In the preface of the first equine neonatology book edited by Koterba, Drummond and Kosch in 1990 it is stated that ‘Regardless of the sophistication of equipment and facilities of neonatal intensive care, the factor that still saves the most foals is careful and intensive nursing care’. This probably still holds true more than 20 years later, manifested by the continued presence and use of the book in many neonatal care facilities all over the world. However, the authors also point out that ‘in many areas of major and minor importance, gross deficiencies in species-specific information exist’ (Koterba et al. 1990). And it is this area, the evidence-based or at least peer-reviewed species-specific literature, where the greatest advances have been made since publication of the book. A literature search using PubMed (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed) and the broad search terms ‘foal or equine neonate’ confirms this impression. Prior to 1970, 93 publications were named. Over the next 4 decades publications increased to 281 in the 1970s, 496 and 477 in the 1980s and 1990s, respectively, and in the last decade 544 publications were listed. In the new decade (up to September 2011) 98 publications are already are listed, and this Equine Veterinary Journal supplement, containing 25 articles, will aid in increasing our understanding of physiology, pathophysiology and treatment of the equine neonate even further. There is some, albeit indirect, evidence that this cumulative increase in knowledge over time has been paralleled by an increase in survival, at least in bacteraemic foals (Fig 1).
Some of the articles presented here will confirm our clinical impressions and reinforce current clinical practice, whereas others might change the way we view and treat hospitalised foals. Indeed, particularly in equine neonatal care, it appears that scientific evidence, rightly or wrongly, occasionally lags behind clinical developments, as demonstrated by the contributions of Jose-Cunilleras et al. (2012), Sanchez and Elfenbein (2012) and Furr et al. (2012) in this supplement.
Nutrition is a key element of neonatal intensive care; however, direct measurements of the resting energy expenditure (REE) of healthy and diseased foals have long been lacking. The study by Jose-Cunilleras et al. (2012) in this supplement corroborates earlier findings by Ousey et al. (1996, 1997) and Paradis (2001). Results of the study indicate that critically ill neonates have a lower REE than healthy controls and provide more support for the current practice of feeding 40–50 kcal/kg bwt/day to sick neonates. Methods of introducing enteral feeding to the recuperating foal vary, but many clinicians prefer to initiate feeding via nasogastric tube owing to fears of milk aspiration, rather than attempting to bottle feed or allowing the weak foal to nurse (McKenzie and Geor 2009). Although widely recognised, the description of dysphagia due to pharyngeal dysfunction in neonatal foals in the peer-reviewed literature has so far been limited to a series of 4 cases (Altmaier and Morris 1993). The report of pharyngeal dysphagia in 16 foals by Holcombe et al. (2012) presents the first step into further investigations of dysphagia in this age group.
Concerns over the severe and potentially fatal consequences of gastric and duodenal ulcerations, perforation and duodenal outflow obstruction, have led to routine use of anti-ulcer medications in a large number of equine neonatal intensive care units. However, during the last 2 decades this attitude has gradually changed and many clinicians no longer supported their indiscriminate use (Barr et al. 2000). The article by Sanchez et al. (2012) provides further evidence supporting the impression that, despite decreasing use of acid-suppressive medication, the prevalence of gastric ulcers has not increased. A reduction in the gastric barrier function and increased risk of colonisation of the intestine by potential pathogens has frequently been quoted as an argument against blanket use of antacid medication. The article by Furr et al. (2012) documents for the first time an increased risk for development of diarrhoea in neonatal foals receiving antiulcer medications in intensive care units. Interestingly, the use of not only ranitidine and omeprazole but also sucralfate alone increased the risk of diarrhoea. Furthermore, the proportion of foals with gastric ulcerations receiving no antiulcer medications did not differ from those of treated foals. The findings of both studies strongly suggest that the indications for use of anti-ulcer medication in critically ill equine neonates need to be reviewed, as prophylactic administration to every neonate may not be appropriate and potentially harmful. The results also highlight that further investigations into the pathogenesis of gastric ulceration in neonatal foals are needed.
