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.

Leucaena leucocephala toxicity in Brazilian horses.

Leucaena leucocephala poisoning is reported in horses in different Brazilian regions. The poisoning occurred one month after the horses were introduced into paddocks invaded by the plant or after 10 days of consuming cut Leucaena administered as the only food. Affected horses showed moderate to severe hair loss on the mane and tail, orthokeratotic hyperkeratosis with marked follicular telogenization, and hyperplasia of thyroid follicular cells. Mimosin concentration in leaves (5.5 mg/g) was determined by a new HLPC-UV method which is also reported.

Cecal dilatation in cattle ingesting Megathyrsus maximus (syn. Panicum maximum) cv. Mombaça and cv. Tanzânia.

Nine outbreaks of cecal dilatation are reported in cattle in rotationally-grazed pastures of Megathyrsus maximus during the rainy season with one day grazing and rest intervals of 23-28 days. Clinical signs, observed 6-24 h after entering the pasture, were inappetence, long periods in sternal recumbency, rough hair coat, arched back, tenesmus with difficult defecation, dry stools, reduced ruminal movements, intestinal tympany with right abdominal distention, and decreased milk production. The animals recovered 8-12 h after their removal from the pastures. All pastures were fertilized at 80-120 kg/ha of urea/year. In six farms, in addition to urea, chicken litter (CL) was also added. Water-soluble carbohydrates (WSC), non-fiber carbohydrates (NCF) and starch concentrations in the pastures causing tympany were higher (P < 0.05) than in control pastures. To demonstrate the relationship of the disease with fertilization of the pastures, a pasture of M. maximus was divided into five blocks of 16 m2 and each block subdivided into four plots each, totaling 20 plots. One plot of each block was randomly chosen for 1 of 4 different treatments: 1. fertilized with 8 t/ha of CL; 2. fertilized with 16 t/ha of CL; 3. fertilized with 180 kg/ha urea; 4. control without fertilization. In general, plots fertilized with urea or with CL had higher NFC and starch concentrations (p < 0,05) than the control plots. In another experiment a pasture of M. maximus was divided into 23 paddocks and rotationally grazed. Ten paddocks were fertilized with 180 kg/ha of urea and five fertilized with 8 t/ha of CL. The concentration of NFC and starch were significantly higher (p < 0.05) in the pastures fertilized with urea and with urea plus CL. These results suggest that cecal dilatation may be caused by the high concentrations of NFC and starch in the pastures fertilized with urea and/or poultry litter.

The Occurrence of Cattle Tick Fever in a Region of the Atlantic Forest on the Border with the Caatinga in Brazil.

The Atlantic Forest biome is considered an area in which tick fever is endemic, while the Caatinga biome is considered an area in which tick fever is non-endemic. A survey on cattle tick fever was carried out in 448 cattle farms located in an area of the Atlantic Forest biome which borders the Caatinga biome. A retrospective study of five years, conducted from January 2018 to October 2022, allowed for the identification of the occurrence of tick fever in 44 out of the 448 herds visited. In 70.5% (31/44) of the herds involved, the disease was caused by Anaplasma marginale; in 6.8% (3/44), the disease was caused by Babesia spp.; and in 22.7% (10/44), the disease was caused by a coinfection of Babesia spp. and A. marginale. The disease mainly occurred from August to November (23/44). Bos taurus or B. taurus crossbreed animals were most affected (29/44) in an area in which 94% of the cattle were Bos indicus and 6% were B. taurus and B. taurus crossbreeds. In 24 herds (with adults affected in 17 and calves in 7), the implicated animals had recently been moved to the Atlantic Forest. In the other 20 herds (calves with heavy tick infestations were affected in 17 and adults in 3), tick fever occurred in non-moved cattle. Even though it is an endemic zone, tick fever is common and mainly affects B. taurus cattle, including adults moved from areas with enzootic instability and calves under nine months old with high tick loads.

Poisoning by Baccharis coridifolia in Early-Weaned Beef Calves: Pathological Study and New Macrocyclic Trichothecene Identification.

