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Topic:Toxins
Toxins in horses refer to a variety of substances that can cause adverse health effects when ingested, inhaled, or absorbed through the skin. These substances can originate from plants, chemicals, feed contaminants, or environmental sources. Common toxins affecting horses include mycotoxins, heavy metals, and certain plants like ragwort and oleander. Exposure to these toxins can lead to a range of clinical symptoms, from mild discomfort to severe illness or death. Research in this area focuses on identifying toxic agents, understanding their mechanisms of action, and developing strategies for prevention and treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the sources, effects, and management of toxins in equine health.
Dose-response effects of estrogenic mycotoxins (zearalenone, alpha- and beta-zearalenol) on motility, hyperactivation and the acrosome reaction of stallion sperm. The aim of this study was to investigate the in vitro effects of the Fusarium fungus-derived mycotoxin, zearalenone and its derivatives alpha-zearalenol and beta-zearalenol on motility parameters and the acrosome reaction of stallion sperm. Since the toxic effects of zearalenone and its derivatives are thought to result from their structural similarity to 17beta-estradiol, 17beta-estradiol was used as a positive control for 'estrogen-like' effects. Methods: Stallion spermatozoa were exposed in vitro to zearalenone, alpha-zearalenol, beta-zearalenol or 17beta-estradiol at concentrations ranging...
Occurrence of fumonisins in feed for swine and horses. Fumonisin B1 (FB1), fumonisin B2 (FB2), and overall mycotoxins feed contamination may cause several effects on crops production and animal health. The contamination occurred predominantly in corn and corn-based foods and feeds. Objective: This survey intends to provide the occurrence of fumonisins in swine and equine mixed feeds in Portugal, making an overview from 2007 to 2010. Methods: A total of 363 samples were analyzed, 258 from swine feed and 105 from horse feed with HPLC method. The detection limit was 50 μg/kg for FB1 and 100 μg/kg for FB2. Results: The overall results were 13% of FB...
Clinical expression of lolitrem B (perennial ryegrass) intoxication in horses. Perennial ryegrass staggers is purported to be a common neurological mycotoxicosis of horses but the case description lacks detail and evidence. Objective: To describe the clinical syndrome of lolitrem B intoxication in horses, limiting tests to those that are applicable to clinical practice, and to assess the potential value of enzyme-linked immunosorbent assay (ELISA) tests for lolitrem B in horse body fluids. Methods: Seven horses in 2 separate groups were fed perennial ryegrass seed and hay containing 2 ppm lolitrem B. Paired data were collected prior to and after 2 weeks exposure to lol...
Effects of cutting frequency and height on alkaloid production in endophyte-infected drunken horse grass (Achnatherum inebrians). An evaluation was performed on the influence of mowing height (2.5, 5.0 or 7.5 cm) and mowing frequency (weekly or fortnightly) on levels of ergot alkaloids (ergine and ergonovine) formed in drunken horse grass, Achnatherum inebrians, grown under greenhouse conditions. Samples were taken monthly and alkaloids were extracted and analyzed by reverse-phase HPLC. Alkaloid levels increased more or less linearly with plant age over the first four months following establishment. Levels were higher in samples cut fortnightly compared to those cut weekly, and were higher when plants were cut at a mowin...
The role of RTX toxins in host specificity of animal pathogenic Pasteurellaceae. RTX toxins are bacterial pore-forming toxins that are particularly abundant among pathogenic species of Pasteurellaceae, in which they play a major role in virulence. RTX toxins of several primary pathogens of the family of Pasteurellaceae are directly involved in causing necrotic lesions in the target organs. Many RTX toxins are known as haemolysins because they lyse erythrocytes in vitro, an effect that is non-specific, but which serves as a useful marker in bacteriological identification and as an easily measurable signal in vitro in experimental studies. More recent studies have shown that...
Pasture composition in a trace element-contaminated area: the particular case of Fe and Cd for grazing horses. Pasture selection by livestock is an essential topic for rangeland management, especially in trace element-contaminated soils. We have studied the composition (nutrients and trace elements) of a grass-based diet from soils affected by a mine spill at different growth stages (October 2008 to May 2009). A diet based on other plants (mainly Compositae species) was also studied (May 2009) for comparison. Faeces and mane hair of horses feeding on these pastures were also analysed. Micronutrient (Cu, Fe, Mn and Zn) and potentially toxic trace element (As, Cd, Pb, Tl) concentrations were below the ma...
