Plants causing poisoning outbreaks of livestock in South America: A review

Oxalate nephropathy in cattle associated with the consumption of Megathyrsus maximus in Argentina

Over a 2-wk period, 20 cows that were grazing a Megathyrsus maximus (Guinea grass) pasture died after developing depression, respiratory difficulty, and recumbency. Affected animals had increased serum urea, phosphorus, and creatinine concentrations, and below-normal calcium concentrations. Autopsy revealed moderate ascites; mildly enlarged, pale, mottled kidneys; and perirenal edema. Microscopically, there was hyperplasia of mesangial cells in the renal glomeruli, renal tubular epithelial necrosis, and hyaline casts and refractive crystals in cortical and medullary renal tubular lumens. Samples of M. maximus from the affected pasture contained elevated concentrations of soluble oxalate (3.71%). Our findings suggest that oxalate produced by M. maximus caused acute tubular injury. Our case highlights the critical need for monitoring oxalate levels in pastures and managing grazing practices, particularly under drought conditions, to prevent similar outbreaks in the future.

Poisoning by Atractylus gummifera L. Roots in Grazing Cattle of a Sicilian Farm

BACKGROUND

In farm animals, the main poisonings are due to the ingestion of toxic plants present in pastures, but their incidence is underestimated, even though they are responsible for serious damage to animal health and livestock production. Atractylis gummifera L. is a plant widespread in Mediterranean countries and in southern Italy that is responsible for serious and often fatal poisonings in both humans and animals. This investigation reports grazing cattle poisoning due to the ingestion of Atractylis gummifera L. roots present in a recently plowed pasture of a Sicilian farm.

METHODS

The investigation describes the clinical symptoms of poisoned cattle, especially the gastro-intestinal type, the alterations in liver and renal function, the course of poisoning (hyperacute-acute), and the necropsy examination of dead animals. In the surviving cattle, symptomatic drug therapy was administered, and hematological and biochemical analyses (blood, liver, and kidney profiles) were carried out during treatment.

RESULTS

The pharmacological therapy, although symptomatic, contributed to the recovery of the intoxicated cattle with a return to normal values of liver and kidney parameters and electrolyte profile 30-40 days after treatment.

CONCLUSIONS

This investigation could be useful to veterinarians for the diagnosis of Astractylus gummifera L. root poisoning in cattle, which is also responsible for the death of some intoxicated animals, with a negative impact on livestock.

Drugs from poisonous plants: Ethnopharmacological relevance to modern perspectives

The world of plant diversity is endlessly fascinating and essential for life on Earth. Since the inception of early civilization, humans have utilized plants for several purposes, particularly for their medicinal value. While some plants are known for their toxicity, they also contain beneficial phytochemicals that are important for both plants and humans, indicating their dual nature. This study aims to explore and synthesize the existing knowledge on various poisonous plant species found worldwide. It primarily focuses on the therapeutic potential of specific types of phytochemicals responsible for treating multiple diseases. This review includes a list of 70 poisonous plants with medicinal properties for treating various ailments, as well as some of their traditional uses. A few of these plants are emphasized, which have been tremendously explored and studied, hold significant potential to contribute to modern drug discovery. Furthermore, it addresses the possible prospects and challenges of using poisonous plants and their phytochemicals as therapeutic agents. Although the therapeutic potential of poisonous plants is substantial, many toxins remain unexplored. This review accentuates the need for rigorous scientific investigations, prior to clinical trials to validate their traditional uses, which would reveal the pharmacological interventions that will eventually advance human health and well-being.

Intoxication of sheep by Astragalus arequipensis in northwestern Argentina

Spontaneous intoxication by Astragalus arequipensis was diagnosed in a flock of 300 sheep in Jujuy province, northwestern Argentina, that grazed an area heavily invaded by this plant. The main clinical signs were intention tremors, ataxia, and progressive loss of condition. Autopsy of 2 affected animals revealed loss of body condition. The main microscopic changes were fine cytoplasmic vacuolation of cells in the cerebrum, cerebellum, thyroid and adrenal glands, kidney, liver, pancreas, urinary bladder, and lymph nodes, and swollen axons in the cerebellum. Ultrastructurally, the cytoplasmic vacuoles consisted of dilated secondary lysosomes. Composite leaf and stem samples of A. arequipensis analyzed by high-performance liquid chromatography contained 0.05% swainsonine. The diagnosis of intoxication by A. arequipensis was made based on the clinical history and signs; gross, microscopic, and ultrastructural changes; and detection of swainsonine in the plant.

