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Biomedical subjects

F Riet-Correa

Publications and source records attributed to F Riet-Correa.

At least 19 recordsLinked to original sources
PubMed2000

Neuronal vacuolation of the trigeminal nuclei in goats caused by ingestion of Prosopis juliflora pods (mesquite beans).

Three groups of 6 goats each were fed a ration containing 30, 60, or 90%, on a dry matter base, of Prosopis juliflora pods. A control group of 4 goats ingested only the basic ration. Two hundred and ten days after the start of the experiment 3 goats that ingested 60% pods in and 4 that ingested 90% had mandibular tremors, mainly during chewing. All animals were killed after 270 d of ingestion. No gross lesions were observed. Histologic lesions were characterized by fine vacuolation of the pericaryon of neurons from the trigeminal nuclei. Occasionally neurons of the oculomotor nuclei were also affected. Wallerian degeneration was occasionally observed in the mandibular and trigeminal nerves. Denervation atrophy of the masseter, temporal, hypoglossus, genioglossus, styloglossus, medial pterygoid and lateral pterygoid muscles was seen. The clinical signs from feeding the P juliflora pods were caused by a selective toxicity to neurons of some cranial nerve nuclei.

Animals↗
PubMed1999

Monensin poisoning in Brazilian horses.

Three outbreaks of monensin poisoning caused 12 deaths in 16 horses. The illnesses were associated with the ingestion of the same batch of a commercial ration labeled for feeder calves which contained 180 +/- 20 ppm sodium monensin. The morbidity rate was 100% and lethality was 60%, 75%, and 100%. Clinical signs were tachycardia and cardiac arrythmia, groaning, incoordination, sudoresis, recumbency, and paddling movements with the limbs before death. Two horses had dark discolored urine (myoglobinuria). Serum levels of creatine phosphokinase activity were increased. Main necropsy findings were in the skeletal muscles and myocardium.

Animals↗
PubMed1998

Experimental intoxication by Myoporum laetum in sheep.

Myoporum laetum was collected in the municipalities of Rio Grande and Capao do Leao in winter and in Santa Vitoria in summer, autumn, winter and spring, in the state of Rio Grande do Sul, Brazil, and in the Department of Rocha, Uruguay, in winter and spring. The fresh green plant was fed to 17 sheep. All sheep developed clinical signs, except 1 that consumed only 4 g/kg bw daily during 10 d. Five of the 9 sheep dosed with 40 g/kg died. Four sheep dosed with plants from Uruguay at 40 g/kg, 6 sheep dosed with 20 g/kg, and 1 sheep dosed with 2 daily doses of 8 g/kg survived. Clinical signs were anorexia, restlessness, ruminal stasis, jaundice and dry feces with mucus or blood. All surviving sheep had photodermatitis in the face, ears, eyes and lips. Histologic lesions were characterized by periportal liver necrosis. Serum levels of AST, GGT and bilirubin were increased. M laetum from Uruguay was less toxic, suggesting a variation in toxicity among plants from different regions.

Animals↗
PubMed1998

Intoxication by Xanthium cavanillesii in cattle and sheep in southern Brazil.

Three outbreaks of Xanthium cavanillesii intoxication occurred in the spring in the State of Rio Grande do Sul, southern Brazil. All outbreaks were observed in paddocks with sandy soils in flood plains along water streams. The paddocks had been under water, and after water withdrawal cattle were introduced to those areas which had seedlings of X cavanillesii and shortage of other forage. Mortality varied between 3 and 58%. Most animals were found dead or died a few hours after observation of clinical signs. The main lesion was a swollen liver with acute diffuse centrilobular necrosis. The disease was produced experimentally by feeding cotyledons at 0.75 and 1% bw in calves, and at 1.5 and 2% bw in sheep. Clinical signs and gross and microscopic lesions were similar to those observed in field cases. X cavanillesii in the 4-leaf stage with the attached cotyledons was also toxic for cattle and sheep, but the same plant without cotyledons lost its liver toxicity. The lethal dose of cotyledons divided in 5 daily doses was not toxic for cattle and sheep, demonstrating the non-cumulative effect of the plant.

Animals↗
PubMed1998

Experimental intoxication by Myoporum laetum in cattle.

Myoporum laetum was collected in the counties of Rio Grande and Capao do Leao in winter and in Santa Vitoria in summer, autumn, winter and spring, in the state of Rio Grande do Sul and in the Department of Rocha, Uruguay, in winter and spring. The fresh green leaves were fed to 16 calves. Two calves that ingested the plant from Capao do Leao at 40 and 44 g/kg bw did not develop clinical signs. The other 14 calves had depression, abdominal pain, ruminal atony, ocular and nasal serous discharge, and dry feces with blood and mucus. Four calves developed icterus. First signs appeared 24-72 h after ingestion, and clinical period varied from 2 to 7 d. One animal had mild photosensitization. Calves dosed with 20 g/kg of plant from Santa Vitoria and 40 g/kg of plant from Uruguay had less severe clinical signs. All cattle recovered except 1 dosed with 40 g/kg of plant collected in winter in Santa Vitoria; it died 70 h after ingestion. Histologic lesions in the liver of this animal and in biopsies obtained 48 h after dosing other calves had centrilobular necrosis, sometimes extending to the midzonal region. Clinical signs and hepatic lesions were also observed in a calf dosed with 5 daily doses at 8 g/kg. Serum AST, GGT and bilirubin were increased. M laetum from Santa Vitoria was the most toxic for cattle, and the plant from Uruguay was the least toxic, suggesting variations in toxicity among plants from different regions.

