Polioencefalomalacia experimental em bovinos induzida por toxicose por enxofre

Ruminal effects of excessive dietary sulphur in feedlot cattle

Sulphur (S) dietary excess can limit productive performance and increase polioencephalomalacia (PEM) incidence in feedlot cattle (FC). Sulphur excess ingested is transformed to hydrogen sulphide (H₂ S) by sulfo-reducing ruminal bacteria (SRB), being high ruminal H₂ S concentration responsible for aforementioned damages. As the ruminal mechanisms involved in H₂ S concentrations increase have not been elucidated, this study aimed to evaluate the ruminal environment, and the association between ruminal H₂ S and dissimilatory SRB (DSRB) concentration in FC experimentally subjected to S dietary excess. Twelve crossbred steers were randomly assigned to one of two dietary S levels (6 animals per treatment): low (LS, 0.19% S) and high (HS, 0.39% S obtained by sodium sulfate inclusion at 0.86%). The study lasted 38 days, and on days 0, 22 and 38, ruminal gas samples were taken to quantify H₂ S concentration, and ruminal fluid to determine total bacteria, DSRB, protozoa, volatile fatty acid and ammonia nitrogen concentration. For ruminal H₂ S concentration, S dietary × sampling day interaction was significant (p < 0.001), so that the greater concentration was observed on days 22 and 38 with the HS diet. The remaining ruminal parameters were not affected by dietary S level, and no significant correlation between H₂ S and DSRB concentrations was observed. The ruminal adaptation that maximizes H₂ S production in FC consuming S excess does not seem to be associated with biological or biochemical alterations, nor DSRB concentration changes. The microbial diversity and ruminal environment were resilient to the S excess evaluated, suggesting that 0.39% of dietary S achieved by 0.86% sodium sulfate addition, could be used without disturbances on digestion nor health of FC.

Cerebrospinal fluid analysis in 58 ruminants showing neurological disorders

ABSTRACT: Ruminants may be affected by a wide variety of central nervous system (CNS) diseases. Cerebrospinal fluid (CSF) analysis forms the basis for ante mortem diagnostic evaluation of ruminants with clinical signs involving the CNS. Despite its importance as a tool to aid diagnosis, data regarding CSF examinations in spontaneous cases of CNS diseases in ruminants from Brazil are limited, and most reports involve experimental studies. Therefore, this study aimed to report the results of CSF analysis in 58 ruminants showing signs of neurological disorders. CSF samples for analysis were obtained from 32 cattle, 20 sheep, and 6 goats by cerebello-medullary cistern (n=54) or lumbosacral space (n=4) puncture. These ruminants showed neurological signs related to viral (n=13), mycotic (n=3), or bacterial (n=15) infections, and toxic (n=21), traumatic (n=4), or congenital disorders (n=2). CSF analysis from ruminants with viral infections presented lymphocytic pleocytosis, even though CSF showed no changes in several cases of rabies. Neutrophilic pleocytosis, cloudiness, presence of fibrin clots, and abnormal coloration were evident in the CSF of most cases of CNS bacterial infection, such as meningoencephalitis, meningitis, abscesses, myelitis, and a case of conidiobolomycosis. On the other hand, CSF was unchanged in most cases of toxic disorders, as botulism and hepatic encephalopathy. Elevated CSF density was observed in 60% of ruminants diagnosed with polioencephalomalacia. Our findings show that evaluation of CSF is a valuable diagnostic tool when used in association with epidemiological, clinical and pathological findings for diagnosis of CNS diseases in ruminants.

Thiamine Deficiency Modulates p38MAPK and Heme Oxygenase-1 in Mouse Brain: Association with Early Tissue and Behavioral Changes

Thiamine deficiency (TD) produces severe neurodegenerative lesions. Studies have suggested that primary neurodegenerative events are associated with both oxidative stress and inflammation. Very little is known about the downstream effects on intracellular signaling pathways involved in neuronal death. The primary aim of this work was to evaluate the modulation of p38^MAPK and the expression of heme oxygenase 1 (HO-1) in the central nervous system (CNS). Behavioral, metabolic, and morphological parameters were assessed. Mice were separated into six groups: control (Cont), TD with pyrithiamine (Ptd), TD with pyrithiamine and Trolox (Ptd + Tr), TD with pyrithiamine and dimethyl sulfoxide (Ptd + Dmso), Trolox (Tr) and DMSO (Dmso) control groups and treated for 9 days. Control groups received standard feed (AIN-93M), while TD groups received thiamine deficient feed (AIN-93DT). All the groups were subjected to behavioral tests, and CNS samples were collected for cell viability, histopathology and western blot analyses. The Ptd group showed a reduction in weight gain and feed intake, as well as a reduction in locomotor, grooming, and motor coordination activities. Also, Ptd group showed a robust increase in p38^MAPK phosphorylation and mild HO-1 expression in the cerebral cortex and thalamus. The Ptd group showed a decreased cell viability, hemorrhage, spongiosis, and astrocytic swelling in the thalamus. Groups treated with Trolox and DMSO displayed diminished p38^MAPK phosphorylation in both the structures, as well as attenuated thalamic lesions and behavioral activities. These data suggest that p38^MAPK and HO-1 are involved in the TD-induced neurodegeneration in vivo, possibly modulated by oxidative stress and neuroinflammation.

