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.
The role of intestinal microflora in the metabolism of trichothecene mycotoxins. The role of faecal and intestinal microflora on the metabolism of trichothecene mycotoxins was examined in this study. Suspensions of microflora obtained from the faeces of horses, cattle, dogs, rats, swine and chickens were incubated anaerobically with the trichothecene mycotoxin, diacetoxyscirpenol (DAS). Micro-organisms from rats, cattle and swine completely biotransformed DAS, primarily to the deacylated deepoxidation products, deepoxy monoacetoxyscirpenol (DE MAS) and deepoxy scirpentriol (DE SCP). By contrast, faecal microflora from chickens, horses and dogs failed to reduce the epoxide ...
Fumonisins–novel mycotoxins with cancer-promoting activity produced by Fusarium moniliforme. Cultures on corn of Fusarium moniliforme MRC 826 are known to cause leukoencephalomalacia in horses and to be toxic and hepatocarcinogenic in rats. Culture material of this F. moniliforme isolate has also been shown to exhibit cancer-promoting activity in a short-term cancer initiation-promotion bioassay with diethylnitrosamine-initiated rats and the induction of gamma-glutamyl-transpeptidase-positive (GGT+) foci as an endpoint after 4 weeks of promotion. This bioassay was used as a monitoring system to isolate cancer-promoting compounds from cultures of F. moniliforme MRC 826. Culture materia...
Isolation of macrocyclic and non-macrocyclic trichothecenes (stachybotrys and fusarium toxins) from the Environment of 200 III Sport Horses. 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.
Toxigenic characteristics of Clostridium perfringens type C in enterotoxemia of domestic animals. Eleven Clostridium perfringens type C strains isolated from fatal cases of hemorrhagic enterotoxemia of Canadian calves, a piglet, and a foal were studied for the production of soluble antigens. All the isolates from calves and a foal failed to produce delta toxin, but were capable of producing large amounts of lethal beta toxin. A strain isolated from a piglet produced delta, but very little beta toxin. Other differences were relatively minor. The results indicated that young domestic animals may be susceptible to all subtypes of C. perfringens type C. A simple method of using blood agar plat...
The effects of four levels of endophyte-infected fescue seed in the diet of pregnant pony mares. Mean weight of 20 Quarter Horse placentas on a wet basis was 3.27 +/- 0.17 kg. These placentas contained mean dry fat-free tissue, DNA, RNA and collagen weights of 411 +/- 24 g, 11.2 +/- 0.6 g, 12.4 +/- 0.7 g and 210 +/- 15 g, respectively. In Ponies and Quarter Horses, there was a trend towards a decrease in these 4 values as gestation length increased. Analysis of placentas of Ponies fed different amounts of endophyte fungus-infected fescue seed showed that weight of dry fat-free tissue increased with increasing percentages of fescue seed in the diet. Diets containing fescue seed resulted in...
Fusariotoxicoses of farm animals and mycotoxic leucoencephalomalacia of the equine associated with the finding of trichothecenes in feedstuffs. Mycotoxicoses involving horses, rabbits and cattle have been studied. Fusarium tricinctum and T-2 toxin were isolated from all incriminated feedstuffs. Other isolated trichothecenes from the feed included HT-2, verrucarins and roridin. The toxins were separated, identified and quantitated using thin-layer chromatography, gas-liquid chromatography and mass spectrometry. T-2 toxin was detected in amounts varying from 0.5-204 ppm. The contaminated feedstuffs in connection with the affected horses and rabbits, included cereal grains (corn, cornstalks, bran and barley), whereas fescue hay was assoc...
Anti-lipopolysaccharide toxin therapy for whole body X-irradiation overdose. Death in humans from ionising radiation overexposure in the 3-8 Gy (300-800 rad) range is in part due to the toxaemia caused by the entry of gram-negative bacteria and/or their lipopolysaccharide toxin (LPS) into the blood circulation through the walls of partially denuded gut. Anti-LPS hyperimmune equine plasma was evaluated for its ability to lower irradiation-induced lethality. Mice were irradiated with 6.3 Gy (630 rad) and six days later received equine Anti-LPS hyperimmune plasma, control plasma or saline. Mortalities in the three groups were 58%, 92% and 79% (p less than 0.01) respective...
