PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

Abstract.- Pavarini S.P., Bezerra Junior P.S., Santos A.S., Pescador C.A. & Driemeier D. 2008. [Clinic pathological features during a winter dysentery outbreak in cattle in Rio Grande do Sul.] Achados clínico patológicos durante um surto de disenteria de inverno em bovinos no Rio Grande do Sul. Pesquisa Veterinária Brasileira 28(12):611- 616. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br The report describes a winter dysentery outbreak that affected 10 dairy cows from a ranch located in the county of Viamão, Rio Grande do Sul. The most significant clinical sign was profuse and watery diarrhea, which ranged from a greenish to a brownish coloration and from occasional blood streaks with mucus to a bloody diarrhea. Most cases persisted for 5 days and also included depression, drastic decrease in milk production and in food consumption. Only one of the affected animals died. The necropsy revealed pale mucosa and sanguineous content with high quantity of blood clots, particularly within the spiral colon, and petechiae on the colonic mucosa. Histopathological lesions were predominant in the spiral colon, and consisted of a high number of dilated crypts without epithelium or with the replacement of a pavement epithelium with occasional immature cuboidal cells, which sometimes showed enlarged nucleus and proeminent nucleolus. Some crypts were filled with epithelial desquamation and polymorphnuclear cells. Bovine coronavirus (8F2) monoclonal antibody was used for immunohistochemistry on sections of the spiral colon that showed positive reactions in the cytoplasm of the infected crypt epithelium, sloughed necrotic cells, and within macrophages in the lamina propria of both.

• Winter dysentery diarrhea spiral colon bovine coronavirus

Abstract in Portuguese:

Abstract.- Pavarini S.P., Bezerra Junior P.S., Santos A.S., Pescador C.A. & Driemeier D. 2008. [Clinic pathological features during a winter dysentery outbreak in cattle in Rio Grande do Sul.] Achados clínico patológicos durante um surto de disenteria de inverno em bovinos no Rio Grande do Sul. Pesquisa Veterinária Brasileira 28(12):611- 616. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br The report describes a winter dysentery outbreak that affected 10 dairy cows from a ranch located in the county of Viamão, Rio Grande do Sul. The most significant clinical sign was profuse and watery diarrhea, which ranged from a greenish to a brownish coloration and from occasional blood streaks with mucus to a bloody diarrhea. Most cases persisted for 5 days and also included depression, drastic decrease in milk production and in food consumption. Only one of the affected animals died. The necropsy revealed pale mucosa and sanguineous content with high quantity of blood clots, particularly within the spiral colon, and petechiae on the colonic mucosa. Histopathological lesions were predominant in the spiral colon, and consisted of a high number of dilated crypts without epithelium or with the replacement of a pavement epithelium with occasional immature cuboidal cells, which sometimes showed enlarged nucleus and proeminent nucleolus. Some crypts were filled with epithelial desquamation and polymorphnuclear cells. Bovine coronavirus (8F2) monoclonal antibody was used for immunohistochemistry on sections of the spiral colon that showed positive reactions in the cytoplasm of the infected crypt epithelium, sloughed necrotic cells, and within macrophages in the lamina propria of both.

Abstract in English:

ABSTRACT.- Pavarini S.P., Sonne L., Antoniassi N.A.B., Santos A.S., Pescador C.A., Corbellini L.G. & Driemeier D. 2008. [Congenital anomalies in aborted bovine fetuses in Southern Brazil.] Anomalias congênitas em fetos bovinos abortados no Sul do Brasil. Pesquisa Veterinária Brasileira 28(3):149-154. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br Abortion, stillbirth and neonatal death are important causes of production losses to the livestock industry. Abortions caused by congenital anomalies may occur sporadically, or appear in epidemics. This retrospective study was conducted at Laboratory of Veterinary Pathology of Federal University of Rio Grande do Sul, and included 307 cases of bovine abortion submitted for diagnosis from September 2001 to March 2007. Most of them were from southern Brazil. Ten cases (3.25%) of congenital anomalies were seen. The most frequent congenital anomalies were artrogryposis, Amorphous globosus, and cleft palate (palatoschisis). Infectious causes were investigated, but only BVDV infection was detected by immunohistochemistry in one case, which was affected with porencephalia.