This study investigated two outbreaks of spontaneous poisoning by Baccharis coridifolia (Asteraceae) in early-weaned beef calves in Tacuarembó, Uruguay. A total of 34 affected calves showed signs of salivation, anorexia, apathy, marked dehydration, and diarrhea. Deaths occurred 36-72 h after consumption and mortality varied from 37.5% to 43.3% for outbreak 1 and outbreak 2, respectively. The main pathological findings include diffuse severe necrosis of the prestomachs and lymphoid tissues. Ultrastructurally, epithelial cells of the rumen showed swelling, lysis of the organelles, degradation of intercellular attachments, and degradation of the nuclear chromatin. Using LC-MS with diagnostic fragmentation filtering, 56 macrocyclic trichothecenes including glycosyl and malonyl conjugates were identified. The total concentration of macrocyclic trichothecenes, including conjugates, was estimated to be 1.2 ± 0.1 mg/g plant material. This is the first report of these malonyl-glucose conjugates from Baccharis coridifolia.

Hepatic arteriovenous malformation in a calf.

A case of hepatic arteriovenous malformation is described in a calf that presented with a marked increase in abdominal volume and died 12 h after birth. At necropsy, the calf had marked abdominal distension and haemoperitoneum. The left hepatic lobe was reduced in size and covered by slightly whitish and intensely vascularized membranous tissue. At the edge of the left lobe there were cystic structures filled with translucent fluid. On cut surface, there were multiple cavitations well delimited by whitish walls and multiple dilated blood vessels that communicated with the cavitations. Histopathology revealed an increase in the number of vascular structures of variable calibre within loose fibrous connective tissue. The diagnosis of hepatic arteriovenous malformation was based on the lesions and confirmed by immunohistochemistry. Hepatic arteriovenous malformations are rare in all species, have not been described in cattle and should be included as a cause of mortality in neonates with post-partum haemoperitoneum.

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.

Epidemiological aspects of cattle tick fever in Brazil.

The present work reviews the epidemiologic situation of Anaplasma marginale and Babesia spp. infections and the occurrence of cattle tick fever outbreaks in Brazil. In areas of tick fever enzootic instability, environmental conditions interfere with the development of Rhipicephalus (Boophilus) microplus: chilly winter in the southern region, floods in the Pantanal, and low humidity in the Caatinga. In contrast, the climatic conditions of stable zones (Cerrado, Amazon and Atlantic Forest biomes) favor tick development. In enzootic areas, tick fever is uncommon because the animals are in frequent contact with the parasite, acquiring immunity naturally during the period of innate resistance; however, outbreaks may occur when calves become infested by considerable numbers of infected ticks during this period or in adults raised in tick-free environments that become infested for the first time when transporting to stable areas. It is necessary to better understand the disease's risk factors under stable conditions and the implications of the mechanical and other vector transmission of A. marginale. To prevent tick fever outbreaks in Brazil, it is important to develop and use anaplasmosis and babesiosis vaccines in cattle from enzootic unstable regions, especially when animals are moved to stable areas.

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

This paper reviews toxic plants for livestock in South America. We included 219 plants in this review, considering only the plants that caused at least one demonstrated outbreak of poisoning. Plants reported as toxic in other regions and present in South America, but with no confirmed outbreaks of poisoning in this region, are not included. We report the main aspects of the epidemiology, clinical signs, pathology and economical importance of the poisonings. Initially, the toxic plants are described based on their toxic compounds, but because the toxic compound is unknown in 92 (42%) of the plants we also classify them according to the affected system. This review highlights the great diversity of toxic plants capable of affecting livestock in South America, and for this reason studies in this regard should be intensified.

Toxic plants from the perspective of a "Quilombola" community in the Cerrado region of Brazil.

