Luiz F. Irigoyen

Experimental infection of pregnant ewes with bovine viral diarrhea virus type-2 (BVDV-2) : effects on the pregnancy and fetus

The reproduction effects of bovine viral diarrhea virus type-2 (BVDV-2) infection were investigated in ewes inoculated with a non-cytopathic BVDV-2 isolate at three stages of gestation. Virus inoculation was followed by a transient viremia, accompanied by a transient and mild hyperthermia and nasal discharge in a few animals. Some ewes were sacrificed at different time-points after virus inoculation to study the kinetics of fetal infection. Infectivity and viral antigens were detected in placentomes from day 7 to 36 post-inoculation (pi) and in fetal fluids and tissues between days 10 and 28 pi. Cardiac petechial hemorrhages and hemoperitoneum accompanied by a severe fibrinous ulcerative placentitis were observed in fetuses examined at days 21, 28 and 36 pi. Inoculation of ewes at days 55-60 of gestation resulted in a prolonged virus replication in placentomes and fetal tissues; ewes that were allowed to proceed with pregnancy had 77% of abortions or fetal and perinatal deaths. Seven stillbirths, unviable and viable lambs born to these ewes were virus-positive at birth. Infectious virus was repeatedly isolated from leukocytes of two lambs up to 2 and 6 months of age, indicating they were persistently infected. Ewes inoculated at days 65-70 of gestation had 66.6% of fetal and perinatal losses. Three viable lambs born to these ewes were healthy, BVDV antibody-positive and virus-negative. A transient viral replication in placentomes and in a few fetal tissues, followed by the rise of fetal neutralizing antibodies and virus clearance was the result of inoculating ewes at days 120-125 of gestation. Lambs born to these ewes were healthy, antibody-positive and virus-negative. These results demonstrate that the biology of BVDV-2 infection in pregnant sheep is essentially similar to that of BVDV-1 in pregnant cattle and sheep. These features make this species an attractive animal model for studying the pathogenesis of congenital BVDV-2 infection.

Causas de morte e razões para eutanásia de cães da Mesorregião do Centro Ocidental Rio-Grandense (1965-2004)

The main objective of this study was to investigate the prevalence of diseases culminating with death or motivating euthanasia of dogs from the midland region of the Midwest of Rio Grande do Sul State, Brazil. The necropsy files of the Laboratorio de Patologia Veterinaria (LPV) of the Universidade Federal de Santa Maria (UFSM) were accessed and necropsy protocols of dogs necropsied between January 1965 and December 2004 were reviewed. During this period 4,844 reports of canine necropsies were filed at the LPV-UFSM. The case distribution in relation to the disease categories diagnosed was as follows: infectious and parasitic diseases (1,693 [35.0%]); neoplasms (378 [7.8%]); disorders caused by physical agents (369 [7.6%]); degenerative diseases (342 [7.1%]); poisonings and toxinfections (112 [2.3%]); euthanasia due to convenience (101 [2.1%]); metabolic and endocrinological diseases (97 [2.0%]); iatrogenic disorders (83 [1.7%]); developmental disorders (25 [0.5%]); immune mediate diseases (10 [0.2%]); and nutritional disorders (6 [0.1%]). Other disorders, including multifactorial or idiopathic diseases contributed 80 (1.6%) cases. In 1,548 (32.0%) out of the 4,844 cases it was not possible to establish either cause of death or reason for euthanasia. Infectious and parasitic diseases (mainly canine distemper, parvoviral enteritis and intestinal parasitism), neoplasia (mainly mammary neoplasms and lymphoma), disorders caused by physical agents (mainly accidents caused by automotive vehicles) and degenerative diseases (mainly chronic renal failure, cirrhosis, and congestive heart failure) were the main disease categories causing death or motivating euthanasia in dogs of this midland region. However, when cases were evaluated in relation with the age of the dog, the disease prevalence differed. The main causes of death in puppies were infectious and parasitic disease (mainly parvoviral enteritis, canine distemper, and intestinal parasitism). In adult dogs the most important causes of death were canine distemper, neoplasia and trauma. In age dogs, approximately half of the deaths could be attributed to neoplasia and degenerative disease.