• Abortion bovine congenital anomalies

Abstract in Portuguese:

ABSTRACT.- Pavarini S.P., Sonne L., Antoniassi N.A.B., Santos A.S., Pescador C.A., Corbellini L.G. & Driemeier D. 2008. [Congenital anomalies in aborted bovine fetuses in Southern Brazil.] Anomalias congênitas em fetos bovinos abortados no Sul do Brasil. Pesquisa Veterinária Brasileira 28(3):149-154. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br Abortion, stillbirth and neonatal death are important causes of production losses to the livestock industry. Abortions caused by congenital anomalies may occur sporadically, or appear in epidemics. This retrospective study was conducted at Laboratory of Veterinary Pathology of Federal University of Rio Grande do Sul, and included 307 cases of bovine abortion submitted for diagnosis from September 2001 to March 2007. Most of them were from southern Brazil. Ten cases (3.25%) of congenital anomalies were seen. The most frequent congenital anomalies were artrogryposis, Amorphous globosus, and cleft palate (palatoschisis). Infectious causes were investigated, but only BVDV infection was detected by immunohistochemistry in one case, which was affected with porencephalia.

Abstract in English:

ABSTRACT.- Corrêa A.M.R., Bezerra P.S.J., Pavarini S.P., Santos A.S., Sonne L., Zlotowski P., Gomes G. & Driemeier D. 2008. Senecio brasiliensis (Asteraceae) poisoning in Murrah buffaloes in Rio Grande do Sul. Pesquisa Veterinária Brasileira 28(3):187-189. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br Thirteen (14.4%) out of 90 Murrah buffaloes (Bubalus bubalis) became ill after con-sumption of Senecio brasiliensis, and 11 (12.2%) of them died. The buffaloes were kept in a highly Senecio brasiliensis infested area. The poisoning occurred in June-August 2006 on a farm in the county of Nova Prata, Rio Grande do Sul, southern Brazil. Clinical signs included weakness, apathy, progressive weight loss, permanent decubitus, and diarrhea. Necropsy was performed in 2 of the 11 buffaloes that died. The pathological findings were typical of poisoning by pyrrolizidine alkaloids. High infestation of pastures with S. brasiliensis, severe drought, and consequent starvation were the main epidemiological factors associated with the poisoning here described.

• Buffaloes pyrrolizidine alkaloids Senecio poisoning

Abstract in Portuguese:

ABSTRACT.- Corrêa A.M.R., Bezerra P.S.J., Pavarini S.P., Santos A.S., Sonne L., Zlotowski P., Gomes G. & Driemeier D. 2008. Senecio brasiliensis (Asteraceae) poisoning in Murrah buffaloes in Rio Grande do Sul. Pesquisa Veterinária Brasileira 28(3):187-189. Departamento de Patologia Clínica Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E-mail: davetpat@ufrgs.br Thirteen (14.4%) out of 90 Murrah buffaloes (Bubalus bubalis) became ill after con-sumption of Senecio brasiliensis, and 11 (12.2%) of them died. The buffaloes were kept in a highly Senecio brasiliensis infested area. The poisoning occurred in June-August 2006 on a farm in the county of Nova Prata, Rio Grande do Sul, southern Brazil. Clinical signs included weakness, apathy, progressive weight loss, permanent decubitus, and diarrhea. Necropsy was performed in 2 of the 11 buffaloes that died. The pathological findings were typical of poisoning by pyrrolizidine alkaloids. High infestation of pastures with S. brasiliensis, severe drought, and consequent starvation were the main epidemiological factors associated with the poisoning here described.

