Crystal-associated cholangiopathy in sheep grazing Brachiaria decumbens containing the saponin protodioscin

Hepatogenic photosensitization in lambs supplemented with different levels of extruded urea in Brachiaria spp. pastures in the Brazilian Cerrado: Case report

The aim was to report cases and risk factors for hepatogenous photosensitization in lambs kept on Brachiaria spp. pastures and supplemented with levels of extruded urea (EU). The herd consisted of 69 Texel crossbred lambs with known parentage (fathers and mothers adapted to the consumption of forage of the genus Brachiaria), randomly divided into 5 groups and distributed in individual paddocks for each group. The animals were supplemented with increasing levels of EU (Amireia® 200S): 0, 6, 12, 18, and 24 g of EU per 100 kg-1 of body weight (BW). The concentration of protodioscin was estimated in the mixed pastures of Brachiaria spp. (cv. Marandu and cv. Basilisk), structural components (leaf, stem, and dead material), samples of each cultivar, and in the months of December (2018), February, and April (2019). The animals were examined daily, and when behavioral changes were identified, they underwent clinical examinations and anamnesis. Weighing was performed every 14 days, followed by necropsy and serum biochemical analysis, including gamma-glutamyltransferase (GGT). The highest concentrations of protodioscin (p < 0.0001) were found in the pastures used by animals supplemented without extruded urea (7.07 ± 0.56), in the Basilisk cultivar (11.35 ± 0.06), in the leaf blade components (2.08 ± 0.05), and thatch (2.20 ± 0.00), and in the month of April (7.34 ± 0.29) (the month with the lowest rainfall), respectively. Fourteen (20.29%) cases of photosensitization were observed in lambs, of which six recovered, and eight died. Serum GGT levels ranged from 42.2 to 225 IU/L; however, in animals that died, values ranged from 209.4 to 225 IU/L. The use of levels 12 g and 18 g per 100 kg-1 of body weight of extruded urea may contribute to the lower occurrence of photosensitization, as the animals selected pastures with lower protodioscin content, presenting a smaller number of cases.

Mathematical models for predicting protodioscin in tropical forage grasses

Protodioscin is a saponin present in grasses that can lead to losses in animal production. Our hypothesis was that mathematical models can accurately and precisely predict the protodioscin concentration in tropical grasses. We evaluated the ability of four mathematical models to describe the protodioscin concentration in Brachiaria and Panicum cultivars with different regrowth periods. Six cultivars of Panicum: Aruana, Massai, Mombaça, Tanzânia, Tamani, and Zuri; and five of Brachiaria-grass: Marandu, Paiaguás, Piatã, Xaraés and Basilisk. Protodioscin concentration evaluations were carried out at 51, 84, 110, and 111 days of age. Linear, Quadratic, Exponential, and Logarithmic models were evaluated, and the adequacy of the models was verified. The models were compared for accuracy and precision by pairwise mean squared error analysis and the delta Akaike information criterion. The models did not differ from each other in terms of accuracy and precision. The exponential model showed a high ability to explain the observed variability between protodioscin concentration and plant age for Brachiaria grasses. Panicum grasses have constant protodioscin concentration. Mathematical models are capable of predicting the protodioscin concentration in grasses of the genus Brachiaria based on plant age. We recommend Exponential model to predict the concentration of protodioscin in Brachiaria grasses.

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.

Outbreaks of Brachiaria ruziziensis and Brachiaria brizantha intoxications in Brazilian experienced cattle

Brachiaria species are some of the most used forage species for raising Brazilian cattle because of their great nutritional value and adaptability to the tropical climate. However, cases of animal intoxication have been described. Animal species, age, genetic resistance, and previous adaptation to the forage can influence the susceptibility to intoxication. Cattle (young or adults), other adult ruminants and animals adapted to consumption (experienced flocks) are considered more resistant. The main clinical presentation is that of hepatogenous photosensitization. Brachiaria brizantha and Brachiaria ruziziensis are considered less toxic. The aim of this study is to describe three outbreaks of intoxication by B. brizantha and B. ruziziensis in experienced cattle, as well as to compare the concentrations of protodioscin in paddocks with and without clinical cases. It was observed that the two forage species are toxic to all age groups of cattle adapted to their consumption, and the concentrations of protodioscin present in the plant cannot be used as the only criterion for determining the occurrence of intoxication.

Economic impact of poisoning by Brachiaria grass in lambs from birth to finishing receiving to different levels of supplementation

This study aims to evaluate the economic impact of poisoning by Brachiaria grass in lambs from birth to weaning (suckling) and from weaning to slaughter (finishing) different levels of energy protein supplementation (EPS). In addition, we estimated the economic efficiency of removing lambs from the pasture as a control measure to minimize the losses caused by Brachiaria grass poisoning. Seventy lambs were used in the suckling phase, distributed in two nutritional treatments (control and creep feeding). Hospitalization expenses were US$ 1580.80 for the control treatment and US$ 256.16 for the creep feeding treatment. In the finishing phase, 48 lambs were distributed in four nutritional treatments, which consisted of increasing levels of EPS (mineral salt, 0.8, 1.6 and 2.4% of LW). The largest difference in total revenue (US$) was observed between 2.4% of BW EPS and mineral salt (- 2300.28) treatments. Hospitalization expenses were similar between nutritional treatments, being higher in the treatment 1.6% of BW EPS (US$ 578.15). The biggest difference in gross income (US$) observed was between 2.4% of BW EPS and mineral salt (- 1439.43) treatments. The Brachiaria grass poisoning caused economic losses to the sheep farming system, due to the death of lambs, reduced weight gain and lower weights at weaning and in the finishing phase. Brachiaria grass poisoning caused economic damage to the production system. There were direct losses, with the death of the lambs without supplementation, in the suckling and finishing phases. The supplementation increases the performance and reduces the mortality. The supplementation in high levels is efficient in reducing the economic impact of poisoning by Brachiaria grass in both periods of suckling and finishing.

