Maria del Carmen Méndez

Aspectos epidemiológicos da seneciose na região sul do Rio Grande do Sul

Seneciosis is the main cause of livestock mortality due to poisonous plants in the State of Rio Grande do Sul, Brazil. This paper presents epidemiological data of 24 outbreaks in cattle and one in horses, diagnosed by the Regional Diagnostic Laboratory at Pelotas University in southern Rio Grande do Sul, from 1998 to 2000. Additionally, data of 54 outbreaks which occurred in 1978-1997 were analyzed. The farms where outbreaks occurred in 1998-2000 were visited to obtain clinical and epidemiological data and to verify the presence of Senecio spp. Eleven outbreaks (45.83%) affected cattle up to 3 years of age, and 13 (54.16%) cattle over 3 years. Nine (37.5%) outbreaks affected females and 15 (62.5%) males. Ten (41.66%) outbreaks occurred in spring, 4 (16.66%) in summer, 5 (20.83%) in autumn, and 5 (20.83%) in winter. Morbidity rate was estimated with 4.92% and case fatality with 95.59%. The predomionating Senecio species were S. brasiliensis on 12 farms (57.14%), S. selloi on 10 (47.61%), S. oxyphyllus on 6 (28.57%), S. heterotrichius on 3 (14.28%), and S. leptolobus on 1 farm (4.76%). The main clinical signs were progressive emaciation, incoordination, diarrhea, tenesmus, rectal prolapse and aggressiveness. The clinical manifestation periods of affected cattle observed during the farm visits, or of cattle sent for post-mortem examination,were 24-96 hours in 4 outbreaks (16.66%), 4-7 days in 7 (29.16%), 1-2 weeks in 4 (16.66%), 2-3 weeks in 2 (8.33%), 1-2 months in 2 (8.33%), and 2-3 months in 1 outbreak (4.16%). In 4 outbreaks (16.66%) the clinical manifestation period was not established. In outbreaks with longer clinical manifestation periods some animals showed photosensitization. The main necropsy findings were a hard and enlarged liver, distended gall bladder, edema of the mesenterium and abomasum, and increased amount of liquid in the cavities. Histopathological findings were fibroplasia, megalocytosis and biliary ductal proliferation of the liver, and spongy degeneration of the cerebral white matter. Samples of different Senecio species, in different seasons, were analyzed for detection of pyrrolizidine alkaloids (PAs) by thin layer chromatography. Retrorsine was found in Senecio brasiliensis, S. heterotrichius, S. selloi and S. oxyphyllus. In S. brasiliensis and S. heterotrichius one and two more non-identified PAs were detected, respectively. The total PAs concentration by spectrophotometric method was 0.25% for S. brasiliensis, 0.19% for S. heterotrichius, 0.03% for S. oxyphyllus, and 0.03% for S. selloi. The highest PAs concentration occurred in winter (June/July). No alkaloids were found in samples of S. leptolobus. These results show that S. brasiliensis is the most important cause of seneciosis in southern Rio Grande do Sul. Additional data obtained dealt with 54 outbreaks of PAs poisoning in 1978-1997. During this period, 7 outbreaks (12.96%) affected cattle up to 3 years of age, 39 (72.22%) cattle over 3 years, and 3 outbreaks (5.55%) affected cattle of different ages. In 5 outbreaks (9.25%) the age was not informed. Seven outbreaks (12.96%) affected males, 39 (72.22%) females, 3 (5.55%) both sexes, and in 5 outbreaks (9.25%) the sex was not informed. Twenty-three outbreaks (42.59%) occurred in spring, 9 (16.66%) in summer, 9 (16.66%) in autumn, and 13 (24.07%) in winter. The greater number of outbreaks during 1998-2000 (24 outbreaks in 3 years) in regard to 1978-1997 (54 outbreaks in 20 years) is probably due to a decrease of more than 50% in the number of sheep in the region.

Fenologia de quatro espécies tóxicas de Senecio (Asteraceae) na região Sul do Rio Grande do Sul

This study aimed to determine the phenology of Senecio brasiliensis, S. oxyphyllus, S. heterotrichius and S. selloi, and their relationship with cattle poisoning in the southern region of the State of Rio Grande do Sul, Brazil. The phenology was studied during two years in the rural area of the municipalities of Bage and Capao do Leao. These phenological observations were made at monthly intervals during the vegetative phase, and every 15 days during the reproductive period. The plants were observed from emergence until the dispersal of seeds, considering their vigor and their relationship with environmental factors. The results indicate that whenever the environmental conditions, like moisture and light, were favorable, Senecio spp emerge. The vegetative phenophases are practically constant during all life cycle of the plant and the whole year. Unfavorable environmental factors like water stress, soil management and damage by insects, associated or not, can alter the cycle of the plants and determine their permanence in the environment. The majority of the species studied behaved like annual and monocarpic plants. According with the permanence during the two years of observation, the most persistent species in the environment was S. heterotrichius (15% of the plants persisted during the two year period), followed by S. selloi (2,8%) and S. brasiliensis (0,9%). S. oxyphyllus did not persist for more than one year.

