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.
Hardeman LC, van der Meij BR, Oosterlinck M, Veraa S, van der Kolk JH, Wijnberg ID, Back W.In the treatment of laminitis, reducing deep digital flexor muscle (DDFM) activity might diminish its pull on the distal phalanx, thereby preventing displacement and providing pain relief. Injection of Clostridium botulinum toxin type A into the DDFM of horses is potentially therapeutic. However, the effects of C. botulinum toxin type A on the gait characteristics of sound horses at the walk are not known. The aim of this study was to test if a reduced DDFM activity would lead to (1) alterations of the sagittal range of motion of the metacarpus (SROM) and range of motion of the carpal joint (C...
Sevigny LM, Booth BJ, Rowley KJ, Leav BA, Cheslock PS, Garrity KA, Sloan SE, Thomas W, Babcock GJ, Wang Y.Diphtheria antitoxin (DAT) has been the cornerstone of the treatment of Corynebacterium diphtheriae infection for more than 100 years. Although the global incidence of diphtheria has declined steadily over the last quarter of the 20th century, the disease remains endemic in many parts of the world, and significant outbreaks still occur. DAT is an equine polyclonal antibody that is not commercially available in the United States and is in short supply globally. A safer, more readily available alternative to DAT would be desirable. In the current study, we obtained human monoclonal antibodies (h...
Diab SS, Rodriguez-Bertos A, Uzal FA.Clostridium difficile is commonly associated with diarrhea and colitis in humans and other mammals, including horses. To this date, the epidemiologic, microbiologic, clinical, and diagnostic aspects of C. difficile-associated disease (CDAD) in horses have been thoroughly described. However, reports describing the enteric pathology of this disease in horses are limited. This study presents a comprehensive description of the pathologic characteristics of CDAD in 21 horses and discusses the criteria for the diagnosis of the disease. Case selection was based on C. difficile A/B toxins detection (e...
Yang N, Mu MY, Yuan GM, Zhang GX, Li HK, He JB.Toxoplasma gondii is an important zoonotic pathogen infecting humans and almost all warm-blooded animals. The most common sources of human infection are ingestion of tissue cysts in raw or undercooked meat. However, limited information is available about T. gondii infection in horses and donkeys in China. In the present study, we report the seroprevalence of T. gondii infection in horses and donkeys in Liaoning province, northeastern China. Methods: Serum samples were collected from 711 and 738 slaughtered horses and donkeys, respectively, in 13 regions of Liaoning province. The modified agglu...
Bailly-Chouriberry L, Cormant F, Garcia P, Kind A, Popot MA, Bonnaire Y.Cobra venom (Naja kaouthia) contains a toxin called α-cobratoxin (α-Cbtx). This toxin is a natural protein containing 71 amino acids (MW 7821 Da) with a reported analgesic potency greater than morphine. In 2007, in USA, this substance was found in the barns of a thoroughbred trainer and since then till date, the lack of a detection of this molecule has remained a recurring problem for the horseracing industry worldwide. To solve this problem, the first method for the detection of α-cobratoxin in equine plasma has now been developed. Plasma sample (3 mL) was treated with ammonium sulfate at ...
Ossedryver SM, Baldwin GI, Stone BM, McKenzie RA, van Eps AW, Murray S, Fletcher MT.Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4-6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes, with mild to moderate periacinar necrosis also ev...
Silva RO, Ribeiro MG, Palhares MS, Borges AS, Maranhão RP, Silva MX, Lucas TM, Olivo G, Lobato FC.Toxin detection and screening could contribute to knowledge of the transmission patterns, risk factors and epidemiology of Clostridium difficile and Clostridium perfringens. Objective: To isolate C. difficile and C. perfringens and to detect A/B toxins in faecal samples from diarrhoeic and nondiarrhoeic foals. Methods: Cross-sectional observational study. Methods: A total of 153 samples from foals were collected: 139 samples from farms and 14 samples from diarrhoeic foals admitted to a veterinary hospital. The A/B toxins were detected by cytotoxicity assay. All suspected colonies of C. perfrin...