Latent infection by bovine herpesvirus type-5 in experimentally infected rabbits: virus reactivation, shedding and recrudescence of neurological disease

Latent infection with bovine herpesvirus type-5 (BHV-5) was established in rabbits inoculated with two South American isolates (EVI-88 and 613) by intranasal or conjunctival routes. Nine rabbits (613, 8/27; EVI-88, 1/34) developed neurological disease and died during acute infection and other three (613, n=2; EVI-88, n=1) developed a delayed neurological disease, at days 34, 41 and 56 post-inoculation (p.i.). Between days 56 and 62 p.i., the remaining rabbits were submitted to five daily administrations of dexamethasone (Dx) to reactivate the infection. Twenty-five out of 44 rabbits (56.8%) shed virus in nasal or ocular secretions after Dx treatment. Virus shedding was first detected at day two post-Dx and lasted from one to 11 days. The highest frequencies of virus reactivation were observed in rabbits inoculated conjunctivally (10/15 versus 15/29); and among rabbits infected with isolate 613 (12/16 versus 13/28). Virus reactivation upon Dx treatment was accompanied by neurological disease in nine rabbits (20.4%), resulting in six deaths (13.6%). Virus in moderate titers and mild to moderate non-suppurative inflammatory changes in the brain characterized the neurological infection. Three other rabbits showed severe neurological signs followed by death after 31 to 54 days of Dx treatment. Virus, viral nucleic acids and inflammatory changes were detected in their brains. The late-onset neurological disease, after acute infection or Dx treatment, was probably a consequence of spontaneous virus reactivation. These results demonstrate that BHV-5 does establish a latent infection in rabbits and that clinical recrudescence may occur upon reactivation.

Aspectos clinicopatológicos de 620 casos neurológicos de cinomose em cães: Clinicopathological features in 620 neurological cases of canine distemper

The files of 5,361 necropsies performed in dogs in the Veterinary Pathology Laboratory of the Federal University of Santa Maria during 1965-2006 were reviewed in search of cases of canine distemper. Six hundred and eighty three cases (12.7%) of the disease were found, 620 of which had neurological signs. From those 620, the following data on each case were retrieved: age, clinical signs, histopathology and concomitance or not of another disease. Age groups were classified as puppies (up to 1 year of age), adults (from 1 to 9 years) and aged (from 10 years on). In 565 out of the 620 (91.1%) neurological cases of canine distemper, histopathological brain changes were observed and in 554 of those 565 the age was registered in the files with following age group distribution: 45.9% of puppies, 51.4% of adults, and 2.7% of aged dogs. Neurological clinical signs encompassed a large spectrum of motor, postural and behavioral disturbances which could occur together or individually. Most frequent clinical signs were myoclonus (38.4%), motor incoordination (25.0%), seizures (18.5%), and paraplegia (13.4%). In 98.4% of the 565 dogs with histopathological changes in the brain demyelination, non-suppurative encephalitis or a combination of these two were found. Intranuclear eosinophilic inclusion bodies were observed in different brain cells of 343 of the 565 dogs with histopathological changes. In 170 (49.6%) the cellular type bearing the inclusions was not mentioned in the file and in the remaining cases the inclusions were seen in astrocytes (94.8% of the cases), neurons (3.5%), oligodendrocytes (1.1%), and ependyma cells (0.6%). Taking in consideration the type of lesions and the age groups, cases with combined demyelination and non-suppurative encephalitis occurred in 40.0% of the puppies, 51.2% of the adult dogs and 72.7% of the aged dogs. Demyelination alone occurred in 48.4% of the puppies, 41.3% of the adults and in 35.7% of the aged dogs. Non-suppurative encephalitis alone occurred 11.6% of the puppies, 7.5% of the adults and in 7.1% of the aged dogs.

Estudo retrospectivo de 1.647 tumores mamários em cães

Mammary gland tumors are common in dogs and are the most common type of neoplasm of female dogs. The main purposes of this study were to establish the prevalence of the mammary gland tumors, as well as of its different histologic types (neoplastic and non-neoplastic), diagnosed in the Laboratorio de Patologia Veterinaria of the Universidade Federal de Santa Maria. There were 1,304 biopsy reports of mammary gland tumors during 1990-2008 and 132 necropsy reports of dogs with mammary tumors in 2000-2008. Data about breed, gender, and age of dogs, tumor localization, morphologic diagnosis, and metastasis occurrence were analyzed. In the biopsy cases, 1,495 tumors were diagnosed, considering the presence of more than one type of tumor in some of the dogs. From those, 1,465 were neoplastic and 30 were non-neoplastic. Within the neoplasms, 390 (26.6%) were benign and 1,075 (73.3%) were malignant. The benign/malignant ratio was 1:2.75. During the years 2000-2008, 1,125 necropsies of dogs were performed, 132 (11.64%) of which with mammary gland tumors. There were 152 morphologic diagnoses, being 150 of neoplastic and two of non-neoplastic lesions. Simple carcinoma was the most prevalent histologic type, both among biopsy and necropsy cases. On necropsy cases, metastases to lymph nodes and distant organs were seen in 39 (29.5%) and 64 (53,3%) cases, respectively.