Alanine Transaminase↗
PubMed1997

Poisoning of cattle and sheep in Uruguay by sawfly (Perreyia flavipes) larvae.

From June to early October of 1993, 1994 and 1995 at least 40 outbreaks of a highly lethal disease occurred in cattle and sheep in the central region of Uruguay. During 1995 total cattle losses probably exceeded 1000 head. Mortalities were 1.6%, 7.0% and 1.3% for calves, yearlings and adults, respectively, but mortalities up to 28% occurred on some farms. Sheep were less frequently affected than cattle. Most animals were just found dead. Cattle had weakness, muscular tremors, depression, stupor and death. Others became highly excited and aggressive. Most affected cattle died within 2 d. Jaundice and mild photosensitization were observed in cattle that survived longer. Gross and microscopic lesions were severe periacinar or massive necrosis of hepatocytes with prominent edema of the gall bladder wall and its attachments. Edema, ecchymoses and petechiae on serous membranes, ascites and dry content of the omasum, colon and rectum were also observed. Invariably larval body fragments and heads of P flavipes were found in the rumen and omasum. The diagnosis of sawfly poisoning was confirmed by experimental feeding of 3 sheep and 2 calves with 9 to 40 g of P flavipes larvae/kg body weight.

Animals↗
PubMed1997

Dating of fibrotic lesions by the Picrosirius-polarization method. An application using the lesions of Lechiguana (bovine focal proliferative fibrogranulomatous panniculitis).

This work was designed to verify if a simple quantitative procedure to estimate the state of collagen aggregation is useful in describing the natural history of a fibrous process. For this purpose sixteen cases of Lechiguana lesion were used. Histochemical evaluation of the collagen content and its state of aggregation was done by the Picrosirius-polarization method. Morphometric studies were done by means of a point-counting procedure, which allowed the determination of the areal fraction of thin and thick collagenous fibers within Lechiguana lesions collected at different times of clinical evolution (14 days through 8 months). Early lesions are characterized by thin collagenous fibers. This population of slender fibers decreases later on, when thick fibers become more prevalent. Curve fitting procedures were employed using the state of collagen aggregation as the dependent variable and time as the independent variable. The best fitting was obtained by linear and exponential functions. Statistical analysis indicates that the quantitative study of the degree of collagen organization allows an adequate determination of the time course of Lechiguana lesions. We concluded that simple determinations of collagen aggregation provide numerical data that may be useful to build mathematical models relating time of evolution of the disease to fibrosis.

Animals↗
PubMed1996

Role of Pasteurella granulomatis and Dermatobia hominis in the etiology of lechiguana in cattle.

Attempts were made to reproduce bovine lechiguana, a disease associated with Dermatobia hominis and Pasteurella granulomatis infections. Suspensions of Pasteurella granulomatis were mixed with each of the following: saponin, oil adjuvant, ground Dermatobia hominis, or 5% mucin. Each preparation was inoculated into 6 cattle. Twelve more cattle, 6 of which received dexamethasone, were inoculated with bacterial suspension alone. Abscesses but no lechiguana was produced in all 36 cattle. After abscess regression, 12 cattle were reinoculated with a suspension of mouse-passed P. granulomatis. Only abscesses were produced. The intralymphatic inoculation of P. granulomatis in 6 cattle did not produce the disease. Eleven cattle infected naturally with D. hominis had lesions containing dead larvae. These lesions were inoculated with P. granulomatis. Nine cattle were experimentally infected with larvae of D. hominis that had been contaminated with the bacteria. No lechiguana lesions were produced in these 20 cattle. Six cattle with severe natural D. hominis infection were inoculated in the larval lesions with P. granulomatis. One developed lesions indistinguishable from those of natural lechiguana. The lesions regressed after treatment with chloramphenicol. D. hominis larvae and exudate from lesions caused by the fly were collected from 7 cattle on 3 farms and examined bacteriologically. P. granulomatis was isolated from the larvae and the exudate of a healthy calf from a farm where lechiguana had never been observed. These results suggest that P. granulomatis has a causal role in lechiguana, and that D. hominis may be a carrier of the bacterium. These observations suggest that lechiguana occurs when severe D. hominis lesions are infected with P. granulomatis. The apparent long incubation period, the negative results obtained in the other experiments, and also the infrequent occurrence of the natural disease suggest that lechiguana is a disease for which Koch's postulates are not easily fulfilled.

Abscess↗
PubMed1996

Experimental intoxication of sheep and cattle with Wedelia glauca.

