Nilton M. Carvalho

Intoxicação de bovinos por Tetrapterys multiglandulosa (Malpighiaceae) em Mato Grosso do Sul

Two outbreaks of poisoning by Tetrapterys multiglandulosa in cattle and the experimental reproduction of the toxicosis in sheep are described. Both outbreaks occurred on the same farm in the municipality of Bataipora, state of Mato Grosso do Sul, Brazil. The first outbreak occurred in July-October 2004 and involved a cattle population at risk of 290 pregnant cows, which were introduced into a 60 hectare pasture with a legal reservation area heavily infested by T. multiglandulosa. Of these, 230 cows (79.3%) aborted, had stillbirths or delivered weak calves that died few days after birth. Seven cows died, and one cow and a 10-day-old calf were necropsied. The second outbreak occurred in September-October 2005, 40 days after 285 2-year-old heifers were introduced into the same pasture infested by T. multiglandulosa and where the first outbreak had occurred in the previous year. Nine heifers got sick and died, and three of then were necropsied. Clinical signs of affected cattle, including a 10-day-old calf, were marked lethargy, loss of weight with distension of the abdomen (ascites), subcutaneous dependant edema, distended and pulsating jugular veins, dyspnea and cardiac arrhythmia. Necropsy findings included a round and dilated heart with whitish and firm areas in the myocardium, and changes related to cardiac failure such as cavitary edema, nutmeg liver, pulmonary edema, a large blood clot in the left ventricle. Histopathological changes included necrosis and fibrosis in the myocardium, chronic passive hepatic centrolobular congestion, pulmonary edema, and spongy degeneration in the white matter of the brain. Experimental sheep died 29 (Sheep 1) and 35 (Sheep 2) days after being fed average daily doses of T. multiglandulosa corresponding to 14g/kg (Sheep 1) and 7,5 g/kg (Sheep 2) per day. Clinical signs were observed from the 7th day (Sheep1) and the 4th day (Sheep 2) of the experiment and included tachycardia, arrhythmia, lethargy and head pressing. Necropsy and histopathologic findings in both experimental sheep were very similar to those observed in affected cattle of the two spontaneous outbreaks.

Intoxicação espontânea por Senna obtusifolia em bovinos no Pantanal Sul-Mato-Grossense

Senna sp. poisoning in livestock has been reported in several occasions in Brazil usually from southern Brazil and involving S. occidentalis as the culprit. The objective of this study is to report the occurrence of an outbreak of S. obtusifolia poisoning in cattle in the Pantanal Region of Mato Grosso do Sul, Brazil. In a herd of 313 heifers, 165 were affected and died (morbidity rate of 52.7% and lethality rate of 100%). The 313 heifers remained in the paddock infested by S. obtusifolia for 37 days. Clinical signs consisted of reluctance to move, incoordination, permanent sternal recumbency, decrease in the tonus of the tongue, alertness, myoglobinuria characterized by dark brown urine, and dry stools with or without mucus; or occasionally diarrhea with streaks of blood. The main gross findings in 12 necropsied cattle were in the skeletal muscles of the hind limbs, and were characterized by varying degrees of paleness of muscle groups. Histologically, the most relevant lesion was segmental multifocal degeneration and necrosis in striated skeletal muscles (multifocal lypolyphasic toxic degenerative myopathy). The epidemiological, clinical and pathological data allowed to conclude for the diagnosis of poisoning by S. obtusifolia in this outbreak.

Resposta imune específica de bovinos experimentalmente sensibilizados com inóculos inativados de Mycobacterium bovis e Mycobacterium avium

The presumptive diagnosis of bovine tuberculosis is based on analysis of the immune response to micobacterial antigens. This experimental simulation of sensibilization by Mycobacterium bovis and Mycobacterium avium in cattle aimed to verify the immune response by both the cervical comparative test and the evolution of the specific production of gamma-interferon, and also to identify interference of unspecified reactions by M. avium on the test results. The results support that the experimental animals started a response of delayed hypersensitivity to the inactivated bacilli, and that both diagnostic tests for bovine tuberculosis were efficient for the identification of animals sensitized with M. bovis and for discrimination of reactions generated by inoculation of cattle with M. avium.

Lesões perinatais em cordeiros induzidas pela administração de Tetrapterys multiglandulosa (Malpighiaceae) a ovelhas em diferentes estágios de gestação

In order to verify the effects of non-lethal doses of Tetrapterys multiglandulosa on ovine fetuses, experimental poisoning in sheep at different days of pregnancy was performed. Green leaves of shooting plants were administered to 9 pregnant ewes divided into three experimental groups. Sheep from Group 1 received four doses of 5g/kg of fresh leaves for 4 days; those from Group 2 received 10g/kg for 2 days; Group 3 sheep received a dose of 20g/kg for one day, and sheep from Group 4 did not receive the plant and served as negative controls. To check the plant toxicity, a male sheep (positive control) received 5g/ kg until the onset of clinical signs. No signs of poisoning were observed in pregnant ewes; three lambs died 1-5 days after birth, and a fourth lamb died within 3 months after have been born. The positive control died after 38 days of daily consumption of the plant, presenting tachypnea, tachycardia, drowsiness, incoordination, weakness and sudden death. All four dead lambs and the positive control sheep were necropsied. The gross lesions were whitish areas in the myocardium, increased lobular pattern of the liver, dark red lungs, metabolization of pericardial fat, and ruminal distention with free gas. Histological findings were cardiac fibrosis, cardiomyocyte necrosis, pulmonary congestion and edema, and spongy degeneration in subcortical cerebral white matter. Tetrapterys multiglandulosa resulted toxic for ovine fetuses at doses that were not suffient to induce clinical signs in the pregnant ewes, demonstrating that the poisoning may be a cause of death of lambs soon after birth, even several months after the ingestion of the plant has been discontinued.