Pathology of Clostridium perfringens type C enterotoxemia in horses. Clostridium perfringens type C is an important cause of enteritis and enterocolitis in foals and occasionally in adult horses. The disease is a classic enterotoxemia, and the enteric lesions and systemic effects are caused primarily by beta toxin, 1 of 2 major toxins produced by C. perfringens type C. Until now, only sporadic cases of C. perfringens type C equine enterotoxemia have been reported. We present a comprehensive description of the lesions in 8 confirmed cases of type C enterotoxemia in foals and adult horses. Grossly, multifocal to segmental hemorrhage and thickening of the intestin...
Real-time PCR and typing of Clostridium difficile isolates colonizing mare-foal pairs. Clostridium difficile infection can occur in the dams of sick foals, but it is unknown if mares and foals share the same isolates. In this study, C. difficile isolates from fecal samples of 11 mares paired with 11 foals were genotyped by arbitrarily primed PCR; two mares and three foals in five mare-foal pairs had diarrhea. Fecal immunoassays were utilized to detect C. difficile common antigen and toxin A. Quantitative real-time PCR (qPCR) systems were developed to detect genes for toxins A and B, as well as for binary toxin B. Sequences of all toxins were present in all isolates, although onl...
Staggers in horses grazing paspalum infected with Claviceps paspali. Invasion of the flowering heads of grasses by Claviceps spp. can produce sclerotia (ergots) containing several toxins. Ingestion of these toxins, through the consumption of paspalum (Paspalum dilatatum), can induce a range of clinical symptoms, including staggers. Cattle are the most commonly affected species, but although sheep and horses have been reported affected there are no published descriptions of paspalum staggers in horses. We describe two occurrences of paspalum staggers, the first in three Australian Stockhorse foals and the second in mature Standardbred horses. All three foals pre...
Toxicological effects of aflatoxins in horses. Aflatoxins are a group of mycotoxins principally produced by Aspergillus flavus and A. parasiticus, which are both natural contaminants of food and feedstuff. Aflatoxin B(1) is the most prevalent member of this group that is normally detected and is the most powerful hepatocarcinogen known. Few naturally occurring episodes of aflatoxicosis in horses have been reported in the literature. Indeed, the published information about aflatoxin exposure, metabolism and the effects on horses is limited and controversial, possibly indicating a lack of awareness rather than the rarity of the occurrence. T...
Validation of a commercial enzyme immunoassay for detection of Clostridium difficile toxins in feces of horses with acute diarrhea. Clostridium difficile infection (CDI) is a recognized cause of colitis in the horse. Identification of its toxins is important for management of individual cases and for prevention of transmission and zoonosis. In humans, CDI diagnosis is performed with enzyme immunoassays, none of which have been validated for horses. Objective: (1) Establish which test for CDI diagnosis was more frequently used by diagnostic laboratories, (2) determine the identified test's performance, sensitivity, and specificity, and (3) validate its use in diarrheic horses. Methods: Samples were obtained from 72 horses p...
Lethal toxin of Clostridium sordellii is associated with fatal equine atypical myopathy. The lethal toxin of Clostridium sordellii (TcsL) evokes severe, mostly fatal disease patterns like toxic shock syndrome in humans and animals. Since this large clostridial toxin-induced severe muscle damaging when injected intramuscularly into mice, we hypothesized that TcsL is also associated with equine atypical myopathy (EAM), a fatal myodystrophy of hitherto unknown etiology. Transmission electron microscopy revealed skeletal and heart muscles of EAM-affected horses to undergo degeneration ultrastructurally similar to the damage found in TcsL-treated mice. Performing immunohistochemistry, ...
Fumonisin B1 neurotoxicity in young carp (Cyprinus carpio L.). For years scientists have suspected that the environment plays a role in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Mycotoxin fumonisin B1 (FB1) is produced by several Fusarium species, mainly by Fusarium verticilioides, which is one of the most common fungi associated with corn worldwide. Fumonisins are known to cause equine leukoencephalomalacia, a disease associated with the consumption of corn-based feeds contaminated with FB1. Here we have reported chronic experimental toxicosis in one-year-old carp (Cyprinus carpio L.) receiving f...
Preliminary molecular analysis of Clostridium difficile isolates from healthy horses in northern Italy. Clostridium difficile, associated with a wide spectrum of diseases in humans, as well as in several animal species, is an important cause of colitis in adult horses and foals. The aim of this study was to investigate by toxin gene profile and PCR-ribotyping the molecular characteristics of 14 C. difficile strains isolated from 42 faeces of healthy horses. Both toxin genes, tcdA and tcdB, were present in only 1 isolate (7.1%). Six isolates (42.9%) demonstrated tcdA-/tcdB+ genotype, and seven isolates (50.0%) were tcdA-/tcdB-. All strains were binary toxin genes negative (cdtA-/cdtB-). The PCR-p...
