Epsilon Archive for Student Projects

Abstract

Boxer dogs are reported to suffer from an increased risk of orthopedic disease affecting the stifle such as osteochondrosis, cruciate ligament disease, patellar luxation and these diseases often lead to osteoarthritis, a disease affecting Boxers even at a young age.
This study aims to investigate possible causes of early development of osteoarthritis in Boxer stifles using computed tomography (CT). Other aims are to investigate whether the observed CT changes can be observed in radiographs as well as investigating the outcome in Boxers that partici-pated in an official Swedish Kennel Club radiographic screening of Boxer stifles.
In the study, patient medical journals, CT images, and radiographs were collected from Evidensia Strömsholm Referral Small Animal Hospital. The CT images of 20 Boxers were assessed for presence of any abnormalities within the joint. Seventeen (85%) of the Boxers evaluated had presence of focal, well defined, hypoattenuating, round or branching tubular structures in one or both stifles in the intercondylar area of the femur and/or the axial aspect of the lateral condyle of the femur. Twelve (60%) Boxers had presence of osteophytes on the medial or lateral condyle of the femur. Twelve (60%) Boxers had presence of osteophytes and/or sclerosis on the proximal aspect of the tibia. Twelve (60%) Boxers had similar hypoattenuating structures to the ones found on the intercondylar surface of the femur but located on the tibia medial to the attachment of the cranial cruciate ligament. All stifles with a hypoattenuating structure located on the tibia had one located on the intercondylar and/or the axial aspect of the lateral condyle. In six stifles (15%) in five dogs, hypoattenuating structures in the stifle (found on the tibia or femur or both) were present without any presence of osteophytes.
In order to assess the presence of these CT hypoattenuating structures in radiographs and investigate if they were present in dogs with radiographically detectable osteophytes, radiographs from the Swedish Kennel Clubs (SKK) public database were used for seven dogs. Additional radiographs were collected for four dogs from Evidensia Strömsholm Referral Small Animal Hospital. In total, eleven dogs that had CT images also had radiographs that could be assessed. Nine (82%) had identifiable changes (osteophytes, increased volume of the soft tissue opacity or enthesophytes) in their radiographs. In five stifles of three individuals, the hypoattenuating struc-tures seen on CT in the intercondylar and lateral condyle axial areas could be seen in the radiographs.
The outcome of dogs participating in the official Boxer stifle health program was assessed using a survey that current and past owners of Boxers could answer. Information was gathered regarding the participation in the health program, grade received, development of stifle problems and the diagnoses set by a veterinarian of any stifle problems. The survey generated 296 answers regarding the outcome of Boxers, 160 about Boxers that did participate in the official program and 136 that did not. Problems with one or both stifles developed in 46 (16%) of Boxers and 41 of these had diagnoses set by veterinarians. Thirty-eight dogs had problems with their left stifle and eleven had problems with their right stifle. Ten dogs were reported to have problems with both their stifles.
The results of this study cannot provide definitive conclusions regarding the underlying cause of early development of stifle osteoarthritis in Boxers, but it did identify new areas of interest such as the presence of hypoattenuating structures in the intercondylar and axial lateral condyle regions of the femur and their possible significance to lameness and development of osteoarthritis. To increase the understanding of the causes of stifle joint problems, future studies could investigate the micro-scopic morphology of hypoattenuating areas commonly seen in this study on the axial aspect of the lateral femoral condyle and in the intercondyloid region of the femur, and studies of CT images from
Abstract
stifles of other dog breeds can further investigate if these hypoattenuating areas are related to specific dog breeds.