Scrapie e seu diagnóstico diferencial em ovinos no Mato Grosso do Sul

Scrapie is a fatal neurodegenerative infectious disease, caused by the scrapie prion (PrPsc), that can both in the as the classic form in genetically susceptible sheep and goats and in the atypical form in sheep. The first official notification of scrapie from Brazil was made to the World Organization for Animal Health (OIE) in 1985, in the state of Rio Grande do Sul, although the disease was first documented in this Brazilian state in 1978. The objective this paper was to describe two outbreaks of scrapie in sheep from Mato Grosso do Sul (MS), Brazil, and to investigate by immunohistochemistry (IHC) the presence of PrPsc in samples from the CNS of sheep examined during 2003 and 2010. The study was conducted in two stages; the first was the observation of two sheep with typical clinical signs of scrapie that underwent clinical examination with emphasis on neurological parameters, epidemiological data collection, necropsy and collection of samples in duplicate forwarded to the diagnosis of rabies, and for the IHC diagnosis of Transmissible Spongiform Encephalopathies. In the second part of the study, a survey was made the necropsy reviewing gross findings and histopathological diagnoses in sheep from May 2003 to March 2010. Samples of the central nervous system of fifty-one cases, including the two sheep mentioned above were subjected to IHC for detection of prion protein. The other 49 sheep, although displaying neurological-disease which should be included as scrapie differential diagnosis, had their tissues submitted to IHC resulting negative.

Administração repetida de doses não tóxicas de monofluoroacetato de sódio não protege contra a intoxicação por este composto em ovinos

With the objective to assess whether repeated non-toxic doses of sodium monofluoroacetate (MFA) induce resistance to poisoning by this compound, 18 sheep were randomly divided into two experimental groups of nine animals each. Sheep from Group 1 ingested non-lethal increasing doses of MFA for six periods: 0.05mg/kg for 5 days; 0.08mg/kg for 4 days; 0.08mg/kg for 4 days; 0.1mg/kg for 3 days; 0.1mg/kg for 3 days and 0.25mg/kg for 3 days. Between the first and second period of administration and between the second and third period the animals did not receive MFA for 10 consecutive days, between the third and fourth period and during the remaining periods of administration the sheep were left 15 days without ingesting MFA. Group 2 was not adapted to the ingestion of MFA and received a single dose of 1mg/kg of MFA at the same time that Group 1 was challenged. After challenge, seven sheep of Group 1 showed clinical signs of poisoning and one sheep recovered. In Group 2, all animals showed clinical signs of poisoning by MFA, however two sheep recovered. The mortality rate was 66.6% in Group 1 and 77.7% for Group 2. These results suggest that repeated administration of non-toxic doses of MFA does not protect against acute poisoning by this compound; therefore other alternatives of prophylaxis for poisoning by plants containing MFA should be searched, mainly the use of intraruminal bacteria that hydrolyze MFA.

Intoxicação experimental por Simarouba versicolor (Simaroubaceae) em ovinos e indução de resistência ao consumo da planta

Simarouba versicolor St. Hil. is a semideciduous tree belonging to the Simaroubaceae family. An outbreak of poisoning in cattle by shoots of S. versicolor present in the pasture in Mato Grosso do Sul and experimental reproduction of the poisoning was described. This study aimed to verify experimentally whether sheep could be used as a clinical-pathological model in the study of the poisoning caused by S. versicolor, to determine if there develops resistance induced by ingestion of small and repeated doses of the leaves, and if the plant keeps its toxicity when dried. Two experiments were conducted: Experiment 1 with green leaves or dried and powdered leave of S. versicolor, given in single doses of 5g/kg, 5g/kg and 3g/kg to three sheep (Sheep 1, 2 and 3 respectively). Experiment 2 was made with different daily doses of dried and powdered leaves of S. versicolor; to four sheep was given 1.5g/kg, 0.75g/kg, 0.6g/kg and 0.3g/kg, and the positive control (Sheep 4) received 3g/kg. The administration was suspended when the animals showed clinical signs of poisoning. After twelve days of recovery, the surviving sheep were challenged with the same daily dose given previously, to assess the development of resistance. Clinical signs observed in both experiments were characterized by anorexia, congested ocular mucosa, polydipsia, drooling, loose stools which evolved into fetid greenish watery diarrhea, lateral decumbency and death of Sheep 1 to 7. The main histological lesions observed were necrosis of lymphoid tissue (lymph nodes, spleen, Peyers patches) and necrotizing enteritis. With the results it can be concluded that sheep can be used as experimental model for the clinic-pathological aspects of poisoning by S. versicolor. The method used has not shown resistance to the daily consumption of the plant by the sheep, and the leaves kept their toxicity when dried.