Saulo A. Caldas

Intoxicação experimental por monofluoroacetato de sódio em bovinos: aspectos clínicos e patológicos

Sodium monofluoroacetate (MF) was identified, by cromatography, in three of the 12 plants that cause sudden death in cattle in Brazil, including Palicourea marcgravii, the most important plant of this group. A special kind of hydropic-vacuolar degeneration (HVD) of the distal convoluted uriniferous tubules was considered typical for the poisoning by some authors. The objective of this study was to verify if the ingestion of MF causes similar clinical signs and lesion in cattle poisoned by plants that cause sudden death. Six cows received orally 0.5 and 1.0mg/kg of M diluted in 50mL of distilled water. Clinically the animals presented tachycardia, engorgement and positive pulse of the jugular vein, abdominal breathing, swaying gait, subtle unbalance, and recumbency with head placed the on the flank. In the agonal phase all the animals in lateral recumbence presented muscular fasciculation, tonic contraction, peddling movements, opisthotonus, nystagmus, and died between 2 and 14 minutes. At postmortem examination, the heart auricles, jugular and pulmonary veins were moderately distended and engorged with blood. Slight to moderate edema of the subserosa was seen around the gall bladder and the duodenum near to the pancreas. At light microscopy, HVD associated with nuclear picnosis of the epithelial cells of the distal convoluted uriniferous tubules was present in all animals. Ultrastructurally, the cell lesion represents formation of cytosolic vacuoles, likely due to accumulation of water. Coagulation necrosis of individual or groups of hepatocytes and slight hepatic congestion secondary to the venous stasis were also observed. Hydropic-vacuolar degeneration has been observed in cases of poisoning by many substances, which cause acute tubular nephrosis, however not restricted to the distal renal tubules and without nuclear picnosis. This study demonstrates that the HVD in the kidney can be caused by MF and, in analogy, the compound should be considered responsible for the death of cattle that ingest toxic plants which cause sudden death in Brazil. Our results can be supportive to studies that will focus on the degradation of MF by rumen bacteria, what might have economic implications, as at least 500.000 cattle die annually by sudden death causing toxic plants in Brazil.

Aspectos clínico-patológicos e laboratoriais do envenenamento crotálico experimental em equinos

Crotalus poisoning was experimentally reproduced by subcutaneous inoculation of Crotalus durissus terrificus (South American rattlesnake) venom into 10 clinically healthy mixed bred 12 to 36-month-old cattle, weighing 125 to 449 kg. Two animals were used as controls. The animal that received a dose of 0.03mg/kg body weight died 7h40min after inoculation. A 0.015mg/kg dose provoked death in 4 out of 7 young oxen. Two animals given 0.0075mg/kg became slightly sick and recovered. Onset of symptoms occurred from 1h30min to 13h45min after inoculation. The clinical course varied from 5h25min to 45h for animals that died, and from 33h15min to 17 days for animals that recovered. The main nervous signs observed were diminished response to external stimuli, hypotonic reflexes, dragging of the hooves, apathy, difficulties in moving around obstacles, ocular globe paralysis, lateral and sternal decubitus, and tongue paralysis. Adipsia and sometimes petechiae in the conjunctival and vaginal mucosa were observed. A slight to moderate increase in bleeding time was noted in 6 animals, and a moderate increase in partial thromboplastin time was found in 7 others. Moderate leukocytosis with neutrophilia, relative lymphopenia, eosinopenia, and monocytosis was found. There was a significant increase in creatine kinase serum levels of a ten-fold order. No significant alterations were revealed by urinalysis. Necropsy revealed minimal edema at the inoculation site, few petechiae and equimoses in the epicardium, omentum, biliary vesicle and bladder mucosa of some animals. Histopathological examination revealed necrosis (hyalinization) of groups or isolated myocytes in different muscles examined, both near and far from the inoculation site, in all animals. The diagnosis of Crotalus poisoning and its differentiation from diseases causing paralysis and muscular necrosis in cattle in Brazil are discussed.

