Laminitis: Risk Factors and Outcome in a Group of Danish Horses

Recent systematic reviews have highlighted the lack of quality information with respect to the epidemiology of equine laminitis. The objectives of this study were to identify in Denmark, the risk factors for new (i.e., not believed to have suffered from laminitis previously) cases of laminitis (NL) and to look at the outcome and incidence of repeated episodes of laminitis in these animals as well as those which had previously suffered an episode of laminitis (i.e., chronic cases) over the following 12 months. Information was obtained from 110 veterinary diagnosed cases of laminitis (69 new and 41 chronic) and 80 control animals (the next nonlaminitic horse/pony seen by that participating practice). All animals were followed for up to 1 year. Univariable and multivariable conditional logistic regression was conducted for the NL case-control pairs. Variables were retained within the final multivariable models if the likelihood ratio P value was <.05. There was no association between sex or gender and laminitis. A recent change of grass, being on what was considered high-quality grass and being a cold-blooded type, <149 cm (i.e., Shetland, Fell, Welsh, or Dartmoor pony, Icelandic horse, Norwegian fjords, or a mix of these breeds) were all significant risk factors for laminitis. Although cresty neck score and body condition score were significantly associated with NL at the univariable screening stage, they were found to be confounders of breed and each other during the multivariable model building process. Other factors such as weight and estimated starch intake were not found to be significant. Thirty-three percent of all the laminitis cases had been humanely destroyed within 12 months of diagnosis, mainly for laminitis-associated reasons, compared with only 7.5% of the controls (none for laminitis associated reasons). This study confirms the importance of grass turnout and breed on laminitis risk. Horses in work at the time of diagnosis as well as those diagnosed in the winter and spring were more likely to be humanely destroyed within the next 12 months than those not in work or diagnosed in the autumn and summer.     

Genetic and Environmental Risk Indicators in Canine Non-Hodgkin's Lymphomas: Breed Associations and Geographic Distribution of 608 Cases Diagnosed throughout France over 1 Year

Background: The etiology of non-Hodgkin's lymphomas (NHL) is multifactorial. Environmental and genetic factors are frequently incriminated both in humans and dogs.
Objectives: Our purpose was to study the geographic distribution of canine NHL (CNHL) in France and to evaluate genetic and environmental influences.
Animals: Six hundred and eight cases of CNHL, diagnosed throughout France over 1 year, were collected from 7 Veterinary Histopathologic Laboratories.
Methods: Retrospective study. Breeds affected by lymphomas were compared with the national population and associations between breed and immunophenotype were studied. The distribution of CNHL and canine T-cell NHL per 100,000 dogs per department was compared with the distribution of waste incinerators, polluted sites, and radioactive waste.
Results: The breeds significantly overrepresented among lymphoma cases were Boxer, Setter, and Cocker Spaniel ( P < .001). There was a significant association between Boxer and T-cell NHL ( P < .001), and between German Shepherd and Rottweiler and B-cell NHL ( P < .01). The geographic distribution of CNHL and canine T-cell NHL indicated significant heterogeneity. Significant association between distributions of CNHL and waste incinerators (ρ= 0.25, P < .05), polluted sites (ρ= 0.36, P < .001), and radioactive waste (ρ= 0.51, P < .001) was found.
Conclusions and Clinical Importance: Influence of genetics in the development of CNHL was supported by the existence of an association between breed and immunophenotype. Waste incinerators, polluted sites, and radioactive waste could just be considered as risk indicators of CNHL, but not as risk factors. Case-control studies around critical sites are necessary to confirm the implication of those environmental factors in the development of CNHL.     

Companion animals symposium: microbes and gastrointestinal health of dogs and cats

