Daniel R. Rissi

Neurological Disease in Cattle in Southern Brazil Associated with Bovine Herpesvirus Infection

The occurrence of neurological disease in cattle caused by Bovine herpesvirus in 11 farms from southern Brazil between 1987 and 2007 is described. Twenty-two animals were necropsied. Major clinical signs included excessive salivation, nasal and ocular discharge, circling, recumbency, depression, incoordination, grinding of teeth, and paddling movements. Necropsy findings in 10 of 22 cattle included hyperemia and softening of the rostral portions of the telencephalic cortex, with flattening of gyri, and malacia. Cattle in 10 cases did not show any gross lesions. Histological examination in most cases revealed nonsuppurative and necrotizing meningoencephalitis with acute neuronal necrosis, edema, eosinophilic intranuclear inclusion bodies in astrocytes and neurons, and infiltration of gitter cells. No histologic lesions could be detected in 4 cases. The initial diagnosis was based upon the clinical, epidemiological, and pathological findings. The diagnosis was confirmed by virus isolation in cell culture followed by virus identification by a glycoprotein C–based polymerase chain reaction. Seven isolates were identified as Bovine herpesvirus 5, and 4 were identified as Bovine herpesvirus 1.

A Retrospective Study of 586 Tumours in Brazilian Cattle

Records from 6,706 necropsy examinations of cattle performed over a 45-year period were surveyed and 586 cases of neoplasia were identified. The organ system most frequently affected by neoplastic disease (n=139 cases) was the alimentary tract. This finding was attributed to a high incidence of squamous cell carcinoma of the upper alimentary tract associated with the chronic ingestion of bracken fern (Pteridium aquilinum). This carcinogenic plant was also associated with a relatively high incidence (n=35 cases) of urinary bladder tumours (enzootic haematuria). Tumours of the alimentary tract were followed, in decreasing order of frequency, by tumours of the skin and subcutis (n=129 cases), haemopoietic tissue (n=101 cases), the eye and periorbital tissues (n=88 cases), the urinary system (n=44 cases), the female reproductive system (n=21 cases), the endocrine system (n=16 cases), the liver and pancreas (n=12 cases), the nervous system (n=6 cases), the respiratory system (n=6 cases) and the mammary gland (n=1 case). The primary anatomical location of 16 tumours was undetermined.

Intoxicações por plantas e micotoxinas associadas a plantas em bovinos no Rio Grande do Sul: 461 casos

From 1990 to 2005, tissues from 2,912 cattle necropsies were examined at the Laboratory of Veterinary Pathology (LPV) of the Federal University of Santa Maria (UFSM), Brazil. These tissues came from necropsies performed by faculty members of the LPV or were mailed-in samples from necropsy performed by veterinarian practitioners. In 461 (15.83%) of these necropsies the cause of death was attributed to the ingestion of poisonous plants. In decreasing order of frequency poisoning by the following plants were registered: Senecio spp (56.14%), Pteridium aquilinum (12.06%), Ateleia glazioviana (10.31%), Solanum fastigiatum (5.04%), Baccharis coridifolia (3.29%), Xanthium cavanillesii (3.07%), Senna occidentalis (2.63%), Ramaria flavo-brunnescens (2.41%), Amaranthus spp (2.19%), Vicia villosa (1.54%), Ipomoea batatas, Prunus sellowii, cytrus pulp (0.44% each), Cestrum parqui, Claviceps paspali, Claviceps purpurea, Brachiaria spp and Lantana sp (0.22% each). In a given outbreak the number of affected cattle was substantially higher than the number of necropsies performed. The following aspects are discussed for each plant: geographical distribution; factors inducing ingestion; morbidity, mortality and lethality rates, clinical signs, necropsy findings, histopathology. For those plants in which information on the active principle and pathogenesis are available, these aspects are included in the discussion.

