Remielinização em camundongos Knockout para conexina 32 desmielinizados experimentalmente

Este estudo visou avaliar o papel da conexina 32 (Cx 32) durante a remielinização no sistema nervoso periférico. Uma injeção local de 0,1% de solução de brometo de etídio foi realizada no nervo ciático de camundongos deletados para a Cx 32, com eutanásia dos animais aos 1, 2, 3, 7, 15, 21 e 30 dias pós-injeção. Avaliações histoquímicas, imunoistoquímicas, por imunofluorescência e por microscopia eletrônica de transmissão foram utilizadas na análise do desenvolvimento das lesões. Nos nervos ciáticos, células de Schwann mostraram inicialmente sinais de intoxicação e rejeitaram suas bainhas. Após sete dias, observaram-se finas bainhas neoformadas, com compactação desigual e alças redundantes (tomácula). Conclui-se que a regeneração de bainhas de mielina perdidas no SNP seguiu o padrão já relatado deste modelo em outras espécies de laboratório. Portanto, estes resultados sugerem que a ausência da Cx 32 não interferiu com o padrão normal de remielinização em camundongos jovens neste modeloThe aim of this study was to evaluate the role of connexin 32 (Cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1% ethidium bromide solution or saline in the sciatic nerve of Cx 32 knockout mice. Euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. Within the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. We concluded that the regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other laboratory species. Therefore, these results suggest that absence of Cx 32 did not interfere with the normal pattern of remyelination in this model in young miceCNPq 475029/2004-6Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Hepatocellular carcinoma associated with hepatocutaneous syndrome in a feline

Hepatocellular carcinoma (HCC) is a primary hepatobiliary neoplasm (PHN) originating in hepatocytes. It is rarely described in felines and represents 27% of the species' liver neoplasms. Patients may present emesis, anorexia, lethargy, weight loss, jaundice, coagulopathy, and hepatomegaly. This article aimed to report the case of a cat of no defined breed, approximately seven years old, with a crusted and hemorrhagic nasal injury, apathy, mild dehydration, a 2/9 body score, and mean systolic blood pressure of 187 mmHg. Abdominal ultrasound suggested renal senility and hepatomegaly, serum biochemistry indicated hyperphosphatemia and azotemia, and there was low urinary density with increased UPro/UCr. Amlodipine besylate was prescribed to control hypertension, and only after two months did the patient return, presenting cushion hyperkeratosis and a clot in the right nostril. The lesions were biopsied. The patient died three days after the procedure, and, at necropsy and histopathological analysis, there was a definitive diagnosis of HCC, presenting vacuolation in neoplastic hepatocytes under microscopy, superficial necrotic dermatitis (SND) in the nostril and cushions by parakeratotic hyperkeratosis on microscopy, and chronic kidney disease as comorbidity. The patient's clinical manifestation was consistent with that described in the literature. HCC is associated with an SND framework, a rare condition in cats.Hepatocellular carcinoma (HCC) is a primary hepatobiliary neoplasm (PHN) originating in hepatocytes. It is rarely described in felines and represents 27% of the species' liver neoplasms. Patients may present emesis, anorexia, lethargy, weight loss, jaundice, coagulopathy, and hepatomegaly. This article aimed to report the case of a cat of no defined breed, approximately seven years old, with a crusted and hemorrhagic nasal injury, apathy, mild dehydration, a 2/9 body score, and mean systolic blood pressure of 187 mmHg. Abdominal ultrasound suggested renal senility and hepatomegaly, serum biochemistry indicated hyperphosphatemia and azotemia, and there was low urinary density with increased UPro/UCr. Amlodipine besylate was prescribed to control hypertension, and only after two months did the patient return, presenting cushion hyperkeratosis and a clot in the right nostril. The lesions were biopsied. The patient died three days after the procedure, and, at necropsy and histopathological analysis, there was a definitive diagnosis of HCC, presenting vacuolation in neoplastic hepatocytes under microscopy, superficial necrotic dermatitis (SND) in the nostril and cushions by parakeratotic hyperkeratosis on microscopy, and chronic kidney disease as comorbidity. The patient's clinical manifestation was consistent with that described in the literature. HCC is associated with an SND framework, a rare condition in cats

