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Topic:Foals
"Foals" encompasses a stage in the lifecycle of equines with distinct physiological and developmental characteristics. Foals are young horses, typically under one year of age, undergoing rapid growth and development. They require specific nutritional, health, and management practices to support their transition to adulthood. This page compiles peer-reviewed research studies and scholarly articles that explore the growth, development, health challenges, and management practices associated with foals and horses, providing insights into their care and welfare across different life stages.
Field triage of the neonatal foal. The purpose of this article is to provide a quick reference for field triage of the sick neonatal foal. Therefore, information is focused toward diagnostics and treatments that can be performed in the field. When evaluating a weak, recumbent, or lethargic foal on a farm, it is often difficult to make a definitive diagnosis. Therefore, the approach should be to treat what is treatable and prevent what is preventable. In many cases, the goal will be to stabilize a foal before referral to a tertiary care facility where more intensive and continuous treatment can be performed.
Blood lactate measurement and interpretation in critically ill equine adults and neonates. Admission blood lactate concentration is widely used as a prognostic indicator in equine medicine and can be a useful indicator of disease severity but typically fails to completely discriminate survivors from nonsurvivors. Increased admission lactate concentrations in adult horses typically return to normal within 12 to 24 hours. Lactate concentrations in neonatal foals are higher than adult concentrations for the first 24 to 72 hours of life. Serial measures reflecting both the magnitude and duration of hyperlactatemia might enable more accurate prognostication and provide insight into dis...
Brainstem auditory evoked responses in an equine patient population. Part II: foals. Reports of the use of brainstem auditory evoked response (BAER) as a diagnostic modality in foals have been limited. Objective: To describe BAER findings and associated causes of hearing loss in foals. Methods: Study group 18 foals (15 neonatal, 3 nonneonatal), control group (5 neonatal foals). Methods: Retrospective. BAER records from the Clinical Neurophysiology Laboratory were reviewed from the years of 1982 to 2013. Peak latencies, amplitudes, and interpeak intervals were measured when visible. Clinical data were extracted from the medical records. Foals were grouped under disease categori...
Update on the management of neonatal sepsis in horses. Despite advances in neonatal intensive care sepsis, severe sepsis and septic shock remain the biggest killers of neonatal foals. Management of this severe syndrome remains difficult, requiring intensive intervention. Key aspects of management include infection control, hemodynamic support, immunomodulatory interventions, and metabolic/endocrine support. Infection control largely consists of early antimicrobial therapy, plasma transfusions, and local therapy for the infected focus. In cases with severe sepsis or septic shock, hemodynamic support with fluids, vasoactive agents, and respiratory s...
Identification of genomic loci associated with Rhodococcus equi susceptibility in foals. Pneumonia caused by Rhodococcus equi is a common cause of disease and death in foals. Although agent and environmental factors contribute to the incidence of this disease, the genetic factors influencing the clinical outcomes of R. equi pneumonia are ill-defined. Here, we performed independent single nucleotide polymorphism (SNP)- and copy number variant (CNV)-based genome-wide association studies to identify genomic loci associated with R. equi pneumonia in foals. Foals at a large Quarter Horse breeding farm were categorized into 3 groups: 1) foals with R. equi pneumonia (clinical group [N = ...
How does the suppression of energy supplementation affect herbage intake, performance and parasitism in lactating saddle mares? Agroecology opens up new perspectives for the design of sustainable farming systems by using the stimulation of natural processes to reduce the inputs needed for production. In horse farming systems, the challenge is to maximize the proportion of forages in the diet, and to develop alternatives to synthetic chemical drugs for controlling gastrointestinal nematodes. Lactating saddle mares, with high nutritional requirements, are commonly supplemented with concentrates at pasture, although the influence of energy supplementation on voluntary intake, performance and immune response against parasi...
Comparison of cardiac output determined by an ultrasound velocity dilution cardiac output method and by the lithium dilution cardiac output method in juvenile horses with experimentally induced hypovolemia. To assess the accuracy of an ultrasound velocity dilution cardiac output (UDCO) method, compared with that of the lithium dilution cardiac output (LiDCO) method, for determination of cardiac output (CO) in juvenile horses with experimentally induced hypovolemia. Methods: 12 anesthetized 2- to 6-month-old horses. Methods: For each anesthetized horse, CO was determined by the LiDCO and UDCO methods prior to any intervention (baseline state), after withdrawal of approximately 40% of the horse's blood volume (low CO state), after maintenance of hypovolemia and infusion of norepinephrine until mean...