Finger MA, Villalobos EM, Lara Mdo C, Cunha EM, Barros Filho IR, Deconto I, Dornbusch PT, Ullmann LS, Biondo AW.Toxoplasma gondii, the agent for toxoplasmosis, has worldwide distribution. Horses normally play a secondary role in its life cycle, but movement around urban areas, feeding on grass and the increasing use of carthorses for gathering recyclable material in some urban areas of Brazil may increase their exposure to T. gondii infection. The aim of the present study was to investigate the frequency of anti-T. gondii antibodies in carthorses in the metropolitan region of Curitiba, PR. IgG antibodies against T. gondii were detected using the indirect fluorescence antibody test (IFAT) (titers ≥ 64)...
Guidolin FR, Tambourgi DV, Guidolin R, Marcelino JR, Okamoto CK, Magnoli FC, Queiroz GP, Dias da Silva W.Crotalus durissus terrificus, C. d. collilineatus, C. d. cascavella and C. d. marajoensis are responsible minor but severe snake bites in Brazil. The venoms of these snakes share the presence of crotoxin, a neurotoxin comprising of two associated components, crotapotin and phospholipase A2 (PLA2). Treatment of the victims with specific antiserum is the unique effective therapeutic measure. The ability of anti-Crotalus antisera produced by the routine using crude venom to immunize horses or purified crotoxin and PLA2 as individual immunogens was compared. Antisera obtained from horses immunized...
Domijan AM.Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium spp. moulds that contaminate crop, predominantly maize, all around the world. More than 15 types of fumonisins have been indentified so far, but FB(1) is the most abundant and toxicologically the most significant one. FB(1) has a wide range of toxic effects, depending on animal species. In horses FB(1) causes equine leukoencephalomalacia (ELEM), in pigs pulmonary oedema and in experimental rodents nephrotoxicity and hepatotoxicity. In humans exposure to FB(1) is linked with higher incidence of primary liver cancer and oesophageal cance...
Minervini F, Giannoccaro A, Nicassio M, Panzarini G, Lacalandra GM.Ochratoxin A (OTA) is a renal mycotoxin and transplacental genotoxic carcinogen. The aim of this study was to evaluate the natural occurrence of OTA in equine blood samples and its placental transfer. For the assessment of OTA levels, serum samples were collected from 12 stallions, 7 cycling mares and 17 pregnant mares. OTA was found in 83% of serum samples (median value = 121.4 pg/mL). For the assessment of placental transfer, serum samples were collected from the 17 mares after delivery and from the umbilical cords of their foals, after foaling. Fourteen serum samples from pregnant mares con...
Gutiérrez JM, Tsai WC, Pla D, Solano G, Lomonte B, Sanz L, Angulo Y, Calvete JJ.A polyspecific antivenom is used in Central America for the treatment of envenomings by viperid snakes. This antivenom is generated in horses hyperimmunized with a mixture of venoms from Bothrops asper, Crotalus simus and Lachesis stenophrys. The present study analyzed the ability of this antivenom to neutralize the venoms of three Central American viperid species of the 'Porthidium group', i.e. Porthidium nasutum, Porthidium ophryomegas and Cerrophidion sasai, formerly classified as Cerrophidion godmani. In addition, the immunorecognition of the components of these venoms was assessed by immu...
Artiushin S, Timoney JF, Fettinger M, Fallon L, Rathgeber R.Enterocolitis caused by Clostridium difficile (C. difficile) is a serious, sometimes fatal, disease of neonatal foals and older horses. Toxins A and B (TcdA and B) produced by C. difficile are important virulence factors. Immunisation of mares with receptor binding domains of toxins may prevent or reduce the severity of C. difficile colitis in foals. Objective: To determine whether antibodies generated in the pregnant mare to the binding regions of TcdA and B will neutralise TcdA and B toxicity. Methods: Sequences encoding the binding domains of each toxin were isolated by PCR amplification fr...