A multi-disciplinary team surveyed ranchers at the Kalunga Historical and Cultural Heritage Site, in the Cerrado region of west central Brazil, to determine impacts promoted by toxic plants on cattle. The expedition to the Kalunga region was carried out by Brazilian and American researchers. Previously selected cattle ranch properties from "Vão das Almas", "Engenho II" and "Vão do Moleque" were visited. Twenty-four interviews were carried out with cattle ranchers and a questionnaire was applied to obtain information about outbreaks of native plant poisoning and their effects on livestock, and the use of local plants in phytotherapy. We classified problematic plants into three distinct categories. First, the toxic plants most cited by residents causing cattle losses were the flowers of Caryocar brasiliense Cambess ("pequi"), the fruits of Terminalia corrugata (Ducke) Gere & Boatwr. (Buchenavia tomentosa Eichler - "mirindiba" or "pau-pilão"), Eugenia dysenterica (Mart.) DC ("cagaita"), and Palicourea marcgravii A. St. Hil ("erva-café" or "cafezinho"). Secondly, other plants considered toxic, but causing less severe losses were Emmotum nitens (Benth.) Miers ("casco d'anta"), Indigofera lespedezioides (Kunth) ("timbozinho"), Ricinus communis L. ("mamona"), Pteridium esculentum (G. Forst.) Cockayne ("samambaia"), Stryphnodendron adstringens (Mart.) Coville ("barbatimão"), and Actinocladum verticillatum (Nees) McClure ex Soderstr. ("cambaúba"). The most important finding was the identification of the C. brasiliense flower as potentially toxic to cattle, which must be subject for future research. Further, we confirmed the toxicity and importance of P. marcgravii, E. dysenterica, and Terminalia corrugata. The survey highlighted phytotherapy plants used by the community, and greatly increased awareness by local livestock producers of poisonous plants for management purposes. We conclude that ethnobotanical knowledge, especially from the traditional community, is essential to understand livestock losses to toxic plants, and should be valued not only for reducing livestock losses, but also for cultural importance to the Kalunga communities in the Cerrado.

Pathologic and Immunohistochemical Evidence of Possible Francisellaceae among Aborted Ovine Fetuses, Uruguay.

The only genus of the Francisellaceae family known to contain species pathogenic to mammals is Francisella, for which reported cases in the Southern Hemisphere have been limited to Australia. We describe severe necrotizing and inflammatory lesions and intralesional immunohistochemical identification of Francisella sp. lipopolysaccharide among aborted ovine fetuses in Uruguay.

Molecular of Anaplasma marginale Theiler (Rickettsiales: Anaplasmataceae) in horseflies (Diptera: Tabanidae) in Uruguay.

Anaplasma marginale is transmitted biologically by infected ticks or mechanically by biting flies and contaminated fomites. In tick-free areas, such as southern Uruguay, horseflies could be the principal vectors of this pathogen for bovines, causing anaplasmosis. The objective of this work was to detect the presence of A. marginale by MSP-5 PCR and Sanger sequencing in the most prevalent species of horseflies obtained using different collection methods in Colonia, Tacuarembó and Paysandú, Uruguay. Eight horsefly species were tested (Dasybasis missionum, Poeciloderas lindneri, Tabanus campestris, T. claripennis, T. fuscofasciatus, T. platensis, T. tacuaremboensis and T. triangulum); four species were found to be positive for A. marginale, with D. missionum and P. lindneri having the most frequent infections, while only one individual each of T. fuscofasciatus and T. tacuaremboensis was positive. Both D. missionum and P. lindneri were positive for A. marginale in tick-free areas, and the implications are discussed in this report.

Primary Photosensitization by Chamaecrista serpens in Santa Inês Sheep.

This study aimed to clarify the type of photosensitization induced by C. serpens and to verify if the plant remains toxic after being collected and stored. Eight crossbred sheep, aged between 6 and 36 months, were divided into three groups (G1 to G3). Over 30 days, daily, G1 received an exclusive diet of C. serpens, and G2 and G3 received 10 g/kg/BW and 20 g/kg/BW, respectively. Two other sheep were used as controls (CG). Before administration, the plant had been harvested every 15 days. Liver biopsies and blood samples were taken from all sheep on day zero and weekly. All sheep that received the plant developed clinical signs of photosensitization, and no changes were observed in the serum activities of AST and GGT. On day 30, all sheep except Ov1 from G1 and Ov7 were euthanized and necropsied. All sheep that received the plant developed clinical signs. Macroscopic or histologic lesions were not observed in the liver. Ov 1 recovered 13 days after the end of ingestion. These results demonstrated that C. serpens causes primary photosensitization. It is advisable to avoid grazing on pastures invaded by the plant or to remove them from the pastures immediately after observing the first signs.

Cestrum axillare (Solanaceae) poisoning in ruminants.