Comparison of the blood supply to the articular-epiphyseal growth complex in horse vs. pony foals. To increase understanding of why the prevalence of clinical/radiographic osteochondrosis (OC) dissecans is high in horses and low in ponies. Objective: To investigate whether the clinical difference in OC occurrence between horses and ponies could partly be explained by a difference in: 1) number of patent vessels in the epiphyseal growth cartilage; 2) duration of the presence of patent cartilage canals; or 3) growth cartilage thickness at predilection sites for OC. The hypothesis was that pony foals would have fewer cartilage canals, shorter duration of blood supply and thinner growth cartila...
Absence of maternal cell contamination in mesenchymal stromal cell cultures derived from equine umbilical cord tissue. This study aimed to determine whether maternal cell contamination exists in cells derived from equine umbilical cord tissue, a perspective material for cell-based therapies in veterinary medicine. Potential maternal cell contamination was analyzed at DNA level via a set of 16 microsatellite markers in cells originating from the cord tissue of 22 foals. In these cells no maternal cell contamination was detected at a sensitivity level of 0.01%. Our results suggest that equine umbilical cord tissue-derived cells are entirely of fetal origin.
Equine placental mixed germ cell tumor with metastasis to the foal. The placenta from an embryo transfer-recipient mare and live foal was examined. The placenta was effaced by multifocal masses, which ranged from less than 1 cm to 14 cm in diameter. The foal represented at 52 days for lethargy, ataxia, and urine dribbling; due to a poor prognosis, the foal was euthanized. At necropsy, the liver was effaced by multifocal, pale, irregular nodules. The lumbar vertebrae and other skeletal sites had multifocal lytic lesions. The placenta had 4 populations of neoplastic cells, including a spindle cell population, tall columnar and transitional epithelial cell popula...
Serological response of foals to polyvalent and monovalent live-attenuated African horse sickness virus vaccines. African horse sickness (AHS) is typically a highly fatal disease in susceptible horses and vaccination is currently used to prevent the occurrence of disease in endemic areas. Similarly, vaccination has been central to the control of incursions of African horse sickness virus (AHSV) into previously unaffected areas and will likely play a significant role in any future incursions. Horses in the AHSV-infected area in South Africa are vaccinated annually with a live-attenuated (modified-live virus [MLV]) vaccine, which includes a cocktail of serotypes 1, 3, 4 (bottle 1) and 2, 6-8 (bottle 2) deli...
Production of a mitochondrial-DNA identical cloned foal using oocytes recovered from immature follicles of selected mares. Cloned animals possess mitochondria derived from the host ooplast, which typically differ genetically from those of the donor. This is of special concern to horse breeders, as maternal lines are prized and athletic performance is a key factor in genetic value. To evaluate the feasibility of producing mitochondrial-identical cloned foals, we collected oocytes from immature follicles of two mares, BL and SM, maternally related to the donor stallion. In vitro matured, enucleated oocytes were treated with roscovitine-synchronized donor cells and blastocysts were transferred transcervically to reci...
Mass envenomation of a mare and foal by bees. The clinical course of toxic envenomation of a mare and her foal after an attack by a swarm of bees in the Upper Hunter Valley of New South Wales is described. Early agitation and urticaria were followed by more severe systemic clinical signs within 18 h. There was severe, generalised angioedema, rhabdomyolysis, hypovolaemia, gastrointestinal stasis and renal injury. A particular feature in the mare was almost maniacal behaviour during the first 48 h. Clinical pathological examination showed evidence of haemoconcentration, intravascular haemolysis, thrombocytopenia, azotaemia, rhabdomyolysis a...
Plasma adrenomedullin concentrations in critically ill neonatal foals. Bacterial sepsis remains a leading cause of morbidity and mortality in neonatal foals, but accurate diagnostic and prognostic markers are lacking. Adrenomedullin (AM) is a polypeptide with diverse biologic effects on the cardiovascular system that increases in septic humans and laboratory animals. Objective: Plasma AM concentration (p[AM]) is increased in septic neonatal foals compared to sick nonseptic and healthy control foals, and p[AM] is predictive of survival in septic neonatal foals. Methods: Ninety critically ill (42 septic, 48 sick nonseptic) and 61 healthy foals <1 week of age. Me...
