Assessment of the equine neonate in ambulatory practice

The ambulatory practitioner is usually the first to evaluate the equine neonate and must assess the foal and determine its health status. If there is suspicion of one or more abnormalities, then the ambulatory veterinarian must initiate appropriate treatment and determine if the foal can be successfully treated in the field or should be referred to a specialty hospital. This article will describe the examination procedure including an accurate history, a comprehensive physical examination, laboratory evaluation and application of point‐of‐care diagnostics. The initial examination is the basis for the correct determination of health or illness and informing the owner of the correct course of action for the neonatal foal.     

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%.     

Nutritional management and practical feeding of the orphan foal

Foals are dependent on a milk‐based diet for the first 3–4 months of life. If they are orphaned during this period they require appropriate nutritional and behavioural management to allow them to develop into sound, well‐grown horses and ponies with well established normal behavioural patterns. In order to meet these needs it is necessary to understand the metabolic requirements of the foal and the composition of mares' milk. Usually managing these foals requires short‐term, emergency feeding of the foal while a long‐term option is sought. Long‐term options include use of a foster mare, induction of lactation in a parous, barren mare or hand rearing with suitable equine company. It is important to monitor growth and development of these foals to ensure that over the long term their nutritional needs are being met to allow normal growth and development.     

Hydranencephaly in a foal

Hydranencephaly is well recognised in several domestic animals, especially ruminants, but is virtually unknown in the horse. This case report describes a premature filly foal that on the day of delivery was found with a severe neurological disorder that initially improved but then progressively worsened. The foal was subjected to euthanasia on humane grounds and post mortem examination revealed somewhat asymmetric but bilateral destruction of the telencephalon identified as hydranencephaly. The possible causes of hydranencephaly in foals are discussed.     

Seizures in an Arabian foal due to suspected prolonged transient neonatal hypoparathyroidism

This Case Report describes a 5‐week‐old male Arabian foal of Egyptian bloodline with generalised seizures due to hypocalcaemia. The laboratory changes in this foal were consistent with an abnormal regulation of calcium as occurs with hypoparathyroidism. Prolonged transient neonatal hypoparathyroidism as reported in man was suspected. The foal received oral calcium and vitamin D₃ supplementation combined with the calcium sparing diuretic carbonic anhydrase inhibitor acetazolamide. Calcium concentrations increased gradually over 6 months. In Arabian foals, especially those of Egyptian bloodline suffering suspected juvenile epilepsy, hypocalcaemia should be ruled out as a cause of seizures.     

Effect of altrenogest‐treatment of mares in late gestation on adrenocortical function,blood count and plasma electrolytes in their foals

Reasons for performing study: Mares with compromised pregnancies are often treated with altrenogest to prevent abortion. However, there is only limited information about effects on the foal when altrenogest treatment is continued during final maturation of the fetus. Objectives: To determine effects of altrenogest treatment during late gestation in mares on maturity, haematology changes, adrenocortical function and serum electrolytes in their newborn foals. Methods: Six mares were treated with altrenogest (0.088 mg/kg bwt) once daily from Day 280 of pregnancy until foaling and 7 mares served as controls. Results: Foals born to altrenogest‐treated mares had a significantly lower neutrophil/lymphocyte ratio on the first day after birth than control foals (P<0.05). Basal plasma cortisol concentrations immediately after birth were higher in foals of altrenogest‐treated mares than in control foals (P<0.05). Cortisol release in response to exogenous adrenocorticotropic hormone (ACTH) ‐ except for higher values 15 min after ACTH injection in foals of altrenogest‐treated mares on Day 1 ‐ revealed no differences in adrenocortical function between the groups of foals. Plasma potassium concentration in foals from altrenogest‐treated mares compared to control foals was significantly lower immediately after birth (P<0.05) and plasma ionised calcium concentration was significantly lower 3 h after birth (P = 0.01). Conclusions and potential relevance: Altrenogest treatment of pregnant mares prolonged labour had no major effects on adrenocortical function in foals. A reduced neutrophil/ lymphocyte ratio in these foals may suggest either immunomodulatory effects of altrenogest or dysmaturity of the foals.