Cestrum axillare poisoning causes significant economic losses in farms of ruminant production due to a fatal acute hepatic disease. The consumption of C. axillare occurs on farms or pastures with a scarcity of feed or with dry forage. Epidemiological, clinical, and pathological data of poisoning outbreaks by C. axillare from 1953 to 2021 in grazing ruminants in southeastern Brazil are reported. A total of 68 bovines, two buffaloes, and two goats exhibited clinical signs and resulted in death due to C. axillare consumption, with 79% of the cases occurring during the dry period. Clinical signs were apathy, anorexia, ruminal arrest, arched back, and constipation with hard stools, sometimes with blood or mucus. Cases with neurological signs due to hepatic encephalopathy showed excitement, aggressiveness, drooling, staggering, and muscle tremors. The pathological findings included hepatocellular necrosis in the liver and microcavitations in the brain's white matter (status spongiosus). The hepatotoxins, carboxyparquin and parquin, were detected in C. axillare leaf samples collected from paddocks grazed by cattle in three southeastern Brazilian municipalities where outbreaks of C. axillare poisoning occurred. This is the first report of parquin and carboxyparquin in C. axillare.

A Retrospective Study of Pythiosis in Domestic Animals in Northeastern Brazil.

Pythiosis is an endemic disease in northeastern Brazil and we now report the epidemiological, clinical and pathological findings in a retrospective study of naturally occurring cases in domestic animals. From January 1985 to December 2020, the Laboratory of Animal Pathology of the Federal University of Campina Grande examined 13,542 tissue samples from necropsies and biopsies. Among these samples, 306 were diagnosed as pythiosis: 195 cases in horses, 75 in sheep, 19 in dogs, six in mules, four in cattle, three in cats, two in goats, one in a donkey and one in an ostrich. Affected equids had lesions in the skin, mammary glands and nasal cavities. Affected sheep had cutaneous, nasal and digestive lesions while cattle and goats had cutaneous lesions. Carnivores developed lesions, mainly in the alimentary tract, of sufficient severity to cause death or result in euthanasia. The single affected bird had lesions in the alimentary tract and surgical excision resulted in remission. The disease had a long and life-threatening clinical course in most affected species but resolved spontaneously in cattle. Clinical signs were directly related to the location of the lesions, which were invariably characterized by chronic inflammation associated with intralesional hyphae. Veterinary clinicians and pathologists should be familiar with the clinicopathological features of pythiosis and the wide range of susceptible animal species.

Neurological and gastrointestinal manifestations of spontaneous poisoning by Ricinus communis in goats.

An outbreak of Ricinus communis poisoning in goats with neurological and digestive changes was related to the ingestion of different vegetative parts of the plant. Two poisoned animals died within 5 h of the plant intake showing necrotic gastroenteritis and hepatocytes degeneration and necrosis. Toxicological analysis by HPLC-DAD assay demonstrated 21.1-25.1 µg/g of ricinine in samples of ruminal fluids and 10.1-10.9 µg/g in the liver of poisoned goats.

Poisoning by Nierembergia veitchii: Effects on vascular smooth muscle cells in the pathogenesis of enzootic calcinosis.

Vascular mineralization is a hallmark of enzootic calcinosis. Histopathological, ultrastructural, and immunohistochemical investigations were performed on the external carotid arteries of seven sheep naturally poisoned by Nierembergia veitchii. Histologically, moderate to marked hyperplasia of the tunica intima was observed without mineralization. The tunica media exhibited mild to severe mineralization and osteochondroid metaplasia. Sheep with enzootic calcinosis showed arterial overexpression of osteopontin and tissue-nonspecific alkaline phosphatase and immunolabeling for osteonectin and osteocalcin in both intima and media layers of the tested arteries. The main ultrastructural finding in the tunica media was a marked phenotypic change of vascular smooth muscle cells from a contractile phenotype (VSMC-C) into a synthetic phenotype (VSMC-S). In the tunica media, VSMC-S produced matrix and extracellular vesicles, forming mineralizable granules associated with arterial mineralization. VSMC-S were also present in the tunica intima, but matrix and extracellular vesicles and mineralization were not observed. The absence of matrix and extracellular vesicles in the intimal hyperplasia, even in the presence of noncollagenous bone proteins, tissue-nonspecific alkaline phosphatase, and vitamin D receptors, reinforces the hypothesis that the presence of matrix and extracellular vesicles are crucial for the development of vascular mineralization in enzootic calcinosis. It is proposed that the two different VSMC-S phenotypes in calcinosis are due to the expression of at least two genetically different types of these cells induced by the action of 1,25(OH)2D3.

