Recumbency decreases mare and foal survival following in-hospital dystocia management

BACKGROUND

Mare and foal survival are increased with prompt dystocia management. Data regarding mortality outcomes in mares and foals, when mares are recumbent at admission for dystocia resolution, are scarce.

OBJECTIVES

To evaluate recumbency at hospital admission as a risk factor for survival of mares and foals following dystocia management. Subsequent mare fertility was also evaluated.

STUDY DESIGN

Retrospective cohort.

METHODS

Data were obtained from medical records at Rood and Riddle Equine Hospital of mares with dystocia between 1995 and 2018. Mare signalment, ambulation status, survival data and foaling records were collected. The proportion of mare survival and mare fertility were analysed using chi-squared tests. Foal survival was analysed using Fisher's exact test. Odds ratios were calculated using multivariable logistic regression.

RESULTS

There were 1038 ambulatory mares and 41 recumbent mares included in the analysis. Survival rates after dystocia resolution were 90.5% (977/1079) in mares and 37.3% (402/1079) in foals. Ambulatory mares had higher odds of survival (OR 6.93, 95% CI: 3.25-14.78, p < 0.001) than recumbent mares. Foals delivered from ambulatory mares had higher odds of survival (OR 22.7, 95% CI: 3.11-165.44, p = 0.002) compared with foals delivered from recumbent mares. Fertility was not statistically different for surviving Thoroughbred mares within 3 years following dystocia resolution between ambulatory and recumbent mares.

MAIN LIMITATIONS

Retrospective study design and small case number of recumbent mares.

CONCLUSIONS

Mare and foal survival was significantly decreased when mares with dystocia were recumbent at hospital admission. Subsequent fertility, as defined for this study, of surviving mares was not affected by ambulation status at the time of dystocia resolution.

[Morbidity and mortality of mare and foal following dystocia - a literature review]

Dystocia represents a life-threatening condition for mare and foal. Morbidity and mortality rates due to a difficult birth, as well as the influence on fertility of the mare were analyzed, based on a review of publications. This was aggravated by the fact that no standardized diagnostic code was used and that most publications do not clearly describe how extensively the examinations were performed beforehand. Retentio secundinarum is the most common complication caused by dystocia. Other complications are injuries to the soft birth canal and the colon. These occur more frequently after surgical obstetrics than following assisted vaginal deliveries. Performing a fetotomy increases the risk of injury to the birth canal. After a caesarean section, the risk for retained placenta increases significantly. In order to evaluate the possibility of medical progress over time, mortality rates of mare and foal were investigated and divided in surgical and conservative obstetrics within the period of 1970-1990 and 1991-2021. The average maternal mortality rate following caesarean section amounted to 18% in the time period between 1970 and 1990 and 14% between the years from 1991-2021. After fetotomy, the two determined mortality rates amounted to 29% and 10% for the time between 1970 and 1990. In the period 1991-2021, the rate varies between 4% and 44% with an average mortality rate of 14%. Following controlled vaginal delivery, the average mortality rate is 9%. Literary sources were however only available for the current time period and range between 6% and 29%. The morbidity and mortality rate of foals is very high. Following caesarean section on average 53% of foals are dead on delivery, with a range of 13-79% in case reports from the years 1991-2021. The number of dead foals in the context of conservative obstetrics is of a similar scale. Postnatal foal diseases are largely due to intrapartum hypoxia during dystocia and obstetric injury. In consequence of a difficult delivery, mares experience reduced fertility. In numerous cases this however may be compensated by pausing from further breeding in the same year. The number of cases evaluated in this context however remains too small to advocate any recommendations for breeding following incidents of dystocia.

Dystocia in the Standardbred Mare: A Retrospective Study from 2004 to 2020

Dystocia as a prolonged stage II parturition (>30 min) was associated with a higher risk of complications. The hypothesis of the study was that any type of dystocia could affect the foal’s health, even when the stage II was <30 min. Clinical reports on 222 Standardbred mares and their foals hospitalized at the Veterinary Teaching Hospital of the University of Bologna from 2004 to 2020 were reviewed. Mares were divided into the Eutocia Group (165, eutocic delivery) and the Dystocia Group (57, dystocic delivery). The incidence of dystocia was 4.9%. Stage II was longer in the Dystocia Group (median 20 min) than in the Eutocia Group (median 12 min). All occurrences of dystocia were retrospectively classified into three categories of severity: mild, moderate and severe dystocia. The occurrence of postpartum complications in mares and neonatal diseases and failure of passive transfer of immunity in foals was higher in the Dystocia Group. Foal venous lactatemia and serum creatine kinase were significantly higher in the Dystocia Group (median 3.9 mmol/L; 262 UI/L respectively) than in the Eutocia Group (median 3.1 mmol/L; 187 UI/L respectively). The APGAR score was lower in the Dystocia Group (median 8) than in the Eutocia Group (median 10) and significantly lower in severe dystocia (median 3). The duration of stage II should not be considered the only parameter of dystocia in mares: even a rapid resolution of dystocia could pose health risks to the foal and the mare.