Fescue-associated oedema of horses grazing on endophyte-inoculated tall fescue grass (Festuca arundinacea) pastures. A new form of toxicity called equine fescue oedema is described. The clinical signs included inappetence, depression, and subcutaneous oedema of the head, neck, chest and abdomen. Affected horses had very low plasma albumin values. The toxicity affected 48 of 56 horses on six farms in different states of Australia, and 4 horses have died. All horses were grazing pastures that had been sown with varieties of Mediterranean tall fescue (Festuca arundinacea) that carry the endophyte known as Max P or Max Q. It is proposed that a pyrrolizidine alkaloid, N-acetyl norloline, which is produced by the ...
Colic caused by Panicum maximum toxicosis in equidae in northern Brazil. In the Amazon region of northern Brazil, Panicum maximum cultivars Mombaça, Tanzânia, and Massai cause severe colic and death in horses and mules. The disease occurs in the rainy season, when sprouting pastures are grazed by equidae. In the 8 separate disease outbreaks studied, a total of 52 out of 153 equidae were affected, including 19 that died (10 mules and 9 horses). Clinical signs were colic and abdominal dilatation, with a clinical manifestation period of 12 hr to 4 days. Serum activities of gamma-glutamyl transferase and aspartate aminotransferase were within reference intervals; how...
[Two horses with neurological symptoms: could this be equine botulism?]. Symptoms, diagnosis and therapy of equine botulism are discussed by the presentation of two detailed reports of horses with neurological symptoms and the results of laboratory investigations over the period 2003-2008 in the Netherlands. In addition a brief summary of the available literature is presented. Prevailing symptoms of botulism in horses include paralysis of the tongue, salvation, dysphagia and paresis and paralysis of the skeletal muscles, as well as signs of colic. Symptoms and prognosis vary with the amount of botulinum neurotoxin (BoNT) involved. For early clinical diagnosis of bo...
Aspergillus fumigatus toxicity and gliotoxin levels in feedstuff for domestic animals and pets in Argentina. To evaluate gliotoxin production by Aspergillus fumigatus strains isolated from feedstuff intended for domestic animals and pets, and to determine the amount of gliotoxin in these substrates. Results: A total of 150 feedstuff samples were collected. They were composed of 30 samples each of five different feed types (pigs, poultry, cattle, horse and pets). Aspergillus fumigatus gliotoxin production ability and gliotoxin presence in feedstuff was determined by HPLC. Aspergillus fumigatus strains were isolated from all of the tested samples. Strains from cattle, horses and pet food were able to p...
Effects of fusariotoxins in the equine species. Fumonisins, trichothecenes and zearalenone are the most commonly occurring Fusarium mycotoxins in cereal grains and animal feed. In this review, the toxicity of these mycotoxins in horses is considered with particular reference to recent data on specific and proposed syndromes. Compared to other animal species, very little information is available on the adverse effects of fusariotoxins in horses. Fumonisin B(1) (FB(1)) is the causative agent of leukoencephalomalacia, which is typified by depression, aimless circling, head pressing, paresis, ataxia, blindness and death. FB(1) has also been sho...
Seroprevalence of toxoplasmosis in horses in Niğde Province of Turkey. The present study was conducted to investigate the prevalence of Toxoplasma gondii specific antibodies in local horses from four districts of Niğde in the middle of Turkey, between April-June 2004. Serum samples were obtained a total of 125 horses which consisted of 81 (50 female, 31 male) 1-10 years old and 44 (25 female, 19 male) 11-20 years old and tested for antibodies to T. gondii using the Sabin Feldman Dye Test (SFDT). According to the results of the SFDT, antibodies to T. gondii were found by the SFDT in 9 (7.2%) of 125 sera with the titers of 1:16 (8 horses) and 1:64 (1 horse). Antib...
Paraspecific neutralization of the venom of African species of cobra by an equine antiserum against Naja melanoleuca: a comparative study. Venoms of snakes belonging to the same Genera tend to share biochemical, toxinological and antigenic characteristics. Accordingly, paraspecific neutralization of venom lethality by experimental antisera and commercial antivenoms has been reported. We studied the spectrum of neutralization of lethality of an experimental monovalent equine antiserum against the strongly neurotoxic African forest cobra (Naja melanoleuca) when tested against venoms of most species of African Naja, both neuro and cytotoxic as described by some authors. We report a comparison of the median lethal doses (LD50) of the...