Visual outcomes of phacoemulsification cataract surgery in horses: 1990-2013. To evaluate the long-term visual outcome of phacoemulsification lens extraction surgery in foals and horses and identify any unique postoperative complications that affect the visual outcome. Methods: This is a retrospective medical records study of phacoemulsification cataract surgery in 95 foals and horses from 1990 to 2013. Results: Cataracts were removed by phacoemulsification from 111 eyes of 95 horses ranging in age from 22 days to 26 years (average 8.0 ± 5.7 years). Forty-four of the 95 animals were foals (46.3%). Sixteen horses or foals had surgery bilaterally. One hundred and two eye...
Hoof renewal time from birth of Thoroughbred foals. A circumferential ring in the hoof horn of foals occurs at birth and grows down to the distal border as the fetal hoof is replaced. Horn growth and complete hoof capsule renewal have not been measured in Thoroughbred foals but the determination of time of hoof renewal may allow accurate predictions of healing time to be made in cases of hoof lesions. The objective of this study was to measure the time taken for the fetal hoof of newborn foals to grow to the distal border and be replaced by hoof grown since birth. The age of the foal in days on the day that routine hoof trimming removed the hoo...
[Clinical relevant procedures for early pregnancy diagnosis in the mare]. This review describes stepwise the recto-manual and transrectal ultrasonographic evidence of early pregnancy detection in the horse. The morphological and physiological conditions in the individual phases of early pregnancy are presented in correlation to the potential clinical findings. The importance of embryonic and early foetal losses is presented. Communication and documentation of findings are also addressed. The final section is devoted to the evaluation of the examination effort. In this regard, it is emphasized that the gynaecological examination for the evaluation of the pregnancy st...
Anthelmintic efficacy on UK Thoroughbred stud farms. Anthelmintic drugs have been applied indiscriminately to control horse nematodes for over 40 years. We undertook a comprehensive study to investigate efficacy of the four available broad-spectrum anthelmintic drugs on 16 Thoroughbred stud farms using the faecal egg count reduction test. Efficacy against strongyles was determined by calculating the percentage of reduction in faecal egg count between the group mean at Day 0 and Days 14-17 post-treatment and the 95% lower confidence intervals estimated by non-parametric bootstrapping. Individual strongyle faecal egg count reduction tests (n=429) ...
Sex-associated differences in pancreatic β cell function in healthy preweaning pony foals. Pancreatic β cells are responsive to a range of stimuli during early post natal life in healthy pony foals. However, little is known about whether these responses are sex-linked. Objective: To determine pancreatic β cell responses to the insulin secretagogues, glucose, arginine and tolbutamide, in fillies and colts during the first 3 months after birth. Methods: In vivo experiment examining sex differences in pancreatic β cell function in foals. Methods: Female (n = 8) and male (n = 5) pony foals were infused i.v. with glucose (0.5 g/kg bwt 40% dextrose), arginine (100 mg/kg bwt) or tol...
Diversity of immunoglobulin lambda light chain gene usage over developmental stages in the horse. To further studies of neonatal immune responses to pathogens and vaccination, we investigated the dynamics of B lymphocyte development and immunoglobulin (Ig) gene diversity. Previously we demonstrated that equine fetal Ig VDJ sequences exhibit combinatorial and junctional diversity levels comparable to those of adult Ig VDJ sequences. Herein, RACE clones from fetal, neonatal, foal, and adult lymphoid tissue were assessed for Ig lambda light chain combinatorial, junctional, and sequence diversity. Remarkably, more lambda variable genes (IGLV) were used during fetal life than later stages and I...
Major histocompatibility complex I mediates immunological tolerance of the trophoblast during pregnancy and may mediate rejection during parturition. During pregnancy in larger mammals, the maternal immune system must tolerate the fetus for months while resisting external infection. This tolerance is facilitated by immunological communication between the fetus and the mother, which is mediated by Major Histocompatibility Complex I (MHC I) proteins, by leukocytes, and by the cytokines secreted by the leukocytes. Fetal-maternal immunological communication also supports pregnancy by inducing physiological changes in the mother. If the mother "misunderstands" the signal sent by the fetus during pregnancy, the fetus will be miscarried or deliver...