Epidemiologia, sinais clínicos e distribuição das lesões encefálicas em bovinos afetados por meningoencefalite por herpesvírus bovino-5

Seven outbreaks and an isolated case of meningoencephalitis caused by bovine herpesvirus-5 (BoHV-5) in cattle in Rio Grande do Sul, Brazil, occurring in 2002-2004, are described. From a total population at risk of 1,359 cattle, 54 1-18-month-old calves from both sexes and several breeds were affected and 50 died spontaneously or were euthanatized while moribund. The highest frequency of cases was in recently weaned calves or calves submitted to other stressing factors. General rates of morbidity, mortality and lethality were respectively 3.97, 3.67 and 92.59%. Clinical courses varied from 3-10 days and included depression, nasal and ocular discharge, grinding of teeth, circling, blindness, fever, nistagmus, trembling, anorexia, dysphagia, drooling, incoordination, head pressing, rough hair coat, tachycardia, tachypnea, abdominal pain, melena, falls, recumbency, opisthotonus, convulsions and paddling. Nineteen calves were necropsied. Necropsy findings were characterized by hyperemia of leptomeninges, swollen rostral portions of the telencephalon, and flattening of frontal lobes gyri; frequently in these frontal areas there were segmental brown-yellow discoloration and softening (malacia) of the cortex. In cases with more protracted clinical courses there were extensive swelling, softening and hemorrhaging of the telencephalic frontal lobes. Microscopically, all affected cattle had a necrotizing non-suppurative meningoencephalitis with variable distribution among the 19 cases and among the various telencephalic regions of the same case. The severity of these changes were more marked, in decreasing order of intensity, in the telencephalic frontal cortex, basal ganglia (nuclei), thalamus, brain stem, parietal telencephalic cortex, occipital telencephalic cortex and cerebellum. Perivascular inflammatory infiltrate consisted predominantly of lymphocytes, plasm cells, and less frequently of neutrophils. Additional microscopic findings included variable degrees of gliosis, edema, neuronal necrosis in the telencephalic cortex characterized by shrinking and eosinophilia of perikaria and nuclear picnosis (red neuron); basophilic intranuclear inclusion bodies in astrocytes and neurons (21.05% of the cases); sattelitosis; and neuronophagia. The areas of softening in the cortical substance consisted of necrosis of the neuroctodermal elements with maintenance of mesenchymal structures (vessels and microglia), infiltrate of Gitter cells, and, in more severe cases, extensive hemorrhages. In chronic cases, only vascular structures and a few Gitter cells remained in the cortical area leaving a cavity between white matter and leptomeninges (residual lesion).

Aceturato de diminazeno e dipropionato de imidocarb no controle de infecção por Trypanosoma evansi em Rattus norvegicus infectados experimentalmente

The aim of this study was to evaluate the efficacy of diminazene aceturate and imidocarb dipropionate in the control of Trypanosoma evansi infection in rats (Rattus norvegicus) experimentally infected. Fifty-four male rats were inoculated through intraperitoneal route with 104 T. evansi trypomastigotes. The rats were evaluated daily by periferic blood smears examination and treated when eight flagellated parasites were observed in 1000x microscopic field. Two therapeutics protocols were used. The first one included Groups A, B, C, D in which the rats were submitted to a single dose of the testing drugs administered by intramuscular route at the day 0 and again when T. evansi was observed in the blood smears. The rats of the second protocol (Groups E, F, G, H) were submitted to the same treatment by five consecutive days. Four rats (Group I) were used as control and were not submitted to any treatment. Tested drugs did not show any curative effect when used in the first protocol, since parasitaemia was evident few days after treatment. The use of diminazene aceturate in the second protocol resulted in elimination of the trypomastigotes from circulation. In this case the rats were euthanized at the day 90. The infection recurred 30 days after the administration of imidocarb dipropionate. Histologically, no lesions were found in the liver or kidney. Diminazene aceturate is effective in treating trypanosomosis in rats when used five days consecutively.

