Taiara M. da Silva

Ocorrência de micoses e pitiose em animais domésticos: 230 casos

A retrospective study was performed to determine the main mycoses and oomycosis that affected domestic animals diagnosed in the Laboratorio de Patologia Veterinaria (LPV) of the Universidade Federal de Santa Maria (UFSM). A total of 29,686 exams (9,487 necropsy reports and 20,199 biopsy reports) performed between January 1990 and December 2012 were analyzed. Two hundred and thirty cases (78% of mycoses and 22% of pythiosis) were found. Data about epidemiology, clinical signs, gross and histologic lesions were obtained from the reports. In two cases the fungi observed were not identified. The main diseases observed, in descending order of prevalence, were: pythiosis, candidiasis, aspergillosis, zygomycosis, dermatophytosis, mallasseziosis, cryptococcosis, megabacteriosis, and sporothrichosis. Others diseases with only one cases each were histoplasmosis and pneumocystosis. Pythiosis affected mainly horses and the mycosis affected mainly companion animals (dogs and cats).

Occurrence of tumours metastatic to bones and multicentric tumours with skeletal involvement in dogs.

The skeletons of 110 dogs with malignant tumours of different origins were examined by necropsy examination over a 3-year period to identify bone metastases. Twenty-one cases of metastatic or multicentric tumours with bone involvement were recorded. In general, more female dogs presented with bony metastases; however, when the dogs with mammary tumours were omitted, the gender distribution of the cases was approximately equivalent. The mammary gland was the primary site of most of the metastatic bone lesions, followed by the musculoskeletal system and the respiratory system. The majority (77%) of metastases were grossly visible and present in multiple bones. However, in 23% of the cases, the metastases could be diagnosed only at the microscopical level. The vertebrae and the humerus were the most frequently affected bones regardless of the primary site and the histogenesis of the tumours. The results of this study revealed a high prevalence of bone metastases and/or bone involvement in dogs with multicentric tumours.

Doenças de caprinos diagnosticadas na região Central no Rio Grande do Sul: 114 casos

A retrospective study of the goat necropsies performed over a period of 48 years (1964 to 2011) at the Laboratorio de Patologia Veterinaria, Universidade Federal de Santa Maria, Rio Grande do Sul (RS) state, Brazil, was performed. A total of 114 reports of goat necropsies were analyzed. Ninety five necropsies (83.33%) had a conclusive diagnosis and 19 (19.66%) had inconclusive diagnosis. Out of the conclusive cases, infectious and parasitary diseases were the most prevalent, followed, in decreasing order of prevalence, by metabolic and nutritional diseases, poisonings and toxi-infections, and developmental diseases. Other conditions or lesions that did not fit any of the above groups of diseases affected about 10% of the necropsied goats. Hemonchosis was the most prevalent cause of death in this study. Eimeriosis and listeriosis were also important causes of goat deaths. Among the metabolic and nutritional diseases, urolithiasis, osteoporosis, pregnancy toxemia, malnutrition, and white muscle disease were the most prevalent. Mostly the infectious and parasitary diseases and the metabolic and nutritional diseases occurred many times as outbreaks, causing even more important economic losses.

Primary bone neoplasms in dogs: 90 cases

A retrospective study of necropsy and biopsy cases of 90 primary bone tumors (89 malignant and one benign) in dogs received over a period of 22 years at the Laboratorio de Patologia Veterinaria, Universidade Federal de Santa Maria, was performed. Osteosarcoma was the most prevalent bone tumor, accounting for 86.7% of all malignant primary bone neoplasms diagnosed. Most cases occurred in dogs of large and giant breeds with ages between 6 and 10-years-old. The neoplasms involved mainly the appendicular skeleton, and were 3.5 times more prevalent in the forelimbs than in the hindlimbs. Osteoblastic osteosarcoma was the predominant histological subtype. Epidemiological and pathological findings of osteosarcomas are reported and discussed.

Características histomorfológicas e histoquímicas determinantes no diagnóstico da criptococose em animais de companhia

Seven cases of cryptococosis (six cats and one dog) were studied to establish the determining histomorphological and histochemical characteristics in the histopathological diagnosis of this condition. Additional data related to the epidemiology, clinical aspects, sites of the lesions, and gross findings were obtained from the necropsy and biopsy protocols. Histologically, yeasts were observed inside macrophages or free in the parenchyma, associated with scarse to severe lymphohistioplasmacytic inflammatory reaction. In the hematoxylin-eosin (HE) sections, the yeasts were round, with a central cell containing a nucleus, surrounded by a clear halo (usually non-stained capsule). The techniques of periodic Schiff acid (PAS), Groccot (GMS), and Fontana-Masson (FM) were utilized and demonstrated the wall of the yeast cells. The FM stain showed the melanin present in these cells. The Alcian blue and Mayers mucicarmin stains showed mainly the yeast polysaccharide capsule. The diameter of the cells ranged from 1.67 to 10.00µm and the full diameter of the encapsulated yeasts varied between 4.17 e 34.16µm. Yeast buddings were better observed through the PAS stain and were narrow based, simple or multiple, mainly in the opposite poles of the cells or forming chains. The definitive diagnosis of cryptococosis was established through the histopathological exam, based on the specific morphology of the agent (encapsulated yeast) and on histochemical proprieties, mostly in the cases without fungal culture.