Aspectos clínico-patológicos e laboratoriais do envenenamento experimental por Bothrops alternatus em bovinos

The aim of this study was to determine the clinical-pathological alterations and laboratory findings in cattle inoculated with Bothrops alternatus venom, with the intention of providing information for the establishment of diagnosis and differential diagnosis procedures, as well as to elucidate some obscurities observed in the pertinent literature. The lyophilized venom was diluted in 1 ml of physiologic solution. It was administered to 5 bovines by the subcutaneous route at doses of 0.0625, 0.125 and 0.25mg/kg body weight, and to 2 bovines by the intramuscular route at doses of 0.25 e 0.45mg/kg. Six bovines died and the only animal that survived, who had subcutaneously received the venom at a dose of 0.0625mg/kg, recovered. The first clinical signs were observed from 25min to 5h30min after the inoculation. The clinical evolution time varied from 7 hours 18 minutes to 92 hours. Regardless of the dose, the clinical picture was characterized by swelling (hemorrhage/hematoma) at the site of inoculation, increase in bleeding time and capillary refill time, paleness of mucous membranes and apathy. The laboratory exams revealed progressive normocytic normochromic anemia, thrombocytopenia, reduction in fibrinogen and total plasma proteins, decreased hematocrit and hemoglobin, and slight increase in creatine kinase and lactate dehydrogenase. When subjected to necropsy, the animals that received the venom through the subcutaneous route showed large hematomas and hemorrhagic areas in the subcutaneous tissue, extending from the site of inoculation. The animals in which inoculation was performed intramuscularly exhibited, in addition, intramuscular hemorrhage. The left endocardium showed extensive hemorrhagic lesions, and petechiae were found on the serosae of rumen, omasum, abomasum and gall bladder. The colon, rectum and perirenal areas were surrounded by clotted blood in three animals. Besides hemorrhage, the histological examination revealed hemorrhage and coagulative muscle necrosis in the vicinities of the inoculation site in the animals that received the venom by the intramuscular route. These lesions were mild in the muscles close to the site of inoculation in the animals inoculated by the subcutaneous route. The swelling on the site of inoculation and its surroundings was a consequence of blood accumulation and not merely edema. Myoglobinuria and gross or microscopic lesions were not observed in the kidneys. This study indicates that B. alternatus can lead adult bovines to death if they release all their venom during a bite. Conversely, since venomous ophidians can control the amount of poison they inoculate and they probably do not identify bovines as potential preys, it is likely that the number of accidents involving this species is small, which is in agreement with the findings of the majority of the centers for anatomical-pathological diagnosis in Brazil.

Intoxicação acidental por monensina em ovinos no Estado do Rio de Janeiro

An outbreak of monensin poisoning in sheep in the State of Rio de Janeiro is described. From 180 animals, eight died after they had been fed with ration containing the ionophore. The poisoning had a variable course and was clinically characterized by apathy, heart arrhythmia, myoglobinuria, incoordenation, incapacity of getting up, and sternal decubitus; one sheep aborted. The macroscopic lesions consisted of pale areas in the myocardium, hydroperitoneum, hydrothorax, and pulmonary edema. Histopathological examination revealed degenerative-necrotic alterations in heart and skeletal muscles. In the myocardium lesions were more severe and were characterized by multifocal necrosis with substitution of the myofibres by fibrous tissue and interstitial mononuclear infiltration. Proliferation of satellite cells and mononuclear inflammatory reaction in skeletal muscles were also verified. It seems that the exaggerated addition of sodic monensin, eventually associated with improper homogenization of monensin in the ration, was responsible for the excessive ingestion of monensin by some animals.