Protodioscin levels in Brachiaria spp. in a sheep production system and a brief review of the literature of Brachiaria spp. poisoning in ruminants

ABSTRACT: Plants of the genus Brachiaria, used in several countries as forage, are poisonous to some livestock species. Their toxic principle is protodioscin, and the main form of clinical presentation of the toxicosis is hepatogenous photosensitization. Here we compare protodioscin levels in B. decumbens and B. brizantha and review the literature on the concentrations and methodologies of collection and analysis of the toxic principle in Brachiaria spp. and the risk of contamination of pastures by more toxic species that may facilitate poisoning by plants of this genus in sheep. The experiment was conducted in pastures originally formed by B. brizantha, with many B. decumbens invasion points. The occurrence of cases of poisoning by Brachiaria spp. was the criterion for confirming pasture toxicity. The forage samples were collected at ten random points every 28 days through manual grazing simulation. The samples were analyzed for protodioscin by high-performance liquid chromatography (HPLC) with light scattering by evaporation (ELSD) after being dried and crushed. In the flock of 69 sheep, five poisoning cases occurred, three sheep died, and two recovered. The protodioscin levels found in the evaluated pastures ranged from 0.70 to 0.45%; higher levels appeared in B. decumbens (7.09%) compared to 1.04% in B. brizantha. We suggest that Brachiaria spp. should be avoided in pastures where sheep are grazing.

Photosensitization by Brachiaria ruziziensis in a sheep herd

Some species of the genus Brachiaria are cultivated worldwide in tropical and subtropical climate regions as the main feed for ruminants. Several studies report photosensitization by Brachiaria decumbens, Brachiaria brizantha, and Brachiaria humidicola, but the poisoning by Brachiaria ruziziensis have been reported only twice. Cutaneous and hepatic lesions may be caused by the steroidal saponins present in the leaves or by the mycotoxin sporidesmin produced by the saprophyte fungus Pithomyces chartarum. The present report describes the clinical and pathological changes observed in an outbreak of hepatogenic photosensitization in sheep kept in B. ruziziensis pastures. In addition, the present study will provide a better understanding of the etiology of this photosensitization through the evaluation of the saponin protodioscin and the spore count of P. chartarum. Santa Inês and Lacaune mixed-breed sheep showed signs of photosensitization after feeding B. ruziziensis. Clinical signs included jaundice, apathy, dehydration, and photosensitization characterized by facial edema and cutaneous scars, especially in the ears. Pathological examination of the liver revealed diffuse infiltrates of foamy cells, rare multinucleated cells, and mild enlargement of hepatocytes (megalocytosis). The skin showed acute epidermal and dermal necrosis with occlusive thrombi. B. ruziziensis showed low levels of protodioscin (0.020 ± 0.024% in mature leaves and 0.065 ± 0.084% in sprouts) but high P. chartarum spore counts (mean of 479,844 ± 443,951 spores/g plant). Thus, sheep grazing B. ruziziensis pastures must be closely monitored because of the risk of photosensitization.

Filling the gap of Brachiaria decumbens (signal grass) research on clinico-pathology and haemato-biochemistry in small ruminants: A review

Brachiaria decumbens (signal grass) is a highly productive tropical grass that is widespread in some tropical countries due to its adaptation to a wide range of environments and soil types. However, a limiting factor for the use of this grass is its toxicity from steroidal saponins. Sporadic outbreaks of hepatogenous photosensitization in ruminants grazing on this grass have been reported. Sheep are more susceptible than other animal species and the young are more susceptible than adults. This review article will critically shed light on the B. decumbens profile, its toxic compounds, mechanisms, clinical responses, blood profile alterations, pathological changes, and acute phase responses related to signal grass intoxication. Further research is needed to integrate new findings on B. decumbens intoxication with previous preventive and therapeutic trials to minimize or remove its deleterious toxic effect.

Comparison of two collection methods to determine protodioscin concentrations in Brachiaria spp. and to monitor Brachiaria spp. Poisoning

ABSTRACT: The objective of this study was to evaluate the methods of collecting Brachiaria spp. (Simulated Grazing vs. Total Collection) for the determination of protodioscin concentrations and to monitor the intoxication in sheep susceptible and resistant to poisoning by Brachiariaspp. The collection of Brachiaria spp. was done through two different methods. The first one consisted in throwing a metallic square at 10 random picket points. The second was performed simulating, with the hands, the grazing behavior of sheep. The leaf blades obtained by the two methods were conditioned in a forced ventilation oven. The extraction and quantification of protodioscin from the dry milled plant material was done by reverse-phase high-performance liquid chromatography (HPLC). The collections were carried out at three stages of the life of experimental lamb (suckling, rearing, and finishing). The lambs were divided into resistant and susceptible to intoxication by Brachiaria spp. The criterion for a lamb to be considered sensitive was to present some clinical signs at some stage of its life. No significant differences were observed between the general averages of the two collections when the evaluation was done in the whole period. However, a significant difference was found at the onset of the clinical signs. The concentrations of protodioscin in this period were higher in Brachiaria spp. collected by the simulating grazing method. Both methodologies were efficient to determine the level of protodioscin in the pastures of Brachiaria spp. However, during the periods when the outbreaks occurred, the simulated grazing method was more reliable.