Equine Lacrimal Gland Adenocarcinoma

Background: Lacrimal gland adenocarcinoma is an extremely rare malignant neoplasm, with few descriptions in the literature. Therefore, its etiology and treatment are not well understood. The present study aims to report the case of an equine histologically diagnosed with lacrimal gland adenocarcinoma in the lower eyelid region and third eyelid treated by surgical excision and intralesional chemotherapy. Case: A 17-year-old male mixed-breed equine weighing 300 kg was treated in the large animal clinic and surgery sector of the Federal University of Santa Catarina in the city of Curitibanos, Santa Catarina, Brazil. The equine revealed an alert and docile temperament without considerable physiological changes in the physical examination. In the evaluation of the right eye, a tumor mass was observed in the region of the lacrimal gland adhered to the third eyelid and lower eyelid, with a light red ulcerated appearance approximately 7 cm in diameter. Therefore, the surgical excision of the adhered tumor mass was performed, with the subsequent intralesional application of 2 mL of Vincristine Sulfate. In the histopathological evaluation following the surgical excision of the tumor mass, yellowish-white fragments of irregular nodules were observed measuring from 3.5×2.0×1.7 cm to 2.0×0.5×0.3 cm, in addition to microscopy focus clusters of weakly basophilic neoplastic glandular cells, some with a randomly arranged lacy aspect, forming disorganized acinar structures and others showed marking islands of the cells organized in a palisade shape by vascular delicate stroma. The neoplastic cells presented anisocytosis, anisokaryosis, prominent nucleoli sometimes binucleated and with basophilic intracytoplasmic secretory material, delimited by scarce connective tissue. In some areas, there were small foci of infiltrated lymphocytes and plasmocytes and areas of necrosis. The mass was surrounded by connective tissue, where red blood vessels were found outside the vessels (hemorrhage), and mitoses were observed two per field at high magnification (40x). After the surgical procedure, it was not possible to follow up and reassess of the patient, so there is no clarification on the possibility of tumor recurrence. Discussion: The case reported is uncommon, being only the second report of adenocarcinoma in the equine lacrimal gland. Therefore, there are few descriptions in the literature about its defined etiology and the best treatment method, although, surgical excision is the method of choice because it is a tumor of high recurrence and invasiveness. In this case, we opted for the exeresis of the tumor mass and later application of chemotherapy, a treatment that was relatively effective, to avoid recurrence and the failure of the technique. In these cases, monitoring the animal after the procedure is recommended, evaluating whether there was tumor recurrence, although this was not possible in the present possible. The third eyelid, lacrimal, and zygomatic salivary glands may be sources of intraorbital neoplasms. These neoplastic processes may have similar histological and behavioral characteristics, and their differentiation is, therefore, problematic. These structures may be differentiated based on the anatomical location, however, clinical appearance and symptoms are identical in most cases. Adenocarcinoma in the equine lacrimal gland is a neoplasm considered rare, so it is important to emphasize an accurate diagnosis through histopathological analyses to differentiate it from other frequent orbital neoplasms in horses, allowing more information about this tumor and establishing different treatment methods. Keywords: adenocarcinoma, tumor, equine, histopathology. Título: Adenocarcinoma em glândula lacrimal de equino Descritores: adenocarcinoma, tumor, equino, histopatologia

