Sensitivity and positive predictive value of CT for bulla detection were low. Results suggested that CT is potentially an ineffective preoperative diagnostic technique in dogs with spontaneous pneumothorax caused by bulla rupture because lesions can be missed or incorrectly diagnosed. Bulla size may affect visibility on CT.

In dogs, obesity appeared to cause airflow limitation during the expiratory phase of breathing, but this was only evident during hyperpnea. This suggests that flow limitation is dynamic and likely occurs in the distal (rather than proximal) portions of the airways. Further studies are warranted to localize the flow-limited segment and understand whether obesity is linked to exercise intolerance via airway dysfunction in dogs.

Background and aims-The formation of cholesterol gallstones is a complex process involving contributions from genes and environmental factors. Although gallbladder inflammation is believed to be common during cholelithogenesis, the role of immunological factors is unknown.

Background: Horses with recurrent airway obstruction (heaves) are described as exhibiting ''increased abdominal effort,'' but it is unknown whether this translates to an effective contribution to ventilation.Hypothesis: We hypothesized that heaves is characterized by asynchrony between rib cage and abdominal motions, and that the abdominal component is the major contributor to ventilation.Animals: The rib cage versus abdominal motion in naturally occurring heaves (n 5 15) was compared to controls at rest (n 5 7) and during hyperpnea because of lobeline treatment, and the effects of histamine-induced bronchoconstriction in controls (n 5 10).Methods: Flow patterns, phase angle (h) between the rib and abdominal compartments, abdominal (V abd ) contribution to tidal volume (V T ), and lung mechanics were measured.Results: Findings unique to the heaves group included the loss of biphasic expiratory flow, severely increased h with the abdomen consistently lagging behind the rib cage, and a reduced contribution of the abdomen to ventilation. A subgroup of heaves (n 5 5) with abdominal paradox showed a significant (P , .05) reduction in tidal volume, and increased respiratory rate. Bronchodilation reduced h in heaves (P 5 .06), but h remained significantly higher after bronchodilation than found in controls.Conclusions and Clinical Importance: We conclude that breathing pattern in horses with heaves is characterized by severe rib cage/abdominal asynchrony, with the rib cage motion in synchrony with flow, therefore dominating ventilation. In a subset of heaves, the abdominal compartment (diaphragm, abdominal muscles) was completely out of synchrony with flow (''abdominal paradox'') despite the clinical appearance of ''increased abdominal effort.''

Metallosis is the accumulation of metallic debris in soft tissues resulting from wear following total joint replacement. A dog was evaluated for lameness 4 years after total hip arthroplasty using a titanium alloy and cobalt chromium total hip system. Radiographs revealed severe acetabular component wear, implant-bone interface deterioration, and peri-acetabular osteolysis. During surgical revision, black periarticular tissue surrounded the implants. Histologically, there was fibrosis and granulomatous inflammation with abundant, intra- and extracellular, black, granular material and smaller amounts of clear punctate to acicular material. Laser capture microdissection followed by x-ray fluorescence microscopy indicated the material contained large amounts of titanium with smaller amounts of vanadium, cobalt, and chromium, confirming the diagnosis of metallosis. The clear material was birefringent under cross-polarized light, stained positive with Oil-Red-O, and thus was consistent with polyethylene. Metallosis exhibits characteristic gross and histologic lesions and is a differential diagnosis for aseptic loosening of hip implants.

Objective -To determine if low tidal volume (V T ) ventilation is associated with the development of respiratory acidosis and changes in lung function in healthy dogs. Design -Randomized prospective experimental cross-over study. Setting -Pulmonary function laboratory at a university teaching hospital. Animals -Five healthy Beagle dogs. Interventions -Dogs were anesthetized and randomly mechanically ventilated with V T of 6, 8, 10, 12, and 15 mL/kg while maintaining a constant minute volume. Measurements and Main Results -Arterial blood gases and pulmonary mechanics were collected after 15 minutes of equilibration at each V T . Repeated measures ANOVA was used to determine the effect of V T with a P-value of <0.05 considered significant, and a Pearson product moment was used to determine correlation between V T and pH and PaCO 2 . V T had a significant effect on PaCO 2 (P < 0.001) and on pH (P < 0.001) with lower V T being associated with higher PaCO 2 and lower pH. There was a strong correlation between V T and PaCO 2 (r = -0.87) and V T and pH (r = 0.83). Increased airway pressures and pulmonary compliance were associated with increasing V T . Conclusions -There is a predictable decrease in the pH, decrease in airway pressure, decrease in compliance, and increase in the PaCO 2 associated with lower V T . Low V T ventilation is well tolerated in healthy dogs; the role of low V T ventilation in dogs with acute lung injury/acute respiratory distress syndrome as well as the influence of positive end expiratory pressure requires further evaluation.

A Miniature Pinscher developed acute blindness and behavioral changes. On magnetic resonance imaging (MRI), there were multiple small intra-axial cystic lesions, and primary differential diagnoses included primary or metastatic neoplasia and neurocysticercosis. These cystic lesions were subsequently diagnosed histopathologically as disseminated choroid plexus carcinoma. This is only the second documented description of this diagnosis in a dog, but both patients had very similar MRI findings. This patient adds to the literature about the MRI characteristics of choroid plexus tumors and indicates that choroid plexus tumor should be considered as a possible cause of small multifocal intra-axial cystic brain lesions in dogs, regardless of whether a primary intraventricular lesion is visible.

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