Recent molecular studies have revealed complex bacterial, fungal, archaeal, and viral communities in the gastrointestinal tract of dogs and cats. More than 10 bacterial phyla have been identified, with Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, and Actinobacteria constituting more than 99% of all gut microbiota. Microbes act as a defending barrier against invading pathogens, aid in digestion, provide nutritional support for enterocytes, and play a crucial role in the development of the immune system. Of significance for gastrointestinal health is their ability to ferment dietary substrates into short-chain fatty acids, predominantly to acetate, propionate, and butyrate. However, microbes can have also a detrimental effect on host health. Specific pathogens (e.g., Salmonella, Campylobacter jejuni, and enterotoxigenic Clostridium perfringens) have been implicated in acute and chronic gastrointestinal disease. Compositional changes in the small intestinal microbiota, potentially leading to changes in intestinal permeability and digestive function, have been suggested in canine small intestinal dysbiosis or antibiotic-responsive diarrhea. There is mounting evidence that microbes play an important role in the pathogenesis of canine and feline inflammatory bowel disease (IBD). Current theories for the development of IBD favor a combination of environmental factors, the intestinal microbiota, and a genetic susceptibility of the host. Recent studies have revealed a genetic susceptibility for defective bacterial clearance in Boxer dogs with granulomatous colitis. Differential expression of pathogen recognition receptors (i.e., Toll-like receptors) were identified in dogs with chronic enteropathies. Similarly to humans, a microbial dysbiosis has been identified in feline and canine IBD. Commonly observed microbial changes are increased Proteobacteria (i.e., Escherichia coli) with concurrent decreases in Firmicutes, especially a reduced diversity in Clostridium clusters XIVa and IV (i.e., Lachnospiraceae, Ruminococcaceae, Faecalibacterium spp.). This would indicate that these bacterial groups, important short-chain fatty acid producers, may play an important role in promoting intestinal health.     

How to succeed as a virus: strategies for dealing with the immune system

Viruses may be viewed as genetic information whose success depends on avoiding elimination from individual hosts, or, if this is not possible, in persisting in the population of their hosts. The immune system represents the crucial defense mechanism responsible for the elimination of viruses from individual hosts and for the establishment of immunity that prevents a recurring infection by the same virus. Herd immunity, i.e., immunity of the population against infection resulting from the immunity of a certain fraction of the individuals of the population, represents an important concept in the interaction of viruses with their hosts. Thus, if the number of susceptible hosts decreases below a critical threshold, viruses may risk extinction because they literally run out of substrate. This possibility is increased due to the viruses' low resistance to inactivation outside their hosts by physical influences, such as heat and ultraviolet radiation. Some viruses have adopted a strategy of dual host tropism, i.e., they may reside in reservoir hosts that permit them to survive for extended periods of times. Examples of such viruses are the large and taxonomically diverse group of arboviruses. Moreover, although not normally discussed under this aspect, influenza viruses can also be said to have adopted this strategy, in view of water fowl representing reservoir hosts from which complete viruses may directly cross over to mammals, as was the case with the equine Jilin (Guo et al., 1995) or, more recently, the H5 subtype of influenza virus in humans (Shortridge et al., 1998). In addition, influenza viruses of birds may be transmitted, albeit only partially, through genetic reassortment (Shu et al., 1996).     

Practical starter pig amino acid requirements in relation to immunity,gut health and growth performance

Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include： anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie：lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources （i.e., soybean meal）. This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid re     

Practical starter pig amino acid requirements in relation to immunity,gut health and growth performance

Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid requirement estimates for nursery pigs.     

The reproductive system at the neuroendocrine-immune interface: focus on LHRH,estrogens and growth factors in LHRH neuron-glial interactions

Bidirectional communication between the neuroendocrine and immune systems plays a pivotal role in health and disease. Signals generated by the hypothalamic-pituitary-gonadal (HPG) axis (i.e. luteinizing hormone-releasing hormone, LHRH, and sex steroids) are major players coordinating the development immune system function. Conversely, products generated by immune system activation exert powerful and longlasting effects on HPG axis activity. In the central nervous system (CNS), one chief neuroendocrine-immune (NEI) compartment is represented by the astroglial cell population and its mediators. Of special interest, the major supporting cells of the brain and the thymus, astrocytes and thymic epithelial cells, share a similar origin and a similar set of peptides, transmitters, hormones and cytokines functioning as paracrine/autocrine regulators. This may explain some fundamental analogies in LHRH regulation of both cell types during ontogeny and in adult life. Hence, the neuropeptide LHRH significantly modulates astrocyte and thymic cell development and function. Here we focus this work on LHRH neuron-glial signaling cascades which dictate major changes during LHRH neuronal differentiation and growth as well as in response to hormonal manipulations and pro-inflammatory challenges. The interplay between LHRH, growth factors, estrogens and pro-inflammatory mediators will be discussed, and the potential physiopathological implications of these findings summarized. The overall study highlights the plasticity of this intersystem cross-talk and emphasize neuron-glial interactions as a key regulatory level of neuroendocrine axes activity.     

