Disseminated sarcocystosis in a cat with lymphosarcoma

Cysts of the protozoan Sarcocystis sp were found in skeletal and cardiac musculature in a 1.5-year-old cat with lymphosarcoma. The cat was FeLV-positive and had grossly visible neoplastic involvement of the spinal cord, mediastinum, bone marrow, and kidneys. Ultrastructural examination of the parasitic cyst wall suggested that the species in this case was different from that described in the only other reported case. It was hypothesized that immunosuppression from FeLV infection permitted an aberrant life cycle with encystment of Sarcocystis sp in this cat.     

Malignant melanoma involving the aorta in a dog

A four year old female Siberian husky presented with shifting hind limb lameness was euthanized and found to have disseminated malignant melanoma without oral, cutaneous or ocular involvement. The largest and possibly primary mass involved the aorta and sublumbar muscles and occluded as well as penetrated the aorta. Numerous smaller tumors were present in skeletal and soft tissues of both hind limbs, suggesting hematogenous spread from the aortic lesion.     

Immunohistochemical identification and fiber type specific localization of protein kinase C isoforms in equine skeletal muscle

OBJECTIVE: To investigate whether protein kinase C (PKC) isoforms are expressed in equine skeletal muscle and determine their distribution in various types of fibers by use of immunofluorescence microscopy. ANIMALS: 5 healthy adult Dutch Warmblood horses. PROCEDURE: In each horse, 2 biopsy specimens were obtained from the vastus lateralis muscle. Cryosections of equine muscle were stained with PKC isoform (alpha, beta1, beta2, delta, epsilon, or zeta)-specific polyclonal antibodies and examined by use of a fluorescence microscope. Homogenized muscle samples were evaluated via western blot analysis. RESULTS: The PKC alpha, beta1, beta2, delta, epsilon, and zeta isoforms were localized within the fibers of equine skeletal muscle. In addition, PKC alpha and beta2 were detected near or in the plasma membrane of muscle cells. For some PKC isoforms, distribution was specific for fiber type. Staining of cell membranes for PKC alpha was observed predominantly in fibers that reacted positively with myosin heavy chain (MHC)-IIa; PKC delta and epsilon staining were more pronounced in MHC-I-positive fibers. In contrast, MHC-I negative fibers contained more PKC zeta than MHC-I-positive fibers. Distribution of PKC beta1 was equal among the different fiber types. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that PKC isoforms are expressed in equine skeletal muscle in a fiber type-specific manner. Therefore, the involvement of PKC isoforms in signal transduction in equine skeletal muscle might be dependent on fiber type.     

Nuclear medical bone imaging and targeted radiography for evaluation of skeletal neoplasms in 23 dogs

Nuclear medical bone imaging was used in combination with targeted radiography to detect metastatic or multicentric lesions in 23 dogs with skeletal neoplasms. Each dog with a radiographically diagnosed skeletal neoplasm was injected with Technetium-99m labeled methylene diphosphonate (99mTc-MDP) (15.0 mCi intravenously) for whole body imaging. All areas with increased uptake of 99mTc-MDP were radiographed. In 19 dogs, the amount of bone shaft involvement in primary sites indicated by bone imaging was larger than the amount indicated by radiography. Eighteen dogs had secondary areas of increased 99mTc-MDP uptake, six of which had secondary areas that were suspected radiographically to be neoplastic. Four dogs had lesions characterized histologically as neoplasia, one as bone infarction and one as normal cortical bone. Positive predictive value for this strategy was 66.7%. Results of this study suggest that nuclear medical bone imaging with targeted radiography is a quick, noninvasive technique with a good positive predictive value for evaluation of the skeleton for metastatic or multicentric sites of neoplasia.     

Acute myelomonocytic leukemia with neurologic manifestations in the dog

A dog was presented with mandibular paralysis, photophobia, and diffuse atrophy of the cranial skeletal muscles. Physical examination also revealed glossal paralysis, reduction of the swallowing reflex, reduction of the pupillary light response, and generalized lymphadenopathy. Cytologic and ultrastructural examinations of blood films, bone marrow, and lymph node aspirates were consistent with acute myelomonocytic leukemia. Post-mortem examination revealed extensive, multisystemic neoplastic infiltration with marked involvement of the central and peripheral nervous systems, especially the cranial and lumbar spinal nerves and associated ganglia. Neurologic manifestations are unusual in acute myelomonocytic leukemia in the dog.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA

A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules.     