Abstract in English:

ABSTRACT.- Binoki D.H., Jatene F.B., Fantoni D.T., Stopiglia A.J., Santos A.L.S., Freitas R.R., Simões E.A., Irino E.T., Monteiro R. & Lofiego R. 2007. [Hemogasometric evaluation in dogs submitted to left pneumonectomy.] Avaliação hemogasométrica em cães submetidos à pneumonectomia esquerda. Pesquisa Veterinária Brasileira 27(8):345-351. Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP 05508-270, Brazil. E-mail: stopa@usp.br It is well known that different diseases of infectious, traumatic or neoplasic origin can occur in the lungs of dogs, and pneumonectomy technique may be an option for the treatment of some of these diseases. The objective was to evaluate hemogasometric parameters, oxygen partial pressure (PaO2), carbon dioxide partial pressure (PaCO2), hydrogen ion concentration (pH) and bicarbonate ion concentration on the pre- and post-operative moments of the left pneumonectomy. Eighteen adult mongrel dogs, males and females, were randomly distributed into two groups with 9 dogs each. In Group A, the left bronchial stump of the dogs was sutured manually with polypropylene 5-0, and, in Group B, the left bronchial stump of the dogs was sutured mechanically with a surgical stapler. The data were collected at 6 moments: Before the pre-anesthetic administration (T0), one hour after the extubation (T1EXT), 48 hours after the surgery (T48h), 7 days after the surgery (T7d), 15 days after the surgery (T15d), and 36 days after the surgery (T36d). The results were statistically analyzed. PaO2 values of Group A on T1EXT (67.00±11.31) were significantly lower in relation to T0 (99.4±18.34), a fact that did not happen in Group B: T1EXT (87.00±8.35) in regard to T0 (87.00±7.55). There was no difference on pH values in dogs of Group A, but in Group B was observed a decrease on T1EXT (7.3644±0.0353) in relation to T0 (7.4189±0.0136), although the animals did not develop acidosis. It was concluded that dogs submitted to left pneumonectomy (sutured manually or sutured mechanically of left bronchial) did not show immediate and mediate acid-basic instability during the study.

• Pneumonectomy manual suture mechanic suture hemogasometric dogs

Abstract in Portuguese:

ABSTRACT.- Binoki D.H., Jatene F.B., Fantoni D.T., Stopiglia A.J., Santos A.L.S., Freitas R.R., Simões E.A., Irino E.T., Monteiro R. & Lofiego R. 2007. [Hemogasometric evaluation in dogs submitted to left pneumonectomy.] Avaliação hemogasométrica em cães submetidos à pneumonectomia esquerda. Pesquisa Veterinária Brasileira 27(8):345-351. Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP 05508-270, Brazil. E-mail: stopa@usp.br It is well known that different diseases of infectious, traumatic or neoplasic origin can occur in the lungs of dogs, and pneumonectomy technique may be an option for the treatment of some of these diseases. The objective was to evaluate hemogasometric parameters, oxygen partial pressure (PaO2), carbon dioxide partial pressure (PaCO2), hydrogen ion concentration (pH) and bicarbonate ion concentration on the pre- and post-operative moments of the left pneumonectomy. Eighteen adult mongrel dogs, males and females, were randomly distributed into two groups with 9 dogs each. In Group A, the left bronchial stump of the dogs was sutured manually with polypropylene 5-0, and, in Group B, the left bronchial stump of the dogs was sutured mechanically with a surgical stapler. The data were collected at 6 moments: Before the pre-anesthetic administration (T0), one hour after the extubation (T1EXT), 48 hours after the surgery (T48h), 7 days after the surgery (T7d), 15 days after the surgery (T15d), and 36 days after the surgery (T36d). The results were statistically analyzed. PaO2 values of Group A on T1EXT (67.00±11.31) were significantly lower in relation to T0 (99.4±18.34), a fact that did not happen in Group B: T1EXT (87.00±8.35) in regard to T0 (87.00±7.55). There was no difference on pH values in dogs of Group A, but in Group B was observed a decrease on T1EXT (7.3644±0.0353) in relation to T0 (7.4189±0.0136), although the animals did not develop acidosis. It was concluded that dogs submitted to left pneumonectomy (sutured manually or sutured mechanically of left bronchial) did not show immediate and mediate acid-basic instability during the study.