Experimental intoxication by larvae of Perreyia flavipes Konow, 1899 (Hymenoptera: Pergidae) in pigs and some aspects on its biology.

Two pigs were dosed with 5 and 10g/kg bw of fresh Perreyia flavipes larvae collected at the municipality of Pelotas. Two other pigs were dosed with 0.87 and 1.7g/kg of dry P. flavipes (equivalent to 5 and 10g/kg bw of fresh larvae). Another pig was dosed with 0.17g/kg of dry larvae, daily, during 20d. Forty-eight hours after the ingestion, all pigs that ingested single doses showed clinical signs and marked rise in serum aspartate aminotransferase. Alanine aminotransferase and gamma glutamiltransferase were also slightly increased. The pig dosed with 10g/kg of fresh larvae died in 96h. The others recovered in 4-5days after ingestion. No clinical signs were observed in the pigs dosed during 20d with 0.17g/kg of dry larvae. The main lesion observed in the pig dosed whit 10g/kg of fresh larvae was a centrilobular liver necrosis. These results confirmed the toxicity of P. flavipes for swine, demonstrated that the larvae maintain the toxicity after being dried, and suggest no cumulative effect in the larval toxicity. The larvae collected in the field were conditioned in boxes containing swards of native grasses and covered with gauze to prevent the escape of adults on emergence. The larvae pupated from August 11 to September 25. Emergency of adults occurred from February 10 to March 4. Adult females and males live only for 18-36 and 24-48h, respectively. The eggs had an incubation period of 26-33d. The larval period extend from March 1 to August 24.

Experimental intoxication by the leaves of Melia azedarach (Meliaceae) in cattle

Green leaves of Melia azedarach were administered at single doses ranging from 5 to 30 g/kg bw to 11 calves. Clinical signs were depression, ruminal stasis, dry feces with blood, ataxia, muscle tremors, sternal recumbency, hypothermia and abdominal pain. Serum AST and CPK were increased. Signs appeared from 8 to 24 hours after dosing, and the clinical course lasted from 2 to 72 hours. Three calves dosed with 30g/kg bw died. The macroscopic findings included intestinal congestion, yellow discoloration of the liver, brain congestion and dry feces with blood in the rectum. The liver showed swollen and vacuolated hepatocytes. Necrotic hepatocytes were scattered throughout the parenchyma or concentrated in the periacinar zone. Degenerative and necrotic changes were observed in the epithelium of the forestomachs. There was also necrosis of the lymphoid tissue. Skeletal muscles showed hyaline degeneration and fiber necrosis. The necrotic fragments contained floccular or granular debris with infiltration by macrophages and satellite cells.

Yersinia pseudotuberculosis infection of buffaloes (Bubalus bubalis).

junctivitis. Because of complex interactions between host and microbial and environmental factors, Koch’s postulates have been difficult to fulfill? Instillation of Neisseria ovis into normal conjunctival sacs has failed to induce appreciable clinical signs. Ultraviolet radiation has been implicated in bovine keratoconjunctivitis caused by Moraxella spp. and may also be a factor in Neisseria spp. infection. Other agents known to cause keratoconjunctivitis have not been isolated. Irradiation seems to have minimal effect on severity of clinical signs, but conjunctivitis develops 24 hours earlier in irradiated goats compared to nonirradiated goats. Conjunctival lymphoid follicles have been described grossly in keratoconjunctivitis . A conjunctival biopsy may have further characterized the conjunctivitis. In the present study, Neisseria ovis was consistently recovered from the conjunctiva of both natural and experimental cases of conjunctivitis. Failure to induce keratitis experimentally may have been due to host susceptibility, different environmental conditions, altered virulence of the organism from in vitro passage, or the small number of goats infected. Recurrence of clinical signs in natural cases may have been due, in part, to incomplete local immunity and persistent infection within the herd. Recurrence of conjunctivitis associated with Neisseria spp. has not been described previously.

Intoxicação experimental com frutos de Melia azedarach (Meliaceae) em suínos

Mature ground fruits of Melia azedarach were administered mixed with the food to 8 pigs at single doses of 5-20g/kg. Transient diarrhea was the only sign observed in the 2 pigs that ingested 5g/kg. Clinical signs observed in the pigs that ingested 10, 15 and 20 g/kg were incoordination, muscular tremors, difficulty to stand or to get up, sternal decubitus and hypothermia. The 2 pigs that ingested 20g/kg died. The gross lesions were congestion and necrosis of the small intestine and the stomach mucosa. The microscopic alterations were characterised by necrosis of the lymphatic tissues and skeletal muscles, congestion and necrosis of the stomach and small intestine, and moderate degenerative alterations of liver and kidneys. The serum levels of AST and CPK increased after the ingestion of the toxic fruits. High values of CPK were observed in the succumbing animals due to the muscle necrosis.These results demonstrate that the ingestion of high doses of Melia azedarach fruits by pigs may induce clinical signs of poisoning and cause lesions in several organs and even death.

