Diagnosing small breed dogs with atlantoaxial subluxation


To assess the accuracy of ultrasound to diagnose small breed dogs with atlantoaxial subluxation compared to a current diagnostic imaging modality (x-rays, CT and/or MRI).


Atlantoaxial subluxation (AAS) is a cause of spinal cord injury in primarily toy breed dogs that results in spinal cord compression of the neck. Congenital anomalies of the AA joint predispose these dogs to vertebral subluxation causing neurological signs ranging from episodic cervical pain with mild neurological deficits, to respiratory compromise and sudden death.

Current methods to diagnose this condition include manual restraint for x-rays or general anesthesia for CT or MRI. Ultrasound is a safe modality that requires minimal restraint and could be useful to diagnose this condition. This method of diagnosis could potentially be performed bedside without the need for anesthesia. This method of diagnosis is currently not reported in the literature. 

While the dogs in the study may not derive immediate benefit from this research, their participation is anticipated to directly help other dogs affected by atlantoaxial subluxation in the future by making available a diagnostic test that may be faster, safer, and cheaper than current standard-of-care diagnostic tests.


  • Study covers cost of cervical ultrasound examination (NB. sedationnotincluded)

Samples Required

  • ultrasound and either x-ray/CT/MRI images

Inclusion Criteria

  • Small breed dog with cervical pain and/or neurological deficits localized to cervical spine, with potential diagnosis of atlantoaxial subluxation
  • Ultrasonographer must be blinded to previous diagnostic imaging (if avail).


Alex zur Linden

Luis Gaitero

Fiona James 


Email: clinical.research@uoguelph.ca

Alex zur Linden
Work Cell #: 226-924-5891

Vicky Sabine, PhD
Clinical Research Coordinator, OVC
Email: vsabine@uoguelph.ca; Work Cell #: 226-218-0338

Funded by OVC Pet Trust