Experimental poisoning by Brachiaria decumbens in rabbits

ABSTRACT: Brachiaria spp. are important sources of forage for ruminants in Brazil, due to the easy cultivation, good resistance to drought, good adaptation to different soils and low maintenance cost. However, the ingestion of this grass has been related to photosensitization outbreaks in cattle and sheep with significant economic losses. The hepatotoxic effects related to the ingestion of grass are the formation of crystals and foamy macrophages due to the accumulation of toxic metabolites. The use of cattle and sheep in experiments involving the plant presents several obstacles in the ethical, economic and animal management. The objective of this study was to evaluate the sensitivity of rabbits as an experimental model for B. decumbens poisoning. Two experiments were carried out. In Experiment 1 four rabbits received the fresh plant in daily doses of 10, 20, 40 and 80g/kg body weight for 120 days. In Experiment 2 three rabbits received the fresh plant in amounts of 500g daily with duration of 210 days. The animals of Experiment 1 showed no clinical signs and no macroscopic and microscopic changes characteristic of B. decumbens poisoning. In Experiment 2 the animals also showed no clinical signs or significant macroscopic alterations. Histological analysis showed isolated foamy macrophages or present in random groups of cells in the liver and mesenteric lymph nodes. Samples of liver and mesenteric lymph nodes of the rabbits of Experiment 2 were submitted to the lectin-histochemistry technique. The WGA, sWGA and RCA lectins showed reactivity in foamy macrophages in both organs. This is the first study of our knowledge that demonstrates histopathological lesions caused expetimentally by Brachiaria spp. in rabbits, demonstrating its potential as an animal model.

Content of the Saponin Protodioscin in Brachiaria spp. from the Eastern Plains of Colombia

Protodioscin is used as a marker of saponin content that could cause hepatotoxicity in ruminants. In Brachiaria spp. from two regions of the Colombian Eastern Plains (east mountain range of the Andean-"piedemonte" and Ariari River Valley) were determined this metabolite at 14 and 28 days post-cutting under different climatic conditions. No protodioscin was detected in B. dictyoneura or B. humidicola. In B. brizantha, B. decumbens and B. ruziziensis x B. decumbens x B. brizantha (hybrid), protodioscin content corresponded to an interaction between species, post-cutting time and season. Concentrations ≥1% (minimum toxic level) were recorded in B. decumbens and the hybrid, and to a lesser extent in B. brizantha. The concentration of protodioscin was higher at 28 days, when the pastures are suitable for consumption. B. brizantha accumulated the lowest saponin concentration, whereas the hybrid had the highest levels, particularly in the "piedemonte" and during drought (3.37%). Dry season favored the protodioscin concentration in B. decumbens (in river valley) and in the hybrid (in "piedemonte"). In the latter, there was a positive correlation with temperature and a negative with humidity, which are typical characteristics of dry periods. This is the first report of protodioscin content in the hybrid.

Serum concentrations of acute phase proteins in goats and ewes with naturally acquired Staphylococcus aureus mastitis

ABSTRACT Serum protein concentrations, including acute phase proteins (APPs), of goats and ewes with naturally acquired Sthaphylococcus aureus mastitis were determined by means of SDS-PAGE electrophoresis to evaluate the relevance of these APPs as biomarkers of the disease in these species. Fifteen healthy goats and 5 goats with naturally acquired staphylococci mastitis, as well as fifteen healthy ewes and 5 ewes with staphylococci mastitis were submitted to daily blood sampling during 7 days. In goats, an increase of 570%, 125%, 621%, and 279% in serum concentrations of ceruloplasmin, fibrinogen, haptoglobin and α1-acid glycoprotein, respectively, was observed. In sheep the increase in serum concentrations of ceruloplasmin, fibrinogen, haptoglobin and α1-acid glycoprotein was of 337%, 90%, 461%, and 225%, respectively. Our results indicate that these APPs have considerable potencial as early and sensible biomarkers of mastitis caused by S. aureus in goats and sheep.

Spontaneous poisoning by Brachiaria decumbens in goats

Abstract: An outbreak of Brachiaria decumbens poisoning in goats in the state of Mato Grosso do Sul, Brazil, is described. Out of a herd of about 1,000 goats, seven goats died after showing photosensitivity (3 out 7 goats) and icterus (4/7). Other clinical signs included lethargy, dehydration and weight loss (7/7). At necropsy there was either hepatomegaly or liver atrophy; orange, yellow or gray discoloration - were observed in the liver of six goats. Two had accentuation of lobular pattern and punctate, linear or stellar fibrous depressions were randomly distributedover the capsular surface. Macroscopic changesattributedto liver failure consisting of hydropericardium (2/7) and ascites (2/7) were observed. Histologically, there was accumulation of refringent crystals in the bile ducts and infiltration of foamy macrophages in the liver of all goats. Foamy macrophages were also present in the hepatic and mesenteric lymph nodes of two goats. The diagnosis of B. decumbens poisoning was based on epidemiology, clinical signs, necropsy findings and histopathology.