Intoxicação experimental por Metternichia princeps (Solanaceae) em coelhos

Metternichia princeps, a tree that belongs to the Solanaceae family, occurs in the Atlantic Forest of Brazil, from the state of Rio de Janeiro to Bahia. In the county of Itaguai, state of Rio de Janeiro, M. princeps was suspected to cause a lethal kidney disease in goats. The poisoning was experimentally reproduced in goats confirming the suspicion. Experiments were then performed in rabbits. Leaves of M. princeps were collected in the county of Itaguai, where the poisoning in goats occurred. Eleven rabbits received the dried plant material, ten received the fresh plant and one rabbit served as control. The dehydrated leaves were ground and mixed with water. Initially the suspension was administered by stomach tube to nine rabbits and caused death of seven of them at doses from 0.125g/kg on. Two rabbits that got sick, but survived at doses of 0.0625g/kg and 0.125g/kg, received doses of 0.5 and 0.25g/kg respectively, two months later and died, indicating that no tolerance to the plant poisoning effects developed. Additionally the dried leaves administered six months after collection to two rabbits at doses of 0.5 and 1g/kg respectively, caused death only of the rabbit that received the dose of 1g/kg, indicating that the stored leaves lost toxicity. Fresh sprouts caused death in three of six rabbits at doses of 1.55g/kg to 3g/kg. Fresh mature leaves caused death in one of four rabbits at the dose of 2g/kg, what suggests that there is no difference in toxicity between mature leaves and sprouts. The dried leaves caused death of rabbits at smaller doses than fresh leaves, what can be explained by the way of administration of the plant; dried leaves were given within a few minutes, whilst fresh leaves were ingested during one or two days, a fact that may influence absorption of the toxic principle. In all experiments with the dried and fresh leaves (sprouts and mature leaves) of M. princeps, liver and heart lesions predominated. The course of the poisoning was peracute to acute. The rabbits became apathetic with pale and cyanotic mucosae and cold ears; they fell down with struggling movements, vocalization and spaced breathing and died. At postmortem examination, the liver was pale with marked hepatic lobules; the other organs were congested and blood vessels were ingurgitated. The histopathological examination revealed as the more important changes in the liver, intense, especially centrilobular congestion, severe swelling of the hepatocytes, and foci of incipient necrosis of hepatocytes. In the heart, beside congestion, small groups of eosiophilic cardiac fibers, with nuclear picnosis and vacuolation were found. In the kidney, congestion and swelling of epithelial cells was seen. The performed experiments show that rabbits are susceptible to poisoning with dried and fresh leaves of M. princeps. It is suggested that the toxic principle of M. princeps, responsible for the clinical and pathological picture in rabbits, may not be the same compound that causes poisoning in goats or that the rabbit reacts differently as react goats; rabbits showed liver and heart lesions whilst goats had kidney lesions.

Intoxicação natural e experimental por Metternichia princeps (Solanaceae) em caprinos

From 2007 to 2009 a nephrotoxic disease of subacute course and high mortality in goats occurred on a farm in the county of Itaguai, Rio de Janeiro. Metternichia princeps, a plant of the Solanaceae family, was suspected to be the cause. Through experiments in goats the clinical-pathological picture of poisoning by the plant and the lethal dose were established. For the experiments 12 young and adult goats of different races, both sexes and with weights above 15 kg were used. The goats that received 30g/kg in 5 days, 15g/kg in 3 days, single doses of 10g/kg and 5g/kg, all died. Of two goats that received single doses of 2.5g/kg, one died but the other did not show any clinical sign; a goat that received the single dose of 1.25g/kg also did not show any symptom of poisoning. First clinical signs were observed from 7 hours to 46h45min after the plant intake. The clinical course varied from 3h6min to 126h40min. First clinical signs were loss of appetite, adipsia, apathy and reluctance to move. After the animals entered in sternal decubitus and when they were placed in standing position, they kept their front limbs flexed, supported only by the posterior limbs on the floor until evolving into flexion of all four limbs followed by lateral decubitus. Postmortem examination revealed edema of the perirenal adipose tissue, pale kidneys which on the cut-surface showed whitish stripes from the cortex to the medullar area. At histopathology, severe coagulative necrosis of epithelial cells of the kidney tubules was seen. Compared with the natural cases, the goats experimentally poisoned by M. princeps, presented a similar clinic-pathological picture. By these experiments it could be proved that Metternichia princeps is the toxic plant that causes a nephrotoxic disease in goats in the Rio de Janeiro area; the minor lethal dose was 2,5g/kg in the experiments.