Amprolium exposure alters mice behavior and metabolism in vivo

BACKGROUND

Thiamine deficiency (TD) models have been developed, mainly using the thiamine analog pyrithiamine. Other analogs have not been used in rodents. We aimed to evaluate the effects and mechanisms of intraperitoneal (ip) amprolium-induced TD in mice. We also evaluated the associated pathogenesis using antioxidant and anti-inflammatory compounds (Trolox, dimethyl sulfoxide).

METHODS

Male mice were separated into two groups, one receiving a standard diet (control animals), and the other a TD diet (deficient groups) for 20 days. Control mice were further subdivided into three groups receiving daily ip injections of saline (NaCl 0.9%; Cont group), Tolox (Tr group) or dimethyl sulfoxide (DMSO; Dmso group). The three TD groups received amprolium (Amp group), amprolium and Trolox (Amp+Tr group), or amprolium and DMSO (Amp+Dmso group). The animals were subjected to behavioral tests and then euthanized. The brain and viscera were analyzed.

RESULTS

Amprolium exposure induced weight loss with hyporexia, reduced the behavioral parameters (locomotion, exploratory activity, and motor coordination), and induced changes in the brain (lower cortical cell viability) and liver (steatosis). Trolox co-treatment partially improved these conditions, but to a lesser extent than DMSO.

CONCLUSIONS

Amprolium-induced TD may be an interesting model, allowing the deficiency to develop more slowly and to a lesser extent. Amprolium exposure also seems to involve oxidative stress and inflammation, suggested as the main mechanisms of cell dysfunction in TD.

Neurological diseases of cattle in the state of Goiás, Brazil (2010-2017)

ABSTRACT: A retrospective study was conducted on neurological diseases of cattle in the state of Goiás, Brazil, from March 2010 to August 2017. Samples of three veterinary diagnostic laboratories were analyzed. Diagnosis was established in 170 out of 407 cattle with neurological signs. Epidemiological, clinical, and anatomic pathology features of each case were researched in the files. Main disorders included diseases caused by viruses (rabies 29.41%, meningoencephalitis by bovine herpesvirus 15.88%, and malignant catarrhal fever 1.76%), by bacteria (botulism 5.88%, suppurative meningitis 3.53%, encephalic abscesses 2.94%, listeriosis 1.76%, and thrombotic meningoencephalitis 1.76%), of metabolic origin (polioencephalomalacia 17.06%), of indefinite cause (lymphoplasmacytic meningoencephalitis 11.18%, traumatic hemorrhages 3.53%, and multifocal malacia with gliosis 1.18%), congenital (hydrocephaly 1.18% and multiple malformations 0.59%), toxic (urea poisoning 1.18% and insecticide poisoning 0.59%), and parasitic (meningoencephalitis associated with infection by Trypanosoma sp. 0.59%).

Occurrence of acid erosion of the teeth, actinomycosis and polioencephalomalacia in flock of sheep fed wet low pectin citrus pulp

ABSTRACT: The citrus pulp can be used as a substitute in ruminant feed reducing costs and maintaining the nutritional quality of food. However, this compound should be used carefully so as not to cause harm to the animals. The present report aims to describe the occurrence of dental erosion, actinomycosis and polioencephalomalacia in sheep raised and kept with a wet low pectin citrus pulp based diet, composing 50% of roughage. Actinomycosis was diagnosed in five animals through clinical and radiographic examinations and microbiological culture, and, after treatment, three animals were cured. Polioencephalomalacia was confirmed in ten animals by clinical diagnostics, in nine out of ten animals by therapeutic diagnosis, and in one animal by post-mortem anatomopathological examination. According to the observed, we recommend caution when large amounts of citrus pulp are used as bulky food.

Aspectos clínicos e laboratoriais em ovinos submetidos a dietas com níveis elevados de enxofre com objetivo de indução de polioencefalomalácia

A polioencefalomalacia (PEM) é uma doença neurológica que acomete ruminantes e pode ser desencadeada por diversos fatores, dentre eles o consumo excessivo de enxofre. Este trabalho teve como objetivo verificar a relação entre dietas ricas em enxofre, altos níveis de gás sulfídrico ruminal e a ocorrência de polioencefalomalácia em ovinos. Foram utilizados 18 ovinos, divididos em três grupos (G1, G2 e G3) que receberam diferentes níveis de enxofre na dieta; 0,2%, 0,9% e 1,2%, respectivamente. Exames físicos (frequência cardíaca, frequência respiratória, temperatura retal e motricidade ruminal) e complementares (concentração de sulfeto de hidrogênio ruminal, hemogasometria venosa, pH do fluído ruminal, concentração de cobre sérico e hepático, tomografia computadorizada, necropsia e histopatologia) foram realizados. A temperatura retal, a hemogasometria venosa e o pH do fluido ruminal permaneceram dentro dos valores de referência para a espécie. A motricidade ruminal estava diminuída nos grupos G2 e G3 em comparação com o G1 (controle). Quanto maior a ingestão de enxofre, menores foram os níveis de cobre sérico e hepático. Valores elevados de sulfeto de hidrogênio ruminal foram detectados nos grupos G2 e G3. Nenhum animal apresentou sinais clínicos de PEM. Nos exames de tomografia computadorizada, necropsia e exame histopatológico do sistema nervoso central (SNC), não foram observadas alterações compatíveis com PEM. É provável que algum outro fator esteja associado ao excesso de enxofre na dieta para o desenvolvimento de PEM em ovinos.