Meningoencefalite por herpesvírus bovino-5

Meningoencephalitis caused by bovine herpesvirus-5 (BoHV-5) is an often fatal, acute or subacute infectious disease that affects mainly young cattle under stressing conditions. The disease has been recognized in several Brazilian regions and in other parts of the world. BoHV-5 is a double stranded DNA virus member of the Herpesviridae family and subfamily Alphaherpesvirinae. The virus is characterized by rapid and lytic replication in cell cultures and by the ability to establish lifelong latent infection in sensory nerve ganglia of the host. BoHV-5 is transmitted mainly by direct and indirect contact and replicates acutely in the oral, nasal, oropharingeal or ocular mucosae. After primary replication, the virus invades nerve endings and is transported to the neuron cell bodies of the sensory ganglia where it replicates actively and/or establishes latency. Viral invasion of the brain may result in massive virus replication and production of neurological disease. Virtually all cattle developing neurological disease die of meningoencephalitis; yet the infection may be subclinical in some animals. These animals recover and become latently infected. Viral dissemination within a herd is facilitated by conditions such as crowding, introduction of cattle from other herds and weaning of calves in ages that coincide with decrease of passive immunity. Certain natural or induced conditions may reactivate the latent virus and favor its transmission and dissemination to other susceptible individuals. The disease may occur as outbreaks or as sporadic cases, with morbidity rates ranging of 0.05%-5%; lethality is almost always 100%. Clinical signs include depression, nasal and ocular discharge, grinding of teeth, circling, blindness, fever, paddling movements, disphagia, abdominal pain, nystagmus, muscle tremors, drooling, incoordinated gait, opisthotonus, head pressing, falls and convulsions. Clinical course is usually 1-15 days. Necropsy findings may be absent but often there is swollen of the rostral portions of the cerebral cortex and flattening of gyri, with softening and segmental yellow discoloration (malacia). As the disease progresses the affected areas become gelatinous and grey and, in advanced cases, there is segmental loss of the cerebral cortex of the frontal lobe of the brain (residual lesion). In several cases there is malacia of the basal nuclei and of the thalamus. Histologically, there is necrotizing non-suppurative meningoencephalitis affecting mainly the cerebral cortex of the frontal lobe associated with eosinophilic intranuclear inclusion bodies in neurons and astrocytes, although the frequency of the inclusion bodies is inconsistent. The diagnosis of meningoencephalitis by BoHV-5 should be based on epidemiology, clinical signs, necropsy and histological findings. The diagnosis should be confirmed by viral isolation in cell culture and/or by detection of viral antigens in brain sections or in exfoliated cells from nasal secretions. The identification and characterization of BoHV-5 can be done by the use of mono clonal antibodies, polymerase chain reaction (PCR) and/or by restriction enzyme analysis of the viral genome. There is no specific treatment for the disease. As BoHV-1 and BoHV-5 are antigenically related, vaccination using BoHV-1 vaccines may be recommended as a means of reducing the losses caused by BoHV-5 infection, mainly during outbreaks of neurologic disease. Additionally, measures such as serologic testing of new additions to the herd; and management practices to prevent stress and to reduce conditions for virus dissemination among animals may help in reducing the incidence and the consequences of BoHV-5 infection and disease.

Intoxicação espontânea por Baccharis coridifolia em bovinos

Two outbreaks of Baccharis coridifolia poisoning in cattle in southern Brazil are described. Cases occurred when stressed, hungry and thirsty cattle brought from pastures free of B. coridifolia were placed into pastures heavily infested by this poisonous plant. In the two outbreaks morbidity was 21.73% and 22.51% and lethality was virtually 100%. Clinical signs included mild bloat, instability of hind limbs, muscle tremors, dry muzzle, dry feces or diarrhea, polydipsia and restlessness. Consistent necropsy findings included dehydration, large amounts of ruminal fluid, reddening and erosions of the mucosae of the forestomachs. Degeneration and necrosis of the lining epithelium of the forestomachs and of lymphoid tissue were the main histopathological changes encountered.