Estudos histomorfométrico e histológico das lesões ósseas causadas por flúor em aves

Sodium fluoride was administered in the water to 2 groups of 25 Shaver female poultry. Group A received fluoride from 1 to 120 days of age and group B from 61 to 120 days. Each group was divided into 5 treatments, with 5 chickens each, which received 0, 25, 50, 200, and 400 ppm of fluoride in the water, respectively. All animals were killed at 120 days of age. For histomorphometric studies the left femur and tibia were used, and for histologic studies the right femur and tibia. In the cortical bone, cortical porosity was slightly increased by fluoride, but the differences with the control group were not significant. Cortical thickness increased in the animals treated with fluoride (p<0,05, r2 = 0,59 ). In the trabecular bone, of group A, trabecular thickness (TT) (p<0,05, r2 = 0,63) and trabecular bone volume (TBV) (p<0,05, r2 = 0,72) increased in treatments receiving 25-200 ppm, and decreased in the 400 ppm treatment, as it was demonstrated by quadratic regression analysis. In group B there was a positive linear correlation on TT (p<0,05, r2 = 0,98) and TBV (p<0,05, r2 = 0,77) with fluoride ingestion.The osteoid surface was also positively correlated with the amount of fluoride ingested by the animals (p<0,001, r2 = 0,80). These results suggest that fluoride improves osteoblastic function resulting in increased osteoid production and bone apposition. In the other hand, in the animals treated with 400 ppm of fluoride for 120 days bone apposition was reduced suggesting a functional alteration of the osteoblasts or improved bone resorption. In the histological study of bone tissue all animals that received fluoride showed an increased trabecular thickness which was more marked in the 200-400 ppm treatments. In chickens treated with 200-400 ppm of fluoride osteoblasts and osteoclasts were more numerous suggesting an increased bone turnover. In cortical bone Haversian canals were narrowed on the periosteal surfaces and resorption spaces were enlarged on the endosteal surfaces.

Axonal Degeneration in Sheep Caused by the Ingestion of Halimium Brasiliense

Nervous system disease is reported in sheep from 2 farms in southern Brazil and in 33 farms in Uruguay. The illness was seasonal, occurring from May to November, during the growing season of Halimium brasiliense, and primarily affected sheep older than 3 years of age. Clinical signs included transient seizures that occurred mainly when sheep were disturbed or frightened. Most affected sheep recovered when removed to other pastures. Feeding trials produced clinical signs in 1 sheep after the ingestion of 2,117 g/kg of body weight of H. brasiliense over 142 days. Two sheep that had previously recovered from spontaneous toxicosis developed clinical signs after the ingestion of 263 g and 565 g of H. brasiliense per kg body weight given over 36 and 31 days, respectively. The main histologic lesion was vacuolation of the brain and spinal cord, with rare axonal spheroid formation. Transmission electron microscopy revealed segmental axonal swelling with degeneration and disappearance of the axonal organelles and vacuolation of the axoplasm. A pigment identified as ceroid was also present in neurons, astrocytes, and macrophages. These lesions suggested a novel morphologic manifestation of a toxic axonopathy.

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.

Fotossensibilização hepatógena em bovinos no sul do Rio Grande do Sul

The epidemiological and pathological aspects of 19 outbreaks of photosensitization in cattle, observed in southern Brazil, between 1984 e 1997 were studied. The disease occurs mainly in spring and fall with morbidity of 0.08% to 64% and mortality of 0 to 14%. Cattle of all ages are affected. The pastures on which outbreaks occur are characterized by low, flat and wet land, used alternatedly for rice or other crops and natural or cultured pastures of clover, oat and ryegrass. The disease is characterized clinically by depression, anorexia, salivation and photosensitization of white or slightly colored and hairless skin such as muzzle, nostrils, eyelids, udder, groin and vulva. In severe cases the skin, mainly of dorsal midline and legs, was thickened, necrotic and sloughed revealing a raw area of subcutaneous tissue. The macroscopic lesions were tipically related to hepatic insuficiency. Jaundice, yellow to orange discoloration and swelling of the liver, edema of the gall bladder, excess of serous fluid in body cavities and occasionally subcutaneous and peritoneal edema were observed. The histological changes are characterized by degenerative changes of hepatocytes that are diffusely or zonal vacuolated and swollen. Individual or ramdomly scattered foci of hepatocellular necrosis, bile ductular proliferation, and portal fibrosis were also observed. The disease was characterized as a bovine hepatogenous photosensitivity syndrome resulting from primary damage to the liver parenchyma. The etiology is unknown and the main known causes of hepatogenous photosensitivity in cattle were ruled out.