Designing and evaluating risk-based surveillance systems: potential unwarranted effects of applying adjusted risk estimates

Risk-based surveillance systems reveal occurrence of disease or infection in a sample of population units, which are selected on the basis of risk factors for the condition under study. The purpose of such systems for supporting practical animal disease policy formulations and management decisions are: A: to detect an emerging disease or infection, if it becomes introduced into a population; or B: to substantiate freedom from a condition in a population; or C: to detect cases and estimate the prevalence of an endemic condition in a population. In risk-based surveillance these aims should be met with prudent use of resources while maintaining acceptable system performance. High-risk category units are selected for testing by identification of the presence of specific high-risk factor(s), while disregarding other factors that might also influence the risk. On this basis we argue that the most applicable risk estimate for use in designing and evaluating a risk-based surveillance system would be a crude (unadjusted) relative risk, odds ratio or apparent prevalence. Risk estimates found in the published literature, however, are often the results of multivariable analyses implicitly adjusting the estimates for confounding from other risk factors. We describe some potential unintentional effects when using adjusted risk estimates in evaluating the efficacy and sensitivity of risk-based surveillance systems (SSe). In two examples, we quantify and compare the efficacy and SSe using adjusted and crude risk estimates. The examples use Danish surveillance data from previously published studies to evaluate systems aimed at risk-based detection of new cases of an endemic infection, i.e. Salmonella in dairy cattle herds (Example 1), and for substantiating the absence of a specific infection, i.e. Trichinella in the national slaughter pig population (Example 2), respectively.     

Immune and endocrine regulation of food intake in sick animals

To understand why sick animals do not eat, investigators have studied how the immune system interacts with the central nervous system (CNS), where motivation to eat is ultimately controlled. The focus has been on the cytokines secreted by activated mononuclear myeloid cells, which include interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Either central or peripheral injection of recombinant IL-1β, IL-6, and TNF-α reduce food-motivated behavior and food intake in rodents. Moreover, these cytokines and their receptors are present in the endocrine system and brain, and antagonism of this system (i.e., the cytokine network) has been shown to block or abrogate anorexia induced by inflammatory stimuli. Recent studies indicate that the same cytokines act on adipocytes and induce secretion of leptin, a protein whose activity has been neuroanatomically mapped to brain areas involved in regulating food intake and energy expenditure. Therefore, many findings converge to suggest that the reduction of food intake in sick animals is mediated by inflammatory cytokines, which convey a message from the immune system to the endocrine system and CNS. The nature of this interaction is the focus of this short review.     

Gut health,stress, and immunity in neonatal dairy calves: the host side of host-pathogen interactions

The cumulative evidence that perinatal events have long-lasting ripple effects through the life of livestock animals should impact future nutritional and management recommendations at the farm level. The implications of fetal programming due to malnutrition, including neonatal survival and lower birth weights, have been characterized,particularly during early and mid-gestation, when placental and early fetal stages are being developed. The accelerated fetal growth during late pregnancy has been known for some time, while the impact of maternal stressors during this time on fetal development and by extent its postnatal repercussions on health and performance are still being defined.Maternal stressors during late pregnancy cannot only influence colostrogenesis but also compromise adequate intestinal development in the fetus, thus, that further limits the newborn's ability to absorb nutrients, bioactive compounds, and immunity(i.e., immunoglobulins, cytokines, and immune cells) from colostrum. These negative effects set the newborn calf to a challenging start in life by compromising passive immunity and intestinal maturation needed to establish a mature postnatal mucosal immune system while needing to digest and absorb nutrients in milk or milk replacer. Besides the dense-nutrient content and immunity in colostrum, it contains bioactive compounds such as growth factors, hormones, and cholesterol as well as molecular signals or instructions [e.g., microRNAs(miRNAs) and long non-coding RNAs(lncRNAs)] transferred from mother to offspring with the aim to influence postnatal gut maturation. The recent change in paradigm regarding prenatal materno-fetal microbiota inoculation and likely the presence of microbiota in the developing fetus intestine needs to be addressed in future research in ruminants. There still much to know on what prenatal or postnatal factors may predispose neonates to become susceptible to enteropathogens(e.g., enterotoxigenic Escherichia coli), causing diarrhea. From the host-side of this host-pathogen interaction, molecular data such as fecal RNA could, over time, help fill those gaps in knowledge. In addition, merging this novel fecal RNA approach with more established microbiome techniques can provide a more holistic picture of an enteropathogenesis and potentially uncover control points that can be addressed through management or nutrition at the farm level to minimize preweaning morbidity and mortality.     

