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Objective—To evaluate clinical and laboratory findings, treatment, and clinical outcome in cats with blastomycosis. Design—Retrospective case series. Animals—8 cats with naturally occurring blastomycosis. Procedures—Medical records of the University of Illinois Veterinary Teaching Hospital were searched for cases of blastomycosis in cats diagnosed via cytologic or histopathologic findings. Clinical and laboratory findings, treatment, and clinical outcome were determined. Radiographs were reviewed for the 8 cases. Results—All cats were systemically ill. Respiratory tract signs and dermal lesions were most commonly observed. All cats had radiographic evidence of respiratory tract disease. Seven of the 8 cats had ill-defined soft-tissue opacities (nodules or masses) or alveolar consolidation of the lungs. Antemortem diagnosis was achieved cytologically in 6 of the 8 cats, and 3 were successfully treated and survived. Conclusions and Clinical Relevance—In contrast to previous reports, diagnosis was achieved antemortem in most of the cats (all by cytologic identification of the organism). Clinical signs, laboratory findings, and outcome were similar to previous descriptions of this rare disease in cats.

Objective—To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI). Sample—Tendons of 8 young adult horses. Procedures—The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points. Results—At 4 weeks after collagenase injection, the area of maximal injury assessed on cross section was similar between ultrasonography and MRI. In lesions of > 4 weeks' duration, ultrasonography underestimated the area of maximal cross-sectional injury by approximately 18%, compared with results for MRI. Signal intensity of lesions on T1-weighted images was the most hyperintense of all the sequences, lesions on short tau inversion recovery images were slightly less hyperintense, and T2-weighted images were the most hypointense. Signal intensity of tendon lesions was significantly higher than the signal intensity for the unaltered deep digital flexor tendon. Histologically, there was a decrease in proteoglycan content, an increase in collagen content, and minimal change in fiber alignment during the 16 weeks of the study. Conclusions and Clinical Relevance—Ultrasonography may underestimate the extent of tendon damage in tendons with long-term injury. Low-field MRI provided a more sensitive technique for evaluation of tendon injury and should be considered in horses with tendinitis of > 4 weeks' duration.

Canine appendicular osteosarcoma (OSA) causes focal bone destruction, leading to chronic pain and reduced quality-of-life scores. Drugs that inhibit pathologic osteolysis might provide additional treatment options for managing cancer-induced bone pain. Aminobisphosphonates induce osteoclast apoptosis, thereby reducing pain associated with malignant osteolysis in human patients with cancer.Treatment of dogs with pamidronate administered intravenously will alleviate bone pain and reduce pathologic bone turnover associated with appendicular OSA in dogs.Forty-three dogs with naturally occurring appendicular OSA administered pamidronate intravenously.Prospective study. Therapeutic responses in dogs treated with pamidronate administered intravenously and nonsteroidal anti-inflammatory drugs (NSAID) were evaluated by using a numerical cumulative pain index score (CPIS), and by quantifying urine N-telopeptide (NTx) excretion and relative primary tumor bone mineral density (rBMD) assessed with dual energy x-ray absorptiometry. In addition, variables, including pamidronate dose, skeletal mass, baseline and change for CPIS, urine NTx and rBMD during treatment, and baseline tumor volume and radiographic pattern were compared between dogs clinically responsive and nonresponsive to pamidronate therapy.Twelve of 43 dogs (28%) had pain alleviation for4 months, lasting a median of 231 days. Changes in CPIS and rBMD during treatment were statistically different between responders and nonresponders (P = .046 and .03, respectively).Substantiated by reductions in CPIS and increases in rBMD, single-agent pamidronate administered intravenously with NSAID therapy relieves pain and diminishes pathologic bone turnover associated with appendicular OSA in a subset of dogs.

Background: Receptor activator of nuclear factor K-B (RANK), RANK-ligand (RANKL), and the soluble decoy receptor osteoprotegerin (OPG) form a key axis modulating osteoclastogenesis. In health, RANKL-expressing bone stromal cells and osteoblasts activate osteoclasts through RANK ligation, resulting in homeostatic bone resorption. Skeletal tumors of dogs and cats, whether primary or metastatic, may express RANKL and directly induce malignant osteolysis. Hypothesis: Bone malignancies of dogs and cats may express RANKL, thereby contributing to pathologic bone resorption and pain. Furthermore, relative RANKL expression in bone tumors may correlate with radiographic characteristics of bone pathology. Animals: Forty-two dogs and 6 cats with spontaneously-occurring tumors involving bones or soft tissues were evaluated. Methods: A polyclonal anti-human RANKL antibody was validated for use in canine and feline cells by flow cytometry and immunocytochemistry. Fifty cytologic specimens were collected from bone and soft tissue tumors of 48 tumor-bearing animals and assessed for RANKL expression. In 15 canine osteosarcoma (OSA) samples, relative RANKL expression was correlated with radiographic characteristics of bone pathology. Results: Expression of RANKL by neoplastic cells was identified in 32/44 canine and 5/6 feline tumor samples. In 15 dogs with OSA, relative RANKL expression did not correlate with either radiographic osteolysis or bone mineral density as assessed by dual energy x-ray absorptiometry. Conclusions and Clinical Importance: In dogs and cats, tumors classically involving bone and causing pain, often may express RANKL. Confirming RANKL expression in tumors is a necessary step toward the rational institution of novel therapies targeting malignant osteolysis via RANKL antagonism.