Immune response of horses to vaccination with the recombinant Hc domain of botulinum neurotoxin types C and D. Botulinum neurotoxins, predominantly serotypes C and D, cause equine botulism through forage poisoning. The C-terminal part of the heavy chain of botulinum neurotoxin types C and D (HcBoNT/C and D) was expressed in Escherichia coli and evaluated as a recombinant mono- and bivalent vaccine in twelve horses in comparison to a commercially available toxoid vaccine. A three-dose subcutaneous immunization of adult horses elicited robust serum antibody response in an ELISA using the immunogen as a capture antigen. Immune sera showed dose-dependent high potency in neutralizing specifically the active...
Equine grass sickness: epidemiology, diagnosis, and global distribution. Equine grass sickness (EGS) is recognized as a debilitating and predominantly fatal neurodegenerative disease affecting grazing equids. The gastrointestinal tract is the most severely affected body system, resulting in the main clinical signs of colic (acute grass sickness), weight loss, or dysphagia (chronic grass sickness). EGS predominantly occurs within Great Britain, although it is also recognized in regions of mainland Europe, and mainly affects young horses with access to pasture in the springtime. There is strong evidence of an association between EGS and the type C toxins produced by ...
Equine colitis X associated with infection by Clostridium difficile NAP1/027. A 14-year-old Quarter Horse with a 48-hr history of colic was euthanized after failure to respond to treatment. At necropsy, cecal and colonic mucosae were congested throughout, and there was segmental edema and significant thickening of the intestinal wall. Excessive numbers of mononuclear cells were found in mucosal lamina propria. Submucosal hemorrhage was diffuse and extensive, and Clostridium difficile toxins A and B were detected. Large numbers of C. difficile were isolated, and genetic characterization revealed them to be North American pulsed-field gel electrophoresis type 1, polymeras...
Evaluation of pastures for horses grazing on soils polluted by trace elements. Pasture established on polluted soil may pose a risk to grazing livestock creating a requirement for mechanical management which may affect biodiversity and expend energy. The risk associated with managing pasture by grazing horses (non-edible livestock) is being assessed in the Guadiamar Valley (SW Spain), where soils are polluted with trace elements following a major pollution incident. Soil pollution does not affect biomass production or floristic composition of pasture, although both variables influence trace element accumulation in herbage. Element concentrations in herbage are below maxi...
Toxoplasmosis in livestock in Italy: an epidemiological update. Infection with Toxoplasma gondii is one of the most common parasitic infections of human being and other warm-blooded animals. It has been found worldwide from Alaska to Australia. Public health organizations repeatedly encourage the collection of accurate data about T. gondii in animals and humans due to its medical importance as a major source of parasitic zoonosis. For these reasons, epidemiological updates on toxoplasmosis in livestock are strongly advised also to plan control strategies. In the present paper, seroprevalence data on T. gondii that have been recorded in livestock from diffe...
Adsorptive effects of di-tri-octahedral smectite on Clostridium perfringens alpha, beta, and beta-2 exotoxins and equine colostral antibodies. To determine the adsorptive capability of di-tri-octahedral smectite (DTOS) on Clostridium perfringens alpha, beta, and beta-2 exotoxins and equine colostral antibodies. Methods: 3 C perfringens exotoxins and 9 colostral samples. Methods: Alpha, beta, and beta-2 exotoxins were individually co-incubated with serial dilutions of DTOS or bismuth subsalicylate, and the amount of toxin remaining after incubation was determined via toxin-specific ELISAs. Colostral samples from healthy mares were individually co-incubated with serial dilutions of DTOS, and colostral IgG concentrations were determined...
Fatal pulmonary hemorrhage associated with RTX toxin producing Actinobacillus equuli subspecies haemolyticus infection in an adult horse. A case of fatal pulmonary hemorrhage in a 6-year-old American Paint mare with a 2-week history of intermittent coughing, fever, and epistaxis is described. Significant macroscopic abnormalities at postmortem examination were restricted to the respiratory system, and microscopically, severe pulmonary hemorrhage with suppurative bronchopneumonia was found. Actinobacillus equuli subsp. haemolyticus was cultured from a transtracheal wash performed antemortem as well as from the lungs at necropsy. The presence of airway-associated hemorrhage in conjunction with bacterial bronchopneumonia suggested ...
Toxins affecting the urinary system. Many different substances can induce toxic damage to various structural components of the equine kidney, and most lack pathognomonic signs. Some of these agents have specific treatments, although many do not. Supportive and symptomatic therapy is an important aspect of treatment of most cases of equine nephrotoxicosis. Regardless of cause, if the toxic substance is removed or neutralized before significant renal damage, full recovery of renal function may occur. Many horses already have significant renal damage before a definitive diagnosis is made, and the prognosis for full recovery thus rem...
