Pimelea trichostachya poisoning (St George disease) in horses

A dense population of Pimelea trichostachya plants (Family Thymelaeaceae) in pasture poisoned a horse herd in southern inland Queensland in October-November 2005. Plant density was 2 to 45 g wet weight/m(2) (mean 16 g/m(2)) from 5 to 69 plants/m(2) (mean 38 plants/m(2)) representing 3 to 20% (mean 9%) of the volume of pasture on offer. Ten of 35 mares, fillies and geldings were affected. Clinical signs were loss of body weight, profound lethargy, serous nasal discharge, severe watery diarrhoea and subcutaneous oedema of the intermandibular space, chest and ventral midline. Pathological findings were anaemia, leucocytopenia, hypoproteinaemia, dilatation of the right ventricle of the heart, dilated hepatic portal veins and periportal hepatic sinusoids (peliosis hepatis), alimentary mucosal hyperaemia and oedema of mesenteric lymph nodes. Cattle grazing the same pasture were affected by Pimelea poisoning simultaneously. Removal of the horses to Pimelea-free pasture initiated recovery. The one other incident of this syndrome, previously only recognised in cattle in Australia, occurred in horses, in South Australia in 2002, with access to a dense Pimelea simplex population.     

An acute case of Pimelea elongata toxicity in cattle in western New South Wales

In May 2019, 96 cattle died from Pimelea toxicity in a period of 19 days after potential exposure, with the first deaths occurring within 5 days. After examining the circumstances, we suspect that several factors contributed to the deaths. These included that recently purchased stock and transported had access to flooded land containing Pimelea elongata. This weed species contains simplexin and 18 other compounds. Roots, flowers and seeds are significantly more toxic than the stem, branches and leaves. We suspect that thirsty and hungry stock consumed seed and roots from flooded pastures and consumed lethal doses of simplexin. Blood tests were not good indicators of the conditions. Management strategies are suggested.     

Nitrate poisoning in cattle

Summary In a series of experiments the effect of administering KNO(2) was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO(2), O(2)-saturation, pH, pCO(2), and (NO(2)) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O(2)-saturation was calculated from the estimated O(2)-saturation by multiplying with the factor Hb (mmol/1) minus MHb (mmol/1), divided by Hb (mmol/1). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours. A dosage of 9 to 12 mg of NO(2)/kg body weight intravenously or of 30 mg of NO(2)/kg body weight orally to the dam caused much higher MHb percentages and NO(2) contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO(2) content td MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O(2)-saturation dropped simultaneously with the increase in methaemoglobin. Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O(2)-saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood. When the oxygen transfer to the foetal blood decreases too sharply, intra-uterine death and ultimately abortion may result.     

Lead poisoning in cattle

Lead poisoning is a frequent cause of poisoning in domestic animals. Signs of encephalopathy and gastroenteritis are commonly observed in cattle following lead poisoning. This article discusses the etiology, epidemiology, pathogenesis, clinical signs, diagnosis, postmortem findings, and treatment of lead poisoning in cattle.     

Nitrate poisoning in cattle

Summary

In a series of experiments the effect of administering KNO₂ was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO₂, O₂‐saturation, pH, pCO₂, and (NO₂) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O₂‐saturation was calculated from the estimated O₂‐saturation by multiplying with the factor Hb (mmol/1) minus MHb (mmol/1), divided by Hb (mmol/1). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours.

A dosage of 9 to 12 mg of NO₂/kg body weight intravenously or of 30 mg of NO₂/kg body weight orally to the dam caused much higher MHb percentages and NO₂ contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO₂ content td MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O₂‐saturation dropped simultaneously with the increase in methaemoglobin.

Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O₂‐saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood.

When the oxygen transfer to the foetal blood decreases too sharply, intra‐uterine death and ultimately abortion may result.     

Cocklebur poisoning in cattle

Cocklebur poisoning occurred in a herd of cattle in Oklahoma during the month of July. The poisonous dicotyledonary stage of cocklebur plant growth usually occurs during the early spring in Oklahoma. In this instance, dicotyledonary sprouts were in a lowland pasture adjacent to a river. Sprouting and growth occurred after receding water and hot dry weather had created favorable conditions for germination. The diagnosis was made on the basis of the finding of the dicotyledonary stage of plant growth and evidence of the plants having been grazed, as well as the clinical signs, gross necropsy findings, and histopathologic findings in the affected cattle.     

Onion poisoning of young cattle

Eighty-five cattle (calves and yearlings) were allowed 1000 kg of onions (Allium cepa) a day. Signs of poisoning were observed after five days; 22 animals were affected, one fatally. New illnesses continued to occur for five days after the withdrawal of onions from the diet. Clinical signs included inappetance, tachycardia, staggering and collapse, with jaundiced conjunctivae and haemoglobinuria. Haemolytic anaemia with Heinz bodies in the red cells and leucocytosis were demonstrated.     

Bryophyllum pinnatum poisoning of cattle

SUMMARY Two adult cattle died within 48 h of being fed a large amount of Bryophyllum pinnatum plants collected from a house garden. Clinical signs became apparent the day after feeding and included hypersalivation, ataxia, severe cardiac arrhythmia and laboured respiration. The main necropsy findings were acute rumenitis, reduction of bronchiolar lumens and emphysema.     

Selenium poisoning in dairy cattle

An outbreak of chronic selenium poisoning occurred in a mob of 30 Friesian dairy cows. These cows were all autumn calvers on a well-managed dairy farm.