Oral squamous cell carcinoma with bone invasion in two dogs - case report

Squamous cell carcinoma (SCC) is the third most prevalent tumor in the oral cavity of dogs with middle to advanced age. This report describes the cases of dogs aged 8 and 13 years. The first animal presented sialorrhea with blood, hyporexia, emaciation, hypocorned mucous membranes, enlarged right submandibular lymph node, and, in the oral cavity, intense halitosis and nodosity in the right maxillary antimer, which was friable, blackened, adhered, and hemorrhagic, starting in the soft palate and infiltrating the hard palate. There was hypochromic microcytic anemia with the presence of anisocytosis and Heinz corpuscles, as well as thrombocytopenia, macroplatelets, leukocytosis due to neutrophilia, monocytosis with the presence of toxic neutrophils, and hyperproteinemia with hypoalbuminemia, decreased ALT, and urea. The patient underwent surgery to remove the nodule but returned for euthanasia days later due to aggressive tumor recurrence. The second animal presented masticatory dysphagia, anorexia, hypocorned mucous membranes, capillary filling time greater than 2 seconds, blowing in the mitral and tricuspid valves, and firm elevation in the lower part of the right mandible in the caudal mentonian region. Additional tests showed erythrocytosis, polychromasia, thrombocytosis, platelet aggregation, macro platelets, and increased ALT. Ultrasound examination showed renal alterations compatible with senile degeneration and/or nephropathy, nodulations in the spleen, prostate, and left testicle, and enlargement of the right adrenal gland. Initial anti-inflammatory and analgesic treatment was instituted, but he died. Necropsy and the histopathological examination of the animals showed a diagnosis of SCC with bone invasion, the latter being an uncommon fact.Squamous cell carcinoma (SCC) is the third most prevalent tumor in the oral cavity of dogs with middle to advanced age. This report describes the cases of dogs aged 8 and 13 years. The first animal presented sialorrhea with blood, hyporexia, emaciation, hypocorned mucous membranes, enlarged right submandibular lymph node, and, in the oral cavity, intense halitosis and nodosity in the right maxillary antimer, which was friable, blackened, adhered, and hemorrhagic, starting in the soft palate and infiltrating the hard palate. There was hypochromic microcytic anemia with the presence of anisocytosis and Heinz corpuscles, as well as thrombocytopenia, macroplatelets, leukocytosis due to neutrophilia, monocytosis with the presence of toxic neutrophils, and hyperproteinemia with hypoalbuminemia, decreased ALT, and urea. The patient underwent surgery to remove the nodule but returned for euthanasia days later due to aggressive tumor recurrence. The second animal presented masticatory dysphagia, anorexia, hypocorned mucous membranes, capillary filling time greater than 2 seconds, blowing in the mitral and tricuspid valves, and firm elevation in the lower part of the right mandible in the caudal mentonian region. Additional tests showed erythrocytosis, polychromasia, thrombocytosis, platelet aggregation, macro platelets, and increased ALT. Ultrasound examination showed renal alterations compatible with senile degeneration and/or nephropathy, nodulations in the spleen, prostate, and left testicle, and enlargement of the right adrenal gland. Initial anti-inflammatory and analgesic treatment was instituted, but he died. Necropsy and the histopathological examination of the animals showed a diagnosis of SCC with bone invasion, the latter being an uncommon fact

Feline plasm cell pododermatitis: case report

Feline Plasmacytic Pododermatitis is an uncommon dermatological disorder that affects one or multiple paw pads and leads to swelling, ulceration, hemorrhage, scaling, erythema, and striation. Its etiopathogenesis is poorly understood, however, an immune-mediated basis is strongly suggested. A two-year-old neutered, mixed breed, male cat was referred to the Veterinary Clinic of the Federal University of Santa Catarina (UFSC), Curitibanos Campus, with a brief clinical history of progressive lesions on palmar and plantar pads for one month. On physical examination, the patient had enlarged popliteal and inguinal lymph nodes, and paw pads with thin, swollen, hyperemic, erythematous, and purple color skin with multiple white striations. Histopathological diagnosis confirmed plasmacytic pododermatitis, and glucocorticoid therapy with prednisolone was prescribed. In the present report, the patient's clinical follow-up was compromised, as the tutor did not perform the prescribed treatment and did not return with the animal for further evaluations. &nbsp