Abstract in English:

ABSTRACT.- Pereira C.S., Amorim S.D., Santos A.F.M., Siciliano S., Moreno I.M.B., Ott P.H. & Rodrigues D.P. 2007. [Vibrio spp. isolated from marine mammals captured in coastal regions from southwestern to southern Brazil.] Vibrio spp. isolados de mamíferos marinhos capturados na região litorânea do sudeste ao sul do Brasil. Pesquisa Veterinária Brasileira 27(2):81-83. Laboratório de Enterobactérias, Departamento de Bacteriologia, Pavilhão Rocha Lima, Instituto Oswaldo Cruz, FIOCruz, Av. Brasil 4365, Rio de Janeiro, RJ 21045-900, Brazil. E-mail: csoarespereira@hotmail.com In the present investigation was evaluated the incidence of Vibrio spp. from superficial lesions at marine mammals beached or captured by fishing net in the southwestern (RJ) and southern (RS) coastal regions of Brazil. One hundred and ninety eight swabs were collected by DEENSP, GEMARS and Ceclimar institutes and sent to Labent/IOC/FIOCruz where the samples were submitted to enrichment in Alkaline Peptone Water (APW) added with 1% and 3% of sodium chloride (NaCl) incubated at 37oC for 18-24 hours. After the samples were streaked onto Thiossulfate Citrate Bile Sucrose Agar (TCBS), the suspected colonies were submitted to biochemical characterization. The results showed 108 strains, and Vibrio alginolyticus, V. parahaemolyticus, V. vulnificus and V. fluvialis were the main pathogens isolated. These results appoint the importance of surveillance and microbiological monitoring accomplishment and reinforcement of environmental protective programs applied to marine mammals endangered with extinction.

• Vibrionaceae aquatic ecosystem public health

Abstract in Portuguese:

ABSTRACT.- Pereira C.S., Amorim S.D., Santos A.F.M., Siciliano S., Moreno I.M.B., Ott P.H. & Rodrigues D.P. 2007. [Vibrio spp. isolated from marine mammals captured in coastal regions from southwestern to southern Brazil.] Vibrio spp. isolados de mamíferos marinhos capturados na região litorânea do sudeste ao sul do Brasil. Pesquisa Veterinária Brasileira 27(2):81-83. Laboratório de Enterobactérias, Departamento de Bacteriologia, Pavilhão Rocha Lima, Instituto Oswaldo Cruz, FIOCruz, Av. Brasil 4365, Rio de Janeiro, RJ 21045-900, Brazil. E-mail: csoarespereira@hotmail.com In the present investigation was evaluated the incidence of Vibrio spp. from superficial lesions at marine mammals beached or captured by fishing net in the southwestern (RJ) and southern (RS) coastal regions of Brazil. One hundred and ninety eight swabs were collected by DEENSP, GEMARS and Ceclimar institutes and sent to Labent/IOC/FIOCruz where the samples were submitted to enrichment in Alkaline Peptone Water (APW) added with 1% and 3% of sodium chloride (NaCl) incubated at 37oC for 18-24 hours. After the samples were streaked onto Thiossulfate Citrate Bile Sucrose Agar (TCBS), the suspected colonies were submitted to biochemical characterization. The results showed 108 strains, and Vibrio alginolyticus, V. parahaemolyticus, V. vulnificus and V. fluvialis were the main pathogens isolated. These results appoint the importance of surveillance and microbiological monitoring accomplishment and reinforcement of environmental protective programs applied to marine mammals endangered with extinction.

