Computed tomographic staging of dogs with anal sac adenocarcinoma.

OBJECTIVES: To describe the CT appearance of anal sac adenocarcinoma lesions in a population of dogs including the relations between primary tumour, and locoregional and distant metastasis. MATERIALS AND METHODS: Retrospective review of dogs with confirmed anal sac adenocarcinoma and available CT images of the thorax, abdomen and pelvis. RESULTS: A population of 70 dogs were included in the study. No association was found between anal sac mass size and presence or absence of iliosacral lymph node enlargement. The prevalence of local metastatic disease characterised by iliosacral lymphadenomegaly in this study was 71%, with pulmonary metastases identified in 11% of cases. There were no cases of distant pulmonary metastasis without concurrent locoregional lymphadenomegaly. CLINICAL SIGNIFICANCE: In our population of dogs local metastatic spread of anal sac adenocarcinoma was common, with a relatively low prevalence of pulmonary metastasis. The study demonstrates the importance of thorough rectal examination and/or imaging to assess the iliosacral lymph centre in this disease irrespective of the size of the anal sac mass.

Outcome following surgery to treat septic peritonitis in 95 cats in the United Kingdom.

OBJECTIVES: To review the cause, management and outcome in cats with septic peritonitis within the United Kingdom (2008 to 2018) and to identify if previously identified prognostic factors were associated with survival in this population. MATERIALS AND METHODS: Clinical records from 10 referral hospitals in United Kingdom were reviewed. Data collected included signalment, clinicopathological data and management techniques. Serum albumin, glucose, lactate and ionised calcium concentration; presence of intraoperative hypotension and correct empirical antibiosis were analysed via logistic regression for association with survival. RESULTS: Ninety-five cats were included. The overall survival rate was 66%. Lethargy (89%) and anorexia (75%) were the most common clinical signs, with abdominal pain and vomiting in 44% and 27% of cases, respectively. Gastro-intestinal leakage was the most common source of contamination. The presence of an abdominal mass on clinical examination was not strongly predictive of the presence of neoplasia on histology and did not confer a worse prognosis. Cats presenting with dehiscence of a previous enterotomy/enterectomy did not have a worse prognosis than those presenting with other aetologies. Intraoperative hypotension (adjusted odds ratio 0.173, 95% confidence intervals 0.034 to 0.866, P=0.033) was associated with non-survival. Cats that survived beyond 1 day postoperatively had an improved likelihood of survival (87.5%). All cats that survived beyond 6 days were successfully discharged. CLINICAL SIGNIFICANCE: This study describes the largest group of cats with septic peritonitis with an overall survival rate of 66%. The presence of an abdominal mass on clinical examination or having dehiscence of a previous gastrointestinal surgery did not confer a worse prognosis.

Reliability of CT measurement of induced radioulnar step in dogs using a circle superimposition technique.

OBJECTIVES: To evaluate the reliability of CT measurement of canine elbow axial radioulnar congruence using a duplicated circle superimposition technique. MATERIALS AND METHODS: CT of six cadaveric canine elbows was performed following either: (1) placement of an external fixator on the radius with ostectomy and radial shortening of 1 to 5 mm; (2) radial lengthening of 1 to 5 mm using a radial lengthening system; or, (3) no axial length adjustment. Four observers, on two occasions, blinded to the amount of radial adjustment, placed a circle of best fit of the ulnar trochlear notch on a sagittal image that was duplicated and transposed to the articular contour of the radial head; then the axial distance between circles relative to the dorsal radius was measured. Statistical analysis assessed differences between actual and observer-assessed radial length adjustment; inter-/intra-observer interclass correlation coefficients and sensitivity/specificity were calculated to evaluate measurement reliability. RESULTS: There was not a significant difference between actual and observer measures of radioulnar congruence. Inter- (intraclass correlation coefficient=0.98) and intra-observer reliability (intraclass correlation coefficient=0.94 to 0.99) were almost perfect for measurement of radioulnar incongruence when compared to the actual radial adjustment. A Bland-Altman plot revealed a 95% confidence interval range of -1.31 to 1.16 mm. Sensitivity and specificity were high for correct identification of congruent elbows and elbows with 1 or 2 mm incongruency. CLINICAL SIGNIFICANCE: The duplicated circle superimposition technique provides a simple and accurate means of assessing radioulnar axial incongruence.

Disuse rescues the age-impaired adaptive response to external loading in mice.

UNLABELLED: We aimed to determine whether aged bone's diminished response to mechanical loading could be rescued by modulating habitual activity. By reducing background loading, aged bone's response to loading increased to a level no different to young mice. This suggests, given the right stimulus, that ageing bone can respond to mechanical loading. INTRODUCTION: Age-related decline in bone mass has been suggested to represent an impaired ability of bone to adapt to its mechanical environment. In young mice, the tibia's response to external mechanical loading has been shown to increase when habitual activity is reduced by sciatic neurectomy. Here we investigate if neurectomy can rescue bone's response to loading in old mice. METHODS: The effect of tibial disuse, induced by unilateral sciatic neurectomy (SN), on the adaptive response to a single peak magnitude of dynamic load-engendered mechanical strain was assessed in 19-month-old (aged) mice. In a second experiment, a range of peak loads was used to assess the load magnitude-related effects of loading on a background of disuse in young adult and aged mice. Bone architecture was analysed using micro-computed tomography (µCT) and dynamic histomorphometry. RESULTS: In the first experiment, SN in aged mice was associated with a significant periosteal osteogenic response to loading not observed in sham-operated mice (7.98 ± 1.7 vs 1.02 ± 2.2 % increase in periosteally enclosed area, p < 0.05). In the second experiment, SN abrogated the expected age-related difference in the bones' osteogenic response to peak strain magnitude (p > 0.05). CONCLUSIONS: These data suggest that bones' age-related decline in osteogenic responsiveness to loading does not originate in bone cells to either assess, or appropriately respond to strain, but rather is likely to be due to inhibitory "averaging" effects derived from the habitual strains to which the bone is already adapted. If such "strain averaging" is applicable to humans, it suggests that gentle exercise may degrade the beneficially osteogenic effects of short periods of more vigorous activity.