Identification of lamb flocks susceptible and resistant against Brachiaria poisoning

Abstract: This study was designed to assess the influence of genetic resistance against brachiaria poisoning in sheep. Two groups of sheep, one identified as susceptible (formed by two ewes and one ram) and the other as resistant against brachiaria poisoning (formed by three ewes and one ram) were selected. Sheep considered susceptible were those that presented clinical signs of brachiaria poisoning at any time of their life; resistant sheep were those that even raised on Brachiaria spp. pastures, did not developed any sign of the poisoning during their life. The offspring of the two flocks (15 lambs from the sensitive flock and 9 lambs from the resistant flock) were placed into brachiaria pasture (initially Brachiaria decumbens and B. brizantha,and only B. decumbens after weaning) and followed up during two years (2013-2014). The determination of protodioscin levels in B. decumbens pasture was performed only in 2014 and revealed significant amounts of the toxic principle. Eleven lambs of the susceptible group were affected to some degree of brachiaria poisoning and six died; no lamb of the resistant group was affected. Clinical signs consisted of varying degrees of subcutaneous edema of the face and, erythema and loss of hair of the ears, crusts on the skin of ears, around the eyes and on planum nasale, scar deformation of the ears, and bilateral ocular discharge; affected lambs also sought for shadowy shelters and they were poor doers. Several sheep recovered from the condition and then relapsed. Necropsy findings in six lambs included pale mucous membranes, emaciation, dermatitis, scar deformation of the ears, large yellow livers with marked lobular pattern, and moderate infestation by Haemonchus contortus. Histologically the liver lesions were similar in all necropsied lambs but with varying degrees of severity; they were consistent with brachiaria poisoning and included architectural disruption of hepatocellular trabecula, clusters of foamy macrophages occasionally forming multinucleated giant cells, swollen and vacuolated hepatocytes, crystals or negative images of crystals in the biliary system, bilestasis, bile duct proliferation and lymphoplasmacytic infiltrate in portal triads. The skin lesions were those of photodermatitis and included epidermal necrosis, hyperkeratosis and dermal neutrophilic infiltrate. The results of this study allow to conclude that there is a genetic related resistance to brachiaria poisoning in sheep since the progeny of resistant sheep did not manifest the poisoning. The use of resistant flocks in brachiaria pastures is suggested as a valuable option for the prevention of brachiaria poisoning in sheep.

Performance of sheep grazing in pastures of Brachiaria decumbens, Brachiaria brizantha, Panicum maximum, and Andropogon gayanus with different protodioscin concentrations

Brachiaria spp. are the most important grasses for ruminants in central-western Brazil. However, the use of these pastures is limited by their toxicity due to steroidal saponins. This experiment was conducted for 60 days to demonstrate the resistance of sheep raised on Brachiaria spp. pastures to steroidal saponin poisoning. The experiment was composed by 48 animals randomly divided into four groups (n = 12). Among them, 32 4- to 5-month-old castrated male crossbred Santa Inês sheep, originating from flocks that had been grazing on Brachiaria spp. for more than three consecutive years, and 16 were non-adapted (naïve) sheep from flocks that never had prior contact with pastures of Brachiaria spp. were randomly divided into four groups. Each of the four experimental groups was composed by eight adapted and four non-adapted animals. The four experimental groups were introduced into paddocks, each of which contained a single grass: either Brachiaria decumbens, Brachiaria brizantha, Panicum maximum, or Andropogon gayanus. The addition of the naïve sheep to the groups was designed to detect pastures' toxicity to naïve sheep and to adjust the stocking rate to optimize the use of forage. The weight gains of sheep grazing on B. decumbens, B. brizantha, and P. maximum were similar; however, the A. gayanus group showed lower weight gains compared with the other groups (P < 0.05). The mean serum activities of γ-glutamyltransferase in the sheep grazing on B. decumbens were higher than those in the sheep from the other groups. No significant differences among the groups were found in aspartate aminotransferase, creatinine, albumin, or total protein serum concentrations. No clinical signs were observed in the adapted sheep in any of the pastures. Of the four non-adapted sheep introduced into the B. decumbens pasture, two showed clinical signs of steroidal saponin poisoning, and one died. No clinical signs were observed in the non-adapted sheep in the other pastures. The saponin (protodioscin) concentrations in the pastures varied from 3.3 to 12.2 g/kg DM in B. decumbens, from 2.8 to 9.1 g/kg DM in B. brizantha, and from 1 to 1.5 g/kg DM in A. gayanus. No saponins were found in P. maximum. It is concluded that sheep from flocks reared in pastures of B. decumbens and B. brizantha were resistant to steroidal saponin poisoning and showed similar weight gains to those of sheep grazing in other tropical pastures.

Avaliação da exposição solar na intoxicação experimental por Brachiaria decumbens em ovinos

Foram utilizados 26 ovinos, entre 3 e 4 meses de idade, divididos em 3 grupos, provenientes de rebanhos que nunca tiveram contato com pastos de Brachiaria spp.. Dois grupos receberam Brachiaria decumbens no cocho diariamente ad libitum, sendo que um deles permaneceu em área com exposição solar (GS) e o outro foi mantido em baias cobertas protegidos do sol (GSB). O grupo controle (GC) foi também mantido em local com exposição solar e alimentado com feno de Cynodon dactylon e capim Pennisetum purpureum triturado. Todos os grupos receberam alimentação em cochos e foram suplementados com 200g/dia/animal de ração comercial para ovinos. Foi realizada a avaliação clínica diária dos ovinos e colhidas amostras duas vezes por semana para dosagem sérica de AST e GGT. Os animais que morreram foram submetidos a necropsia e em todos os ovinos sobreviventes foi realizada biópsia hepática no final do experimento. Três animais do grupo GS adoeceram e dois morreram. Um ovino do grupo GSB adoeceu e morreu. Não houve alterações clínicas nos ovinos controles. Os principais sinais clínicos observados nos animais que adoeceram foram apatia, emagrecimento, fotofobia, hiperemia e secreção ocular e icterícia. Nenhum animal apresentou lesões cutâneas de fotossensibilização. O grupo que permaneceu no sol apresentou atividades séricas médias de AST e GGT significativamente maiores que a dos demais grupos (p<0,05) e os animais que permaneceram na sombra apresentaram níveis maiores de GGT (p<0,05) em comparação ao grupo controle. A histopatologia das amostras de fígados dos ovinos com sinais clínicos demonstrou tumefação e vacuolização de hepatócitos, necrose individual de hepatócitos, macrófagos espumosos com cristais birrefringentes intracitoplasmáticos e dentro de ductos biliares e infiltrado mononuclear periportal. Amostras do capim fornecidas aos cordeiros evidenciaram níveis médios de 0,94±0,80% da saponina protodioscina. As observações do presente experimento sugerem que a não exposição ao sol não evita a presença de sinais clínicos da intoxicação, mas que a exposição solar exacerba os sinais clínicos.

