Diagnostic records from 338 canine oral melanomas in 338 dogs received at the Veterinary Medical Diagnostic Laboratory (1992-1999) were reviewed. Of these tumors, 122 plus an additional 7 metastatic melanomas of unknown origin were selected for clinical follow-up, histologic review, and immunohistochemistry. Chow Chow, Golden Retriever, and Pekingese/Poodle mix breeds were overrepresented, whereas Boxer and German Shepherd breeds were underrepresented. There was no gender predisposition and the average age at presentation was 11.4 years. Forty-nine dogs were euthanized due to recurrence or metastasis. The average postsurgical survival time was 173 days. The gingiva and the labial mucosa were the most common sites. Most tumors were composed of either polygonal cells (27 cases, 20.9%), spindle cells (44 cases, 34.1%), or a mixture of the two (polygonal and spindle) (54 cases, 41.9%). Clear cell (3 cases, 2.3%) and adenoid/papillary (1 case, 0.8%) patterns were uncommon. The metastases of 6/6 oral melanomas had morphologic and immunohistochemical features similar to those of the primary tumors. Immunohistochemically, Melan A was detected in 113/122 oral (92.6%) and 5/7 (71.9%) metastatic melanomas. Only 4/163 nonmelanocytic tumors were focally and weakly positive for Melan A. Antibodies against vimentin, S100 protein, and neuron-specific enolase stained 129 (100%), 98 (76%), and 115 (89.1%) of 129 melanomas, respectively. Antibodies against other melanocytic-associated antigens (tyrosinase, glycoprotein 100) did not yield adequate staining. We conclude that Melan A is a specific and sensitive marker for canine melanomas.

A method was developed to simulate the human gastrointestinal environment and to estimate bioavailability of arsenic in contaminated soil and solid media. In this in vitro gastrointestinal (IVG) method, arsenic is sequentially extracted from contaminated soil with simulated gastric and intestinal solutions. A modified IVG-AB method, where iron hydroxide gel is used to simulate the absorption of arsenic, was also evaluated. Fifteen contaminated soils collected from mining/smelter sites ranging from 401 to 17 460 mg As kg -1 were analyzed. In vitro results were compared with in vivo relative bioavailable arsenic (RBA) determined from dosing trials using immature swine which ranged from 2.7 to 42.8% RBA. Arsenic extracted by the IVG and IVG-AB methods was not statistically different than RBA arsenic measured by the in vivo method. Arsenic extracted by the IVG stomach and intestinal phases was linearly correlated (r ) 0.83 and 0.82, respectively) with in vivo arsenic (P < 0.01). Similarly, the IVG-AB method was linearly correlated (r ) 0.79) with in vivo bioavailable arsenic (P < 0.05). All IVG methods extracted similar amounts of arsenic and provided estimates of bioavailable As in contaminated media. The IVG method may aid in the design and cost-effectiveness of remedial strategies of arsenic-contaminated sites.

Abstract. A total of 340 cases of cutaneous neoplasia were diagnosed in 340 of 3,564 cats that were examined by biopsy or necropsy during a 41-month period from January I , 1986 through May 3 1, 1989. Eighteen types of tumor occurred, but four types comprised 77% of the cases. These were basal cell tum or, 89 cases (26%, mean age 10.3); mast cell tumor, 72 cases (21%, mean age 8.6); squamous cell carcinoma, 52 cases (15%, mean age 11.6); and fibrosarcoma, 50 cases (15%, mean age 10.2). For each of these four types of tumors , peak number of cases occurred in cats older than 10 years. Mast cell tum or was the only tumor diagnosed in cats younger than I year. The head was the most common site for basal cell tumors, mast cell tumors, and squamous cell carcinomas. The legs were the most common location of fi brosarcomas . Siamese cats had approximately three times as many mast cell tumors as statistically expected, but only one-fourth as many squamous cell carcinomas. Breed predilection for other skin tum ors was not apparent. Sex predilection was not detected for any skin tumor.Key words: Basal cell tumor; cat; cutaneous neoplasms; fibrosarcoma; mast cell tumor; squamous cell carcinoma. Resultssectioned, and stained with hemat oxylin and eosin, Other histologic stains (mainly, Giemsa and toluidine blue) were used at the discretion of the case pathologist.The histologic diagnosis, signalment, and sites of the tumors are summarized in Tables I , 2, and 3, Data were evaluated for statistical significance by adjusted chi-square analysis, Follow-up information was not available for these cats, Ski n tumors com prised 9. 6% of feline necr op sy or biopsy accessions during th e 41 -month study . The skin sites accounted for 29 .6% of all neoplasms diagnosed in the cats, m aking it the most common sit e for tumors in our laboratory, Eighteen different types ofcutane o us neoplasms were recognized . Sex di stribution and age ofaffected ca ts are su m marize d for each tumor in Table I. Sign ificant sex pred ilection wa s not apparent for an y skin tumor. Site d istribution of th e tumors is summarized in Table 3.Basal cell tumor, mast cell tumor, squamous cell carcinoma, and fibrosarcoma were the m ost commonly diagnosed tumors, com pris ing 77.1 % ofall skin tumors d iagnosed during th e study period. The in ciden ce of th ese four com m on tumors is su m marize d by breed in T able 2. Materials and MethodsIn most stud ies, skin has been second only to th e lymphoid syste m as the most co m m on site of tumors in th e caL I4.25.31.35 A lthough some ea rly surveys lack diagnoses of mast cell tumor,9,11 ,26 ba sal cell tumor,4.1 4.25.26 or fibrosarcoma," more recent British," German," and Swiss" reports have cited fibrosarcoma , basal cell tumor, squamous cell carcinoma, and mast cell tumor (with variation in order of prevalence) as th e most co m mon feline skin tumors. These fou r tumors had been reported as early as 1953 in a retrospec tive study of 26 feline skin tumors." Reports of breed,13,20,31 ,36 sex,23,31.34 and...