Description of bovine babesiosis and anaplasmosis outbreaks in northern Uruguay between 2016 and 2018.

Bovine babesiosis and anaplasmosis cause important economic losses in livestock production. In Uruguay, the main aetiological agents of bovine babesiosis and anaplasmosis are Babesia bovis, B. bigemina and Anaplasma marginale. The aim of this work was to describe the outbreaks of bovine babesiosis and anaplasmosis in northern Uruguay between 2016 and 2018. Convenience sampling was carried out. We worked with blood and organ samples from bovines with clinical signs and autopsy findings compatible with babesiosis and anaplasmosis. A total of 140 presumptive outbreaks were studied. Epidemiological information such as place, date of occurrence, age, number of sick and dead animals, clinical signs, autopsy findings, the presence of ticks and health management that involved injectables were registered. The diagnoses were carried out by blood and organ smears stained with Giemsa and confirmed by multiplex PCR. There were 83 (59.2%) positive outbreaks, comprising 35 (42.2%) A. marginale, 19 (22.9%) B. bigemina, 18 (21.7%) B. bovis and 11 (13.2%) mixed infections (Babesia spp. + A. marginale). Cows were the most commonly affected category. The clinical signs and autopsy findings with a significant association (p ≤ 0.05) were anaemia, pale mucous membranes, fever, jaundice, ataxia and aggressiveness, splenomegaly, and orange discolouration of the liver. Babesiosis had a seasonal occurrence, mainly in autumn, while anaplasmosis cases were recorded throughout the year. The use of injectable agents was associated with A. marginale transmission. This work contributes updated information about epidemiological and clinical patterns of bovine babesiosis and anaplasmosis in northern Uruguay, which is important for implementing preventive measures and control.

Evaluation of the one-side tick counting technique and of the level of infestation of bovines with Rhipicephalus microplus.

Counting ticks on one side of a bovine has been widely used to estimate the overall number of ticks; however, the accuracy of this method has not been determined. This work aimed to evaluate the one-side technique for counting ticks, identify bovines with a higher level of infestation, and determine the prevalence of infestation of adults and calves. To evaluate the one-side technique, ticks were counted on both sides of 352 bovines from three farms in nine months, and total numbers were correlated with the numbers counted on the left sides. The intraclass correlation coefficients reached values >0.99 for all farms, independent of the season. These results demonstrated that counting ticks on one-side and multiplying by 2 is a reliable method for estimating the overall number of ticks. To evaluate the level of infestation of various bovines, ticks were counted monthly, for 12 months, on the same bovines from seven farms. An animal was considered highly infested if the Anscombe residuals from a negative binomial GLM were ≥4, at least 2×. The number of bovines with infestation levels higher than expected varied among farms from zero to 3. Using this method, it is possible to evaluate the most infested bovines in order to remove them from the herd. The prevalence of infestation in calves reached 100% in five of the seven farms and 3- to 15-month-old calves had significantly higher infestation than adults.

Design and analysis of a structured questionnaire to assess the probability of elimination of Rhipicephalus microplus from farms in a subtropical area.

In areas in which R. microplus may be eliminated from farms, it is essential to evaluate the infestation situation and the biosecurity measures available when deciding whether or not to undertake an elimination effort. Multiple questionnaires have been developed to evaluate the cattle tick situation on farms, however, the validity of those questionnaires has not been evaluated. This study aimed to develop a standardized and validated questionnaire to estimate the likelihood of cattle tick elimination from farms. A list of items (topics) to be covered was sent to 25 experts for their evaluation, with 11 responding. Based on the selected items, thirty-five closed questions were developed and evaluated through a cognitive interview process with 8 veterinarians and 5 farmers. Subsequently, a focus group evaluation was carried out with 30 farmers and a pretest of the revised questionnaire was performed with 94 farmers. A test, re-test evaluation was carried out in a subset of the pretest respondents after two-weeks. The questionnaire took approximately 10 min to complete. The ability of the questionnaire to reliably produce a score reflecting the expected probability of a farm eliminating ticks was evaluated through the use of a two-parameter logistic item-response theory model. A subset of questions related to a unidimensional latent variable were identified. This set of items appeared to have good ability to predict which farms were more likely to achieve the elimination, although the evaluation of that predictive ability was beyond the scope of this work.