The effectiveness of anti-R. equi hyperimmune plasma against R. equi challenge in thoroughbred Arabian foals of mares vaccinated with R. equi vaccine. This study aimed to determine the effectiveness of a pregnant mare immunization of a Rhodococcus equi (R. equi) vaccine candidate containing a water-based nanoparticle mineral oil adjuvanted (Montanide IMS 3012) inactive bacterin and virulence-associated protein A (VapA), as well as the administration of anti-R. equi hyperimmune (HI) plasma against R. equi challenge in the mares' foals. The efficacy of passive immunizations (colostral passive immunity by mare vaccination and artificial passive immunity by HI plasma administration) was evaluated based on clinical signs, complete blood count, bl...
Effects of age and macrophage lineage on intracellular survival and cytokine induction after infection with Rhodococcus equi. Rhodococcus equi, a facultative intracellular pathogen of macrophages, causes life-threatening pneumonia in foals and in people with underlying immune deficiencies. As a basis for this study, we hypothesized that macrophage lineage and age would affect intracellular survival of R. equi and cytokine induction after infection. Monocyte-derived and bronchoalveolar macrophages from 10 adult horses and from 10 foals (sampled at 1-3 days, 2 weeks, 1 month, 3 months, and 5 months of age) were infected ex vivo with virulent R. equi. Intracellular R. equi were quantified and mRNA expression of IL-1β, ...
Parturition in horses is dominated by parasympathetic activity of the autonomous nervous system. External and internal stressors prolong parturition in different species. At parturition, sympathoadrenal activation should be avoided because an increased sympathetic tone may cause uterine atonia via β2-receptors. We hypothesized that at physiological parturition, horses are under parasympathetic dominance, and stress-response mechanisms are not activated during delivery of the foal. To evaluate stress responses, heart rate, heart rate variability, catecholamines, and cortisol were analyzed in mares (n = 17) throughout foaling. Heart rate decreased from 2 hours before (51 ± 1 beats/minute)...
Immunology of infective preterm delivery in the mare. Placentitis is reported to be the cause of 9.8-33.5% of abortions, stillbirths and perinatal losses in horses. Bacterial infections are responsible for 53% of placentitis cases with Streptococcus equi ssp. zooepidemicus being isolated in 28% of these cases. Clinically, mares may have a vaginal discharge, show udder development, lactate prenatally and deliver a premature or dead foal. Major aspects of the pathogenesis of infectious preterm delivery that may require more effective therapeutic targeting are myometrial contraction, immunological aspects of preterm delivery, and the effects of proi...
Luteoprotective role of equine chorionic gonadotropin (eCG) during pregnancy in the mare. The effects of repeated cloprostenol administration were compared in mares impregnated by horses and mares impregnated by donkeys in order to assess the role of eCG on the development of pregnancy-associated resistance to the luteolytic and abortifacient effects of PGF2α. Eleven mares impregnated by donkey (mule pregnancy) and 9 mares impregnated by horse (horse pregnancy) were used. Six mares with mule pregnancy and four with horse pregnancy were injected with cloprostenol (0.25 mg) when they were between day 65 and day 75 of pregnancy, and the treatment was repeated 48, 72 and 96 h latter...
Esophageal cyst in the duodenum of a foal. A 21-day-old Thoroughbred colt was euthanized following a history of recurrent colic. A 4.5 cm in diameter, occlusive, submucosal cyst was identified in the duodenum at necropsy. Histologically, the cyst was surrounded by a smooth muscle wall and was lined by both squamous and attenuated cuboidal to columnar epithelium. A diagnosis of an esophageal cyst was made based on the gross and histologic findings.
Gross placental morphology and foal serum biochemistry as predictors of foal health. The aim of this study was to verify if changes in blood glucose, creatinine, urea, and fibrinogen concentrations evaluated at birth reflect gross placenta abnormalities, and are useful to identify foals that suffered from placental dysfunction. A total of 92 mares were included in the present study: 68 delivered healthy foals and they were included in group 1; 24 delivered sick foals and they were included in group 2. In group 2, foals' clinical diagnoses included perinatal asphyxia syndrome (PAS; n = 20) and prematurity and/or dysmaturity (n = 4). The proportion of sick foals was greater when...