Persistence of encysted Toxoplasma gondii in tissues of equids fed oocysts. Thirteen 6-month- to 13-year-old equids were each inoculated orally with 10,000 infective Toxoplasma gondii oocysts. The equids remained clinically normal. Equids were euthanatized on postinoculation days 33, 45, 90, 104, 120, 140, 162, 183, 197, 204, 211, 294, and 476. Their tissues were bioassayed for viable oocysts by feeding muscles to Toxoplasma-free cats and by inoculation of pepsin digests of 13 organs into mice. Using mouse inoculation, T gondii was recovered from tissues of the 9 equids euthanatized on each of postinoculation days 33, 45, 120, 140, 183, 197, 211, 294, and 476. Toxopla...
Diagnosis of gastroduodenojejunitis and its surgical treatment by a temporary duodenocaecostomy. Gastroduodenojejunitis is a catarrhal inflammation of the stomach and proximal portion of the small intestine. Secondary overloading of the stomach occurs so that affected horses rapidly enter a state of hypovolaemic shock which is further complicated by the presence of toxins. The condition can occur in a mild or severe form. In mild cases, conservative treatment comprising intravenous electrolyte therapy and repeated gastric decompression is indicated and is usually successful. In severe cases surgical treatment creating duodenocaecal anastomosis has given good results. This should be carrie...
The prevalence of Toxoplasma gondii antibodies in man in Plateau State and meat animals in Nigeria. Toxoplasma gondii antibodies were found in the sera of 22.86% of people in the Jos area of Plateau State, Nigeria. The incidence of antibodies in Nigerian food animals was 17.40%, the highest being in sheep (21.92%) and lowest in goats (13.88%). Cattle and horses were roughly equally infected--about 17.0%. The zoonotic potential of T. gondii in food animals is stressed and epidemiological factors are reviewed.
Thirteen cases of botulism in horses fed big bale silage. 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...
Outbreak of botulism in horses. An outbreak of nervous disease in Standardbred horses occurred near Bendigo, in south-eastern Australia, in October 1980. Over a two week period 11 horses in four training stables were affected with gait abnormalities, depression and recumbency. Eight of the 11 died. The results of an investigation implicated Clostridium botulinum toxin as the cause. The toxin was food-borne as a contaminant of oaten chaff.
Antitoxin levels in botulism patients treated with trivalent equine botulism antitoxin to toxin types A, B, and E. Serum levels of equine-botulism antitoxin to toxin types A, B, and E were measured in four type-A botulism patients who had received equine-botulism antitoxin. High circulating levels capable of neutralizing in excess of 1 X 10(8), 9 X 10(7), and 6 X 10(6) 50% mouse lethal doses of toxin of types A, B, and E, respectively, were detected. There was little depletion of type-A antitoxin even though two of the patients had circulating type-A toxin before treatment. The half-life for antitoxin persistence for one patient was calculated as being 6.5, 7.6, and 5.3 days for antitoxin types A, B, and E...
Acute diarrhea in horses of the Potomac River area: examination for clostridial toxins. Fecal specimens from horses in Montgomery County, Md, and in Fairfax and Loudoun counties, Va, were examined for Clostridium perfringens type A enterotoxin and for C difficile cytotoxin (92 and 108 specimens, respectively). The toxins were found in feces from horses that had experienced an acute diarrhea syndrome and from clinically normal horses. The toxins did not appear to be primary determinants of the diarrhea syndrome, although they may have contributed to the spectrum of clinical entities observed.
Identification of swainsonine as a probable contributory mycotoxin in moldy forage mycotoxicoses. When infested with the fungus Rhizoctonia leguminicola, certain forages, e.g., red clover hay, can cause a "slobber syndrome" of varying severity when consumed by ruminants. The causative agent has been presumed to be slaframine [(1S,6S,8aS)-1-acetoxy-6-aminooctahydroindolizine], which is produced by R. leguminicola. In one serious outbreak of the slobber syndrome in horses, the red clover forage involved was carefully examined and found to contain R. leguminicola and slaframine. An identical hay sample is shown here by ion-exchange chromatographic and gas chromatographic-mass spectrometric an...