Endotoxins and endocrine system

There is good evidence for the interaction of neuroendocrine and immune systems. Endotoxin (LPS)-induced mediators (e.g., cytokines, prostaglandins etc) set on endocrine organs (e.g., the hypothalamo-pituitry-adrenal axis; thyroid glands etc). Endotoxin-treated, intestinal ischemic, or irradiated rats show decreased T₄ levels of blood. These animals cannot respond to TSH because the TSH-receptors of follicular membranes are disturbed by LPS in the thyroid glands. Radiodetoxified endotoxin is an effective immunstimulator and does not disturb the follicular membrane of thyroid gland. Thus, the T₄ production remains normal. The bile acids—as the end-product of cholesterol metabolism—play an important role in the physiological defense of macroorganisms against endotoxin and other lipid-like agents (Physico-chemical defense) and in the regulation of endocrine system, including the reproduction.     

Evaluation of factors associated with infection of commercial layers with Mycoplasma gallisepticum and M. synoviae

Information on factors possibly associated with the risk of infection with Mycoplasma gallisepticum (MG) or M. synoviae (MS) were collected from nearly 400 layer flocks in California. Factors associated with the probability of flock infection with either MG or MS were identified, and their magnitude was quantified by statistical analysis. More frequent administration of several vaccines was associated with decreased probability of both MG and MS infection of flocks. Also identified were housing or hygiene factors and system of management (i.e., multiple-age status) that could reduce the probability of infection of flocks with mycoplasma. The change in probability of MG infection resulting from modifying certain management factors was examined.     

Biological characters of bats in relation to natural reservoir of emerging viruses

Many investigators focused on bats (Chiroptera) for their specific character, i.e. echolocation system, phylogenic tree, food practice and unique reproduction. However, most of basic information about the vital functions related to anti-viral activity has been unclear. For evaluating some animals as a natural reservoir or host of infectious pathogens, it is necessary that not only their immune system but also their biology, the environment of their living, food habits and physiological features should be clarified and they should be analyzed from these multi-view points. The majority of current studies on infectious diseases have been conducted for the elucidation of viral virulence using experimental animals or viral gene function in vitro, but in a few case, researchers focused on wild animal itself. In this paper, we described basic information about bats as follows; genetic background, character of the immunological factors, histological character of immune organs, the physiological function and sensitivity of bat cells to viral infection.     

Growth and skeletal development in the dog in relation to nutrition; a review

Summary

Longitudinal growth of the appendicular skeleton in the growth plates and the adjacent metaphyseal area includes chondrocyte differentiation, proliferation, maturation, and hypertrophy in the physis and bone (re‐)modelling in the metaphysis. The rate and extent of longitudinal growth are regulated by interactions between biomechanical factors and endogenous growth regulators, i.e., systemic endocrine factors, and local paraor autocrine factors, that act on the growth plate chondrocytes. The most important endogenous regulators of growth and skeletal development are growth hormone (GH) and insulin‐like growth factors (IGFs), and calciotropic hormones, i.e., parathyroid hormone (PTH), vitamin D (vitD), and calcitonin (CT).

The biochemistry, synthesis, secretion, target organs, and effects of these endogenous factors are reviewed, and the calcium homeostatic mechanisms, dietary intake, bone turnover, and calcium excretion are discussed. Energy, protein, and calcium are nutritional factors of great importance to (skeletal) growth. The effects of low and high dietary intake of these nutrients are discussed, especially with reference to longitudinal growth and disturbances in endochondral ossification.     