Equine Podotrochlear Apparatus - Histologic Characterization

Background: The navicular syndrome may be associated with alterations in other podotrochlear apparatus components, such as the deep digital flexor tendon, collareral sesamoid and distal sesamoid ligaments, podotrochlear bursa and distal sesamoid bone. However, the clinical significance and nature of these changes are not well understood, many of descriptive reports about distal sesamoid bone lesions are rarely accompanied by a complete and comprehensive comparison with animals of the control group. The aim of this study was to described histologically findings of the podrotrochlear apparatus components, allowing the understanding of the inserts and their microscopic appearance, thus providing the future recognize of their alterations.Materials, Methods & Results: Fourteen samples of the podotrochlear apparatus were taken out of 44 equine thoracic limbs specimens, separated at the radiocarpal joint of Crioulo and Thoroughbred horses, with an average age of 6.0-year-old, coming from a private clinic in southern Brazil. The thoracic limbs specimens were refrigerated at 4ºC at the clinic and then they were sent to the University Federal of Santa Maria (UFSM). Once at the University laboratory, the specimens were dissected to isolate the podotrochlear apparatus from each one.  Subsequently, transversal and longitudinal samples from the distal sesamoid bone, deep digital flexor tendo,             distal sesamoid ligament, colateral sesamoid ligament, were collected and podotrochlear            bursa which were processed at the Veterinary Pathology Laboratory of the UFSM and University Federal of Santa Catarina (UFSC). The tissues samples were fixed in a 10% formaldehyde solution for 14 days and routinely processed for histology. The samples were sectioned at 3 µm and stained using the hematoxylin-eosin (H-E) routine method. The bone samples, after fixation, underwent a decalcified process in a formic acid-sodium citrate aqueous solution and routinely processed for histopathology. Histologic tendons evaluation showed that it is arranged in honeycombs fascicles in a transverse section observation. The tendinous fibers have a more compact and aligned collagen fibers arrangement due to the dense connective tissue. The synovial membrane of the podotrochlear bursa is composed of a cubic pseudo conjunctival epithelium arranged with a layer of synoviocytes forming villi towards the lumen. This characterization is very similar to that of the synovial joint membrane. The collateral sesamoid ligament fibers are not perfectly aligned, occurring at their confluence in some areas accompanied by the dissection of adipose tissue. The distal sesamoide ligament fibers, composed by of loose connective tissue associated with synoviocytes and vascular stroma. The articular surface of the distal sesamoid bone is arranged in 3 layers of chondrocytes embedded in a hyaline matrix. There was a clear differentiation between the subchondral bone area and the fibrocartilage tissue in the palmar aspect of the distal sesamoid bone.Discussion: The morphophysiological characterization of the podotrochlear structures inside the hoof capsule it is important for the future recognition of abnormalities and the possible hypothesis that originates the podotrochlear syndrome. These changes have great clinical relevance and very often associated of distal limb lameness in horses. The normal macroscopic, ultrasonographic and radiographic images along with the histomorphometric study of the podotrochlear structures have contributed for the morphophysiological comprehension and consequently future interpretation of the podotrochlear structures diseases.Keywords: podotrochlear apparatus, distal sesamoide bone, deep digital flexor tendon, navicular syndrome, histological findings

Carcinoma mamário misto em porquinho-da-Índia (Cavia porcellus)