Prognostic Indicators for Survival and Athletic Outcome in Critically Ill Neonatal Foals

Equine neonatal intensive care units have expanded knowledge and understanding of the normal and abnormal physiology of the equine neonate, resulting in successful treatment of critically ill equine neonates. The overall survival rate has increased tremendously since the early 1980s, from a little more than 50% to 80% or more for most facilities. The severely septic foal and the very premature foal still remain large treatment challenges, but less severely septic foals and foals challenged by adverse peripartum events such as dystocia and placentitis are surviving to hospital discharge and performing to the owners' expectation in larger numbers.

Dystocia in dromedary camels: Prevalence, forms, risks and hematobiochemical changes

The objectives of this study were to investigate the prevalence of dystocia in camel herds, its forms in primi- and multipara, the risks to fetus and dam, and the associated hematobiochemical changes. A total of 1890 calvings were surveyed for the prevalence of dystocia. Cases with dystocia (n=107) were examined for causes and treated with traction, fetotomy or Cesarean section. Logistic regression was performed to identify risk factors. The dependent variables were the fetal and maternal mortality, while the independent variables were parity, duration of dystocia, causes of dystocia, and method of treatment. Blood samples were collected from all dystocia camels and six controls for hematology and concentrations of serum amyloid A (SAA), haptoglobin (Hp), estradiol-17β (E2), progesterone (P4), total protein, albumin, calcium, phosphorus, magnesium, blood urea nitrogen (BUN), creatinine and aspartate aminotransferase (AST). The overall prevalence of dystocia was 8.6%. Risk of dystocia was higher in camels managed in an intensive system than in those in a free system (Odds ratio=1.9, P=0.0003) and higher in primipara than in multipara (Odds ratio 1.7, P=0.005). Abnormal posture was the most important cause of dystocia (51.4%). Uterine torsion was the second most important cause (23.4%) and was mainly observed in multipara (P=0.0006). Dystocia was linked to high fetal mortality (87.9%). A significant relationship was found between fetal death and duration of dystocia (Odds ratio=8.04, P=0.005). The percentage of dam mortality was 17.8%. Significant associations were detected between dam mortality rate and the duration of dystocia (Odds ratio=4.74, P=0.03) and fetal viability (Odds ratio=5.82, P=0.02). Increasing duration of dystocia was associated with significant increases in SAA, Hp, BUN and AST, but with decreases in E2 (P<0.05). After a transient period of elevation, the white blood cell and neutrophil counts decreased (P<0.05). In conclusion, abnormal posture and uterine torsion were found to be the common causes of dystocia in dromedary camels, and fetal and maternal deaths were mainly associated with the duration of dystocia.

A review of equine sepsis

Sepsis is defined as an exaggerated, systemic inflammatory response to infection and is a common condition in horses. Systemic inflammatory response syndrome (SIRS) associated with bacterial infection is a hallmark of sepsis. Sepsis in neonatal foals is a common sequela of failure of passive transfer and, in addition to development of SIRS, may be characterised by bacteraemia, pneumonia, enterocolitis, omphalophlebitis, meningoencephalitis or arthritis. Sepsis in mature horses is most commonly observed secondary to gastrointestinal lesions that result in disrupted mucosa and bacterial translocation into circulation (endotoxaemia). Pleuropneumonia and metritis may also cause sepsis in mature horses. Diagnosis of sepsis is based on SIRS criteria as well as suspected or confirmed infection. Due to the relatively low sensitivity of microbial culture and the subjectivity of sepsis scoring, many sepsis biomarkers are being studied for their usefulness in diagnosis and prognostication of sepsis in horses. Treatment of sepsis requires an intensive care approach that includes antimicrobial drug administration, fluid resuscitation and pressure support, and treatment for inflammation, endotoxaemia and coagulopathy. Early recognition of sepsis and prompt antimicrobial drug treatment are critical for a successful outcome. Multiple organ dysfunction syndrome may occur in severe cases of sepsis, with common manifestations including laminitis and coagulopathies. Although prognosis for septic mature horses depends highly on the primary disease process, the overall survival rate in septic neonatal foals ranges from 26 to 86%, with most studies indicating a survival rate of 45-60%.

Fertility after fetotomy: a clinical study focusing on heavy draft mares

Although fetotomy is recommended for all mares when the fetus is dead and difficult to extract, little has been written about fetotomy and heavy draft mares. This lack includes indications for fetotomy in heavy draft mares, differences in treatment and prognosis of heavy mares kept by farmers of low socioeconomic status, and how this procedure affects the mare's further fertility. The literature on mares, in general, also differs on the survival rate of mares that undergo fetotomy, the prevalence of postpartum complications, and further fertility. To answer these questions, we reviewed the medical records of 102 mares that underwent fetotomy, mostly heavy draft mares (n=93). Head malposture (62.7 per cent) was the most common fetal maldisposition, which required fetotomy in all cases. The survival rate was 84.3 per cent (n=86). The most common postpartum complications were endometritis puerperalis (32.5 per cent) and retained placenta (27.9 per cent). 61 mares (70.9 per cent) both showed foal heat and cycled regularly in the first season after fetotomy. Out of 45 mares that were bred in the first season, 14 became pregnant (31.1 per cent). Survival rate and further fertility were reduced by delayed requests for veterinary assistance due to the difficult economic situation of the owners. Fetotomy is the method of choice for serious maldispositions, especially head malpostures, because in contrast with cesarean sections, it has a higher survival rate and allows the mare to return to breeding in the same season.