Diagnosis and Treatment of Aflatoxin Poisoning in Cattle

Aflatoxins are a class of hepatotoxic substances. After animals are poisoned, liver damage predominates, accompanied by increased vascular permeability and central nervous system damage, with clinical features including jaundice, hemorrhage, edema and neurological symptoms. Acute poisoning is mostly seen in calves, while chronic poisoning is mostly seen in adult cattle. Aflatoxin poisoning can be preliminarily diagnosed based on clinical manifestations and pathological changes. This disease is mainly prevented, and there is still no specific therapy; the specific treatment methods are mainly introduced below.

1. Clinical symptoms of aflatoxin poisoning in cattle. Calves are more sensitive to aflatoxins than adult cattle and may show acute poisoning, while adult cattle have stronger resistance to the toxin and mostly show a chronic course. ① Acute poisoning: mostly seen in calves, mainly manifested as depression, complete loss of appetite, arched back, convulsions, circling movement, unsteady standing, easy falling; ear tremor, dry muzzle, foaming at the mouth, teeth grinding; submandibular edema; conjunctivitis, corneal opacity, yellow staining of mucous membranes, photosensitivity, blindness in one or both eyes; diarrhea, abdominal pain, tenesmus, blood clots and mucus mixed in the feces, rectal prolapse, collapse. Death occurs within about 48 h, with a high mortality rate. ② Chronic poisoning: calves show poor appetite, slow growth and development, malnutrition, coarse, erect and mostly lusterless hair coat, dry and cracked muzzle, emaciation. Fright, aimless wandering, diarrhea; adult cattle show depression, reduced feed intake, teeth grinding, jaundice, decreased milk yield, forestomach atony, ruminal tympany, intermittent diarrhea, and a relatively low mortality rate. 2. Pathology of aflatoxin poisoning in cattle. Acute cases show microcytic anemia, increased neutrophils especially segmented neutrophils, increased blood bilirubin, decreased erythrocyte sedimentation, and prolonged clotting time. Conjugated bilirubin is 39.2 mg/L, and total bilirubin rises to 117.6 mg/L[2]. Serum aspartate aminotransferase (AST) is elevated, serum γ-glutamyl transpeptidase is elevated, alkaline phosphatase activity is elevated, and plasma carotene and vitamin A are significantly decreased. Isocitrate dehydrogenase activity is close to normal, but serum lactate dehydrogenase activity is decreased. Blood urea nitrogen, albumin and total protein levels are decreased. 3. Diagnosis of aflatoxin poisoning in cattle. For the diagnosis of this disease, veterinary personnel should start with a history investigation and examine feed samples fed on site, combining clinical manifestations such as jaundice, hemorrhage, edema, digestive disorders and neurological symptoms; pathological changes such as hepatocyte degeneration, necrosis, hyperplasia and liver cancer, for a preliminary diagnosis. Confirmation requires isolation and culture of toxigenic fungi from suspected feed and determination of aflatoxin content in the feed; when necessary, biological identification methods, namely toxicity tests, can also be carried out. The operation method of the visual screening method is: take suspected feed samples, such as a small amount of corn, peanuts, etc., place them in batches in a tray, spread them into a thin layer, and place them under an ultraviolet lamp with a wavelength of 365 nm for fluorescence observation. If the feed contains aflatoxins G1 and G2, yellow-green fluorescence can be seen emitted from particles such as corn and peanuts; if the feed contains aflatoxins B1 and B2, blue-purple fluorescence can be seen. When these fluorescences are not seen, repeat the operation and place it again under the ultraviolet lamp for observation; if fluorescence is still not seen, it can be judged as a negative sample. It should be noted that yellow-green and blue-purple fluorescence observed under an ultraviolet lamp must be distinguished from the fluorescence intensity presented by other impurities, otherwise it easily leads to false positives of the sample. Methods for determining aflatoxins include biological methods, immunological methods and chemical methods, etc. The commonly used methods are silica gel thin-layer chromatography or microcolumn chromatography. In recent years, aflatoxin detection methods such as immunochemical analysis, enzyme-linked immunoassay, gold-labeled test strips and affinity microsphere rapid detection technology have been continuously established and applied. Generally, when the aflatoxin content in cattle diets exceeds 100μg/g and in milk exceeds 0.5μg/g, it can be confirmed as poisoning. 4. Treatment of aflatoxin poisoning in cattle. There is currently no specific therapy for this disease. When aflatoxin poisoning is already suspected, the entire dairy cattle farm must immediately stop feeding the existing feed and instead feed feed rich in energy substances, such as green fodder and high-protein feed, and not feed or feed less high-fat feed. Organize personnel to carefully observe the herd, promptly find other sick cattle and isolate them, and treat them as early as possible. Mildly affected cattle usually recover in a short period as long as nursing care is strengthened, generally without harm to health. However, for severely poisoned cattle, salt-based purgatives should be administered in time to facilitate toxin elimination; in addition, it is also necessary to use some liver-protecting, detoxifying and hemostatic drugs, such as applying 20% calcium gluconate injection 500-1000 mL; or applying 25%-30% glucose injection plus vitamin C preparation, for a single intravenous injection. For cattle with heart failure, sodium camphorsulfonate (cardiotonic) can be injected subcutaneously or intramuscularly. In order to control or avoid secondary infection, antibiotics such as penicillin and streptomycin should be used as appropriate, but sulfonamides must not be used. Intramuscular injection of oxytetracycline has a certain therapeutic effect, 10 mg per kg body weight, 1-2 times daily, for 5 consecutive days. Oral alkaline activated carbon can also be used to promote intestinal excretion of aflatoxin; activated carbon diluted with pH 7 phosphate buffer solution is administered by large-volume drenching; combined with a sterol compound 2 mg/kg·w, once/day, intramuscular injection, for 5 consecutive days. Cysteine or methionine 200 mg/kg·w can also be used for treatment, by a single intraperitoneal injection; or sodium thiosulfate, 50 mg/kg·w, by a single intraperitoneal injection.