Background: Thirteen mammary neoplasms types are described in Cavia porcellus in the literature. Among these, the most prevalent are the benign and spontaneous neoplasms (70%), between the malignant stand out the adenocarcinomas (majoritary), tubular and tubulopapillary, however, when it comes to mixed carcinomas, despite being rare, they present greater malignancy. The present study aims to report the case of a guinea pig cytologic and histologically diagnosed with mammary gland mixed carcinoma treated by surgical excision. Case: A 1-year-old female Abyssinian guinea pig weighing 1.1 kg was treated at the Wild and Exotic Animal Sector of the Federal University of Santa Catarina (UFSC)in the city of Curitibanos, SC, Brazil. The patient revealed an alert and docile temperament without considerable physiological changes in the physical examination. The patient presented a mass, measuring 1.4 x 1.6 cm with a nodular appearance, firm consistency and not adhered in the region of the left inguinal mammary gland. A sample was collected by fine needle aspiration biopsy technique (FNAB), which revealed to be suggestive of malignant neoplasm from epithelial tissue, due observation of presence of 3-dimensional clusters of epithelial cells, with discrete anisocytosis and anisokaryosis. In 7 days, the nodule showed gradual and progressive growth, measuring 2.0 x 1.6 cm. Radiographs were taken in order to rule out the presence of metastases in other organs and systems. The suitable treatment was surgical excision of the nodule and mammary gland, which occurred without intercurrences, and the material was sent for histopathological analysis. On the day of the surgical procedure, the nodule measured 2.4 x 1.6 cm. As a result, it was noted the rupture of tubules, isolated cells or forming nests in the middle of the stroma composed mainly of myoepithelial cells and adipocytes and presence of lymphoplasmacytic and neutrophilic infiltrate, compatible with mixed mammary gland carcinoma in a grade I. After 10 days of the procedure, the patient was released healthy and weighing 1.18 kg. Due to the absence of metastasis was not indicated post-surgical chemotherapy, however it was proposed ovariohysterectomy in order to prevent recurrence. So far, there has been no sign of recurrence or development of metastases in the patient. Discussion: In fact, guinea pig mammary neoplasms are locally invasive, large in size and highly vascularized, but they rarely metastasize, and there is no sexual predisposition. An important characteristic of the guinea pigs neoplasms is the fast growth that can be associated with the accelerated metabolism in these animals. Diagnostic methods such as FNAB are important to differentiate non-neoplastic from neoplastic processes, as mastitis or mammary hyperplasia. However, the cytologic appearance may vary greatly depending on the type of neoplasm, thus the histopathology provides the definitive diagnosis. Surgical excision is the treatment of choice, once these animals are poorly tolerant to chemotherapy. The adoption of measures, as ovariohysterectomy, can help the treatment or prevention of mammary neoplasms, although the tutor refutes the indication in this case. On the other hand, there is a still gap in the knowledge of neoplasms in guinea pig, making studies allow us to understand the pathophysiology of these diseases in this specie. Keywords: mammary carcinoma, mammary gland, neoplasm, guinea pig. Título: Carcinoma mamário misto em porquinho-da-Índia (Cavia porcellus) Descritores: carcinoma mamário, glândula mamária, neoplasia, porquinho-da-índia.Introdução: Treze tipos de neoplasias mamárias são descritos na literatura em Cavia porcellus. Dentre estes, os mais prevalentes são as neoplasias benignas e espontâneas (70%), entre os malignos destacam-se os adenocarcinomas (majoritários), tubulares e tubulopapilares, porém, quando se trata de carcinomas mistos, apesar de raros, apresentam maior malignidade. O presente estudo tem como objetivo relatar o caso de um porquinho da índia (PDI) com diagnóstico citológico e histológico de carcinoma misto de glândula mamária tratado por excisão cirúrgica. Caso: Foi atendida no setor de animais silvestres e exóticos da Universidade Federal de Santa Catarina na cidade de Curitibanos, Santa Catarina, Brasil, um PDI Abissínio, fêmea, com 1 ano de idade, pesando 1,1 kg. A paciente revelou temperamento alerta e dócil, sem alterações fisiológicas consideráveis ao exame físico. A paciente apresentava massa medindo 1,4 x 1,6 cm de aspecto nodular, consistência firme e não aderida em região de glândula mamária inguinal esquerda. Foi coletada amostra pela técnica de punção aspirativa com agulha fina (PAAF), que se revelou sugestiva de neoplasia maligna de tecido epitelial, pela observação da presença de aglomerados tridimensionais de células epiteliais, com discreta anisocitose e anisocariose. Em sete dias, o nódulo apresentou crescimento gradual e progressivo, medindo 2,0 x 1,6 cm. Radiografias foram realizadas para descartar a presença de metástases em outros órgãos e sistemas. O tratamento indicado foi a excisão cirúrgica do nódulo e da glândula mamária, que ocorreu sem intercorrências, sendo o material enviado para análise histopatológica. No dia do procedimento cirúrgico, o nódulo media 2,4 x 1,6 cm. Como resultado, notou-se ruptura de túbulos, células isoladas ou formando ninhos no meio do estroma composto principalmente por células mioepiteliais e adipócitos e presença de infiltrado linfoplasmocítico e neutrofílico, compatível com carcinoma misto de glândula mamária grau I. Após 10 dias do procedimento, a paciente apresentou-se hígida e pesando 1,18 kg, recebendo alta médica. Devido à ausência de metástase não foi indicada quimioterapia pós-cirúrgica, porém foi proposta a ovariohisterectomia a fim de prevenir a recidiva. Não houve nenhum sinal de recorrência ou desenvolvimento de metástases no paciente, até o momento. Discussão: De fato, as neoplasias mamárias em PDI são localmente invasivas, grandes e altamente vascularizadas, mas raramente metastatizam e não há predisposição sexual. Uma característica importante das neoplasias PDI é o crescimento rápido que pode estar associado ao metabolismo acelerado desses animais. Métodos diagnósticos como PAAF são importantes para diferenciar processos não neoplásicos de neoplásicos, como mastite ou hiperplasia mamária. No entanto, o aspecto citológico pode variar muito dependendo do tipo de neoplasia, portanto a histopatologia fornece o diagnóstico definitivo. A excisão cirúrgica é o tratamento de escolha, uma vez que esses animais são pouco tolerantes à quimioterapia. A adoção de medidas, como a ovariohisterectomia, pode auxiliar no tratamento ou prevenção de neoplasias mamárias, embora o tutor tenha refutado a indicação neste caso. Por outro lado, ainda existe uma lacuna no conhecimento das neoplasias em cobaias, fazendo com que estudos nos permitam entender a fisiopatologia dessas doenças nessa espécie