Envenenamento experimental por Bothropoides jararaca e Bothrops jararacussu em ovinos: aspectos clínico-patológicos e laboratoriais

The purpose of this study was to establish the clinic-pathological and laboratory changes in sheep inoculated with Bothropoides jararaca and Bothrops jararacussu venom to provide subsidies for the differential diagnosis of snake bites. The liofilized venoms were diluted in 1 ml saline and administrated subcutaneously to four sheep. Three of the animals died, and the one that received 0.5mg/kg (B. jararaca venom) recovered. First symptoms were observed from 7 minutes to 1 hour after inoculation, and the clinical course varied from 7 hours and 9 minutes to 21 hours and 59 minutes. The symptoms, independent of the dosage, were swelling of the inoculation site, increased bleeding time and capillary filling, tachycardia, dyspnea, pale mucous membranes and diminished reaction to external stimuli. Laboratory tests revealed pronounced normocytic and normochromic anemia, trombocytopenia, slight reduction of fibrogen and total plasmatic protein, in two animals diminished hematocrit, besides pronounced increase of creatinaquinase and lactic dehydrogenase. At necropsy, the main findings at the inoculation site and adjacent tissues were extensive hemorrhages in the sheep inoculated with jararaca venom, and predominantly edema in the two animals inoculated with jararacussu venom. In two sheep which received jararacussu venom, acute pulmonary edema was observed. Hemorrhage and edema as the main histopathological changes, besides necrosis of muscle fibers and vessels at the inoculation site and adjacent tissue was observed. The renal tubular necrosis was attributed to shock. The volume increase at the inoculation site and surroundings was mainly due to hemorrhage (B. jararaca) or edema (B. jararacussu).

Aspectos clinicopatológicos e laboratoriais do envenenamento experimental por Bothrops moojeni e Bothropoides neuwiedi em ovinos

Spontaneous envenoming by snake bite is described as a cause of death in domestic animals. However, there are just few information about the species of snake involved, course, and clinicopathological and laboratory findings. Thus, this research aimed to determine the clinicopathological and laboratory changes induced by Bothrops moojeni and Bothropoides neuwiedi snake venoms in sheep, in order to provide additional information regarding snakebites in farm animals and to help establish the diagnosis of this condition. The lyophilized snake venoms were dissolved in 1mL saline solution and administered subcutaneously into the right face of four sheep, at doses of 0.41mg/kg and 0.82mg/kg of B. moojeni venom for two sheep, and 1.0mg/kg of B. neuwiedi venom for two other sheep. Only the sheep which had received the lowest dose (0.41mg/kg) survived, but developed severe clinical signs, similar to the others. First clinical signs were observed about 10 minutes after inoculation in all sheep. The course varied from 2 to 4 days. The clinical findings in all sheep were characterized by apathy, marked swelling of the face, the ventral neck and esternal region, and mild swelling of the proximal portion of the forelimbs, as well as increased bleeding time, tachycardia, pale mucous membranes, and large quantity of undigested blood in the intestinal lumen. Laboratory exams showed mainly a reduction in serum protein and increased creatine kinase in all sheep. At necropsy, extensive hematomas were observed in the subcutaneous tissue of the swollen areas. Also petechiae, bruises and mild to moderate hemorrhagic suffusions on the serosa of various organs, and blood within the intestinal contents of the distal rectum were observed. In addition to hemorrhages, the main histopathological changes were necrosis of skeletal muscle fibers and blood vessel walls next to the inoculation site. The swollen areas on face, neck, sternum and limbs of the sheep were due the hematomas.

Efeito protetor da acetamida sobre as intoxicações experimentais em ratos por monofluoroacetato de sódio e por algumas plantas brasileiras que causam morte súbita