Experimental infection of sheep with bovine herpesvirus type-5 (BHV-5): acute and latent infection

We demonstrated that sheep are susceptible to acute and latent infection by bovine herpesvirus type-5 (BHV-5). Lambs inoculated intranasally with two South American BHV-5 isolates replicated the virus with titers up to 10(7.1) TCID50/ml for up to 15 days and showed mild signs of rhinitis. Four lambs in contact with the inoculated animals acquired the infection and excreted virus for up to seven days. One lamb developed progressive signs of neurological disease and was euthanized in extremis. Clinical signs consisted of tremors of the face, bruxism, ptyalism, incoordination, lateral flexion of the neck and head, circling, walking backwards, recumbency and paddling. The virus was detected in the anterior and posterior cerebrum, dorso- and ventro-lateral cortex, cerebellum, pons, midbrain and olfactory bulb. Viral nucleic acids were demonstrated in neurons and astrocytes of the anterior and ventro-lateral cortex by in situ hybridization. Histological changes consisting of non-suppurative meningitis, perivascular mononuclear cuffing, focal gliosis, neuronal necrosis and intranuclear inclusions were observed in the anterior cerebrum, ventro-lateral cortex and midbrain. Dexamethasone treatment at Day 50 pi resulted in reactivation of the latent infection and virus shedding in 13/16 (81%) of the lambs. Together with previous reports of BHV-5 antibodies in sheep, these findings show that sheep are fully susceptible to BHV-5 suggesting that infection by BHV-5 in sheep may occur naturally.

Intoxicação espontânea pelos frutos de Xanthium cavanillesii (Asteraceae) em bovinos no Rio Grande do Sul

Two outbreaks of Xanthium cavanillesii poisoning in feedlot cattle in the counties of Casca and Cachoeira do Sul, Rio Grande do Sul, southern Brazil, are described. The disease occurred on two farms in late April and mid August 1996. On one farm, 17 heifers out of 310 cattle died. On the other, 11 out of 83 yearling calves died. Clinical signs included depression, anorexia, progressive dehydration, sunken eyes, tenesmus and slight rectal prolapse, muscle tremors, incoordination of gait, blindness, aggressivity and recumbency. Blindness was present in the terminal stages prior to death that occurred within 3 to 24 hours after the onset of the clinical signs. Necropsy findings included accentuation of the lobular pattern of the liver with pinpoint hemorrhages on capsular and cut surfaces; perirenal edema, hydropericardium, and translucent and gelatinous edema of the gall bladder wall, mesentery, abomasal ligaments and folds. The feces were scant, dry and formed balls coated by mucus and streaks of clotted blood. There were widespread petechiae, ecchymoses and suffusions. Burs of X. cavanillesii were found mixed with the solid and dried contents of the rumen and reticulum. The main histopathological findings were marked centrilobular coagulative hepatocellular necrosis associated with congestion and hemorrhages, surrounded or not by a narrow rim of markedly swollen and vesicular hepatocytes. The animals were being fed with whole or milled leftovers from soybean crops contaminated with large amounts of burs of X. cavanillesii. Deaths stopped after the feeding with the soybean leftovers was discountinued. The diagnosis was based on epidemiological data, clinical signs, necropsy findings, histological lesions and experimental reproduction of the toxicosis in cattle and sheep. The morphology and pathogenesis of the hepatic lesion and the clinical and pathological aspects of the toxicosis are discussed and compared with other reports of Xanthium spp poisoning and other acute hepatotoxicoses in cattle.

Febre catarral maligna em bovinos no Rio Grande do Sul: transmissão experimental para bovinos e caracterização do agente etiológico

