Recognition memory was assessed by submitting the same adult monkeys to visual paired comparison (VPC) with mixed delays (10 -120 sec), followed by three consecutive versions of object-delayed nonmatching-to-sample (DNMS): increasing delays (10 -600 sec), lengthened lists (3-10 objects), and intervening distractors in the delays (light at 10 sec, motor task at 30 -600 sec, or context change at 600 sec). Four groups were tested: normal controls, monkeys with ibotenic acid lesions of the hippocampal formation (H), and monkeys with aspiration lesions of either the perirhinal (PRh) or parahippocampal (areas TH/TF) cortex. Group H was impaired on VPC at delays Ն60 sec but had difficulty on DNMS only at 600 sec delays with distraction. In group TH/TF, the VPC impairment emerged earlier (30 sec); yet, once the nonmatching rule was mastered, no significant change occurred on any DNMS condition. Only group PRh behaved congruently on VPC and DNMS, exhibiting a deficit at the easiest condition that worsened with increasing delays as well as in DNMS lengthened list and distraction conditions. These results led us to postulate that VPC and DNMS, as previously administered to monkeys, were not equivalent visual recognition memory probes. Specifically, we propose that, for VPC, because of passive (incidental) encoding, the animal's performance rests on both item familiarity and event recollection, whereas, for DNMS, because of active (purposeful) encoding, performance relies more on item familiarity. This proposal converges with current models postulating distinct, but interactive, mnemonic roles for the hippocampal and adjacent TH/TF regions.

To clarify the specific contribution of the medial temporal lobe structures in spatial memory, we tested monkeys (Macaca mulatta) with sham operations and with lesions of either the hippocampal formation, areas TH/TF or perirhinal cortex on two versions of the visual-paired comparison task, measuring Spatial Location, and Object-in-Place associations. In the Spatial Location version, the comparison was between two identical objects presented simultaneously in a familiar and a novel location. In the Object-in-Place version, the comparison was between an image consisting of five objects and another image showing the same five objects, but with the position of 2, 3, or 4 of the objects rearranged. Finally, a VPC-Control task was given to animals with hippocampal and perirhinal lesions, in which the comparison was between an image consisting of five objects and another image showing four of the five familiar objects and a new one. Perirhinal lesions yielded no deficit in the Spatial Location task and a deficit in the Object-in-Place task associated with a deficit in the VPC-control task, suggesting that this cortical area does not participate in spatial memory unless the stimuli have overlapping features. Areas TH/TF lesions produced a deficit in both Spatial Location and Object-in-Place tasks, whereas the hippocampal lesions resulted in a deficit of Object-in-Place associations only. The data showed that the hippocampal formation, areas TH/TF, and perirhinal cortex appear to contribute interactively to object and spatial memory processes.

Imaging studies in people indicate that x-ray computed tomography (CT) is a more sensitive technique than thoracic radiography for the detection of pulmonary metastasic neoplasia. Systematic studies comparing CT and thoracic radiographic techniques in veterinary patients have not been performed. The present retrospective study was designed to directly compare the efficacy of these 2 techniques in detecting pulmonary nodules in dogs. Eighteen dogs with histologically confirmed pulmonary metastatic neoplasia had contemporaneous thoracic radiographs and pulmonary CT scans compared. Quantitative analyses included estimation of pulmonary nodule size, number, and lobar distribution on thoracic radiographs and CT images. Only 9% of CT-detected pulmonary nodules were identified on thoracic radiographs (P , .003). The lower size threshold was approximately 1 mm to detect pulmonary nodules on CT images and 7-9 mm to reliably detect nodules on radiographs (P , .0001). Additionally, pulmonary nodules were detected in a significantly greater number of lung lobes using CT as compared with thoracic radiographs (P , .0001). These data indicate that CT is significantly more sensitive than thoracic radiography for detecting soft-tissue nodules in dogs. As such, thoracic CT should be considered in any patient with neoplasia that has potential for pulmonary metastasis to more reliably stage the disease, particularly when accurate characterization of the extent and distribution of pulmonary metastatic disease affects therapeutic planning. T horacic radiography is currently the most commonly employed test to screen for pulmonary metas-tases in veterinary cancer patients. However, computed tomography (CT) has been used as a standard screening test in human medicine for many years and has been found to be more accurate than thoracic radiography for detecting pulmonary nodules. 1-7 The improved sensitivity of CT compared with thoracic radiography for detecting pulmonary metastases is due primarily to the superior contrast resolution of CT and the lack of anatomic superimposition on pulmonary parenchyma due to thin-section collimation of CT images. However, the specificity of CT for detecting pulmonary metastatic nodules can be lower than that of thoracic radiography because more small, nonneoplastic, and clinically insignificant nodules are likely to be identified. 8-11 Systematic studies comparing thoracic radiographic and CT techniques in veterinary patients with suspected pulmonary metastatic disease have, to our knowledge, not been reported. A study that directly compared the 2 techniques in a canine model of human disease found that CT was more sensitive than thoracic radiography for detecting pulmonary infarcts. 12 Further, in a case series report that investigated 3 dogs with metastatic carcinoma for which thoracic radiographic studies revealed only an interstitial pattern, high-resolution CT was found to be helpful in defining additional pulmonary pathology; however, overt nodules were found in only a single patient. 13 In anoth...

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Objective-To characterize historical, clinicopathologic, ultrasonographic, microbiological, surgical, and histopathologic features of bacterial cholecystitis and bactibilia in dogs and evaluate response to treatment and outcomes in these patients. Design-Retrospective case-control study. Animals-40 client-owned dogs (10 with bacterial cholecystitis on histologic analysis or bactibilia on cytologic examination [case dogs] and 30 without bactibilia [controls]) evaluated at a veterinary teaching hospital between 2010 and 2014. Procedures-Signalment, history, clinicopathologic findings, ultrasonographic features, microbiological results, surgical findings, histopathologic changes, treatments, and outcomes of case dogs were derived from medical records and summarized. Demographic and clinicopathologic data and ultrasonographic findings were compared between case and control dogs. Relationships among prior antimicrobial treatment, sediment formation in the gallbladder, presence of immobile biliary sludge, and presence of bactibilia or bacterial cholecystitis were assessed. Results-No finding was pathognomonic for bactibilia or bacterial cholecystitis in dogs. Case dogs were significantly more likely to have immobile biliary sludge and had a greater degree of biliary sediment formation than did control dogs. All case dogs for which gallbladders were examined histologically (6/6) had bacterial cholecystitis. Five of 10 case dogs were Dachshunds. Medical or surgical treatment resulted in good outcomes. Conclusions and Clinical Relevance-Bactibilia and bacterial cholecystitis were important differential diagnoses in dogs with signs referable to biliary tract disease. Dachshunds were overrepresented, which may suggest a breed predisposition. Cytologic evaluation of bile should be considered in the routine assessment of dogs with hepatobiliary disease if immobile biliary sludge is present. (J Am Vet Med Assoc 2015;246:982-989).