Modeling of the spread of infection in the interdigital spaces of the manus in limbs from clinically normal dogs

Objective - To determine whether the pattern of extension of modeled infection from the interdigital web spaces in dogs is predictable and whether the distribution differs among initial injury sites. Sample Population - Thawed frozen forelimbs from 23 cadavers of previously healthy adult medium- to large-breed dogs. Procedures - The manus of each forelimb was evaluated by use of computed tomography (CT) before and after injection of radiopaque blue-staining contrast medium into the interdigital web spaces. Two veterinary radiologists reviewed the CT images and recorded the extent of contrast medium from each site. Each manus was dissected or sectioned transversely after imaging, and the extent of contrast medium accumulation was recorded and compared with locations of CT contrast enhancement. The Fisher exact test was performed to determine whether the pattern of contrast medium extension differed by injection site. Results - Injections made in the interdigital web spaces of the canine manus led to unique and predictable patterns of extension into the surrounding soft tissues. That pattern of extension primarily involved the soft tissues of the digits. Conclusions and Clinical Relevance - In humans, knowledge of common extension patterns from infected soft tissue spaces is used to predict the spread of disease within the hand and develop surgical plans that will minimize patient illness. Identification of the common sites of disease spread from the interdigital web spaces in dogs may help improve surgical planning and treatment for infection in the manus.