Nuclear Medical Bone Imaging and Targeted Radiography for Evaluation of Skeletal Neoplasms in 23 Dogs

Nuclear medical bone imaging was used in combination with targeted radiography to detect metastatic or multicentric lesions in 23 dogs with skeletal neoplasms. Each dog with a radio-graphically diagnosed skeletal neoplasm was injected with Technetium-99m labeled methylene diphosphonate (^99mTc-MDP) (15.0 mCi intravenously) for whole body imaging. All areas with increased uptake of ^99mTc-MDP were radiographed. In 19 dogs, the amount of bone shaft involvement in primary sites indicated by bone imaging was larger than the amount indicated by radiography. Eighteen dogs had secondary areas of increased ^99mTc-MDP uptake, six of which had secondary areas that were suspected radiographically to be neoplastic. Four dogs had lesions characterized histologically as neoplasia, one as bone infarction and one as normal cortical bone. Positive predictive value for this strategy was 66.7%. Results of this study suggest that nuclear medical bone imaging with targeted radiography is a quick, noninvasive technique with a good positive predictive value for evaluation of the skeleton for metastatic or multicentric sites of neoplasia.     

Enhanced myotoxicity and involvement of both type I and II fibers in monensin-tiamulin toxicosis in pigs

Simultaneous administration of monensin and tiamulin to pigs resulted in enhanced myotoxicity. Skeletal muscles of tongue, diaphragm and legs were preferentially affected, whereas the masseter, longissimus thoracis and cardiac muscles, including the left auricle, were spared. Histochemical examination revealed an involvement of both type I and II fibers of skeletal muscles.     

MULTICENTRIC LYMPHOSARCOMA IN A DOG WITH MULTIPLE-SITE SKELETAL INVOLVEMENT

In this report the authors describe an unusual clinical presentation of lymphosarcoma (LSA) in a dog. A 9-year-old, neutered male, Golden Retriever was presented with a primary complaint of sudden onset of tetraparesis. Routine survey radiographs revealed multiple-site bony lesions and the histology revealed a diagnosis of LSA with diffuse skeletal and soft tissue involvement. The dog responded poorly to medical management and was euthanized on day two due to poor prognosis. Malignant LSA of the bone is a rare extranodal clinicopathologic entity and presents both a diagnostic and therapeutic hurdle. Reports of this kind are sparse and currently no optimal treatment for this entity has been determined.     

Extraosseous osteosarcoma in a maned wolf (Chrysocyon brachyurus).

A 6-yr-old maned wolf (Chrysocyon brachyurus) was diagnosed with an extraosseous osteosarcoma on the lateral aspect of the right thigh. Antemortem radiography revealed a calcified mass with no skeletal involvement. The mass was excised, but visible regrowth of the tumor was evident within 5 wk. Histologic examination and immunohistochemistry, including staining for p53 tumor suppression gene protein, were performed on the excised mass. The maned wolf was euthanized 13 wk after the initial diagnosis. The neoplasm was located in a site commonly used for the delivery of intramuscular injections, including vaccinations. Although no definitive association can be made, it is worth noting this relationship, as vaccine-site neoplasias have been observed in other species, most notably the domestic cat (Felis domesticus).     

Osteosarcoma with multiple metastases and subcutaneous involvement in a rabbit (Oryctolagus cuniculus)

BACKGROUND: Osteogenic sarcomas are rare in rabbits, but cases involving the mandible, ribs, frontal bones, and tibia have been reported. OBJECTIVE: The purpose of this study was to describe the clinical and pathologic findings in a rabbit with osteosarcoma and multiple metastases with subcutaneous involvement. METHODS: A 1-year-old female Polish rabbit was evaluated for dysorexia, lameness, gait difficulties with the hind limbs, and the presence of 2 subcutaneous nodules, on the left thigh and in the dorsal region. A hard swelling was also present at the base of the tail. Radiographic findings revealed multiple abnormalities in several bones, which were more severe in the sacrococcygeal region and femur. Several areas of calcification involving the thorax and abdomen as well as skeletal muscles, also were noted. The thigh nodule was surgically removed, and cytologic and histologic evaluations were performed. Following the rabbit's death, postmortem radiographs were taken and necropsy was performed. Samples of tissues and organs, involved bone segments, and other subcutaneous nodules were collected and examined by cytology and histology. RESULTS: Both the subcutaneous nodules and the majority of tissues and organs contained neoplastic cells whose appearance was consistent with osteogenic sarcoma. CONCLUSION: Clinical, radiologic, and pathologic data supported a diagnosis of osteosarcoma with multiple metastases and subcutaneous involvement.     

