Contrast-enhanced CT predictors of lymph nodal metastasis in dogs with oral melanoma.

Canine oral melanoma (OM) has highly aggressive behavior, with frequent local metastasis. Computed tomography 3D volumetric analysis is an accurate predictor of lymph node (LN) metastasis of oral cancers in humans but whether this is true for dogs with OM is unknown. In this retrospective observational study, CT imaging was used to assess mandibular and retropharyngeal lymphocenter (LC) changes in dogs with nodal metastatic (n = 12) and non-metastatic (n = 10) OM, then these findings were compared with those of healthy control dogs (n = 11). Using commercial software (Analyze, Biomedical Imaging Resource), lymphocenters were defined as regions of interest. LC voxels, area (mm2 ), volume (mm3 ), and degree of attenuation (HU) were compared between groups. Mandibular lymphocenter (MLC) metastasis was present in 12 of 22 (54.5%) dogs; no dogs had confirmed retropharyngeal lymphocenter (RLC) metastasis. Mandibular lymphocenter volume was significantly different between positive and negative LCs (median 2221 and 1048 mm3 , respectively, P = 0.008), and between positive and control LCs (median 880 mm3 , P < 0.01). There was no evidence of a significant difference in voxel number or attenuation between groups. Mandibular lymphocenter volume moderately discriminated for metastatic status (AUC 0.754 [95% CI = 0.572-0.894, P = 0.02]), with a positive predictive value of 57.1% (95% CI = 0.389-0.754). Adjusting for patient weight did not improve discrimination (AUC = 0.659 (95% CI = 0.439-0.879, P = 0.13]). In conclusion, these findings suggest 3D CT volume measurement of MLC can predict nodal metastasis in dogs with OM and shows promise but further research, perhaps in combination with other modalities, is required to improve accuracy.

Fracture Healing in 37 Dogs and Cats with Implant Failure after Surgery (2013-2018).

Implant failure is common in small animal orthopedics, but risk factors are rarely reported. Our objective was to determine whether abnormal fracture healing was associated with implant failure after fracture fixation in dogs and cats in a consecutive series of cases. Thirty-seven client-owned animals (thirty-two dogs, five cats) diagnosed with implant failure after fracture treatment from January 2013-September 2018 were studied. Medical and radiographic records were retrospectively reviewed to identify patients that underwent fracture fixation using open reduction and internal fixation with subsequent radiographic evidence of implant failure. Area moment of inertia (AMI), plate working length, and bone screw density were determined. Implant failure was found in 39 fractures in 37 animals, representing 23% of fracture cases during the study period. Cases of implant failure were at increased risk of delayed union, malunion, or non-union (p < 0.0001). The most common cause of implant failure was loosening (54%); the second most common was plate failure that included low AMI locking plates (28%). Major complications found in 22/39 fractures (56%) were associated with delayed union (p < 0.01). Surgical revision was performed in 49% of implant failure cases. Complications were most frequently identified after treatment of humeral fractures (26%). We conclude mechanical failure of implants increases the risk for delayed or abnormal fracture healing and often requires revision surgery. Implant AMI should be considered during preoperative planning. Locking plates are associated with implant failure if plate bending stiffness is not sufficient, based on findings from this case series.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.