A pitfall on postoperative radiographs in dogs after tibial plateau leveling osteotomy.

OBJECTIVE: To identify the cause of an occasional radiolucent line in the tibia on postoperative radiographs after tibial plateau leveling osteotomy (TPLO) in dogs. STUDY DESIGN: Retrospective case series and ex vivo experiment. SAMPLE POPULATION: Dogs (n = 80; 87 stifles) with cranial cruciate ligament (CCL) rupture that had TPLO; and 4 canine tibia specimens. METHODS: Medical records (2007-2010) and radiographs of dogs that had TPLO were reviewed and examined for presence of a radiolucent line on postoperative radiographs. The TPLO procedure was reproduced ex vivo to determine the origin of this line by use of metallic wires to identify bone contours. RESULTS: A curvilinear radiolucent line was visible in 14 (16%) tibias and was 5.4 times more likely to be visible with lateral misalignment of the tibial diaphysis relative to the plateau and 2.6 times more likely visible on caudocranial radiographs with the stifle in outward rotation. Fracture complication rate was higher in dogs with this radiolucent line (P = .02) and with lateral misalignment of the tibial diaphysis relative to the plateau (risk ratio, 3.8). The line could be reproduced ex vivo and caused by superimposition of the craniomedial border of osteotomy with the tibial plateau. CONCLUSIONS: The radiolucent line was a spurious fracture line created by the medial margin of the tibial osteotomy and confounding factors such as tibial misalignment may explain the apparently associated higher complication rate.

Diagnostic accuracy of magnetic resonance imaging for meniscal tears in dogs affected with naturally occuring cranial cruciate ligament rupture.

A stifle magnetic resonance (MR) imaging protocol was developed based on the appearance of the cruciate ligaments and menisci in normal dogs. Proton density images were subjectively considered to have the highest likelihood of detecting a meniscal lesion. Following this initial evaluation, the accuracy of high-field MR imaging to detect meniscal tears in dogs was evaluated in 11 dogs suffering from naturally occurring cranial cruciate ligament rupture. Dogs underwent MR imaging of the affected stifle before surgery. MR imaging and surgical findings were assessed independently, and then compared. Five tears of the medial meniscus were correctly diagnosed with MR imaging and 19 normal menisci were accurately characterized as such, based on MR images. In one medial meniscus, changes consistent with meniscal degeneration were seen on MR images but this was not seen at surgery. With regard to the lateral meniscus, one false positive diagnosis of a tear was made and this likely represented a normal variation. One other lateral meniscus had changes consistent with meniscal degeneration but, as with the similar lesion seen in the medial meniscus, this was not confirmed surgically. The global sensitivity of MR imaging for the diagnosis of a meniscal tear was 100% and the specificity was 94%. High-field MR imaging is a reliable method to diagnose meniscal tears preoperatively and this may be useful in selecting the surgical approach to clinically abnormal joints and may decrease the need for arthrotomy.

In vitro 3-dimensional kinematic evaluation of 2 corrective operations for cranial cruciate ligament-deficient stifle.

The objective of this study was to determine the immediate postoperative effect of 2 corrective operations for cranial cruciate ligament (CCL)-deficient stifle by evaluating 3-dimensional (3-D) stifle kinematics. Ten hindlimbs from large-breed canine cadavers were used. Range of motion was induced by applying 100 N of traction on the quadriceps tendon and recorded with electromagnetic movement sensors for each situation: intact stifle (control), CCL-sectioned stifle, and surgical correction of the sectioned ligament with the modified retinacular imbrication technique (MRIT) and then with a tibial plateau leveling osteotomy--Montavon (TPLO-M). The results for the experimental situations were compared with the results for the control situation by 1-way repeated-measures analysis of variance and with each other by post-hoc analysis with the least-significant-difference method. Range of motion was significantly decreased by MRIT as compared with the other situations. Normal cranial tibial translation was restored after MRIT, whereas TPLO-M resulted in significant caudal translation. A significant increase in external rotation was observed after both MRIT and TPLO-M. A significant increase in tibial adduction throughout the range of motion was observed with TPLO-M, whereas a significant increase in tibial abduction was observed after MRIT. This study allowed us to better understand objectively the effects on 3-D canine stifle kinematics of MRIT and TPLO-M. We suggest that this type of in vitro study would be useful to evaluate established and upcoming surgical techniques and potentially improve corrective surgery.

Noninvasive correction of a fractured endoluminal nitinol tracheal stent in a dog.

An 11-year-old, castrated male Pomeranian was presented for intractable cough and dyspnea secondary to severe tracheal collapse. An endoluminal nitinol tracheal stent was placed with good results. Five months following placement of the prosthesis, clinical signs acutely recurred and failure of the implant was noted. A second stent was superimposed over the fractured stent and resulted in resolution of all clinical signs. The dog died several months later from progression of the tracheal collapse to the carina and mainstem bronchi.

Efficacy of selamectin in the treatment of naturally acquired cheyletiellosis in cats.

The purpose of this study was to evaluate the efficacy of a topical formulation of selamectin in the treatment of cheyletiellosis in cats. Fifteen adult domestic cats from the same household with naturally occurring Cheyletiella sp. infestation were enrolled in the study. On each cat, 45 mg of selamectin was applied on days 0, 30, and 60. No other treatment or environmental decontamination was performed during the trial. On days 0, 30, 60, and 120, all cats were examined, epidermal debris was collected over the dorsal area of the body with flea combs for microscopic examination, and fecal flotations were done. Clinical signs had subsided by day 60 in all 15 cats and no signs of recurrence were apparent on follow-up 1 year later. All epidermal and fecal samples were negative by day 60. No adverse reactions were observed. Under the conditions of our study, topical selamectin was a practical and well-tolerated means of treatment for cheyletiellosis in cats.