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A 9-year-old rabbit was evaluated for a mass on the right elbow. As a result of preoperative radiography, another mass was identified in the cranial portion of the mediastinum. Ultrasound guided fine needle aspiration was used for cytologic evaluation of the mass in the mediastinum and resulted in a presumptive diagnosis of thymoma. A median sternotomy approach was chosen to allow wide exposure for meticulous dissection in the cranial portion of the thoracic region. Histologic examination and immunoperoxidase labeling of lymphocytes with CD3 (a T cell marker) confirmed the diagnosis. The mass on the right elbow was subsequently removed and identified as a neurofibrosarcoma. Multiple appendicular masses that developed at separate locations and distinct times were excised and classified as locally invasive primary neurofibrosarcomas. Postmortem examination 9 months after initial evaluation confirmed recurrence of the neurofibrosarcoma at previous surgical sites. Gross or histologic evidence of thymoma was not evident. Prognosis is dismal for incompletely excised soft tissue sarcomas, because they are locally invasive and often recur.

Objective: To determine the outcome of implantation of an intraocular silicone prosthesis (ISP) in the eyes of dogs and cats with intraocular neoplasia., Design: Retrospective case series., Animals: Eight dogs and 1 cat with histologically confirmed intraocular neoplasia., Procedure: Signalment, clinical signs before and after surgery, results of microscopic examination of eviscerated intraocular tissues, follow-up information, and necropsy findings, if available, were recorded for each animal., Results: Five dogs and 1 cat had primary intraocular neoplasms. Two of the dogs developed regrowth of the neoplasm around the ISP 6 to 24 months after implantation, and the eyes were enucleated. The cat developed signs compatible with systemic metastasis 4 years after surgery and was euthanatized. Three dogs had multicentric or metastatic neoplasia involving the eye. Two of these dogs were euthanatized because of their systemic disease 1.5 to 7 months after ISP implantation. The third dog is alive without evidence of regrowth 3 years after surgery., Clinical Implication: Intraocular neoplasia is not an absolute contraindication to ISP implantation.

Hyperthyroidism associated with thyroid adenoma was diagnosed in a dog. Typical clinical signs of hyperthyroidism were resolved with surgical excision of the adenoma. Hyperthyroidism in dogs usually is associated with thyroid carcinoma, which has a poor prognosis. This case emphasizes the importance of obtaining a histologic diagnosis of thyroid tumors in hyperthyroid dogs before giving a prognosis.

A mediastinal squamous cell carcinoma and thyroid carcinoma were found in an aged horse. Clinical signs consisted of bilateral thyroid gland enlargement, chronic cough, and mild respiratory distress. The neoplasms were not treated. Squamous cell carcinoma is a common neoplasm in horses, but not in the cranial portion of the mediastinum. Thyroid carcinomas in horses are uncommon. This combination of neoplasms is rare and may have been associated with a defect in the immune system.

Forty-two dogs with primary bone tumors underwent radiographic bone surveys. The use of radiographic bone surveys led to a higher yield in finding other nonclinically detectable neoplastic sites (7.1%) than did thoracic radiographs (4.7%). Multicentric bone tumors accounted for 9.5% of total cases. Bone infarcts were identified in 3 dogs (7.1%).

An aged Boxer dog had 9 distinct primary tumors: chemodectoma, osteosarcoma, bronchiolo-alveolar adenocarcinoma, interstitial cell tumor, seminoma, basal cell tumor, fibropapilloma, adrenal cortical adenoma, and pancreatic adenoma. From this report, as well as from other studies, it is clear that Boxers have special susceptibilities to a variety of tumors. Analysis of clinical data on canine tumors indicated that the risk of Boxers for multiple tumors is only slightly higher than all tumors, indicating little or no specific predisposition for multiple tumors. In Boxers, however, certain tumor types occurred more frequently as multiple primary tumors than would be expected by chance.

Renal adenoma, a benign tumor of epithelial origin, was diagnosed in a 10-year-old cat. Clinical signs included decreased appetite and weight loss. Nephrectomy resulted in clinical improvement. Seven months after surgery, the cat died, and pulmonary papillary adenocarcinoma was discovered. The pulmonary neoplasm differed markedly from the renal neoplasm.

An antemortem diagnosis of lymphosarcoma was made in a captive Eastern king snake and a rhinoceros viper. The Eastern king snake died on the 1st day after biopsy of a liver nodule, and necropsy revealed multiple tumor nodules throughout all major organ systems. The rhinoceros viper died after chemotherapy with cytosine arabinoside. The major gross lesion was a large paracolonic coelomic tumor that extended into the adjacent musculature and subcutaneous tissue of the lateral abdominal wall. The immediate cause of death of the rhinoceros viper was believed to be severe renal tubular necrosis.