Avaliação lectino-histoquímica de fígado e rim de ovinos com fotossensibilização causada por Brachiaria decumbens

Embora sejam as forrageiras mais importantes para a pecuária de corte (bovinocultura de corte) no Brasil, em certas épocas ou condições, Brachiaria spp. podem ser tóxicas e causar surtos de fotossensibilização hepatógena que determinam significativas perdas econômicas. Animais que se alimentam em pastos de Brachiaria spp. comumente apresentam macrófagos espumosos isolados ou agrupados, além de cristais no interior de ductos biliares. Saponinas esteroidais têm sido identificadas nestes cristais e são responsabilizadas por lesar o fígado levando ao acúmulo de filoeritrina. Por vezes, imagens negativas desses cristais podem estar presentes no citoplasma de macrófagos espumosos. A patogênese de formação e o tipo de material armazenado nas células espumosas ainda são desconhecidos. A técnica de lectino-histoquímica visa auxiliar na detecção desses macrófagos e, consequentemente, no diagnóstico, além de identificar quais os resíduos de açúcares específicos que estão presentes no citoplasma das células espumosas. Assim, este trabalho teve por objetivo identificar quais lectinas são mais indicadas na detecção de saponinas esteroidais no fígado e rim de ovinos com fotossensibilização causada por Brachiaria decumbens. Fragmentos de fígado e rim de quinze ovinos, de ambos os sexos e idade variável, oriundos de Conceição do Mato Dentro, Minas Gerais, e um ovino mantido em pastagem livre de Brachiaria spp. foram avaliados pela técnica de lectino-histoquímica. Quatorze lectinas foram utilizadas (Con-A, DBA, SBA, PNA, SJA, RCA-I, UEA-I, WGA, SWGA, GSL, PSA, PHA-L, PHA-E e LCA). Verificou-se que, no fígado de ovinos com fotossensibilização provocada pela ingestão de Brachiaria decumbens, a lectina PNA apresentou especificidade e acentuada reatividade aos macrófagos espumosos, bem como especificidade e leve reatividade aos hepatócitos; a lectina WGA teve especificidade e moderada reatividade aos macrófagos espumosos do fígado e especificidade e leve reatividade aos hepatócitos; e as lectinas SBA, GSL e LCA apresentaram especificidade e moderada reatividade aos macrófagos espumosos, entretanto, não foram específicas para hepatócitos. No rim dos ovinos, a lectina PNA foi a que apresentou maior reatividade. Avaliações lectino-histoquímicas ainda não haviam sido realizadas em fígado e rim de ovinos com fotossensibilização provocada por Brachiaria spp.

Hepatic photosensitization in buffaloes intoxicated by Brachiaria decumbens in Minas Gerais state, Brazil

The aim of this paper is to report the study of hepatogenous photosensitization in buffaloes during two outbreaks provoked by ingestion of Brachiaria decumbens in Minas Gerais state, Brazil. Ten young buffaloes in outbreak 1 and seven buffaloes in outbreak 2 were intoxicated by B. decumbens. Nine clinically healthy buffaloes raised under the same conditions as the sick animals served as the control group. All animals were subjected to clinical examination, and serum was collected to measure gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), direct bilirubin (DB), indirect bilirubin (IB) and total bilirubin (TB) as indicators of liver function and urea and creatinine as indicators of renal function. Histopathology of liver fragments from five different animals was carried out. During the outbreaks and every two months for one year, samples of grass from paddocks where the animals got sick were collected for quantitative evaluation of the saponin protodioscin, combined with observations of pasture characteristics and daily rainfall. Clinical signs included apathy, weight loss, restlessness, scar retraction of the ears and intense itching at the skin lesions, mainly on the rump, the tail head, neck and hindlimbs, similar to the signs observed in other ruminants. Only the GGT enzyme presented significantly different (P < 0.01) serum levels between intoxicated animals (n = 17) and healthy animals (n = 9), indicating liver damage in buffaloes bred in B. decumbens pastures. Microscopy of the liver showed foamy macrophages and lesions of liver disease associated with the presence of crystals in the bile ducts, which have also been found in sheep and cattle poisoned by grasses of the genus Brachiaria. During the outbreaks, protodioscin levels were higher than 3%, and shortly after, these levels were reduced to less than 0.80%, suggesting a hepatic injury etiology. The outbreaks took place at the beginning of the rainy season, and there was a positive correlation between saponin and the amount of rainfall, as well as between saponin and the amount of green leaves in the pasture. These findings indicate that the grass was more toxic in this period. This is the first report of photosensitization by B. decumbens in buffalo.

