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2-Deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (FDG PET/CT) is becoming increasingly available as an imaging modality in veterinary medicine. The purpose of this study was to report semiquantitative standard uptake values (SUV) of malignant and nonmalignant tissues and organs in canine cancer patients. FDG PET/CT was performed in 14 dogs including, nine mesenchymal tumors, four carcinomas, and one incompletely excised mast cell tumor. A generally higher FDG uptake was observed in carcinomas relative to sarcomas. Maximum SUV of carcinomas ranged from 7.6 to 27.0, and for sarcomas from 2.0 to 10.6. The FDG SUV of several organs and tissues, including regional brain uptake is reported, to serve as a reference for future FDG PET studies in canine cancer patients. Several potential pitfalls have been recognized in interpretation of FDG PET images of human patients, a number of these were also observed in this study.

Antifibrin monoclonal antibodies show potential as clot targeting agents for diagnosis and possibly therapy in thrombotic disease. To be effective the antibody must bind to the fibrin component of the clot. The ability of two antifibrin mabs (NIB 1H10 and NIB 12B3) to penetrate occlusive clots in vivo was investigated. Both mabs react with human fibrin but not with human fibrinogen nor with the fibrin or fibrinogen from the species used in this study. Two heterologous animal (sheep and rabbit) thrombus models were used. Clots in both cases were made within isolated vein segments using a mixture of human and native fibrinogen. The clots in sheep veins were observed radiographically and found to be occlusive for a mean of 4.2 +/- 2.2 days and thereafter appeared only partially occlusive. When targeted in their occlusive phase (131)I labelled mab accumulated in the clot reaching a maximum ratio of 1.82 +/- 0.42 when compared to counts in homologous sheep clots in the contralateral limb. It was confirmed in the rabbit jugular vein model that total occlusivity did not prevent antibody accumulation in the heterologous clot by injecting the fibrin specific mab 1H10 and examining the clot excised after 1, 6 and 24 h using immunofluorescence. In a further series of similar experiments (125)I labelled mab 1H10 was used and detected using autoradiography. Both sets of experiments indicated that penetration of occlusive clots by the antibody occurred and that considerable accumulation was present at 6 and 24 h. The results indicate that a circulating antibody can readily gain access to experimentally produced clots in occluded veins.

Four monoclonal antibodies have previously been raised in our laboratory for possible use in thrombus imaging and the targeting of thrombolytic agents. These antibodies were raised to various human fibrin-related immunogens and each antibody had been selected for its specificity towards fibrin and not fibrinogen. To study further these antibodies in animal circulation models both in vivo and in vitro, their selectivity towards human fibrin as opposed to other animal fibrins was examined. In this study dissociation constants for each antibody with each of six species fibrins (human, baboon, pig, dog, sheep and rabbit) were estimated using both fibrin clots and monolayers. Some limited data were also obtained with Sepharose-fibrin. Of the antibodies two (denoted 12B3B10 and 12B3A11) are seen to bind almost exclusively to human fibrin with dissociation constants of about 8 x 10(-10) M using fibrin clots and monolayers. These same two mabs bound to baboon fibrin with a dissociation constant of 2 x 10(-9) M, while neither displayed significant levels of binding to the fibrins from dog, pig, sheep and rabbit. The other two antibodies investigated (1H10 and 5F3) were found to bind well to fibrins of human, baboon, pig and dog, with dissociation constants in the range of 1.4-4.2 x 10(-9) M. However neither 1H10 nor 5F3 displayed significant recognition of sheep and rabbit fibrins. Both 1H10 and 5F3 were also found by means of competitive ELISA's to retain their selectivity to baboon, dog and pig fibrins in the presence of their respective fibrinogens.

The clinical, ultrasonographic and histopathological features of a pancreatic multihormonal islet cell tumour are described in a 12-year-old dachshund with cutaneous lesions suggestive of metabolic epidermal necrosis. This condition was suspected because of the compatible cutaneous signs, a high plasma glucagon concentration and the detection of a well defined pancreatic mass by ultrasonography. The diagnosis was confirmed postmortem and by histology.