Aspectos epidemiológicos, clinicopatológicos e imuno-histoquímicos de carcinomas de células escamosas vulvares em 33 vacas

Vulvar squamous cell carcinomas (VSCCs) in cattle were retrospectively studied regarding the prevalence, epidemiology, clinicopathological, and immunohistochemical aspects. The degree of vulvar pigmentation was also evaluated. In the 48 years analyzed, necropsy and biopsy reports of 7,483 cattle were found. Out of these, 664 (8.87%) cases of various neoplasms were identified; 33 (4.97%) of these cases were of VSCCs. Nineteen cows were Holstein, three were Charolais, one was Jersey, and 10 were mix breed cows. Grossly, the main change was vulvar swelling, with bleeding and concomitant myiasis. The tumor masses were firm, ulcerated and with yellow areas. It was possible to reevaluate microscopically 30 out of the 33 cases. Eight of them were well differentiated, 17 were moderately differentiated, and five were poorly differentiated VSCCs. The evaluation of squamous intraepithelial lesions (SILs) was performed in 21 cases. Epithelial hyperplasia was observed in 10 cases, mild dysplasia in two, moderate in one, and severe in five cases; in three cases no SILs were observed. Fontana-Masson stain for melanin was performed in 21 cases. In 17 cases the epidermal pigmentation was absent; it was mild in two and moderate in other two cases. Independently of the degree of differentiation, most neoplastic keratinocytes were strongly positive for bovine pancytokeratine through the immunohistochemistry (IHC) technique. Bovine papillomavirus was not detected by IHC in this study.

Osteopatia hipertrófica em sete cães

Clinical and pathological aspects of hypertrophic osteopathy in seven dogs were studied. Affected dogs had clinical signs of bone involvement and lesions mainly in the long bones of the limbs. The lesions consisted of periosteal new bone formation detected on radiographic examination, inspection of bones during the necropsy, and with great detail, in macerated bone specimens. The bone proliferation observed was partially circumferential and occurred mainly in the diaphysis of long bones. It consisted of bone trabeculae of irregular size and thickness that were arranged perpendicularly to the original bone cortex. In all cases the lesions were associated with lung neoplasms (primary or metastatic).

Chemically induced disseminated pythiosis in BALB/c mice: A new experimental model for Pythium insidiosum infection

Pythiosis is a severe and life-threatening disease that affects humans and various animal species. We report a model of vascular/disseminated pythiosis occurring after subcutaneous inoculation of 2 x 104 Pythium insidiosum zoospores/mL in immunocompromised BALB/c mice. For this model, we carried out two rounds of experiments. First, we evaluated two protocols of immunosuppression before inoculation: cyclophosphamide at 150 mg/kg (CYP group) and cyclophosphamide 200 mg/kg plus hydrocortisone acetate at 250 mg/kg (CYP+HCA group). It was not possible to obtain mortality in the CYP group; however, the combination of CYP+HCA altered disease outcomes, with mortality rates reaching 60%. Second, we used the CYP+HCA immunosuppression protocol to analyze the histological and immunological statuses triggered by disease. When we inoculated immunocompetent mice with P. insidiosum zoospores, self-healing occurred via increased levels of IL-2, IFN-γ and IL-17A, which are characteristic of the Th1/Th17 cytokine response. For infected and immunosuppressed mice, the cytokine profiles showed high levels of IL-10, IL-6 and TNF-α. Increased IL-10 values are related to fungal infection susceptibility and led us to speculate that infection may be established through suppression of the host immune response. In addition, histopathological evaluation of the kidneys and liver demonstrated the presence of hyphae and the cellular findings suggested an acute vascular inflammation that mimics vascular/disseminated pythiosis in humans. This is the first murine model for pythiosis that is useful both for understanding the pathogenesis of this disease and for evaluating new treatment approaches.

Utilização de três métodos imuno-histoquímicos na detecção de aspergilose e zigomicose em animais

Aiming to optimize the usage of the immunohistochemical technique (IHC) in the detection of Aspergillus spp. and zygomycetes (members of the Mucoraceae family), two fungal-specific monoclonal antibodies were used in tissue fragments (formalin-fixed paraffin-embedded), previously diagnosed by histomorphology as aspergillosis and zygomycosis. Tissues were submitted to three different detection systems (two biotinilated and one non biotinilated). Both antibodies showed high specificity and sensitivity in the examined tissues. No cross-reactions were observed between the antibodies used and the agents evaluated (including cases of aspergillosis, zygomycosis, candidiasis and pythiosis). However, nonspecific reactions in hyphae were observed in some cases, but were eliminated by mean of one of the detection systems used. In the aspergillosis cases, with the streptavidin-biotin-alkaline phosphatase method, nonspecific reactions were not observed. In the zygomycosis cases, nonspecific reactions did not occur using a polymer (nonbiotinilated). The IHC technique showed to be a useful tool detecting and confirming aspergillosis and zygomycosis in this retrospective study.

Osteoporose em caprinos

A study of cases of osteoporosis in goats diagnosed in the Laboratorio de Patologia Veterinaria, Universidade Federal de Santa Maria, Rio Grande do Sul state, Brazil, was performed. The epidemiology, clinicopathological changes and possible pathogenetic mechanisms were determined and discussed. Five goats, females, mixed breed, with six months to six years of age were affected. The goats were kept on natural pasture without supplemental feed and under overcrowding condition. The main clinical signs were weight loss, limited mobility, and recumbence for long periods. The main gross bone changes, observed on the cutting surface, were depletion of cancellous bone (porosity) and marked reduction in the thickness of the cortical bone. Severe serous atrophy of medullary adipose tissue was also observed. Microscopically, in the evaluated regions (proximal humerus, distal radius, distal femur, proximal tibia and lumbar vertebral bodies), moderate to marked reduction in the number and thickness of bone trabeculae in the epiphyses and metaphyses of long bones and in the vertebral bodies were observed. The clinicopathological features indicated that the osteoporosis observed was probably caused by malnutrition. The bone changes (decrease in the number and thickness of trabeculae of cancellous bone) suggest that both mechanisms, poor bone formation and increased bone resorption, contributed to the occurrence of osteoporosis in the goats of this study.