Abstract in English:

ABSTRACT.- Santos S.B., Faccini J.L.H. & Santos A.C.G. 2006. [Seasonal variation of Bovicola caprae parasitizing goats in the State of Paraíba, northeastern Brazil.] Variação estacional de Bovicola caprae parasitando caprinos no Estado da Paraíba. Pesquisa Veterinária Brasileira 26(4):249-253. Departamento de Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: faccini@ufrrj.br The effects of temperature, humidity and rainfall on field population trend of the biting louse Bovicola caprae, parasitizing goats bred in the semiarid region of the State of Paraiba, northeastern Brazil were monthly evaluated from August 1999 to July 2002. In the first two years (August 1999 to July 2001) 30 goats were examined, whereas 16 goats were examined in the last year (August 2001 to July 2002). All goats were crossbred, both sexes and abated for human consumption. The lice were collected in an area 4cm of diameter at three body sites: maxillary, back line and haunch. Spearman correlation analysis was conducted (p< 0.05) between monthly average intensity of infestation of all stages (egg, larva, nymph, male and female) of the life cycle pooled and monthly total counts of each stage and mean temperature, mean relative humidity and rainfall. B. caprae was found throughout the year with prevalence of 75-100%. Increase of the louse population during the drier months was probably a consequence of poor nutrition due to reduced pasture and inadequate husbandry practices instead the influence of abiotic factors.

• Bovicola caprae Trichodectidae Mallophaga seasonal variation goats northeastern Brazil

Abstract in Portuguese:

ABSTRACT.- Santos S.B., Faccini J.L.H. & Santos A.C.G. 2006. [Seasonal variation of Bovicola caprae parasitizing goats in the State of Paraíba, northeastern Brazil.] Variação estacional de Bovicola caprae parasitando caprinos no Estado da Paraíba. Pesquisa Veterinária Brasileira 26(4):249-253. Departamento de Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: faccini@ufrrj.br The effects of temperature, humidity and rainfall on field population trend of the biting louse Bovicola caprae, parasitizing goats bred in the semiarid region of the State of Paraiba, northeastern Brazil were monthly evaluated from August 1999 to July 2002. In the first two years (August 1999 to July 2001) 30 goats were examined, whereas 16 goats were examined in the last year (August 2001 to July 2002). All goats were crossbred, both sexes and abated for human consumption. The lice were collected in an area 4cm of diameter at three body sites: maxillary, back line and haunch. Spearman correlation analysis was conducted (p< 0.05) between monthly average intensity of infestation of all stages (egg, larva, nymph, male and female) of the life cycle pooled and monthly total counts of each stage and mean temperature, mean relative humidity and rainfall. B. caprae was found throughout the year with prevalence of 75-100%. Increase of the louse population during the drier months was probably a consequence of poor nutrition due to reduced pasture and inadequate husbandry practices instead the influence of abiotic factors.

Abstract in English:

Faccini J.L.H., Santos A.C.G. & Bechara G.H. 2004. [Bovine demodicosis in the state of Paraíba, northeastern Brazil.] Demodicose bovina no Estado da Paraíba. Pesquisa Veterinária Brasileira 24(3):149-152. Depto Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: faccini@ufrrj.br Cases of bovine demodicosis caused by Demodex bovis were reported in a Sindhi herd from December 1989 to January 1992. Both localized and generalized forms were diagnosed. This is the first report of the generalized form in Brazil. In the first two years, demodicosis was diagnosed only in cattle < 2 years old, whereas animals of all ages were positive in the last two years. Prevalence varied from 20.4% (11/54) to 53.1% (26/49) and 13.2% (12/91) to 14.8% (9/61) for cattle < 2 years old and > 2 years old, respectively. Clinical signs varied from a few small nodules to a thickened skin with soft large nodules in the localized and generalized forms, respectively. Main microscopic features of the nodules in the generalized form consisted of acanthosis with hyperqueratosis, chronic sebaceous adenitis, subcutaneous muscular necrosis, focal cellular degeneration of the epidermis basal layer and presence of large number of mites inside the lumen of dilated hair follicles. In addition, a chronic perifoliculitis was observed, characterized by lymphoplasmocytic infiltrate which also contained macrophages and neutrophils. It is suggested that poor nutrition and stress due to prolonged drought probably contributed to the increase of susceptibility of the herd to mite infestation.