The availability of third- and now fourth-generation cephalosporines with an extended Gram-negative spectrum has lead to an increased use of this class as single-drug treatment for neonatal sepsis. Many clinicians have opted to use higher doses of ceftiofur than recommended by the manufacturer, with the aim of extending its efficacy against Enterobacteriaceae even further. However, until recently (Meyer et al. 2009; Hall et al. 2010) this practice was not supported by published evidence. A similar pattern has emerged with the availability of cefquinome and doses of up to 5 mg/kg bwt have anecdotally been administered to neonatal foals twice daily. The pharmacokinetic study of cefquinome in neonatal and 6-week-old foals reported by Smiet et al. (2012) provides a scientific basis for clinical use of higher doses in selected cases.
Owing to the small size of foals and their relative ease of handling, the more widely available imaging modalities of magnetic resonance imaging and computed tomography (CT) are likely to gain importance as diagnostic tools for neonatal conditions in the coming years. The case reported by Haggett et al. (2012) demonstrates how advanced imaging, in this case CT, can aid in describing the extent and nature of musculoskeletal lesions and complement the often equivocal or incomplete information provided by radiographic and/or ultrasonographic examination. Ultrasonography remains an invaluable tool for evaluation of critically ill foals and, as described by Navas de Solis et al. (2012), may aid in establishing disease severity and prognosis in foals where pneumatosis intestinalis is detected. Although necrotising enterocolitis, a common cause of pneumatosis intestinalis, has been reported in foals (Cudd and Pauly 1987; Wehrli Eser et al. 2002) and anecdotally described in several texts, further studies are needed to delineate this fascinating syndrome further in the equine species.
Sepsis is the leading cause of morbidity and mortality in young foals. The term sepsis is defined as systemic inflammation caused by microbial invasion of normally sterile parts of the body. The diagnosis of sepsis does not require laboratory evidence of bacteraemia and is preferred to the previously more commonly used term septicaemia (Lever and Mackenzie 2007); therefore, this terminology is used throughout this issue. Consensus on the most appropriate terminology for neonatal maladjustment syndrome has not yet been reached and it is also known as hypoxic–ischaemic encephalopathy, neonatal encephalopathy, perinatal asphyxia syndrome and dummy foal syndrome. Throughout the issue, authors have used their preferred term. Madigan et al. (2012) present preliminary evidence that, in addition to hypoxic and ischaemic events, the neurobehaviour displayed by these foals may be associated with increased circulating progestagen concentrations, and Armengou et al. (2012) highlight the need for a high index of suspicion that meningitis may be present in young foals showing neurological abnormalities.
The ability to give a more accurate prognosis based on published literature, rather than clinical impressions and anecdotal reports, continues to increase. Two studies reported in this issue investigated the association between foal-related factors and subsequent performance in life and both reached encouraging conclusions. Low birthweight has previously been associated with decreased racing performance (Platt 1978). In contrast to these earlier findings, the study presented by Whittaker et al. (2012) did not identify a significant correlation between birthweight and racing performance. Although these results are encouraging, it remains to be established whether these findings can be extrapolated to foals with very low birthweights (<8% of their dam's weight), the population Platt (1978) focused on, and to those judged small for gestational age. Corley and Corley (2012) showed that treatment at a referral hospital within the first 125 days of life did not affect sales outcomes at public auctions and no differences in the mean sales prices between treated foals and controls could be established. This information can be used as guideline for owners and trainers questioning whether it is financially viable to invest in treatment of a foal intended for sale.
Other aspects of neonatology have not changed over recent decades. Dystocia and prolongation of Stage II labour still have a significant impact on foal morbidity and mortality, and increased times to standing and/or nursing remain good indicators of a compromised newborn foal (McCue and Ferris 2012). The findings confirm yet again observations by Koterba and Drummond published almost a quarter of a century ago that close observation by educated personnel and rapid intervention are essential to maximise the chances of a successful outcome (Koterba and Drummond 1988).
In summary, the articles included in this supplement represent a significant contribution to the evidence base needed to underpin clinical practice of equine neonatology. Peter Rossdale has, throughout his career, championed clinical research in many and all aspects of equine medicine, but in particular in relation to the foal, and we are delighted to have contributed to the production of this supplement honouring his achievements.