Valberg SJ, Sponseller BT, Hegeman AD, Earing J, Bender JB, Martinson KL, Patterson SE, Sweetman L.We hypothesised that seasonal pasture myopathy (SPM), which closely resembles atypical myopathy (AM), was caused by ingestion of a seed-bearing plant abundant in autumn pastures. Objective: To identify a common seed-bearing plant among autumn pastures of horses with SPM, and to determine whether the toxic amino acid hypoglycin A was present in the seeds and whether hypoglycin metabolites were present in SPM horse serum or urine. Methods: Twelve SPM cases, 11 SPM pastures and 23 control farms were visited to identify a plant common to all SPM farms in autumn. A common seed was analysed for amin...
Votion DM.Atypical myopathy (AM) is a frequently fatal seasonal pasture myopathy that emerges in Europe. Outbreaks are of an acute and unexpected nature and practitioners should be prepared to handle these critically ill patients. This review retraces the history of AM and describes results of epidemiological investigations that were conducted to raise hypotheses concerning the etiology of this devastating disease as well as to be able to suggest potential preventive measures. Also, clinical studies have contributed to a better definition and recognition of the syndrome, whereas elucidation of the patho...
Johnstone LK, Mayhew IG.To investigate the effects of lolitrem B intoxication on renal K(+) secretion in response to increased tubular flow rates. Methods: Results are derived from a repeated measure pilot study of seven horses fed non-perennial ryegrass feed for a week prior to exposing them to perennial ryegrass seed and hay that contained an average of 2 ppm lolitrem B. At the end of the control and treatment period frusemide (1 mg/kg I/V) was administered and serial fractional excretion of K(+)(FEK(+)) and fractional excretion of Na(+)(FENa(+)) calculated. Baseline concentration of aldosterone in plasma, serum K(...
Villalta M, Pla D, Yang SL, Sanz L, Segura A, Vargas M, Chen PY, Herrera M, Estrada R, Cheng YF, Lee CD, Cerdas M, Chiang JR, Angulo Y, León G....The proteomes of the venoms of the snakes Viridovipera stejnegeri and Protobothrops mucrosquamatus from Taiwan were characterized by N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation tandem mass spectrometry of in-gel generated tryptic peptides. Proteins belonging to the following toxin classes were identified: metalloproteinase, phospholipase A(2) (PLA(2)), serine proteinase, C-type lectin-like, CRISP, l-amino acid oxidase, disintegrin, and peptides (vasoactive and inhibitors of SVMPs). Nine horses were immunized with a mixture of these venoms. All horse...
Khol-Parisini A, Hellweg P, Razzazi-Fazeli E, Saalmüller A, Strasser A, Tichy A, Zenteke J.The aim of the present study was to investigate the impact of deoxynivalenol (DON) on cellular and humoral immune parameters in horses. A feeding trial using naturally contaminated oats with high (20.2 mg/kg) and low (0.49 mg/kg) levels of DON was conducted. Two groups of five mares were fed 2 kg oats daily with high or low DON levels for two weeks, using a crossover design with a three-week wash-out period. No adverse effects on general health were observed. Only minor diet-related changes in differential blood counts and serum biochemistry were noted. Serum haptoglobin concentration was sign...
Li D, Mattoo P, Keller JE.Hyperimmune monovalent antitoxins to botulinum neurotoxin serotypes A and B have been produced by immunizing horses with newly developed formalin toxoids. After primary immunization, horses developed acceptable prophylactic antibody titers (1-5 IU/mL). Three horses received additional toxoid booster injections to induce hyperimmune antibody titers with antitoxin-A and antitoxin-B titers reaching peaks of approximately 2000 IU/mL and 150-625 IU/mL, respectively. Titers were quantified throughout the process by antigen-capture ELISA and by in-vivo neutralization. ELISA titers and neutralization ...
Lima EF, Riet-Correa F, Gardner DR, Barros SS, Medeiros RM, Soares MP, Riet-Correa G.Poisoning by Indigofera lespedezioides is reported in horses in the state of Roraima, northern Brazil. The main clinical signs are anorexia, sleepiness, unsteady gait, severe ataxia, weakness, stumbling, and progressive weight loss. To induce the disease experimentally, a 7-year-old horse was introduced in a small paddock invaded by the plant. The first nervous signs were observed 44 days from the start of grazing. The animal was euthanized on day 59. No significant gross lesions were observed upon necropsies of the experimental horse as well as one spontaneously affected horse. Upon histologi...