• Demodex bovis demodicosis cattle pathology Brazil.

Abstract in Portuguese:

Faccini J.L.H., Santos A.C.G. & Bechara G.H. 2004. [Bovine demodicosis in the state of Paraíba, northeastern Brazil.] Demodicose bovina no Estado da Paraíba. Pesquisa Veterinária Brasileira 24(3):149-152. Depto Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: faccini@ufrrj.br Cases of bovine demodicosis caused by Demodex bovis were reported in a Sindhi herd from December 1989 to January 1992. Both localized and generalized forms were diagnosed. This is the first report of the generalized form in Brazil. In the first two years, demodicosis was diagnosed only in cattle < 2 years old, whereas animals of all ages were positive in the last two years. Prevalence varied from 20.4% (11/54) to 53.1% (26/49) and 13.2% (12/91) to 14.8% (9/61) for cattle < 2 years old and > 2 years old, respectively. Clinical signs varied from a few small nodules to a thickened skin with soft large nodules in the localized and generalized forms, respectively. Main microscopic features of the nodules in the generalized form consisted of acanthosis with hyperqueratosis, chronic sebaceous adenitis, subcutaneous muscular necrosis, focal cellular degeneration of the epidermis basal layer and presence of large number of mites inside the lumen of dilated hair follicles. In addition, a chronic perifoliculitis was observed, characterized by lymphoplasmocytic infiltrate which also contained macrophages and neutrophils. It is suggested that poor nutrition and stress due to prolonged drought probably contributed to the increase of susceptibility of the herd to mite infestation.

Abstract in English:

This is the first description of adenocarcinomas of the bile ducts of the cat (Felix cattus domesticus), naturally infected with the parasite Platynosornum fastosurn. The studies were based on four old female cats. The authors hypothesize a relationship between the parasites and the neoplasms, which is suggested by the appearance of neoplasms at the sites of parasitism. In a series of neoplasms diagnosed in cats in Brazil over a 20 year period by the authors, only 5 were primary to the liver, 4 of those being the duct carcinomas described. These findings are analagous to those reported in humans, cats and dogs parasitized by Clonorchis sinensis or Opistorchis felineus. The relatively advanced age of the animals studied and the long survival of certain trematodes in the biliary ducts indicate a chronic state of the lesions and their subsequent development into cancer.

• Platynosomum fastosum cholangiocellular carcinoma carcinogenesis by helminths cat

Abstract in Portuguese:

Os autores fazem a primeira descrição de adenocarcinomas de dutos biliares em gatos (Felix cattus domesticus) com parasitismo dutal por Platynosomum fastosum. A observação é baseada em quatro casos e os animais tinham respectivamente 8,9 e 13 anos de idade, não havendo indicações da idade no 4º caso. Todos os animais eram fêmeas. Os autores concluem pela interdependência entre a parasitose e as neoplasias surgidas, o que é patenteado pelo aparecimento das mesmas ao nível dos sítios parasitados; de outro lado, em uma série de neoplasias diagnosticadas em gatos pelos autores ao longo de 20 anos, apenas cinco eram primárias do fígado, quatro dos quais eram os carcinomas dutais ora descritos. O problema apresenta analogia com os carcinomas de dutos biliares registrados em humanos, gatos e cães parasitados por Clonorchis sinensis ou por Opistorchis felineus. A idade relativamente avançada dos animais estudados e a sobrevivência longa de certos trematódeos das vias biliares indicam uma cronicidade de lesões dutais e a sua posterior cancerização.

• Platynosomum fastosum colangiocarcinoma carcinogênese por helmintos gato