Equine herpesvirus-1 is a highly prevalent and frequently pathogenic infection of equids. The most serious clinical consequences of infection are abortion and equine herpesvirus myeloencephalopathy (EHM). In recent years, there has been an apparent increase in the incidence of EHM in North America, with serious consequences for horses and the horse industry. This consensus statement draws together current knowledge in the areas of pathogenesis, strain variation, epidemiology, diagnostic testing, vaccination, outbreak prevention and control, and treatment.Key words: Abortion; Horse; Immunology; Infectious diseases; Myeloencephalopathy; Respiratory tract; Viral.E quine herpesvirus-1 (EHV-1) infection is ubiquitous in most horse populations throughout the world, and causes disease in horses and extensive economic losses through frequent outbreaks of respiratory disease, abortion, neonatal foal death, and myeloencephalopathy. [1][2][3][4] Infections caused by EHV-1 are particularly common in young performance horses, and typically result in establishment of latent infection within the 1st weeks or months of life 5 with subsequent viral reactivation causing clinical disease and viral shedding during periods of stress. The relevant effects of this virus on the equine population are 3-fold. Firstly, sporadic occurrence of mild respiratory disease associated with pyrexia, principally affecting horses under 2 years of age, can lead to interruptions in athletic training programs; this is economically the least important manifestation of EHV-1 disease. Secondly, abortion occurring during the 3rd trimester of pregnancy, results in important economic losses. Thirdly, outbreaks of neurological disease (equine herpes myeloencephalopathy or EHM) cause suffering and loss of life and also lead to extensive movement restrictions, disrupting breeding or training schedules and causing management difficulties at training centers, racetracks, and horse events. A perceived increase in the incidence of EHM outbreaks in North America in recent years has led to the proposal that it could represent an emerging disease threat. 6 The recent increased impact of EHM in North America provided the impetus for this consensus statement. The renewed focus on EHV-1 infection and its control, new developments in our understanding of this virus and its behavior in horses, and the development of new viral detection technologies have resulted in renewed challenges for clinicians in responding to the threat of EHV-1 and to outbreaks. In an attempt to address this challenge, this statement is structured as a series of critical questions, which we believe capture the key challenges for equine clinicians and scientists. The responses seek to distill current evidence-based knowledge Abbreviations:CTL cytotoxic T-lymphocyte EHM equine herpesvirus myeloencephalopathy EHV-1 equine herpesvirus-1 Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the veterinary community with up-to-date information on the pathophysiolo...

Recent studies associate obesity and insulin resistance in horses with development of abnormal reproductive function and debilitating laminitis. The factors contributing to insulin resistance in obese horses are unknown. However, human studies provide evidence that elevated inflammatory cytokines such as tumor necrosis factor alpha (TNFalpha), IL1, and IL6 play direct roles in development of obesity-associated insulin resistance. Thus, inflammation may be a key link between obesity and insulin resistance in horses. The aim of the current investigation was to examine possible relationships between obesity, inflammatory cytokines, and insulin sensitivity (IS) in the horse. Age was recorded and BCS and percent body fat (% FAT) were determined as measures of obesity in 60 mares. In addition, blood mRNA expression of IL1, IL6, and TNFalpha and circulating concentrations of TNFalpha protein (TNFp) were determined in each mare. Finally, fasted concentrations of insulin were determined, and IS was determined using the hyperinsulinemic, euglycemic clamp. Significant correlations between several variables provided evidence for the design of 4 population regression models to estimate relationships between measures of obesity, inflammatory factors, and IS in the sample population. The results of these analyses revealed that IS decreased as BCS and % FAT increased (P < 0.001) in the sample population. Additionally, increased IL1 (P < 0.05) and TNFp (P < 0.01) were associated with decreased IS. However, increased TNFalpha (P < 0.001) was associated with decreased IS only in mares 20 yr of age and older. Increased BCS and % FAT were associated with increased expression of TNFalpha (P = 0.053) and IL1 (P < 0.05), and increased TNFp (P < 0.05). Surprisingly, increased BCS and % FAT were associated with decreased IL6 expression (P = 0.05) in mares <20 yr of age. Finally, evaluation of the influence of obesity and inflammatory cytokines on IS within the same model suggested that BCS and % FAT (P < 0.001) with TNFalpha [mRNA (P = 0.07) and protein (P < 0.05)] are inversely associated with IS independently of one another. Combined, these results provide the first evidence associating obesity with increased inflammatory factors in the horse. Furthermore, the results suggest that an interrelationship exists among obesity, inflammatory cytokines, and IS in the horse and emphasize the need for further studies to elucidate the nature of these relationships.

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Gastrointestinal nematode parasitism is arguably the most serious constraint affecting sheep production worldwide. Economic losses are caused by decreased production, the costs of prophylaxis and treatment, and the death of the infected animals. The nematode of particular concern is Haemonchus contortus, which can cause severe blood loss resulting in anemia, anorexia, depression, loss of condition, and eventual death. The control of nematode parasites traditionally relies on anthelmintic treatment. The evolution of anthelmintic resistance in nematode populations threatens the success of drug treatment programs. Alternative strategies for control of nematode infections are being developed, and one approach is to take advantage of the host's natural or acquired immune responses, which can be used in selection programs to increase the level of resistance in the population. Vaccination can also be used to stimulate or boost the host's acquired immunity. The induction of protective resistance is dependent on the pattern of cytokine gene expression induced during infection by two defined CD4+ T-helper cell subsets, which have been designated as Th1 or Th2. Intracellular parasites most often invoke a Th1-type response, and helminth parasites a Th2-type response. Breeds of sheep resistant to infection have developed resistance over a much longer term of host-parasite relationship than genetically selected resistant lines. The immune components involved in these different responses and types of host-parasite relationships will be reviewed. The potential for using vaccines has been investigated, with variable results, for several decades. The few successes and potential new antigen candidates will also be reviewed.

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