Ostrowski SR, Kubiski SV, Palmero J, Reilly CM, Higgins JK, Cook-Cronin S, Tawde SN, Crossley BM, Yant P, Cazarez R, Uzal FA.In September 2010, an outbreak of type A botulism involved 4 horses in northern California that were fed grass clippings obtained from a nearby park. All 4 animals developed a progressive flaccid paralysis syndrome clinically consistent with exposure to preformed Clostridium botulinum neurotoxin (BoNT). Within 48 hr of consuming the grass clippings, all 4 horses showed marked cervical weakness (inability to raise their heads to a normal position) and died or were euthanized within 96 hr. One horse was submitted for diagnostic examination and subsequent necropsy. At necropsy, extensive edema wa...
Macias Rioseco M, Beingesser J, Uzal FA.Clostridium perfringens type C causes necrotizing enteritis mostly in neonatal animals of several species, including horses. The virulence of C. perfringens type C is mostly mediated by beta toxin (CPB). This toxin is highly sensitive to the action of trypsin and other proteases, which explains the increased susceptibility of neonatal animals to type C infections. Final confirmation of type C disease diagnosis should be based on detection of CPB in the intestinal content of affected animals. However, because CPB is so sensitive to the action of proteases, it is believed that this toxin persist...
Uzal FA, Diab SS, Blanchard P, Moore J, Anthenill L, Shahriar F, Garcia JP, Songer JG.Clostridium perfringens type C is one of the most important agents of enteric disease in newborn foals. Clostridium difficile is now recognized as an important cause of enterocolitis in horses of all ages. While infections by C. perfringens type C or C. difficile are frequently seen, we are not aware of any report describing combined infection by these two microorganisms in foals. We present here five cases of foal enterocolitis associated with C. difficile and C. perfringens type C infection. Five foals between one and seven days of age were submitted for necropsy examination to the Californi...
Songsermsakul P, Böhm J, Aurich C, Zentek J, Razzazi-Fazeli E.Concentration profile of zearalenone (ZON) and its metabolites in plasma, urine and faeces samples of horses fed with Fusarium toxin-contaminated oats is described. In plasma, β-zearalenol (β-ZOL) was detected at high levels on day 10 of the study (3.21-6.24 μg/l). β-Zearalenol and α-zearalenol were the major metabolites in urine. Zearalenone, α-ZOL and β-ZOL were predominantly found in faeces. Zearalanone could also be detected in urine (1.34-5.79 μg/l) and faeces (1 μg/kg). The degree of glucuronidation was established in all sample types, approximately 100% in urine and plasm...
Schwarz B, Brunthaler R, Hahn C, van den Hoven R.Equine grass sickness (EGS) occurs mainly in Great Britain, but has once been reported in Hungary. The stud which was affected by EGS in 2001 had no new cases until 2009/10, when 11 of 60 and five of 12 one- to three-year-old colts died or were euthanased due to EGS. Following a few hours in the high-risk field during the winter of 2010/11 further four cases of acute EGS were noted among these horses. The affected horses showed somewhat different clinical signs compared with the cases reported in Great Britain. Histopathological findings in these horses were consistent with EGS. In most examin...
Dawson DR.This article provides an overview of the more common toxins and adverse drug reactions, along with more rare toxins and reactions (Table 1), that result in neurologic dysfunction in horses. A wide variety of symptoms, treatments, and outcomes are seen with toxic neurologic disease in horses. An in-depth history and thorough physical examination are needed to determine if a toxin or adverse drug reaction is responsible for the clinical signs. Once a toxin or adverse drug reaction is identified, the specific antidote, if available, and supportive care should be administered promptly.
Boughattas S, Bergaoui R, Essid R, Aoun K, Bouratbine A.The present study was conducted to investigate the serological survey of Toxoplasma antibodies in local.horses from three major regions: a neighbourhood of a city in the North (Sidi Thabet), a neighbourhood of a city on the coast (Monastir) and a neighbourhood of a city in the middle (Battan) of Tunisia (North of Africa). Methods: A total of 158 serum samples were obtained from clinically healthy horses which consisted of 111 (32 female, 79 male) 2-10 years old and 47 (11 female, 36 male) older than 10 years. All of the horses were tested for antibodies to T. gondii using the Modified Agglutin...