New understanding of immunological mechanisms

The understanding and importance of antigen-specific immune responses after vaccination has completely changed in recent years. In the past, the focus for monitoring a vaccine-specific immune reaction was principally on the humoral branch of the immune system. The efficacy of vaccines, as assessed by the induction of protective immunity was mainly correlated with antibodies and antibody-titers. However, this correlation often failed and other parts of the immune system had also to be considered: namely, the innate immune system and the cellular branch of the antigen-specific immune system. With regard to vaccines, the innate immune system plays its main role in the effective activation of the antigen-specific immune response, in antigen-uptake and antigen-presentation. The dendritic cells (DCs) are the most important antigen presenting cells which present processed protein antigens (peptides) through MHC-molecules: MHC-class I, for the presentation of endogenous synthesised antigen; MHC-class II for exogenous antigen. Activation of DC leads to an enhanced production of cytokines and chemokines, to an up-regulation of co-stimulatory and activation molecules and also molecules for cell-cell interactions, e.g. interactions with cells of the antigen-specific immune system. T lymphocytes are the effector cells of the cellular branch of the antigen-specific immune system. They act either as MHC-class I-restricted cytolytic T lymphocytes (CTL) or as MHC-class II-restricted T-helper cells providing support for B lymphocytes (T(H)2) and the cellular part of the antigen-specific immune system (T(H)1). In order to achieve effective vaccination, the activation of all T-cell subpopulations is of advantage, but more important is the generation of antigen-specific memory T and B lymphocytes. In addition to these 'generic' immunological factors which are essential for the design of more efficacious vaccines, our detailed knowledge about feline and canine immune reactions after vaccination, which is still poor, has to be improved.     

Fish pathogen screening and its influence on the likelihood of accidental pathogen introduction during fish translocations

Fish translocations are an important tool in fisheries management, yet translocating fish carries the risk of introducing unwanted pathogens. Although pathogen screening can be a useful tool for managing the risk associated with fish translocations, screening cannot eliminate this risk. This paper addresses these problems by demonstrating that two elements must be considered when designing efficient and effective aquatic pathogen screening programs: (1) how many fish to screen and (2) how long to continue screening programs when repeated testing detects zero infected individuals. The chance that infected fish are translocated despite screening is the joint probability of (1) the failure of the screening to detect infected fish in the sample and (2) the actual presence of infected fish in the translocation batch. Our analysis demonstrates that transfer of an infected fish is most likely to occur at moderately low levels of pathogen prevalence because the probability of detecting at least one infected fish through screening increases as pathogen prevalence increases. Small screening samples (i.e., with a low number of individuals) are most likely to detect infected fish when pathogen prevalence is relatively high (i.e., > 5%). Screening programs should terminate after some number of successive screening events in which no infected individuals have been detected. The number of screening events is a function of the cost of the screening program, the cost of a pathogen translocation, and the probability that an infected fish will be transferred. Furthermore, our analysis indicates that the cost of a disease outbreak has relatively little effect on the length of time the screening program should continue. A more pronounced result is that screening programs that are inexpensive or allow a higher probability of pathogen translocation should be continued longer.     

Effect of three different housing systems on immune responses and body weight of chicken lines divergently selected for antibody responses to sheep red blood cells

There is an urgent need for knowledge on the effects of alternative housing conditions on parameters of health and production in current food animals, which are usually selected for a prolonged period for production traits. Thus, it is as yet unknown, whether genotype or environmental factors, or both, are major determinants of these traits. Therefore, as a model, the effects of keeping layers in three different types of housing: solitary in battery cages (BC), on a colony basis in a barn provided with litter and perches (BPL) and free range housing with access to the outdoors (FR), respectively, on immune competence and body weight (gain) of chicken lines divergently selected for high (H line) or low (L line) antibody responses to sheep red blood cells (SRBCs), next to a random bred control (C) line were studied. Antibody responses to keyhole limpet haemocyanin (KLH), Escherichia coli lipopolysaccharide (LPS) and ovalbumin (OVA) were significantly higher in the H line as compared to the C and L lines in all three housing systems, whereas in vitro mitogenesis of peripheral blood leukocytes to concanavalin (Con) A, and body weight (BW) were significantly higher in the L line in all three housing systems. No differences between the lines were found with respect to phagocyte activity. Housing conditions affected antibody responses to KLH, i.e. birds kept solitary in BC, and birds kept in BPL systems showed significantly higher antibody responses to KLH, than birds kept in the FR system. Also in vitro T-cell responses to KLH were significantly higher in BC birds than in the FR birds, but T cell responses to Con A were higher in the FR birds. Antibody responses to KLH, but also LPS and OVA were significantly affected by a housing×time interaction. Titers to these three antigens remained at a higher level in the BC then in the FR system. Birds kept in battery cages were heavier, and produced their first eggs approximately 2 and 3 weeks earlier than birds in the BPL and the FR system, respectively. The absence in the present study of significant interactions between line and housing systems on immune competence suggests that regardless of genotype, the animals respond similarly to different environments. The modulation of the magnitude of specific, but not innate immune responses in the three lines by environmental (housing) conditions suggest that the environment may favour types of specific immune responses. In addition, our data suggest that specific genotypes and specific environments may be additive in disease resistance.     