Doenças de ovinos diagnosticadas no Laboratório de Anatomia Patológica Animal da Universidade Federal de Mato Grosso do Sul (1996-2010)

Nas últimas décadas a pecuária ovina cresceu significativamente no Brasil. Concomitantemente, grupos de pesquisas e laboratórios de diagnósticos realizam estudos retrospectivos com a finalidade de fornecer subsídios técnico-científicos para os médicos veterinários. Desta forma, realizou-se um estudo de prevalência nos arquivos do Laboratório de Anatomia Patológica Animal (LAP) da Universidade Federal de Mato Grosso do Sul (UFMS) no período de Janeiro de 1996 a Dezembro de 2010. O Laboratório de Bacteriologia da UFMS e o Setor de Patologia Veterinária da Universidade Federal do Rio Grande do Sul forneceram apoio diagnóstico nos casos de mannheimiose pulmonar e scrapie, respectivamente. Os laudos da espécie ovina foram revisados e agrupados em conclusivos e inconclusivos, dos quais foram excluídos os casos experimentais e de outros estados e países. Os casos conclusivos foram classificados de acordo com a etiologia da doença. Os exames da espécie ovina somaram 331 laudos (3,97 %) de um total de 8.333 casos diagnosticados no período. Destes, foram excluídos sessenta e quatro (19,3%) casos experimentais e materiais oriundos de outros estados ou países. Dos 267 casos remanescentes, 87 (32,6%) foram inconclusivos e 180 (67,4%) considerados conclusivos, sendo 60 (33,3%) doenças infecciosas e parasitárias; 45 (25%) intoxicações e toxi-infecções; 41 (22,8%) "lesões sem causa definida"; 22 (12,2%) doenças metabólicas e nutricionais; 10 (5,6%) foram classificadas como "outros distúrbios" e 2 (1,1%) neoplasmas. A hemoncose, intoxicação por Brachiaria spp., pleuropneumonias, broncopneumonias, pneumonias fibrinonecrosante ou fibrinossupurativa sem causa definida e a intoxicação por cobre foram as doenças mais prevalentes no período estudado. Dois casos de scrapie foram diagnosticados no período.

Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central

Brachiaria spp. é a principal forrageira utilizada para ruminantes no Brasil Central, mas a sua toxicidade, devida à presença de saponinas esteroidais, torna-se um importante entrave à sua utilização. Neste trabalho descrevem-se 34 surtos e um foco de intoxicação por Brachiaria spp em ovinos, que ocorreram em diferentes épocas do ano. A morbidade geral foi de 23,2% e a letalidade foi 88,3%. O tempo que os animais permaneceram no pasto até o surgimento dos sinais clínicos da intoxicação por Brachiaria spp. variou de 15 dias até mais de 12 meses. Em 90,1% dos surtos os animais eram menores de 12 meses de idade. O curso clínico da intoxicação variou de 2 a 45 dias. Os sinais clínicos e as lesões macroscópicas foram características de fotossenssibilização hepatógena, no entanto, nos casos mais agudos não foram observadas dermatite nem icterícia, ocorrendo severo edema em face e orelhas. Na histologia do fígado as lesões mais características foram a presença de macrófagos com citoplasma espumoso, encontrados principalmente nos sinusoides hepáticos e, às vezes, com imagens negativas de cristais acutiformes no citoplasma. Em oito das 11 fazendas visitadas os surtos ocorreram em pastagens de Brachiaria decumbens; em duas em pastagens de B. brizantha e uma em pastagem de B. decumbens, B. humidicola e Andropogon sp. As concentrações de saponinas nas pastagens, em 5 surtos, variou de 0.3% a 2.56%. As informações geradas neste trabalho permitem a proposta de medidas para controle e profilaxia da intoxicação por Brachiaria spp. no Brasil Central.

Intoxicação espontânea e experimental por Pterodon emarginatus (Fabaceae Faboideae) em bovinos e experimental em ovinos

Relatam-se mortalidades de bovinos nos Estados de Mato Grosso e Mato Grosso do Sul relacionadas ao consumo de folhas de Pterodon emarginatus. Três surtos ocorreram no período de seca na região Centro-Oeste, após a queda de árvores devido a ventos fortes ou após serem derrubadas para aproveitamento da madeira. Morreram 40 bovinos em três diferentes surtos. A intoxicação foi reproduzida com administração de folhas de P. emarginatus; a dose tóxica mínima foi 20g/kg para ovinos e 6g/kg para bovinos. Os sinais clínicos iniciaram-se entre 24 e 72 horas após o consumo da planta. A evolução clínica da doença letal foi de 12 a 36 horas. Os sinais clínicos se caracterizaram por apatia, depressão, andar a esmo, pressão da cabeça contra objetos. Em dois dos surtos, os bovinos que sobreviveram a fase aguda da doença, desenvolveram fotossensibilização. Os principais achados macroscópicos nos casos espontâneos e experimentais foram no fígado; estes se caracterizaram por hepatomegalia e evidenciação do padrão lobular na superfície capsular e de corte. Notaram-se também hemorragias nas serosas abdominais e torácicas. Microscopicamente observou-se necrose coagulativa hepatocelular, que variou de centrolobular a massiva, por vezes associada à congestão e hemorragia; ocorreu também marcada tumefação e vacuolização de hepatócitos na região periacinar. O diagnóstico foi baseado nos dados epidemiológicos, clínicos, patológicos e na reprodução experimental da intoxicação em bovinos e ovinos. Estes achados caracterizam P. emarginatus como planta hepatotóxica de interesse pecuário na região Centro-Oeste do Brasil.