Abortions and Congenital Malformations in Small Ruminants Associated with Toxic Plant Consumption in the Brazilian Semi-Arid Region

The Northeast of Brazil is a leading region for small ruminants. However, these herds are primarily located in the semi-arid region and face significant losses due to fetal and perinatal mortality, frequently linked to the consumption of teratogenic toxic plants during pregnancy. This study investigated the clinical and epidemiological aspects related to abortions and malformations in 80 small ruminant farms in the semi-arid region of Brazil. Necropsies were also performed on fetuses and neonates, along with histopathological, molecular, and serological analyses of the herds to differentiate other conditions. Malformations were identified on approximately 42 farms, with arthrogryposis being the most common abnormality. Toxic plants, including Mimosa tenuiflora and Cenostigma pyramidalis, were recorded on 95.23% of the properties with reported malformations. Additionally, necropsies confirmed the association between the occurrence of these plants and malformations, abortions, and mortality, excluding infectious causes. These results underscore the urgent need for prevention and control strategies to mitigate the impact of toxic plants on small ruminant production in the semi-arid region.

Subacute and chronic toxic hepatopathy in cattle grazing pasture with Crotalaria spectabilis

This report describes subacute and chronic toxic hepatopathy in cattle due to Crotalaria spectabilis poisoning. A total of 200 male Nellore cattle were introduced into a paddock contaminated with C. spectabilis. After spending 20 days grazing in this area, 6 cattle became ill and died. The remaining 194 cattle were moved to non-contaminated pasture in a nearby farm and, 45 days after arrival, 15 cattle became ill and died. Three affected cattle were necropsied. The main clinical changes consisted of anorexia, isolation from the herd, weight loss, jaundice, recumbency, and death. The primary lesions were observed in the liver. Subacutely poisoned cattle had slightly firm livers with an accentuated lobular pattern. Histologically, hepatocyte loss with dilated sinusoids, hepatomegalocytosis, and fibrosis was observed. Cattle with chronic disease had small, pale, firm livers with an irregular hepatic capsular surface. Microscopic changes included hepatocyte loss, hepatomegalocytosis, bile duct proliferation, and fibrosis.

Hepatic and renal lesions in sheep intoxicated with Urochloa hybrid Mulato II in Argentina

A flock of 48 sheep in Argentina grazing on a pasture of hybrid Urochloa (formerly Brachiaria) Mulato II (Urochloa ruziziensis × Urochloa decumbens × Urochloa brizantha) developed facial dermatitis, severe jaundice, and weakness after brief physical activity. Blood biochemistry of 3 animals revealed azotemia, elevated aspartate aminotransferase activity, and increased direct, indirect, and total bilirubin concentrations. The urine was markedly turbid and contained large concentrations of bile pigments and protein. At autopsy of 2 animals, there was severe jaundice and subcutaneous submandibular edema. The livers were enlarged, intensely yellow, and had a marked acinar pattern. Gallbladders were distended, and the kidneys were diffusely dark in one animal and yellow-green in the other. Microscopically, there was lymphoplasmacytic and histiocytic cholangiohepatitis with abundant crystals in the lumen of bile ducts and in the cytoplasm of macrophages. The proximal and distal convoluted renal tubules had protein casts in their lumens, and crystals were observed in the lumen and epithelial cells. Lectin histochemistry showed strong affinity for Arachis hypogaea agglutinin in hepatic macrophages. In the one sheep that was tested for heavy metals, copper concentrations in the liver and kidney were within the RIs. Despite the immediate change of pasture, morbidity and mortality were 100% within 3 mo. The association between the consumption of this pasture, and the clinical, biochemical, pathology, and lectin histochemistry findings confirmed intoxication with Urochloa hybrid Mulato II. To our knowledge, intoxication by this hybrid of Urochloa has not been reported previously.

Overview of Cyanide Poisoning in Cattle from Sorghum halepense and S. bicolor Cultivars in Northwest Italy

Sorghum plants naturally produce dhurrin, a cyanogenic glycoside that may be hydrolysed to cyanide, resulting in often-lethal toxicoses. Ruminants are particularly sensitive to cyanogenic glycosides due to the active role of rumen microbiota in dhurrin hydrolysis. This work provides an overview of a poisoning outbreak that occurred in 5 farms in Northwest Italy in August 2022; a total of 66 cows died, and many others developed acute toxicosis after being fed on either cultivated (Sorghum bicolor) or wild Sorghum (Sorghum halepense). Clinical signs were recorded, and all cows received antidotal/supportive therapy. Dead animals were subjected to necropsy, and dhurrin content was determined in Sorghum specimens using an LC-MS/MS method. Rapid onset, severe respiratory distress, recumbency and convulsions were the main clinical features; bright red blood, a bitter almond smell and lung emphysema were consistently observed on necropsy. The combined i.v. and oral administration of sodium thiosulphate resulted in a rapid improvement of clinical signs. Dhurrin concentrations corresponding to cyanide levels higher than the tolerated threshold of 200 mg/kg were detected in sorghum specimens from 4 out of 5 involved farms; thereafter, such levels declined, reaching tolerable concentrations in September-October. Feeding cattle with wild or cultivated Sorghum as green fodder is a common practice in Northern Italy, especially in summer. However, care should be taken in case of adverse climatic conditions, such as severe drought and tropical temperatures (characterising summer 2022), which are reported to increase dhurrin synthesis and storage.

