In this episode, we delve into the complexities of the canine sacroiliac joint (SIJ), exploring its anatomy, dysfunction, and treatment options, based on the latest research on biomechanics, diagnostic challenges, and therapeutic interventions.Note: This episode is not meant to be taken as veterinary advice. It was created for background information for anyone interested in the topic. In this episode, we explore a commonly overlooked source of pain and performance issues in dogs: sacroiliac joint (SIJ) dysfunction. Drawing on veterinary physiotherapy sources and clinical experience, we examine the structure and function of the SIJ, the challenges of diagnosing dysfunction, and its relevance for working dogs, agility competitors, and companion animals alike. We also consider how SIJ dysfunction interacts with other musculoskeletal issues, the behavioural signs owners might notice, and the treatment options available.Key topics* Anatomy and biomechanics of the sacroiliac joint* Causes and consequences of SIJ dysfunction in dogs* Clinical signs and behavioural indicators* Challenges in diagnosis and differential considerations* Manual therapy, rehabilitation, and management options* Relevance for trainers, owners, and allied professionalsLong-read articleIntroduction: the hidden hinge of canine movementThe sacroiliac joint is a crucial but often neglected component of the canine musculoskeletal system. Located where the sacrum meets the ilium on each side of the pelvis, it forms a weight-transferring bridge between the hindlimbs and the spine. Unlike freely mobile joints, the SIJ is a combination of a fibrous and synovial joint, allowing only small degrees of movement—but those micromovements are essential for shock absorption and locomotor coordination.When functioning well, the SIJ supports efficient, powerful movement. When compromised, it can become a source of pain, instability, and compensation throughout the body. Yet because its symptoms often mimic or overlap with other conditions, SIJ dysfunction in dogs remains underdiagnosed.Anatomy and biomechanicsThe sacroiliac joint consists of:* A cranial synovial portion that permits minimal gliding movements* A caudal fibrous portion with ligamentous stabilisation* Surrounding ligaments including the sacrotuberous ligament and dorsal sacroiliac ligamentsThe joint's stability depends more on ligamentous support and muscular tension than bony congruence. Key muscles influencing SIJ mechanics include the gluteals, multifidus, iliopsoas, and hamstrings. These muscles form part of the lumbopelvic stabilising system and are also involved in broader locomotor chains. Even minor disruptions in this system—from injury, overuse, or compensation—can destabilise the joint.Because the SIJ lies at the intersection of load transfer between the hindlimbs and spine, even subtle biomechanical inefficiencies can have far-reaching effects. Instability here often creates a chain reaction: altered stride mechanics, compensatory lumbar stiffness, and chronic muscle tension in surrounding areas.Causes of dysfunctionSIJ dysfunction can result from:* Repetitive strain (e.g., agility, flyball, or working dogs performing repeated high-impact movements)* Trauma (e.g., slipping on slick surfaces, being knocked over, vehicular accidents)* Compensation from other lameness or spinal issues (e.g., stifle or hip pathology, intervertebral disc disease)* Pelvic asymmetry or chronic postural imbalances (e.g., habitual crooked sitting or trotting)* Inadequate core strength or poor proprioceptive trainingIn younger dogs, trauma or early-onset lameness may be the trigger. In older dogs, SIJ dysfunction may develop gradually due to cumulative biomechanical stress, arthritis, or muscle weakness. Dogs with hypermobility or underlying connective tissue laxity may be especially prone. In b*****s, parturition or hormone-related ligamentous changes may also play a role.Signs and symptomsSIJ dysfunction presents with a mix of vague and specific signs, such as:* Hindlimb lameness or gait asymmetry, often intermittent or shifting* Shortened stride length or reduced drive from the rear limbs* Difficulty rising, jumping, climbing stairs, or making tight turns* Pelvic stiffness or a 'bunny hop' motion in fast trot or canter* Discomfort on palpation or mobilisation of the pelvis, particularly asymmetrically* Uneven muscle development or tone in the gluteals, hamstrings, or lumbar spine* Behavioural signs such as irritability, flinching when touched, reluctance to work or play, or loss of performance in trained dogsIt may coexist with or mimic hip dysplasia, stifle instability, lumbosacral disease, iliopsoas strain, or lumbar facet joint pain. Without careful assessment, it can easily be missed or misattributed.Assessment and diagnosisVeterinary diagnosis typically requires a combination of:* Orthopaedic and neurological exams to rule out primary limb or spinal causes* Careful palpation of the pelvis ...