Generalized steatitis associated with selenium deficiency and normal vitamin E status in a foal

A 7-month-old male Quarter Horse was examined because of severe cachexia, which had begun 2 months earlier. The foal was emaciated and weak despite an excellent appetite. Percutaneous biopsy revealed multiple areas of subcutaneous steatitis with mineralization. Radiography demonstrated calcification of the nuchal ligament. The foal died 9 days after admission. Necropsy revealed mineralized lesions throughout the fascial planes and adipose tissues of the thorax, abdomen, and skeletal muscles, with little to no involvement of muscular tissue. Serum magnesium, copper, and thyroxine concentrations were slightly lower than normal. The serum selenium concentration was unusually low. Renal selenium content was significantly lower (P less than 0.01) than that in similarly prepared sections of kidneys from 3 clinically normal ponies. Low dietary selenium intake was suspected as the cause of the problem.     

Disseminated hemangiosarcoma in the horse: 35 cases

Thirty-five cases of disseminated hemangiosarcoma (21 clinical cases and 14 previously reported cases) were reviewed to describe the disease in horses. Hemangiosarcoma occurred in mature, particularly middle-aged horses, with no apparent sex predilection. Thoroughbreds seemed to be overrepresented (13 cases) but a true breed predilection could not be established. The respiratory and musculoskeletal systems were most commonly affected and presenting complaints included dyspnea (26%), subcutaneous or muscular swelling (24%), epistaxis (17%), and lameness (12%). Heart and respiratory rates were usually increased and mucous membrane color was frequently pale or icteric. Capillary refill time and rectal temperature were often normal. Anemia (88%), neutrophilic leukocytosis (62%), and thrombocytopenia (48%) were common. Examination of tissue samples collected by fine-needle aspirate or biopsy established an antemortem diagnosis in 4 horses. The diagnosis was made during postmortem examination in the remaining 31 horses. The lung and pleura (77%), skeletal muscle (46%), and spleen (43%) were most commonly affected. A primary site of tumor involvement could be identified in 22 horses. Hemangiosarcoma should be included as a differential diagnosis for horses with evidence of hemorrhage into body cavities, skeletal muscle, or subcutaneous locations.     

Cutaneous extraskeletal mesenchymal chondrosarcoma in a cat

A 4-year-old, male cat was presented with a fixed, subcutaneous mass in the lumbosacral region. A histopathological examination revealed a well-defined but nonencapsulated neoplasm characterized by a proliferation of predominantly spindle cells, with high mitotic activity. Interspersed between these cells were single cellular elements with chondroid differentiation. Large areas of cartilaginous tissue with foci of endochondral ossification, necrosis and myxoid tissue were also observed within the neoplastic parenchyma. A diagnosis of extraskeletal mesenchymal chondrosarcoma was made based on the histological pattern - characterized by the coexistence of cartilaginous islands and undifferentiated mesenchymal cells, results of Alcian blue staining at various pH, immunohistochemical reactivity against vimentin and S-100, and the absence of skeletal involvement or other primary tumour sites. Clinical history of the cat excluded traumas, vaccinations or other types of subcutaneous inoculation. Six months on from surgical treatment, neither recurrence nor metastases have been detected.     

Experimental myopathy in vitamin E- and selenium-depleted calves with and without added dietary polyunsaturated fatty acids as a model for nutritional degenerative myopathy in ruminant cattle

Fourteen calves, 14 weeks old, fed a low vitamin E and selenium diet based on sodium hydroxide-treated, selenium-deficient barley showed a rapid decline in plasma alpha-tocopherol, a gradual decline in erythrocyte glutathione peroxidase (GSHPX) activity, elevated plasma creatine kinase (CK) activity, teeth grinding and (in three cases) electrocardiographic changes, but no clinical abnormalities after 127 to 137 days. Necropsy of six depleted calves at that stage revealed pale muscles in two animals and mild histopathological lesions of skeletal myopathy in all six calves. Ten control calves were fed a similar diet supplemented with alpha-tocopherol and selenium. Plasma alpha-tocopherol and erythrocyte GSHPX activity remained high in these calves and no clinical abnormalities or evidence of myodegeneration were observed. When protected linseed oil was fed as a source of polyunsaturated fatty acids to the remaining eight depleted calves, rapid elevations in plasma CK activity and linolenic acid associated with a variety of cardiopulmonary and locomotory signs, electrocardiographic changes and myoglobinuria occurred within six to 11 days. Necropsy revealed widespread severe skeletal myodegeneration (eight calves) and myocardial lesions (five calves) with preferential involvement of the left ventricular myocardium. Clinical signs and pathological changes were similar to those reported in field outbreaks of nutritional degenerative myopathy in ruminant cattle and establish the experimental regime as the first successful model for reproduction of this disease.     