Brachiaria spp. poisoning of ruminants in Brazil

Brachiaria species are the most important grasses for cattle production in Brazil. However, a limiting factor for the use of Brachiaria spp. is their toxicity. Most outbreaks of hepatogenous photosensitization are caused by B. decumbens; however B. brizantha, B. humidicola and B. ruziziensis can also cause poisoning. The poisoning affects cattle, sheep, goats and buffalo. Sheep are more susceptible than other animal species and the young are more susceptible than adults. There are differences in susceptibility among animals of the same species and it has been suggested that this resistance is genetic. Also has been suggested that buffalo and probably some sheep are resilient, i.e. when poisoned these animals have histologic lesions and high GGT serum concentrations, but do not show clinical signs. In general, saponin concentrations are higher in growing plants, but outbreaks occur all over the year, probably due to unexplained rise in saponin concentration in the plant. A clinical syndrome of progressive weight loss and death, without photosensitization, has been reported in cattle poisoned by B. decumbens. Main preventive measures are based on the selection of resistant or resilient animals and on the development of Brachiaria species or varieties with low saponin concentration.

Intoxicação por Brachiaria spp. em bovinos no Mato Grosso do Sul

Mediante a revisão dos arquivos das fichas de necropsia do Laboratório de Patologia Animal, Universidade Federal do Mato Grosso do Sul, foram estudados a epidemiologia, o quadro clínico e a patologia de 29 surtos de intoxicação por Brachiaria spp., ocorridos em bovinos de corte, no Mato Grosso do Sul, de março de 1996 a novembro de 2009. Os surtos ocorreram em todas as épocas do ano, tanto na seca quanto na chuva. Em 24 dos 29 surtos o principal sinal clínico foi a fotossensibilização e em cinco o principal sinal foi o emagrecimento progressivo. Dos 24 surtos de fotossensibilização, 11 ocorreram em pastagens de B. decumbens, dois em pastagens mistas de B. decumbens e B. brizantha, um em B. brizantha e em 10 surtos não foi informada a espécie de Brachiaria envolvida. A morbidade variou de 0,2% a 50% e a letalidade de 44,4% a 100%. Nos casos de fotossensibilização o edema de barbela foi o sinal clínico mais encontrado em bovinos, seguido de dermatite com pele espessada no flanco e períneo, retração cicatricial auricular, icterícia, corrimento ocular. crostas auriculares e oculares, e ulcerações na parte ventral da língua. Em dois surtos foram observados sinais nervosos e em um, diarréia. Nas necropsias o fígado estava aumentado de tamanho, amarelado, com padrão lobular aumentado e, ocasionalmente, com áreas esbranquiçadas e deprimidas. Os rins estavam acastanhados e a urina escura. No exame histológico do fígado encontrou-se tumefação e vacuolização de hepatócitos, proliferação de células epiteliais dos ductos biliares, retenção biliar, fibroplasia periportal discreta ou moderada e infiltrado mononuclear periportal. Todos os casos de fotossensibilização apresentaram macrófagos espumosos no parênquima hepático e em 21 foram observados cristais birrefringentes nos ductos biliares. Cinco surtos com emagrecimento progressivo dos bovinos afetados foram diagnosticados em pastagens de B. decumbens. A principal lesão macroscópica foi o fígado aumentado de volume e amarelado. No estudo histológico, as lesões foram semelhantes às observadas nos casos de fotossensibilização, sendo que cristais refringentes nos ductos biliares foram observados em três animais. Conclui-se que B. decumbens é mais tóxica que B. brizantha e que a intoxicação ocorre, principalmente, em bovinos jovens nas diferentes épocas do ano. No entanto, pesquisas são necessárias para determinar as variações no conteúdo de saponinas litogênicas em Brachiaria spp. e as diferenças de resistência/susceptibilidade à intoxicação de bovinos de diferentes idades e raças em diferentes regiões.

Alterações histológicas em fígados e linfonodos de búfalos (Bubalus bubalis) mantidos em pastagens de Brachiaria spp

