity protocols can prevent the introduction of infectious agents that may contribute to placentitis. Any new horses coming onto your stud farm must be kept away from your breeding stock for at least 6 weeks and if close to foaling until a healthy foal as been born.
• Monitoring and Prompt Intervention: Regularly monitor pregnant mares for any signs of distress or abnormal behavior. If any concerning signs emerge, prompt veterinary intervention is crucial to address potential issues before they escalate.
• Controlled Exercise: Moderate, controlled exercise is beneficial for pregnant mares. However, excessive physical stress should be avoided, as it can contribute to hormonal imbalances that may increase the risk of placentitis.

Implementing a comprehensive prevention plan that includes good management practices, vaccination considerations, and environmental modifications is essential for reducing the risk of placentitis in pregnant mares. Regular collaboration with a knowledgeable veterinarian ensures that these strategies are tailored to the specific needs of the individual mare and her pregnancy.

• Progesterone Supplementation: Progesterone supplementation may be considered to support the maintenance of pregnancy, especially if placentitis has led to hormonal imbalances. This can help stabilize the uterine environment and support fetal development.
• Fluid Therapy: Mares with placentitis may benefit from intravenous fluid therapy to address dehydration, maintain electrolyte balance, and support overall physiological function.
• Pain Management: If the mare is experiencing discomfort or pain, appropriate pain management measures may be implemented to improve her overall well-being.
• Nutritional Support: Providing a carefully balanced and nutritionally appropriate diet is crucial during treatment. Proper nutrition supports the mare’s overall health and the developing foal, aiding in their recovery.

• Ultrasound Monitoring: Regular ultrasound examinations are essential for monitoring the progress of treatment. This includes assessing the health of the placenta, monitoring fetal development, and ensuring the effectiveness of interventions.
• Bloodwork: Continued blood tests may be conducted to monitor the mare’s overall health, assess the response to antibiotic therapy, and detect any signs of systemic infection.
• Reassessment of Treatment Plan: Treatment plans are dynamic and may need adjustment based on the mare’s response to therapy. Veterinarians may reassess the situation periodically, making necessary changes to optimize outcomes.
• Preventive Measures for Future Pregnancies: Following successful treatment, considerations for preventive measures in future pregnancies may be discussed. This may include vaccination protocols, environmental management strategies, and ongoing monitoring.
• Pregnancy Monitoring until Term: Mares treated for placentitis require continuous monitoring until term to ensure a successful outcome. This involves vigilant observation for any signs of relapse or complications that may arise in the later stages of pregnancy.

The success of the treatment for placentitis hinges on early detection, prompt veterinary intervention, and a comprehensive approach to address both the mare’s and the foal’s well-being. Ongoing collaboration with a knowledgeable veterinarian is crucial for navigating the complexities of treatment and ensuring the best possible outcome for the pregnant mare and her foal.

• Case Study 1: “Whisper”
• Background: Whisper, a 10-year-old Thoroughbred mare, was in her second trimester of pregnancy when she exhibited signs of discomfort and a vaginal discharge. Upon veterinary examination and ultrasound, placentitis was diagnosed.
• Interventions: Whisper underwent a comprehensive treatment plan which included antibiotic therapy and anti-inflammatory medications. She was hospitalized for close monitoring, and cervical cerclage was performed to prevent further complications.
• Outcome: With diligent veterinary care and supportive measures, Whisper successfully carried her pregnancy to term. The foal, although born prematurely, received neonatal care and grew into a healthy, thriving individual. This case highlighted the importance of early detection and a multidimensional treatment approach.
• Case Study 2: “Luna”
• Background: Luna, a 7-year-old Quarter Horse mare, presented with a sudden decrease in appetite and changes in behavior during her third trimester. Ultrasound examination revealed signs of placentitis.
• Interventions: Luna was promptly started on a course of antibiotics and anti-inflammatory medications. She received nutritional support and was closely monitored through regular ultrasound examinations.
• Outcome: Despite intensive care, Luna experienced premature placental separation, leading to an emergency cesarean section. Unfortunately, the foal did not survive. This case emphasized the unpredictable nature of placentitis and the need for immediate and vigilant intervention.

• Lessons from Whisper’s Case:
  • Importance of Early Detection: Whisper’s case underscored the significance of early detection through regular veterinary check-ups and prompt response to subtle signs.
  • Multifaceted Treatment: The success in Whisper’s case was attributed to a comprehensive treatment plan, combining antibiotics, anti-inflammatories, and cervical cerclage.
• Lessons from Luna’s Case:
  • Unpredictability of Placentitis: Luna’s case highlighted the unpredictable nature of placentitis, even with early detection and aggressive treatment.
  • Emergency Preparedness: Luna’s case emphasized the need for preparedness for potential complications, including the possibility of an emergency cesarean section.
  These case studies illustrate the diverse nature of placentitis cases and the importance of tailoring treatment plans based on individual circumstances. They also emphasize the need for ongoing research and education to enhance our understanding of this complex condition and improve outcomes for pregnant mares and their foals.

The key to mitigating the impact of placentitis lies in awareness and early detection. Vigilant caretakers and breeders play a pivotal role in recognizing the subtle signs that may indicate the presence of this silent threat. Routine veterinary check-ups, thorough monitoring, and a keen understanding of risk factors enable early intervention, offering the best chance for successful outcomes in equine pregnancies.

Awareness is the cornerstone of proactive equine care. Horse owners and breeders must familiarize themselves with the nuances of placentitis, staying attuned to changes in behavior, signs of distress, and other subtle indicators that may hint at an underlying issue. Regular communication with veterinarians, especially during the later stages of pregnancy, facilitates the timely implementation of diagnostic tests and intervention strategies.

Responsible breeding practices encompass more than selecting suitable stallions and ensuring optimal living conditions for pregnant mares. They involve a commitment to thorough veterinary care, proactive management, and a dedication to the overall well-being of the equine population. Breeders should prioritize preventive measures, including vaccinations, hygiene protocols, and environmental modifications that reduce the risk of placentitis.

The message is clear: responsible breeding is synonymous with responsible care. Through informed decision-making, early detection, and collaborative efforts between caretakers and veterinarians, the equine community can collectively work towards minimizing the impact of placentitis. By placing the health and welfare of mares and foals at the forefront, we contribute to the sustainability and vitality of the equine world.

In conclusion, placentitis remains a silent adversary, but with knowledge, vigilance, and a commitment to responsible care, we can navigate its challenges and ensure the health and prosperity of future equine generations. As stewards of these magnificent creatures, our dedication to their well-being echoes through each pregnancy, and each foal’s first steps, and resonates in the enduring legacy of the equine world.

1. Books:
   • “Equine Reproductive Procedures” by John Dascanio, DVM
   • “Manual of Equine Reproduction” by Steven P. Brinsko, Terry L. Blanchard, Dickson D. Varner
2. Articles:
   • “Recent Advances in Assisted Reproductive Technologies in Horses”
   • “Factors Affecting Fertility in Mares: A Review”

These resources provide valuable information on various aspects of equine reproductive health, including placentitis, and are trusted references for horse owners, breeders, and enthusiasts seeking to deepen their understanding of equine reproduction. Always ensure to cross-reference information from multiple reputable sources to obtain a well-rounded perspective on the topic.