Fletcher MT, Hayes PY, Somerville MJ, De Voss JJ.Crotalaria medicaginea has been implicated in horse poisoning in grazing regions of central-west Queensland, which resulted in the deaths of more than 35 horses from hepatotoxicosis in 2010. Liver pathology was suggestive of pyrrolizidine alkaloidosis, and we report here the isolation of two previously uncharacterized pyrrolizidine alkaloids from C. medicaginea plant specimens collected from pastures where the horses died. The first alkaloid was shown by mass spectometric and NMR analyses to be 1β,2β-epoxy-7β-hydroxy-1α-methoxymethyl-8α-pyrrolizidine, which, like other alkaloids previousl...
Filannino A, Stout TA, Gadella BM, Sostaric E, Pizzi F, Colenbrander B, Dell'Aquila ME, Minervini F.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...
Khol-Parisini A, Hellweg P, Razzazi-Fazeli E, Saalmüller A, Strasser A, Tichy A, Zenteke J.The aim of the present study was to investigate the impact of deoxynivalenol (DON) on cellular and humoral immune parameters in horses. A feeding trial using naturally contaminated oats with high (20.2 mg/kg) and low (0.49 mg/kg) levels of DON was conducted. Two groups of five mares were fed 2 kg oats daily with high or low DON levels for two weeks, using a crossover design with a three-week wash-out period. No adverse effects on general health were observed. Only minor diet-related changes in differential blood counts and serum biochemistry were noted. Serum haptoglobin concentration was sign...
Qi T, Ai J, Sun Y, Ma H, Kang M, You X, Li J.Toxoplasmosis is a zoonotic disease caused by the obligate intracellular protozoan parasite which is widely prevalent in humans and animals worldwide. The diagnosis of toxoplasmosis and distinguishing acute or chronic infections have utmost importance for humans and animals. The SAG1, GRA7, and BAG1 proteins were used in the present study to develop the serological rSAG1-ELISA, rGRA7-ELISA and rBAG1-ELISA methods for the testing of specific IgG and IgM antibodies and differentiating acute or chronic toxoplasmosis in 3733 animals, including Tibetan sheep, yaks, pigs, cows, cattle, horses, ch...
Reisinger N, Dohnal I, Nagl V, Schaumberger S, Schatzmayr G, Mayer E.One of the most important hoof diseases is laminitis. Yet, the pathology of laminitis is not fully understood. Different bacterial toxins, e.g. endotoxins or exotoxins, seem to play an important role. Additionally, ingestion of mycotoxins, toxic secondary metabolites of fungi, might contribute to the onset of laminitis. In this respect, fumonsins are of special interest since horses are regarded as species most susceptible to this group of mycotoxins. The aim of our study was to investigate the influence of fumonisin B₁ (FB₁) on primary isolated epidermal and dermal hoof cells, as well as ...
Cawdell-Smith AJ, Scrivener CJ, Bryden WL.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...
Juhász J, Nagy P, Kulcsár M, Szigeti G, Reiczigel J, Huszenicza G.The effect of 10-day zearalenone administration starting 10 days after ovulation was studied in 6 cycling trotter mares in the summer period. After an entire oestrous cycle (Cycle 1), mares were given 7 mg purified zearalenone per os daily (1 mg/ml in ethyl alcohol) beginning on Day 10 of Cycle 2. Toxin exposure was continued until the subsequent ovulation. Luteal function and follicular activity were monitored daily by rectal palpation, ultrasonography and blood sampling for progesterone. During toxin exposure, all animals were in good physical condition. The toxin had no effect on the length...
Magdesian KG, Leutenegger CM.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...
Wilson TM, Ross PF, Owens DL, Rice LG, Green SA, Jenkins SJ, Nelson HA.An experiment to gain insight into the minimum toxic dose of fumonisins was conducted by feeding ponies rations with known fumonisin concentrations. Naturally contaminated corn screenings (CS) were blended with pellets, corn, and molasses to formulate individual daily diets. One group of 4 ponies was fed a ration with fumonisin B1 (FB1) varying from less than 1 ppm to 22 ppm. A second group of 5 ponies was fed a ration at varying rates containing 8 ppm FB1 for 180 days. A panel of clinical chemistry parameters was evaluated twice weekly for both groups. One pony in the first group died of equi...