The protective effect of acetamide in poisoning by sodium monofluoroacetate (MF) and by eight Brazilian sudden death causing plants (BSDCP) (Palicourea marcgravii, P. juruana, Pseudocalymma elegans, Arrabidaea bilabiata, Amorimia (Mascagnia) rigida, M. pubiflora, Amorimia (Mascagnia) exotropica and M. aff. rigida) was studied using rats. Additionally the clinical and pathological picture of the poisoning was described. In these experiments 33 Wistar rats (Rattus norvegicus albinus) were used. Nine rats ate spontaneously the fresh leaves of P. marcgravii at amounts of 2.0 and 4.0g/kg. Two of the rats received orally single doses of acetamide (2.0 and 4.0g/kg) one minute before the plant was supplied. A third rat received 4.0g/kg of acetamide after consumption of 4.0g/kg of the plant and showed severe symptoms of poisoning. In the experiments with MF, doses of 4.0 and 8.0mg/kg were administered to four rats. The interval between the administration of either acetamide and concentrated plant extracts or MF ranged from 2 to 4 hours; the dose of acetamide ranged from 2.0 to 8.0g/ kg. In the experiments with concentrated extracts of eight BSDCP, 20 rats were orally poisoned with single or repeated doses. Acetamide, when previously administered, prevented the appearance of clinical signs and death in all of the rats poisoned by MF, as well as of the ones poisoned by fresh P. marcgravii leaves and by the concentrated extracts of each of the other BSDCP. These rats were re-subjected to the same experimental protocol, yet without the administration of acetamide. In these experiments, all of the rats evidenced clinical signs and death (except M. aff. rigida). All of the rats showed mild to markedly engorged atria, and sometimes also of the cranial and caudal vena cava. In three of the rats, there was a moderate right and left cardiac dilatation. The liver of all rats was slightly or markedly congested, with lobular pattern in some. There was frothy liquid on the cut surface of the lungs in three of the rats. The histopathology of the kidneys in six rats showed slight cytoplasmic swelling of the distal convoluted tubules and sometimes also of the collecting tubules. But only in four rats a vacuolar-hydropic degeneration with nuclear pyknosis was seen. Twenty-six rats showed liver congestion, three of them with compressive narrowing of the hepatic cords, and in eight rats shock corpuscles were observed; another three rats showed slight to moderate focal liver necrosis. A slight to moderate vacuolation of hepatocytes was observed in 16 rats. It can be concluded that acetamide had a protective effect, capable to prevent clinical signs and death of the rats poisoned by MF, and by fresh P. marcgravii leaves and concentrated extracts of seven other BSDCP. The clinical and pathological picture observed in the rats poisoned by MF and BSDCP, associated with the protective effect of acetamide, indicate that MF is the toxic principle responsible for death of the rats, and by extension, for the death of cattle that ate BSDCP.

Aborto em bovinos devido à intoxicação por Tetrapterys acutifolia (Malpighiaceae)

Tetrapterys acutifolia Cav. (fam. Malpighiacae) stands out among the most important toxic plants of the Brazilian Southeast Region. These plants are responsible for a significant number of deaths in over 1-year-old cattle, especially in the states of Rio de Janeiro and Sao Paulo. This study aims to demonstrate that T. acutifolia is also able to induce abortion in cattle and to characterize the clinic-pathological alterations in cows and fetuses. Four cows, kept on pasture were used in the experiments which were performed on a farm in the county of Barra do Pirai, RJ, Brazil. The sprouts and young leaves of T. acutifolia were collected from the vicinity shortly before disposed in a trough. The experimental cows ingested the plant material at doses of 2.5g/kg/day (one cow), 5g/kg/day (two cows) and 10g/kg/day (one cow) until abortion occurred. All four cows aborted. The cows showed cardiac arrhythmia, muscular tremors, anorexia, ascites, distended jugular veins, edema of the sternal region and dewlap, and abortion (23 to 76 days after the beginning of ingestion of the plasnt) from the 5th to the 28th day of the experiment. Only one cow which received 10g/kg/day died with characteristic signs of heart failure, 36 days after she had aborted. Gross examination of the fetuses revealed hydrothorax, hydropericardium, hydroperitoneum, nutmeg appearance of the liver, few petechiae and ecchymoses in the epicardium, and pale areas in cross sections of the myocardium. The main postmortem findings in the cow that died were hydrothorax, hydropericardium and hydroperitoneum, engorged vessels at the heart base, exceedingly pale heart muscle with marked spots and stripes in cross sections. Distended jugular veins and severe edema in the sternal region and the abdominal wall were also observed. Histological examination of the fetal hearts revealed interstitial edema with incipient fibrosis and degenerative/necrotic changes of the myocytes. In the succumbed cow was found interstitial fibrosis, as well as necrotic areas and/or necrosis of individual myocytes in extensive portions of the heart, besides passive congestion of the liver. This study shows that Tetrapterys acutifolia can induce abortion in cattle and, depending on the dosage, can cause death.