Degeneração mixomatosa valvar em cães: um estudo retrospectivo

Artigo apresentado na forma de "banner" na Primeira Mostra Científica e Tecnológica da UFSC CuritibanosA Degeneração Mixomatosa Valvar (DMV), anteriormente conhecida como endocardiose, é uma patologia que acomete as válvulas cardíacas de diversas espécies, principalmente cães. Durante a necropsia, na análise macroscópica, as válvulas acometidas apresentam-se encurtadas e espessas de forma focal ou difusa, também apresentam-se lisas e brilhantes. Já na análise microscópica observa-se a proliferação de miofibroblastos, componente das valvas cardíacas, com deposição de mucopolissacarídeos ácidos. Os animais que apresentam essa patologia, inicialmente apresentam-se assintomáticos, devido aos processos compensatórios do organismo como sistema renina-angiotensina-aldosterona. Por ser de caráter crônico, com o avançar da idade, o animal pode apresentar sinais clínicos e se não for devidamente tratado o animal pode vir à óbito por insuficiência cardíaca. No laboratório de patologia veterinária foram necropsiados 1228 animais no período de janeiro de 2014 a março de 2020, desses animais 451 eram cães. Do total de cães, 19,95% (90/451) apresentaram alguma válvula acometida pela DMV. Os principais dados obtidos destes animais foram idade, sexo, raça, porte e, a (s) valva (s) acometida (s). O objetivo deste trabalho é verificar se a população canina estudada apresenta características de DMV quanto a idade, sexo, raça, porte e valva acometidos, condizentes ou divergentes em relação à literatura