Karlíková R, Široká J, Jahn P, Friedecký D, Gardlo A, Janečková H, Hrdinová F, Drábková Z, Adam T.Atypical myopathy (AM) is a potentially fatal disease of grazing horses. It is reportedly caused by the ingestion of sycamore seeds containing toxic hypoglycin A. In order to study metabolic changes, serum and urine samples from nine horses with atypical myopathy and 12 control samples from clinically healthy horses were collected and then analysed using a high-performance liquid chromatography coupled with tandem mass spectrometry; serum metabolic profiles as the disease progressed were also studied. Metabolic data were evaluated using unsupervised and supervised multivariate analyses. Signif...
González Medina S, Hyde C, Lovera I, Piercy RJ.Hypoglycin A (HGA) toxicity, following ingestion of material from certain plants, is linked to an acquired multiple acyl-CoA dehydrogenase deficiency known as atypical myopathy, a commonly fatal form of equine rhabdomyolysis seen worldwide. Whilst some plants are known to contain this toxin, little is known about its function or the mechanisms that lead to varied HGA concentrations between plants. Consequently, reliable tools to detect this amino acid in plant samples are needed. Analytical methods for HGA detection have previously been validated for the food industry, however, these technique...
Gutiérrez JM, Tsai WC, Pla D, Solano G, Lomonte B, Sanz L, Angulo Y, Calvete JJ.A polyspecific antivenom is used in Central America for the treatment of envenomings by viperid snakes. This antivenom is generated in horses hyperimmunized with a mixture of venoms from Bothrops asper, Crotalus simus and Lachesis stenophrys. The present study analyzed the ability of this antivenom to neutralize the venoms of three Central American viperid species of the 'Porthidium group', i.e. Porthidium nasutum, Porthidium ophryomegas and Cerrophidion sasai, formerly classified as Cerrophidion godmani. In addition, the immunorecognition of the components of these venoms was assessed by immu...
Schrenk D, Bignami M, Bodin L, Del Mazo JKCJ, Grasl-Kraupp B, Hogstrand C, Leblanc JC, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T....In 2017, the EFSA Panel on Contaminants in the Food Chain (CONTAM) adopted a Scientific Opinion on the risks for animal health related to the presence of deoxynivalenol (DON) and its acetylated and modified forms in food and feed. No observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) were derived for different animal species. For horses, an NOAEL of 36 mg DON/kg feed was established, the highest concentration tested and not showing adverse effects. For poultry, an NOAEL of 5 mg DON/kg feed for broiler chickens and laying hens, and an NOAEL of 7 mg DO...
Roy Chowdhury P, DeMaere M, Chapman T, Worden P, Charles IG, Darling AE, Djordjevic SP.Clostridium difficile infections (CDI) are a significant health problem to humans and food animals. Clostridial toxins ToxA and ToxB encoded by genes tcdA and tcdB are located on a pathogenicity locus known as the PaLoc and are the major virulence factors of C. difficile. While toxin-negative strains of C. difficile are often isolated from faeces of animals and patients suffering from CDI, they are not considered to play a role in disease. Toxin-negative strains of C. difficile have been used successfully to treat recurring CDI but their propensity to acquire the PaLoc via lateral gene transfe...
Navarro D, Vargas M, Herrera M, Segura Á, Gómez A, Villalta M, Ramírez N, Williams D, Gutiérrez JM, León G.A chicken-derived antivenom (ChDAv) towards taipan snake (Oxyuranus scutellatus) venom was produced by purifying anti-taipan IgY from egg yolks of hens immunized with taipan venom. The productivity, antivenomic profile, neutralization ability, pharmacokinetic properties and immunogenicity of the ChDAv were compared with those of an antivenom produced in horses (EDAv). We found that 382 eggs are required to produce the mass of anti-taipan antibodies contained in one liter of equine hyperimmune plasma, and that 63 chickens would be needed to generate the amount of anti-taipan antibodies annually...