Fish immunity and parasite infections: from innate immunity to immunoprophylactic prospects

The increasing economic importance of fish parasitoses for aquaculture and fisheries has enhanced the interest in the defence mechanisms against these infections. Both innate and adaptive immune responses are mounted by fish to control parasite infections, and several mechanisms described for mammalian parasitoses have also been demonstrated in teleosts. Innate immune initiation relies on the recognition of pathogen-associated molecular patterns (PAMPs) by pathogen recognizing receptors (PRRs). A number of PRRs, mainly Toll-like receptors (TLRs), have been characterized in fish, and some molecules susceptible of functioning as PAMPs are known for some fish parasites. A lectin-carbohydrate interaction has also been described in some host fish-parasite systems, thus probably involving C-type lectin receptors. Inflammatory reactions involving cellular reactions, as phagocytosis and phagocyte activity (including oxidative mechanisms), as well as complement activity, are modulated by many fish parasites, including mainly ciliates, flagellates and myxozoans. Besides complement, a number of humoral immune factors (peroxidases, lysozyme, acute-phase proteins) are also implicated in the response to some parasites. Among adaptive responses, most data deal with the presence of B lymphocytes and the production of specific antibodies (Abs). Although an increasing number of T-cell markers have been described for teleosts, the specific characterization of those involved in their response is far from being obtained. Gene expression studies have demonstrated the involvement of other mediators of the innate and adaptive responses, i.e., cytokines [interleukins (IL-1, IL-8), tumor necrosis factor (TNF), interferon (IFN)], chemokines (CXC, CC), as well as several oxidative enzymes [inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX-2)]. Information is scarcer for factors more directly linked to adaptive responses, such as major histocompatibility (MH) receptors, T cell receptors (TCRs) and IgM. Expression of some immune genes varied according to the phase of infection, and proinflammatory cytokines were mainly activated in the early stages. Gene expression was generally higher in the target tissues for some skin and gill parasites, as Ichthyophthirius multifiliis, Neoparamoeba spp. and Lepeophtheirus salmonis, thus confirming the relevance of mucosal immunity in these infections. The existence of protective responses has been demonstrated for several fish parasites, both in natural infections and in immunization studies. Most information on the mechanisms involved in protection deals with the production of specific Abs. Nevertheless, their levels are not always correlated to protection, and the precise involvement of immune mechanisms in the response is unknown in many cases. No commercial vaccine is currently available for piscine parasitoses, although experimental vaccines have been assayed against I. multifiliis, Cryptobia salmositica and scuticociliates. The known information points to the need for integrated studies of the mechanisms involved in protection, in order to choose the optimum antigen candidates, adjuvants and formulations.     

Immune responses in dogs with cutaneous adverse food reactions

Adverse food reactions (AFR) in dogs are reactions due to apparently harmless food antigens, with an unknown aetiology, i.e. immunopathogenesis. Despite the entry of food allergens via the intestinal tract, in the majority of dogs with AFR, clinical symptoms are only associated with the skin (CAFR). In the present review, factors are presented of relevance in triggering the differentiation of naive T cells into effector T cell types and the role of these T cell types in allergy. More specifically, the allergic immune responses in intestine and skin are discussed in this article as well as the potential pathways, e.g. homing of antigen presenting cells or allergen-induced T cells to the skin, of induction of cutaneous symptoms.