Educational Memorial Program Can Help Find Treatments for Atlantoaxial Instability

The education of health professionals has always relied on study of anatomy to ensure that practitioners have the knowledge and experience required to provide optimal care for their patients.

The Ontario Veterinary College (OVC) is working with pet owners and animal shelters to provide learning opportunities for our students and to support investigations to find answers for specific diseases. To assist us, we have an Educational Memorial Program whereby owners whose pets are being euthanized can donate their pet’s body to OVC. During this difficult time after loss of a pet, owners may find some consolation for their grief in knowing that their pet will help others in the future.
The OVC Educational Memorial Program is similar to the University of Guelph’s willed body program that supports the human anatomy program. The OVC Educational Memorial Program helps veterinary students learn and helps investigators find solutions to disease problems.

Investigators are looking at a specific disease, atlantoaxial instability, that affects miniature and toy breeds. Due to their small size, these breeds have variations in the anatomy of their neck that affects the success of treatment of this disease.

Any toy breed dog owner can help support this important research by donating the body of their late pets to the OVC Educational Memorial Program. Breeders and veterinarians can encourage their clients to do the same. The dog does not have to have this disease in order to be helpful.

This generous gift will be greatly appreciated as each donation will help us take better care for our beloved pets. The donation is usually done through the family veterinarian who can directly contact the OVC. This research can also been supported simply by communicating this information to the toy breed community. So please “spread the word” among your friends and other members of toy breed clubs. Current research on atlantoaxial instability is funded by the OVC Pet Trust Fund. Therefore, supporting the OVC Pet Trust Fund is another way to support this field of research. You can find further information on this charitable fund at

Information about Atlantoaxial (AA) Instability

Atlantoaxial (AA) instability is most commonly caused by congenital malformations of the second neck vertebra (also known as axis). These malformations are most frequently seen in younger to middle-aged toy breed dogs (including Yorkshire terriers, Chihuahuas, miniature and toy poodles, and Pomeranians). Dogs may start showing signs early in life after a minor incident such as playing with another dog or falling from a chair. The symptoms can range from neck pain to paralysis and may even cause breathing problems and sudden death.

Treatment options include conservative management or surgical stabilization. For conservative management of AA instability, the neck is immobilized with a brace for several weeks to several months. This treatment has been reported to have a 57% success rate and is usually considered a viable option in younger dogs with an initial, acute onset of clinical signs.

Surgical management involves stabilizing the AA joint through placement of vertebral implants and sometimes bone grafts to fuse the atlas and axis. Surgical AA fusion offers a 65-86% success rate and is considered the best therapeutic option in many cases. However, while AA surgical stabilization provides the best clinical outcome, it remains one of the most challenging procedures performed by veterinary neurosurgeons. Due to the small size of the affected dogs, there is a very small margin for error.
In the past 15 years, most of the research on atlantoaxial instability has been focused on determining the best surgical technique to stabilize the atlantoaxial joint. Veterinary neurosurgeons have shared their experience and compared their success using various bone methods. However, at this time the choice of the technique and the type of implants to be used relies mainly on the personal experience of the surgeon rather than scientific data. Proving the superiority of one technique over another will require studies using cadavers.

A research group at the OVC is working to establish detailed data on anatomy of the atlantoaxial joint of miniature and toy breed dogs. The research group is also determining which surgical techniques provide the safest and strongest spinal stabilization. The long-term goal is to formulate guidelines to help neurosurgeons choose the safest and most appropriate surgical technique for their patients. The goal is to reduce the risks associated with these procedures so that more of these dogs live normal, happy lives.

To learn more about the ongoing research on atlantoaxial instability, or if you have questions about the importance of donating the bodies of deceased pets, contact Dr. Guillaume Leblond (Neurology Resident at the OVC Health Sciences Centre) at This email address is being protected from spambots. You need JavaScript enabled to view it. or Dr. Luis Gaitero (Assistant Professor Neurology and Neurosurgery at the OVC) at This email address is being protected from spambots. You need JavaScript enabled to view it..