Prevalence, outcome and risk factors for postoperative pyothorax in 232 dogs undergoing thoracic surgery.

OBJECTIVE: To determine the prevalence, outcome and risk factors for postoperative pyothorax in dogs undergoing thoracic surgery. METHODS: Case records were reviewed retrospectively to identify dogs with post thoracic surgery pyothorax, defined as septic neutrophilic inflammation within the pleural space based on cytology and/or a positive bacterial culture of pleural fluid. Those identified were reviewed for potential risk factors for postoperative pyothorax based on biological plausibility and previously published data. These potential risk factors were explored by multivariable logistic regression. RESULTS: Of 232 dogs undergoing thoracic surgery, 15 (6.5%) dogs developed pyothorax. Bacteria cultured included methicillin-resistant Staphylococcus aureus and multi-resistant Escherichia coli. Of these dogs, six died, four were euthanased and five were treated successfully. A diagnosis of idiopathic chylothorax [Odds Ratio (OR)=12.5, 95% Confidence Interval (CI)=2.7-58.5, P=0.001], preoperative intrathoracic biopsy (OR=14.3, 95% CI=1.7-118.7, P=0.014) and preoperative thoracocentesis (OR=11.2, 95% CI=1.6-78.2, P=0.015) were identified as independent risk factors for development of postoperative pyothorax. CLINICAL SIGNIFICANCE: Idiopathic chylothorax, intrathoracic biopsy and prior thoracocentesis are independent risk factors for postoperative pyothorax, which was associated with a 67% mortality rate.

The cyclooxygenase-2 selective inhibitor NS-398 does not influence trabecular or cortical bone gain resulting from repeated mechanical loading in female mice.

UNLABELLED: A single injection of the cyclooxygenase-2 (COX-2) selective inhibitor NS-398 reduces bone's osteogenic response to a single period of mechanical loading in female rats, while women taking COX-2 selective inhibitors do not have lower bone mass. We show that daily NS-398 injection does not influence bone gain from repeated loading in female mice. INTRODUCTION: Prostaglandins are mediators of bone cells' early response to mechanical stimulation. COX-2 expression is up-regulated by exposure of these cells to mechanical strain or fluid flow, and the osteogenic response to a single loading period is reduced by COX-2 inhibition. This study determined, in female mice in vivo, the effect of longer term COX-2 inhibition on adaptive (re)modelling of cortical and trabecular bone in response to repeated loading. METHODS: Nineteen-week-old female C57BL/6 mice were injected with vehicle or NS-398 (5 mg/kg/day) 5 days a week for 2 weeks. On three alternate days each week, the right tibiae/fibulae were axially loaded [40 cycles (7 min)/day] three hours after injection. Left limbs acted as internal controls. Changes in three-dimensional bone architecture were analysed by high-resolution micro-computed tomography. RESULTS: In control limbs NS-398 was associated with reduced trabecular number but had no influence on cortical bone. In loaded limbs trabecular thickness and cortical periosteally enclosed volume increased. NS-398 showed no effect on this response. CONCLUSION: Pharmacological inhibition of COX-2 by NS-398 does not affect trabecular or cortical bone's response to repeated mechanical loading in female mice and thus would not be expected to impair the functional adaptation of bone to physical activity in women.

Estrogen receptors α and ß have different gender-dependent effects on the adaptive responses to load bearing in cancellous and cortical bone.

To determine the effect of estrogen receptors (ER) α and ß on bones' adaptive response to loading, we subjected the right tibiae of mice lacking ERα or ERß activity to either axial loading or to disuse. Adaptive changes in architecture were assessed by comparing differences between the right (treated) and left (control) tibiae in these genotypes as assessed by microcomputed tomography. In female ERα(-/-) mice, the net-osteogenic response to loading was lower in cortical bone compared with their wild-type littermates (11.2 vs. 20.9% in ERα(+/+)), but it was higher in both cortical and cancellous bone of male ERα(-/-) mice (cortical 20.0 vs. 4.6% in ERα(+/+); cancellous 30.0 vs. 5.3% in ERα(+/+), P < 0.05). In ERß(-/-) male and female mice, the net-osteogenic response to loading was higher in cortical bone (males 10.9 vs. 3.9% in ERß(+/+); females 18.5 vs. 15.8% in ERß(+/+), P < 0.05) but no different from controls in cancellous bone. The bone loss in response to disuse was less in cancellous bone of ERα(-/-) mice than in controls (-15.9 vs. -21.3%, respectively, P < 0.05) but no different at any other site or between any other groups. Our conclusion is that functional ERα enhances the net-osteogenic response to loading in cortical but not cancellous bone in female mice but reduces it in males. ERß decreases the response to loading in cortical bone of males and females but has no effect in cancellous bone. Bone loss due to disuse in cortical bone is unaffected by ER status, but in cancellous bone, functional ERα contributes to greater disuse-related bone loss.