Diagnostic imaging characteristics of canine infectious sacroiliitis.

Infectious sacroiliitis has not been described in dogs. This retrospective case series describes the presentation, diagnostic imaging characteristics, and outcomes of 2 canine patients with infectious sacroiliitis. Selection criteria included presentation with back pain from 2010 to 2017, diagnostic imaging of the sacroiliac joints, and short- and long-term response to antibiotic therapy. Medical records, and magnetic resonance imaging (MRI) were reviewed by a Board-certified veterinary radiologist, a neurologist, and a small animal intern. Two dogs met the inclusion criteria. Magnetic resonance imaging revealed unilaterally wide and irregular sacroiliac joint spaces, with juxta-articular soft tissue contrast enhancement and bone marrow edema. One patient had a communicating abscess of the psoas muscle, which cultured positive for Pasteurella canis. Following treatment with pain relief medications and antibiotics, both patients made a complete clinical recovery, with no signs of lameness 2 to 4 weeks after cessation of treatment, and no lameness reported by the owner afterwards. Infectious sacroiliitis should be considered when dogs are presented with lumbosacral pain.