Rocha-Campos AC, Gonçalves LR, Higashi HG, Yamagushi IK, Fernandes I, Oliveira JE, Ribela MT, Sousa-E-Silva MC, da Silva WD.Contact with Lonomia obliqua caterpillars results in a bleeding syndrome characterized by hemorrhage and blood coagulation disturbances. Conventional therapy using antifibrinolytics or cryoprecipitates has been unable to treat pathophysiologic alterations. As antivenoms are effective therapy for treatment of victims of venomous animals, a process of manufacturing a specific antilonomic serum by immunizing horses with Lonomia caterpillar bristle extracts (LBE) was developed. Lonomia caterpillar bristle extracts exhibited several protein bands on SDS-PAGE, induced blood coagulation abnormalities...
Schultze AE, Rohrbach BW, Fribourg HA, Waller JC, Oliver JW.Tall fescue (Festuca arundinacea) is a forage grass that is widely used in pastures in the eastern US for cattle, sheep and horses. The endophytic fungus Neotyphodium coenophialum is endemic in tall fescue pastures in the US. The turfgrass industry intentionally infects fescue cultivars with strains of the fungus to impart desirable growth and disease tolerance qualities to the plants. In contrast, ergot and pyrrolizidine alkaloid toxins produced by fungus-infected plants have been incriminated causally in bovine tall fescue toxicosis, a poorly defined syndrome of morbidity that occurs in catt...
Ricketts SW, Greet TR, Glyn PJ, Ginnett CD, McAllister EP, McCaig J, Skinner PH, Webbon PM, Frape DL, Smith GR.An outbreak of pharyngeal and limb paresis involving four horses and nine ponies in the south east of England is described. Nine of the animals died or were destroyed on humane grounds. The clinical features suggested a diagnosis of botulism and mouse innoculation tests confirmed the presence of type B toxin in the serum of one case. All animals were fed big bale silage. It is describe how, in plastic wrapped silage manufacture, conditions of fermentation may be inadequate to prevent the growth of Clostridium botulism. Examination of a sample of silage fed to the affected horses suggested that...
Larsson P, Persson E, Tydén E, Tjälve H.Horses may be exposed to aflatoxin B(1) (AFB(1)) via inhalation of mouldy dust, leading to high exposure of olfactory and respiratory tissues. In the present study the metabolic activation of AFB(1) was examined in olfactory and respiratory tissues in horse. The results showed covalent binding of AFB(1)-metabolites in sustentacular cells and cells of Bowman's glands in the olfactory mucosa, in some cells of the surface epithelium of nasal respiratory, tracheal, bronchial and bronchiolar mucosa and in some glands in these areas. Immunohistochemistry revealed that cells expressing proteins react...
Larsen J.This review article describes the different aetiological agents known or suspected to cause colitis in the adult horse, namely Salmonella spp., Clostridium spp., Ehrlichia risticii, Cyathostomes, fungi, various antibiotics, drugs, and toxins, with emphasis on their mechanism of action. For each of the infectious agents, diagnostic procedures are indicated. The effects of endotoxin can be important in all forms of equine colitis.
Kinde H, Bettey RL, Ardans A, Galey FD, Daft BM, Walker RL, Eklund MW, Byrd JW.An episode of nervous system dysfunction was observed in horses on 17 premises in 4 counties of southern California. Thirty-eight horses were affected, and 31 of those died. The common clinical signs of disease in the affected horses were: increased appetite; anxious attitude; rythmic, intermittent muscle tremors in the area of the tricep muscles; decreased palpebral tone; mydriasis; small hard fecal balls; and tendency to become sternally recumbent with the neck extended. The temporal distribution of cases on all 17 premises suggested a relationship between exposure to a common batch of alfal...