Two oubreaks of malignant catarrhal fever (MCF) occurring in cattle on two farms (A and B) in the municipality of Santiago, state of Rio Grande do Sul (RS), Brazil, and the transmission of the disease to susceptible calves as well as the detection of ovine herpesvirus-2 (OvHV-2) in tissues of affected cattle are reported. The two epizootics occurred from November 2001 to February 2002 (Farm A) and in January-February 2003 (Farm B). Numbers of cattle at risk, morbidity and letality rates were respectively 170, 10.59% and 83.33% for Farm A and 500, 2.4% and 100% for Farm B. Contact between affected cattle and sheep was detected in both farms, but lambing ewes were present only in farm A. Duration of clinical courses, gross findings and histopathology were the same for the affected cattle in both farms. Most affected cattle died or were euthanatized in extremis after a clinical course of 2-8 days. Clinical signs included fever (40.5 and 41.5°C), nasal and ocular discharge, corneal opacity, conjunctivitis, drooling, erosions and ulcerations of the mucosae, diarrhea, hematuria, and neurological disturbances. Eleven necropsies (9 on Farm A, 2 on Farm B) were performed. Gross lesions included erosions and ulcers affecting the mucosae of nasal turbinates, oral cavity, gastrointestinal and urogenital tracts; hemorrhage and necrosis of the tip of the buccal papillae, lymph node enlargement, multifocal white foci in renal cortex, and hyperemia of leptomeninges. Microscopically, there were arteritis and fibrinoid degeneration in medium and small arteries and arterioles of multiple organs and tissues, necrosis and inflammation in several mucosal surfaces, keratitis, conjunctivitis, uveitis, intersticial nephritis, and encephalitis. Transmission experiments were attempted in five calves (E1-E5) by inocculating each of them intravenously with 500 ml of whole heparinized blood from a MCF affected cow. The transmission was suscessful in at least three (E1-E3) of the experimental calves which became sick after an incubation period of 15-27 days. Four experimental calves either died or were euthanatized in extremis after a clinical course which varied from 3 days to 8 weeks. The remaining experimental calf (E5) recovered from a mild disease and was euthanatized 14 weeks after inocculation. Necropsies were performed in all five calves. Clinical signs, necropsy and histopathological findings of three calves (E1-E3) were characteristic of MCF. OvHV-2 viral DNA was detected by the polimerase chain reaction (PCR) test in paraffin embedded tissues from seven cattle out of the 11 spontaneous MCF cases and from three experimental calves (E1-E3). PCR tests resulted negative in the remaining four of the 11 spontaneous MCF cases tested and in two (E4,E5) of the five experimental calves. Immunohistochemistry performed in sections of lymphoid tissue from calf E4 failed to detect BVD virus antigen. The experimental transmission of MCF and the characterization of the etiological agent as OvHV-2 were successfully attempted in cattle for the first time in Brazil.

Doenças de ovinos da região Central do Rio Grande do Sul: 361 casos

An 18-year (1990-2007) database search in the files of the Laboratory of Veterinary Pathology (LPV) of the Universidade Federal de Santa Maria (UFSM), Rio Grande do Sul state, Brazil was carried out. In this period, 19,476 exams in domestic animals were done. Out of these exams, 6,816 (34.9%) were necropsies and 12,660 (65.1%) were performed in mailed samples from practitioners. Experimental cases were excluded from this study and corresponded to 54 necropsies and 15 histopathologic exams. After the exclusion 354 (5.1%) necropsies and 163 (1.2%) histopathologic exams were found in sheep. Out of these, 265 (74.8%) cases were conclusive in the group of necropsies and 96 (59%) were conclusive in the group of the histopathologic exams. The resulting 361 conclusive cases were grouped according to the etiology: 150 (41.6%) cases of poisoning or toxi-infections; 142 (39.3%) cases of infectious and parasitary diseases; 31 (8.6%) of metabolic and nutritional diseases; 13 (3.6%) cases of neoplasms and neoplasm-like lesions; 7 (1.9%) cases of diseases caused by physical agents; 6 (1.7%) cases of iatrogenic conditions; and 4 (1.1%) of developmental diseases. Eight cases did not fit in any of the above categories and were grouped under the denomination of other conditions. Hemonchosis and poisoning by Nierembergia veitchii were the most prevalent diseases in sheep during the 18 years of this study.

A retrospective search for bovine respiratory syncytial virus (BRSV) antigens in histological specimens by immunofluorescence and immunohistochemistry

Bovine respiratory syncytial virus (BRSV) has been only sporadically identified as a causative agent of respiratory disease in Brazil. This contrasts with frequent reports of clinical and histopathological findings suggestive of BRSV-associated disease. In order to examine a possible involvement of BRSV in cases of calf pneumonia, a retrospective search was performed for BRSV antigens in histological specimens submitted to veterinary diagnostic services from the states of Rio Grande do Sul and Minas Gerais. Ten out of 41 cases examined (24.4%) were positive for BRSV antigens by immunohistochemistry (IPX). Eight of these cases (19.5%) were also positive by indirect immunofluorescence (IFA), and 31 cases (75.6%) were negative in both assays. In the lungs, BRSV antigens were predominantly observed in epithelial cells of bronchioles and less frequently found in alveoli. In one case, antigens were detected only in the epithelium of the alveolar septae. The presence of antigen-positive cells was largely restricted to epithelial cells of these airways. In two cases, positive staining was also observed in cells and cellular debris in the exudate within the pulmonary airways. The clinical cases positive for BRSV antigens were observed mainly in young animals (2 to 12 month-old) from dairy herds. The main microscopic changes included bronchointerstitial pneumonia characterized by thickening of alveolar septae adjacent to airways by mononuclear cell infiltrates, and the presence of alveolar syncytial giant cells. In summary, the results demonstrate the suitability of the immunodetection of viral antigens in routinely fixed tissue specimens as a diagnostic tool for BRSV infection. Moreover, the findings provide further evidence of the importance of BRSV as a respiratory pathogen of young cattle in southeastern and southern Brazil.