Metastatic intraocular chondrosarcoma in a dog

Chondrosarcoma accounts for about 10% of all canine bone tumors and is the second most common primary bone tumor in dogs. In veterinary medicine, chondrosarcomas are classified as skeletal and extraskeletal. Extraskeletal chondrosarcomas are mesenchymal neoplasms of soft tissues and visceral organs that produce neoplastic chondrocytes in a fibrillary matrix. There is no involvement of bone or periosteal tissues in extraskeletal chondrosarcomas. The aim of this report is to describe the first case of a metastatic intraocular extraskeletal chondrosarcoma in a dog.     

干扰MSTN对牛骨骼肌卫星细胞增殖分化的影响

为研究肌肉生长抑制素（myostatin,MSTN）对牛骨骼肌卫星细胞增殖与成肌分化的影响,本试验以牛骨骼肌卫星细胞体外诱导成肌分化模型为对象,以前期设计合成3个干扰RNA（si-MSTN-1、si-MSTN-2、si-MSTN-3）并对其进行干扰效果筛选为基础,将干扰效果极显著的si-MSTN-2（si-MSTN）转染牛骨骼肌卫星细胞,通过EdU染色法检测干扰MSTN对牛骨骼肌卫星细胞增殖的影响;进一步对干扰MSTN的牛骨骼肌卫星细胞进行体外成肌诱导分化,通过肌管形成状态和分化标志因子综合分析干扰MSTN对牛骨骼肌卫星细胞分化的影响：首先通过显微镜观察牛骨骼肌卫星细胞分化时期的肌管形成状态,然后利用实时荧光定量PCR和Western blotting技术检测牛骨骼肌卫星细胞分化标志因子MyoG和MyHC在mRNA和蛋白水平的表达情况。结果显示,干扰MSTN后,牛骨骼肌卫星细胞中EdU阳性细胞率极显著增加（P < 0.01）,说明下调MSTN表达极显著促进了牛骨骼肌卫星细胞的增殖;牛骨骼肌卫星细胞诱导分化后形成的肌管数量和直径均呈现增大趋势,牛骨骼肌卫星细胞成肌分化标志因子MyHC在mRNA和蛋白水平的表达均极显著高于对照组（P < 0.01）,说明下调MSTN表达能够促进牛骨骼肌卫星细胞的成肌分化过程。本研究结果表明,干扰MSTN可以显著促进牛骨骼肌卫星细胞的增殖及成肌分化过程。本试验结果为进一步开展MSTN对牛骨骼肌卫星细胞成肌分化的调控机制研究提供了参考。     

Clinical, radiographic, pathologic, and genetic features of osteochondrodysplasia in Scottish deerhounds

Clinical, radiographic, pathologic, and genetic features of a form of osteochondrodysplasia in 5 related Scottish Deerhound pups from 2 litters were evaluated. All pups appeared to be phenotypically normal at birth. At approximately 4 or 5 weeks, exercise intolerance and retarded growth were observed. Kyphosis, limb deformities, and joint laxity gradually developed. Radiography of the affected pups revealed skeletal changes characterized by abnormalities in long bones and vertebrae, with involvement of epiphyses, growth plates, and metaphyses. Short long bones and vertebrae and irregular and delayed epiphyseal ossification were most noticeable in younger pups; in older pups, bony deformities became more prominent. In skeletally mature dogs, osteopenia and severe deformities were seen. The histologic changes of the growth plate were compatible with a diagnosis of chondrodysplasia. Growth plate chondrocytes contained periodic acid Schiff-positive, diastase-resistant cytoplasmic inclusions. A single autosomal recessive mode of inheritance was suspected.     

Invasive ductal carcinoma of the mammary gland in a mare

A 21-year-old thoroughbred mare had a 35 x 14 x 10 cm mass involving the mammary gland. Metastases were found in the kidneys, lungs, skeletal muscles, and regional lymph nodes. Histopathologic examination of the tumor revealed a ductal solid carcinoma with extensive intraductal and intralobular involvement and focal infiltration of the adjacent stroma. The intralobular neoplasms were divided into irregularly shaped islands and sheets of polygonal and spindle-shaped epithelial cells by thick or thin fibrous connective tissue bundles. The neoplastic cells had a small or moderate amount of cytoplasm that stained faintly with eosin and round or oval hyperchromatic nuclei. Immunohistochemically, the neoplastic cells were strongly positive for Lu-5, weakly positive for AE1/AE3, vimentin, and glial fibrillary acidic protein, and negative for cytokeratin 8, cytokeratin 14, alpha-smooth muscle actin, calponin, and S100. The neoplasm was diagnosed as an invasive ductal carcinoma of the mammary gland with multiple metastases.