Abstract. Thirteen uterine tumors were diagnosed in 13 cats and accounted for 0.29% of all feline neoplasms received during a 9.6-year period. Age at diagnosis ranged from 3 to 16 years; median 9 years. Six were Domestic Shorthair cats, and 7 were purebred cats of 5 different breeds. Eight adenocarcinomas and 1 mixed Müllerian tumor (adenosarcoma) comprised the endometrial tumors. Myometrial tumors included 3 leiomyomas and 1 leiomyosarcoma. One of the adenocarcinomas developed in the uterine stump of an ovariohysterectomized cat; the other cats were sexually intact. Concurrent mammary adenocarcinoma was diagnosed in 1 cat with uterine adenocarcinoma and in another with uterine leiomyoma. Tumors were discovered during elective ovariohysterectomy in 2 cats, but at least 3 others had experienced reproductive problems (infertility or pyometra). Five cats presented for abdominal or pelvic masses. Endometrial adenocarcinomas were positive immunohistochemically for cytokeratins and negative for smooth muscle actin (SMA); 1 of 6 cats was positive for vimentin and 4 of 8 were positive for estrogen receptor-␣ (ER␣). Adenosarcoma stromal cells were positive for vimentin and ER␣ but negative for cytokeratins and SMA. Smooth muscle tumors were positive for vimentin and SMA and negative for cytokeratins. Leiomyomas, but not the leiomyosarcomas, were positive for ER␣. Adenocarcinomas in 4 cats had metastasized by the time of ovariohysterectomy. Two other cats were euthanized 5 months after ovariohysterectomy; at least one of these cats had developed an abdominal mass that was not examined histologically. Only 2 cats with endometrial adenocarcinoma had disease-free intervals longer than 5 months after surgery. Metastasis was not detected in any mesenchymal tumor; however, these cats were either euthanized on discovery of the tumor or the tumor was first detected at necropsy.Endometrial adenocarcinoma, the most common uterine epithelial tumor, is rare in domestic animals other than rabbits and cattle. 26 The most common mesenchymal tumor of the uterus is leiomyoma. 28 Uterine neoplasia is seemingly rare in cats. 44 No uterine neoplasms were recorded in separate reviews of 395 7 and 621 feline tumors, 17 and only 1-4 cases of uterine neoplasia (leiomyoma, 12,38,46 adenocarcinoma, 14,43,46 adenoma, 43 leiomyosarcoma, 46 or lymphosarcoma 13 ) were found in retrospective surveys of 165-571 cats with tumors. Uterine leiomyoma has been the most common tumor in retrospective studies limited to feline genital tract neoplasia. Four leiomyomas, 2 leiomyosarcomas, and 1 endometrial adenocarcinoma comprised the uterine tumors in 1 review. 24 In another report, 8 there were 8 leiomyomas, 4 adenocarcinomas, and 3 leiomyosarcomas. In a 20-year survey, 7 leiomyomas, 1 leiomyosarcoma, and no adenocarcinomas were recorded.