Enzootic calcinosis in Toggenburg goats in New Zealand

CASE HISTORY

Necropsies on Toggenburg goats culled from a small farm in the Manawatū district of New Zealand, performed at Massey University (Palmerston North, NZ) over a period of 29 years (1991-2019), revealed soft tissue mineralisation, particularly of cardiovascular tissues. The farm spans 10 acres and runs between 15 and 30 Toggenburg goats. The goats are predominantly on pasture comprising a variety of types.

PATHOLOGICAL FINDINGS

Necropsies were performed on all adult goats (n = 45) that died or were euthanised. Histopathology was performed on 42 goats (93%), of which 33 (73%) included sufficient tissues diagnostically relevant to soft tissue mineralisation. The most significant gross findings were in various arteries, with the aorta most commonly affected, followed by the heart and lungs. The aortic intima showed prominent, multifocal to coalescing, raised, wrinkled, white plaques. Microscopically there were multiphasic lesions of mineralisation, chondroid, and osseous metaplasia in the elastic arteries, aorta, heart and lungs. A lumbar vertebra from one goat had prominent, basophilic, fibrillar, tangled matrix lining Haversian canals and lamellae.

LABORATORY FINDINGS

Blood samples were collected from 15 adult goats in the affected herd and from 10 adult Toggenburg goats from an unaffected herd. Samples were collected by jugular venipuncture at 2-month intervals for 12 months (April 2018-March 2019). Concentrations of calcium, phosphorus, 25-hydroxyvitamin D2 and D3 (25OHD2, 25OHD3) in serum were analysed. The concentration of total 25OHD in serum was 34.2 (95% CI = 18.9-49.4) nmol/L (p < 0.001) higher in goats from the affected herd than in goats from the unaffected herd. Serum 25OHD2 concentration was 46.2 (95% CI = 39.2-53.2) nmol/L higher (p < 0.001) in goats from the affected herd compared to the unaffected herd. Serum Ca concentrations in affected goats were 0.101 (95% CI = 0.005-0.196) mmol/L higher (p = 0.039) than unaffected goats, but remained within the reference range. There was no evidence of a difference in serum 25OHD3 and P concentration between the herds.

VEGETATION SURVEY

All paddocks on the property were surveyed every 2 months along evenly spaced line transects, and then further traversed perpendicularly to form a grid. No known calcinogenic species were identified. Known plant sources of vitamin D identified on the farm included mushrooms (species not defined), Dactylis glomerata, lichen, pine pollen, and algae.

DIAGNOSIS

Soft tissue mineralisation and enzootic calcinosis.

CLINICAL RELEVANCE

Veterinarians are alerted to the possibility of either enzootic calcinosis in goats and the potential occurrence of calcinogenic plants in New Zealand; or chronic vitamin D toxicosis of non-plant origin.

Acute necrotic hepatotoxicity caused by Melanthera latifolia (Asteraceae) in cattle

This study aims to report a spontaneous and experimental intoxication in cattle by Melanthera latifolia (Asteraceae) for the first time, and to describe its epidemiological, clinical, and pathological findings. An outbreak of acute toxic hepatopathy in cattle occurred from December of 2021 to January of 2022 in a beef cattle farm from Rio Grande do Sul state, Southern Brazil, and resulted in 94 deaths from a herd of 430 animals. At necropsy, lesions consisted of enhanced lobular pattern of the liver, transmural gallbladder edema, and hemorrhages on the surface of multiple organs. The main microscopic lesion was marked hepatocellular necrosis in the centrilobular region associated with hemorrhage and infiltration of neutrophils. During the outbreak, multiple specimens of M. latifolia were noted in the paddocks where affected cattle were grazing and many showed signs of consumption. No other known acute hepatotoxic plants were found. Two 12-month-old steers were experimentally intoxicated with a single oral dose of the fresh plant (flowers, leaves, and less fibrous stalks). One bovine ingested a dose of 10  g/kg and was euthanized after 48 h, and the other ingested 15  g/kg and was euthanized 17 h later. Clinical signs, macroscopic, and microscopic lesions in both animals were similar to those observed in the spontaneous cases. Thus, this study demonstrates that M. latifolia was the cause of the outbreak of acute toxic hepatopathy with significant mortality in cattle. M. latifolia nor any plant of the genus Melanthera had ever been reported as toxic.

Lantana camara poisoning in cattle that took refuge during a storm in a forest invaded by this plant

An outbreak of poisoning by Lantana camara occurred in cattle when a herd sought refuge in a Eucalyptus forest heavily infested by this plant. The animals showed apathy, elevated serum activities of hepatic enzymes, severe photosensitivity, jaundice, hepatomegaly and nephrosis. After a clinical manifestation period of 2-15 days, 74 out of 170 heifers died. The main histological changes were random hepatocellular necrosis, cholestasis, biliary proliferation and, in one animal, centrilobular necrosis. Immunostaining for Caspase 3 detected scattered apoptotic hepatocytes.