Perilla ketone toxicity: a chemical model for the study of equine restrictive lung disease. Perilla ketone was assessed for its usefulness as a model of equine restrictive pulmonary disease. Three ponies were given 18 mg/kg bodyweight synthetic perilla ketone in dimethyl-sulphoxide. Within 24 h of administration, respiratory rate, peak inspiratory and expiratory flow rates and minute volume were increased. By 48 h there was a significant decrease in tidal volume, and blood pH and base excess were also decreased but not outside normal limits. At necropsy there was congestion and oedema of the lungs. Histologically there was diffuse alveolar injury but no evidence of significant obstru...
Clostridial cellulitis in the horse: a report of five cases. Five horses with fatal clostridial cellulitis are described. The characteristic findings were the rapid development of a crepitant swelling with an associated toxemia, which in four cases followed intramuscular injections. The clinical features, diagnostic techniques and pathogenesis are discussed. The importance of an early diagnosis is emphasized.
Toxoplasma antibodies in polo horses of Nigeria. A serological survey of Toxoplasma antibodies was carried out amongst horses used for polo game in Nigeria using the indirect haemagglutination test (IHA). A total of 70 horses from Kaduna, Kano and Jos that were assembled in Zaria for the annual national tournament were sampled. 26 (37.1%) of these were seropositive to T. gondii with the highest serological titre at 1:256. Out of the 52 local breeds, 20 (38.5%) were seropositive while of the 18 Argentine breeds, 6 (33.0%) were seropositive. No significant difference was found amongst the breeds. With the increasing interest in the game of pol...
Serum protein changes in grass sickness. Polyacrylamide gel electrophoresis was used to compare serum taken from ponies before and during clinical illness confirmed as grass sickness. A consistent rise in the level of haptoglobin was seen in serum from animals which had shown symptoms for more than two days. Serum albumin was also shown to have altered mobility at the onset of clinical disease. Estimation of the haemoglobin-binding capacity confirmed the haptoglobin increase. This haptoglobin has been purified and some of its properties determined. In contrast to the situation in acute inflammatory conditions no other acute-phase pro...
Polymorphonuclear neutrophil leucocytes of peritoneal fluid. Cells in the peritoneal fluid from 179 horses were examined in Giemsa stained preparations using light microscopy. Neutrophils were found in all samples whether transudative or exudative although their proportions varied enormously. They were well preserved in "normal" or sterile effusions and hardly differed morphologically from those seen on a peripheral blood film although hypersegmentation was commonly observed. In purulent effusions a reliable correlation was found between degenerative changes in neutrophils such as karyolysis and karyorrhexsis and the presence of toxin-producing microorg...
Experimental equine aflatoxicosis. Adult male Shetland ponies, two per dose level, were given aflatoxin daily at levels of 0.3, 0.15, or 0.075 mg/kg. Signs of toxicosis included inappetence, depression, tremors, and terminal prostration. Deaths occurred at 12 and 16 days (0.3 mg/kg), 25 and 32 days (0.15 mg/kg), and 36 and 39 days (0.075 mg/kg). Prothrombin time, sulfabromophthalein clearance time, total plasma bilirubin, and icteric index increased markedly before death. Elevations in plasma activity of aspartate amino transferase (AST) were observed 1 to 4 days after the start of aflatoxin administration in the high dose grou...
Salivary syndrome in horses: identification of slaframine in red clover hay. An outbreak of salivary syndrome in horses in North Carolina was investigated. Rhizoctonia leguminicola was the predominant fungus isolated from toxic red clover hay. The fungus was less prevalent in the hay after 10 months of storage, and the hay had also decreased in biological activity after 10 months. Toxic hay caused extreme salivation, piloerection, respiratory distress, and increased frequency of defecation when fed to guinea pigs, and purified extracts of toxic hay and pure slaframine elicited these same responses when injected intraperitoneally into guinea pigs. The freshly acquired h...