Biópsia hepática no diagnóstico da intoxicação por Senecio brasiliensis (Asteraceae) em bovinos

Liver lesions caused by Senecio spp poisoning in cattle are progressive and deaths may occur many months after the plant is ingested. Laboratory tests of liver function are not always reliable indicators of subclinical affected animals. Liver biopsy could be useful to identify cattle with hepatic lesions but without clinical signs and would have also a prognostic value since it is generally believed that hepatic lesions will eventually cause liver failure and death. Such animals could be picked out by liver biopsy before clinical signs develop and be sent to slaughter, minimizing economic losses. This study was aimed to evaluate the liver biopsy as a diagnostic and prognostic tool in cases of Senecio spp. poisoning in cattle. An outbreak of Senecio brasiliensis was diagnosed in dairy calves which ingested hay contaminated by 5-10% of this Senecio species. Liver biopsy using a Menghini needle by right transthoracic approach was carried out in 135 calves that ingested the contaminated hay. Biopsed calves were followed up for 26 months after the biopsy. Seventeen biopsied calves had typical lesions of Senecio spp poisoning (positive calves) and 118 had histologically normal livers (negative calves). Hepatic lesions of positive calves included fibrosis, hepatomeglocytosis, and biliary hyperplasia. Fifteen out of the 17 positive calves died with typical clinical signs of Senecio spp poisoning within 17-149 days after the biopsy; 13 of those were necropsied and had typical gross and histopathological lesions of Senecio spp poisoning. Two positive calves were clinically normal at the end of the post-biopsy observation period. The prognostic value (sensibility) of the test was considered high since 88.23% of the positive calves died. The specificity of the test was considered very high (99.16%) since only one of the 118 negative calves died in the observation period. In none of the biopsed calves a negative effect related to the biopsy technique was observed.

Intoxicação por alcaloides pirrolizidínicos em ruminantes e equinos no Brasil

Casos de intoxicacao por alcaloides pirrolizidinicos (APs) em ruminantes e equinos foram investigados retrospectivamente atraves do acesso aos arquivos de dois laboratorios de diagnostico veterinario no Sul e Nordeste brasileiro. Os dados obtidos foram comparados com aqueles retirados da literatura concernentes a surtos dessa toxicose no Brasil, onde ela e associada com a ingestao de plantas que contem APs dos generos Senecio, Crotalaria e Echium. Formas aguda e cronica da toxicose foram encontradas. A doenca aguda foi observada em associacao com a ingestao de Crotalaria retusa em ovinos e caprinos. C. retusa e Senecio spp. tambem foram responsaveis pela intoxicacao cronica em bovinos, equinos e ovinos. A intoxicacao por APs e uma importante causa de morte em animais pecuarios no Brasil. Essa e a principal causa de morte em bovinos na regiao Central do Rio Grande do Sul e uma das principais causas de morte em equinos na Paraiba. A epidemiologia, os sinais clinicos, a patologia e a importância da intoxicacao por APs sao descritos e discutidos.

Achados de necropsia relacionados com a morte de 335 eqüinos: 1968-2007

The necropsy reports of 335 horses necropsied at the LPV-UFSM between 1968-2007 were reviewed in order to determine the necropsy findings related with cause of death or reason for euthanasia. The distribution of these findings by organ system were as follows: digestive (79/335 [23.6%]), striated muscle and skeleton (47/335 [14.0%]), nervous (37/335 [11.0%]), respiratory (35/335 [10.4%]), integument (31/335 [9.3%]), hematopoietic (24/335 [7.2%]), cardiovascular (13/335 [3.9%]), reproductive (12/335 [3.5%]), urinary (7/335 [2.1%]), and endocrine (3/335 [0.9%]). The cause of death was not possible to be determined in 47 (14.0%) necropsied horses. Displacements of the intestines (17/79 [21.5%]) were the main findings in digestive system, followed by obstruction and impactation (14/79 [17.7%]). Torsion were the type of displacement more frequently observed in the intestines (14/17 [82.4%]). Among those the more prevalent affected the small intestine (7/14 [50%]). Most horses dying from fractured bones were 1-5-year-old. The most prevalent diseases in the nervous system were leukoencephalo-malacia and trypanosomiasis, whereas respiratory depression due to anesthesia was the leading cause of death related to the respiratory system. Equine infectious anemia was the most diagnosed infectious disease and the main reason leading to euthanasia.