Comparación fotomicrográfica de fibras de colágeno equino de la inserción proximal del músculo interóseo III

O objetivo do presente trabalho foi comparar quantitativamente as fibras colágenas tipo I e tipo III pela avaliação histológicas da inserção proximal de músculo interósseo terceiro (I.P.M.I III) de equinos das raças Crioulo (n=26) e Puro Sangue de Corrida (n=6), hígidos com idade média de 5,7 anos. As lâminas foram coradas pelo método picrosirius red e examinadas em microscópio óptico sob luz polarizada. De cada lâmina foram capturadas imagens de 5 campos em aumento de 10 vezes. A porcentagem da área ocupada por cada tipo de colágeno foi determinada pelo plugin threshold colour do software Image J, por meio de análise da segmentação de cor. Pela análise da variância, a proporção de colágenos tipo I e tipo III na I.P.M.I III não diferiu significativamente entre as amostras das raças avaliadas. Entretanto, houve diferença significativa entre os dois tipos de colágeno numa mesma raça, de forma que o colágeno tipo I prevaleceu em relação ao tipo III. Ainda que possuam predisposições distintas, não houve diferença significativa na quantidade de colágeno entre a raça Crioulo e Puro Sangue de Corrida, por se tratar da mesma espécie em questão. Contudo a diferença significativa entre os colágenos tipo I e III era prevista, uma vez que a quantidade do colágeno original do tecido, tipo I deve ser maior que o colágeno de remodelação, tipo III nos casos em que se tratam de animais hígidos.The aim of this study was to quantitatively compare type I and type III collagen fibers in histological evaluation of the proximal insertion of the third interosseous muscle (P.I.I.M III) of healthy Crioulo (n=26) and Thoroughbred (n=6) horses, with a mean age of 5.7 years. The histological sections were stained with picrosirius red and examined under an optical microscope under polarized light. Images of 5 fields were captured from each slide at 10x magnification. The percentage of the area occupied by each type of collagen was determined by the threshold color plugin of the Image J software, through analysis of the color segmentation. Nevertheless, the analysis of variance is not demonstrating the significantly variations of the proportion of type I and type III collagen in I.P.M.I III of the evaluated breeds. However, there was a significant difference between the two types of collagens in the same breed, because that type I collagen prevailed over the type III.El objetivo de este estudio fue comparar cuantitativamente las fibras de colágeno tipo I y tipo III a través de la evaluación histológica de la inserción proximal del tercer músculo interóseo (I.P.M.I III) de caballos Criollos (n=26) y Pura Sangre de Carrera (n=6) sanos. con edad media de 5,7 años. Las coloraciones de las secciones histológicas se hicieron con picrosirius red y se examinaron al microscopio óptico con luz polarizada. Se capturaron imágenes de 5 campos de cada sección con un aumento de 10x. El porcentaje del área ocupada por cada tipo de colágeno se determinó mediante el complemento threshold colour del software Image J, mediante el análisis de la segmentación del color. Por análisis de varianza, la proporción de colágeno tipo I y tipo III en I.P.M.I III no difirió significativamente entre las muestras de las razas evaluadas. Sin embargo, hubo una diferencia significativa entre los dos tipos de colágeno en la misma raza, por lo que prevaleció el colágeno tipo I sobre el tipo III. Aunque, tienen distintas predisposiciones raciales, no hubo diferencia significativa en la cantidad de colágeno entre las razas Criolla y Pura Sangre de Carrera, ya que se trata de la misma especie. Se predijo la diferencia significativa entre el colágeno tipo I y III, ya que la cantidad de colágeno tisular original, tipo I, debe ser mayor que el colágeno remodelador, tipo III en los casos en que los animales están sanos