The radiation response of acanthomatous epulis in 32 dogs was good, with an estimated median survival time of 21 months. Of the 32 patients, 14 have died. In 4 of those 14, malignant tumors developed at the site of the acanthomatous epulis. The tumors were of epithelial origin in 3 patients and of mesenchymal origin in 1 patient. Possibilities explaining the appearance of the malignancies included spontaneous malignant transformation, radiation induction of neoplasms, and radiation induction of malignant transformation. This uncommon complication was not considered contradictory to radiotherapy of acanthomatous epulides, because of their excellent response to irradiation and the long latent period between irradiation and appearance of the malignant tumor.

Mucocutaneous plasmacytomas were diagnosed in 75 dogs. Medical records and communication with owners and referring veterinarians provided information regarding location and description of the tumor, clinicopathologic data, treatment, and postoperative status of the dogs. Males and females were equally represented, and most dogs were aged adults (mean, 9.7 years). Tumors developed most commonly in the mouth, on the feet or trunk, and in the ears. Plasmacytomas were confined to the skin and mucosa in 70 dogs. Two dogs had disseminated lymphoid neoplasia, and 1 dog developed cutaneous plasmacytoma during clinical remission of lymphosarcoma. Two dogs had multiple myeloma, which was diagnosed concurrently or within a few weeks of diagnosis of the cutaneous tumor. Multiple plasmacytomas were found in 10 dogs but were not associated with clinical signs of generalized disease. Tumors did not recur after surgical excision. Clinicopathologic values, when determined, were normal in all dogs with localized plasmacytomas.

Nerve sheath fibrosarcomas of the left 5th through 8th cranial nerve roots were diagnosed in 1 dog and of the left 4th through 8th cranial nerve roots in another dog. Clinical signs in both dogs included head tilt to the left, circling to the left, left hemiparesis and proprioception deficits, rotary nystagmus, left-sided atrophy of masticatory muscles, and cutaneous hypalgesia of the left side of the face. Cranial nerve roots from both dogs were incorporated in discrete, firm, encapsulated, lobulated, tan masses of various sizes that compressed adjacent brain stem and cranial nerves. There were no regional or distant metastases; however, there was enlargement of nerve roots adjacent to the masses. The masses were composed of bundles and sheets of anaplastic, polymorphic to spindle-shaped cells that infiltrated cranial nerves and ganglia and extended into the brain along nerve roots. Masses contained various amounts of collagen and reticulin fibers, but no mucopolysaccharide ground substance. There was no myelin or S-100 protein associated with neoplastic cells. The tumors appeared to have a multicentric origin from cranial nerve sheaths.

A moribund juvenile gray squirrel (Sciurus carolinensis) with numerous skin fibromas was submitted to the Northeastern Research Center for Wildlife Diseases. Necropsy revealed multiple firm white nodules in the lungs. On histologic examination, in addition to the skin lesions, fibromatous proliferations were seen in the wall of the alimentary tract, in 1 mesenteric lymph node, and in the myocardium. Tubular adenomas were seen in the renal cortex, and the lung nodules were bronchoalveolar adenomas. Eosinophilic intracytoplasmic poxvirus inclusion bodies were seen in both the mesenchymal and epithelial tumors.

Both ovaries in a 10-year-old American Saddle Horse mare were determined to be larger than normal. The mare had problems with infertility during the preceding 3 years. Clinical evaluation revealed that the mare was polyuric, polydypsic, hyperinsulinemic, and hyperglycemic, and had reduced tolerance to exogenous glucose. Bilateral granulosa cell tumors were identified on histologic examination of the ovaries. The precise mechanism for the secondary diabetes mellitus was not determined; however, the cause was suspected to be a result of the synthesis and release of a hormonal substance by the tumor that affected carbohydrate metabolism and resulted in decreased peripheral sensitivity to insulin.

Generalized, nodular dermatofibrosis with coexisting bilateral renal cystadenocarcinomas was diagnosed in a 6-year-old male German Shepherd Dog. Approximately 3 years earlier, the dog had been examined because of lameness attributable to 2 nodular growths between the third and fourth digits of the right front limb. Biopsy revealed dense collagenous dermal fibrosis, often in a nodular arrangement. As the disease progressed, attempts to alleviate the discomfort and lameness caused by the nodular growths were performed by surgical excision. During this period, other nodular growths that developed apparently did not bother the dog. Because of the long and protracted clinical progression of the disease and poor prognosis for successful treatment, the dog was euthanatized. At necropsy, multiple multicentric nodules were found in the skin and subcutis, with most located on the limbs. The nodules were well-circumscribed and hard. Epithelial ulceration and inflammation were confined to nodules on the feet. Small foci of collagenous proliferation were found along fascial planes. In addition, cystic neoplasms were in both kidneys. The microscopic diagnosis was generalized nodular dermatofibrosis, with bilateral renal cystadenocarcinomas.

Two yearling, paternal half-sibling Appaloosa fillies were ovariohysterectomized for treatment of multiple uterocervical leiomyomas. The tumors recurred in both fillies, originating from cervical tissue that could not be removed at surgery. Previously reported cases of uterine leiomyoma in the mare have been of solitary tumors in older mares that were treated successfully by surgical removal.