Riquelme G, Sepúlveda JM, Al Ghumgham Z, Del Campo M, Montero C, Lagos N.Local anesthesia is an effective method to control pain. Neosaxitoxin is a phycotoxin whose molecular mechanism includes a reversible inhibition of voltage-gated sodium channels at the axonal level, impeding nerve impulse propagation. The present study was designed to evaluate the clinical efficacy of Neosaxitoxin as a local long-acting pain blocker in horse bucked shins, and it was found to effectively control pain. While Neosaxitoxin and Gonyautoxin, another Paralytic Shellfish Poison (PSP) toxin, have been successfully used in humans as long-lasting pain blockers, this finding marks the fir...
Lawler JB, Hassel DM, Magnuson RJ, Hill AE, McCue PM, Traub-Dargatz JL.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...
Galey FD.Botulism should be considered in cases where weakness, paralysis, or intolerance to exercise might be seen in the horse. Dysphagia may also be present, although it is not a consistent finding. Potential sources include carrion in hay, moldy or otherwise rotted vegetation or forage, birds carrying material from animal burial or other similar sites, and contaminated carcasses on-site. Horses, especially foals, may also suffer from toxicoinfectious botulism, a condition where the C. botulinum might colonize and produce toxin within the gastrointestinal tract. Wounds also may harbor the organism a...
Meireles MC, Corrêa B, Fischman O, Gambale W, Paula CR, Chacon-Reche NO, Pozzi CR.The mycoflora of 39 feed samples associated with 29 Equine Leukoencephalomalacia (ELEM) outbreaks was studied from 1988 to 1990, in Brazil. Microbiological examination indicated Fusarium spp. as the most frequent mold which occurred in 97.4% of samples followed by Penicillium spp. in 61.5% and Aspergillus spp. in 35.9%. The moisture content of feed implicated in death of horses was above 15% which can favor the development of Fusarium spp. From the genus, F. moniliforme was the predominant species with an occurrence of 82.0%. Two additional species, not commonly associated with animal toxicosi...
Krägeloh T, Cavalleri JMV, Ziegler J, Sander J, Terhardt M, Breves G, Cehak A.Intestinal absorption of hypoglycin A (HGA) and its metabolism are considered major prerequisites for atypical myopathy (AM). The increasing incidence and the high mortality rate of AM urgently necessitate new therapeutic and/or preventative approaches. Objective: To identify a substance for oral administration capable of binding HGA in the intestinal lumen and effectively reducing the intestinal absorption of the toxin. Methods: Experimental in vitro study. Methods: Substances commonly used in equine practice (activated charcoal composition, di-tri-octahedral smectite, mineral oil and activat...
Harrach B, Bata A, Sándor G, Ványi A.Satratoxins H and G, verrucarin J, and roridin E were isolated from the bedding straw of 200 sport horses exhibiting typical symptoms of stachybotryo-toxicosis. At the same time, the oat feed consumed by the horses contained non-macrocyclicFusarium trichothecenes: T-2 toxin and diacetoxyscirpenol.
Newton JR, Hedderson EJ, Adams VJ, McGorum BC, Proudman CJ, Wood JL.The reasons why equine grass sickness (EGS) recurs on premises are unknown and, consequently, practical methods for reducing the risk of recurrence are not available. Objective: To identify risk factors associated with recurrence of EGS on premises and to gain possible insights into the pathogenesis of the disease. Methods: Data on disease history and risk factors were collected by postal questionnaire from premises with EGS cases between 1st January 1997 and 31st December 2001. Data on variation in rates of recurrence of EGS for different risk factors were analysed using Poisson regression an...
Songer JG, Trinh HT, Dial SM, Brazier JS, Glock RD.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...
Schoenbaum MA, Hall SM, Glock RD, Grant K, Jenny AL, Schiefer TJ, Sciglibaglio P, Whitlock RH.A USDA Early Response Team investigated deaths of several horses and a mule in northern Arizona at the request of local animal health officials. Thirteen animals (12 horses and 1 mule) housed at 5 facilities in a 7.4 square mile area died between August 1998 and January 1999. Clinical signs consisted of muscular weakness that rapidly progressed to lateral recumbency. Ten animals had paresis of the tongue, throat, or lips. Affected animals appeared alert and were interested in eating and drinking, even while recumbent. All 13 animals were euthanatized. Clostridium botulinum type C was isolated ...
Medina-Torres CE, Weese JS, Staempfli HR.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...