Wedelia glauca was administered experimentally to 11 sheep and 4 cattle. The minimum toxic dose for both species was of 4 to 5 g of fresh plant/kg bw. Clinical signs were depression, muscle fasciculations, increased respiratory and cardiac frequencies, opisthotonous, sternal or lateral recumbency and terminal paddling movements. Time of onset of signs ranged from 12 to 40 h after dosing. Serum AST, LDH and GGT were increased. Three cattle and 5 sheep died after clinical manifestation periods of 2 to 18 h, and 2 sheep survived after being affected for 14 and 46 h. Macroscopic and histologic lesions were similar in cattle and sheep; the liver was swollen and dark reddish, and the wall of the gall bladder was edematous. The cavities had yellowish fluid. Petechiae and echymoses were seen on serous membranes. Microscopically the liver had periacinar hemorrhagic necrosis. Two sheep dosed with 1 g/kg bw daily for 20 d and 1 dosed with 1 g/kg bw for 10 d were not affected. Six sheep were transferred from an area free of W glauca to an area where this plant was present. These animals ate small amounts of the plant and lost weight rapidly, but clinical intoxication did not occur. Two sheep were fed with lucerne hay containing 9% W glauca. They ingested 2.5 g/kg of the dry plant (corresponding to 10 g/kg bw of fresh plant) in 24 h, but did not show intoxication. Because the intoxication occurred in sheep and cattle administered 4 to 10 g/kg bw of the plant in a period of 1 to 2 h, the intoxication may only occur when animals ingest a single toxic dose in a short time.

Animals↗
PubMed1995

Snakebite in sheep.

Snakebite caused by Bothrops neuwiedi in sheep of southern Brazil is described. In a flock of 135 sheep, 22 were bitten and 11 died. Most cases occurred at the end of December and during January when the pastures were overgrazed due to severe drought. No more cases were observed after the end of January when abundant rainfall began. The main clinical signs were local edema followed by necrosis and sloughing of the skin.

Animals↗
PubMed1994

Hereditary suprabasilar acantholytic mechanobullous dermatosis in buffaloes (Bubalus bubalis).

A skin disease characterized by trauma-induced sloughing of haired skin, hooves, and horns is described in four calves from a herd of Murrah buffaloes (Bubalus bubalis) in Brazil. Affected calves were detected shortly after birth by the presence of lesions affecting the distal extremities, the scapular and gluteal regions, and the tip of the tail. On histologic evaluation of affected skin, the lesions were characterized by suprabasilar vesicles and acantholysis affecting the epidermis and outer root sheath of the hair follicle infundibulum. The basal cell layer was intact and appeared as a single layer of cuboidal cells attached to the dermis. Ultrastructurally, the region between the stratum basale and the lower stratum spinosum had widened intercellular spaces with loss of desmosomal attachments, which led to the suprabasilar separation. The disease appears to be inherited as an autosomal recessive trait.

Animals↗
PubMed1992

Bovine focal proliferative fibrogranulomatous panniculitis (Lechiguana) associated with Pasteurella granulomatis.

In southern Brazil, cattle are affected by a disease known locally as Lechiguana and characterized by large subcutaneous swellings. Eighteen cases were examined clinically; 17 of the cattle had a single swelling, and one had two swellings. In 14 of the 18 cases, the swellings were located over the scapula and adjacent regions. The subcutaneous masses reached maximum dimensions of 45 x 50 cm, with heights above the skin surface of 5-25 cm. Growth was rapid, often taking place in 15 to 60 days. Histologically, all lesions were focal proliferative fibrogranulomatous panniculitis and consisted of focal proliferation of fibrous tissue that was infiltrated by plasma cells, eosinophils, lymphocytes, and sometimes neutrophils. An eosinophilic lymphangitis was also present, which sometimes resulted in the destruction of the lymphatics and the formation of eosinophilic microabscesses. Small granulomas, sometimes containing radiating clubs, and Splendore-Hoeppli material were present in the regional lymph node. Pasteurella granulomatis was isolated from the subcutaneous masses of 14 of the 18 natural cases. All 11 of these cases recovered following treatment with 3 g of chloramphenicol daily for 5 days. Untreated animals died. Because the area of anatomic distribution is similar to that infested by Dermatobia hominis, we postulate that this insect may transmit the causative agent. In one steer, a subcutaneous injection of P. granulomatis caused a large subcutaneous swelling consisting of interlacing bundles of collagen infiltrated by neutrophils, eosinophils, and some lymphocytes. Microabscesses, but not lymphangitis and granulomas, were detected. In all 11 cattle inoculated either intramuscularly or subcutaneously with P. granulomatis, purulent abscesses were produced at the sites of the injection, and P. granulomatis was recovered from all lesions.

Animals↗
PubMed1991

Hereditary lymphedema in Hereford cattle.

Congenital lymphedema is described in Hereford cattle. The disease was characterized by edema of the hind limbs, sometimes forelimbs, tail, and prepuce. Lymphatic system lesions were hypoplasia and aplasia of lymph vessels and prescapular, iliofemoral, and popliteal lymph nodes. Test matings demonstrated the transmission of the disease by an autosomal dominant trait with variable expressivity and incomplete penetrance.

Animals↗