Infiltração por macrófagos espumosos e outras lesões podem ser encontradas em bovinos clinicamente sadios em pastagens de Brachiaria spp. Com o objetivo de determinar as alterações histológicas do fígado e linfonodos mesentéricos em búfalos no Pará foram estudadas as alterações histológicas de fragmentos desses órgãos de 142 búfalos da raça Murrah e de 15 bovinos da raça Nelore, coletados em frigoríficos. As coletas foram separadas em grupos de animais de acordo com sua origem e tempo de permanência na pastagem de Brachiaria spp., sendo o Grupo (G) 1 composto por 79 búfalos provenientes da Ilha de Marajó, criados em pastagens de campo nativo; o G2 composto por 17 búfalos mantidos desde o nascimento em pastagens de Brachiaria brizantha; o G3 composto por 29 búfalos adquiridos na Ilha do Marajó e introduzidos em pastagem de B. decumbens por aproximadamente 12 meses; o G4 composto por 17 búfalos adquiridos na Ilha de Marajó e introduzidos em pastagem de B. brizantha por aproximadamente 18 meses; e o G5 composto por 15 bovinos mantidos em pastagem de B. brizantha por aproximadamente 12 meses. Para avaliar a gravidade da lesão hepática foram estabelecidos graus de acordo com a quantidade e tamanho dos grupos de macrófagos espumosos, seguindo uma escala de 0 a 4. Nos animais do G1, provenientes da Ilha de Marajó, não foram observadas alterações histológicas significativas no fígado e linfonodos mesentéricos. Em todas as amostras dos grupos G2, G3 e G4 foram observados quantidades variáveis de macrófagos espumosos no fígado e linfonodos mesentéricos. Os animais dos grupos G2 e do G4, que permaneceram um período maior em pastagens de Brachiaria spp, apresentaram lesões mais acentuadas (P<0,05) de macrófagos espumosos do que os animais do G3. Além da presença de macrófagos espumosos, foram observadas também, no fígado desses três grupos, tumefação, vacuolização e necrose de hepatócitos, principalmente da região centrolobular. Essas lesões eram mais acentuadas nas áreas onde havia maior infiltração de macrófagos espumosos. Havia fibrose capsular e as lesões dos hepatócitos nesta localização eram mais severas. Nos bovinos do G5 foram observados pequenos grupos de macrófagos espumosos nos linfonodos mesentéricos e ausência dessas células no fígado. Esses resultados sugerem que as lesões hepáticas observadas na histologia em búfalos sem sinais clínicos são ocasionadas pela ingestão de Brachiaria spp. A presença de lesões severas em búfalos sem sinais clínicos, bem mais graves do que as observadas em bovinos, assim como a ausência de surtos de intoxicação por Brachiaria nessa espécie, sugere sua resiliência à intoxicação por Brachiaria spp. Dentro de cada grupo não foi comprovada associação entre o peso ao abate e a gravidade das lesões. A presença de lesões severas no fígado de búfalos sem sinais clínicos alerta para o fato de que lesões semelhantes encontradas durante necropsias de búfalos mortos por outras causas possam levar ao diagnóstico errado de intoxicação por Brachiaria spp.

Intoxicação experimental por Brachiaria decumbens em ovinos confinados

Foi realizado estudo experimental de intoxicação por Brachiaria decumbens em ovinos confinados que receberam apenas esta forrageira como alimento. Os animais foram avaliados em três períodos do ano, com duração de 60 dias cada. As análises incluíram exame clínico e amostras de sangue para mensuração da atividade sérica das enzimas gama glutamiltransferase e aspartato aminotransferase com o objetivo de avaliar sua importância e utilidade no diagnóstico de fotossensibilização hepatógena causada pela planta. Foram descritos ainda, achados de necropsia e histopatológicos. Dos vinte e quatro animais confinados, cinco morreram no primeiro período (fevereiro a abril), quatro no segundo (junho a agosto) e dois no terceiro (outubro a dezembro), tendo como principais sinais clínicos anorexia, icterícia, fotofobia, dermatite leve, além de desidratação e apatia. Nos achados de necropsia foram constatados icterícia generalizada, vesícula biliar repleta e distendida, padrão lobular hepático evidente e, em dois casos, opacidade de córnea. As alterações microscópicas foram mais significativas no fígado com bilestase, tumefação e vacuolização de hepatócitos, sinusóides com macrófagos, proliferação de ductos e dúctulos biliares com infiltração linfocítica, que variaram na sua severidade conforme o tempo decorrido da ingestão da planta, além de imagens negativas de cristais no citoplasma de macrófagos presentes nos sinusóides hepáticos e no espaço periportal e cristais refringentes oticamente ativos, ocluindo a luz de ductos biliares. Os achados foram característicos de fotossensibilização hepatógena por B. decumbens, principalmente pela presença de fotofobia, mesmo quando os animais não apresentaram fotodermatite. O aumento da atividade sérica da gama glutamiltransferase teve alta correlação com a morte dos animais. O surgimento da elevação da atividade sérica de gama glutamiltransferase foi, em média, 11 dias antes da constatação dos sinais clínicos, validando sua importância no diagnóstico e na prevenção. A aspartato aminotransferase teve resultados inconsistentes. Treze animais não apresentaram sinais clínicos, apesar de serem constatadas significativas elevações nos níveis séricos das enzimas em questão, sugerindo a existência de indivíduos tolerantes/resistentes dentro do intervalo estabelecido. O modelo experimental foi adequado na caracterização da intoxicação de ovinos por B. decumbens, oferecendo subsídios para estimar preventivamente o risco de morte de ovinos intoxicados pela planta, além de ser útil para a realização de novos estudos da intoxicação por B. decumbens.

Sheep poisoning by Panicum dichotomiflorum in northeastern Brazil

Different species of Panicum, including P. dichotomiflorum,have been reported as a cause of photosensitization in sheep, horses, cattle and goats. An outbreak of hepatogenous photosensitization occurred in 3 flocks of hair sheep in the Brazilian semiarid region. Eighty one out of 365 sheep were affected and 39 died. The main affected animals were nursing lambs and sheep younger than one year old. Donkeys, goats and cattle grazing in the same pasture were not affected. Clinical signs were edema of the head, followed by dermatitis, mainly in the face, ears, and croup, ocular discharge, corneal opacity with blindness, and redness of the coronary band and hoof. At necropsy of one affected lamb the liver was yellowish. Upon histologic examination scattered necrotic hepatocytes were observed in the liver and focal areas of necrosis of myocytes appeared in the heart. Samples of P. dicotomiflorum were analyzed by TLC and those containing saponins were isolated by HPLC using RP-C18 column and eluted with a mixture of MeOH and H2O. The isolated compounds were submitted to ¹H and 13C NMR spectroscopy. Reactions were positive to furostanol saponins with the same Rf of the standard protodioscin (0.21) and methylprotodioscin (0.32). The spectroscopic results indicated a mixture of (25R)- and (25S)-protodioscin isomers in a proportion of 3:1, and methylprotodioscin.