Large breed dogs in particular are susceptible to injuries in the cervical spine. By understanding the biomechanics of this part of the spine, we are better able to prevent injuries and rehabilitate dogs following injury to their neck.

Where is the cervical spine on a dog?

Dogs have seven (7) cervical vertebrae which extend from the back of the dog’s skull to their shoulders. While the dog’s spine from the head to the shoulders appears straight, it actually curves downward from the head to the shoulders. When the dog is trotting and galloping, the cervical spine is “straightened”. In these gaits the dog thrusts it’s head forward as a cantilever to balance the body.

What part of the dog’s cervical spine bears the most forces?

A study aimed to determine how the muscles of the cervical spine are recruited and impose forces on the surrounding tissues during the dog’s normal daily activities.

For this study, the researchers lured the dog to move its head laterally, side to side and to flex and extend the neck by raising the dog’s nose up and down.

The study observed the recruitment of the following muscle pairs and their role in applying forces to the dog’s cervical spine:

• Longissmus – This muscle extends from the ilium (pelvis) to the head. The section of the muscle that innervates the cervical vertebrae is the longissimus cervicis. In large dogs, this section of the muscle can be 1 – 1.5cm thick. This muscle extends the dog’s neck and its unilateral action turns the dog’s head to one side.

• Complexus – This muscle attaches from the first thoracic vertebrae to the third cervical vertebrae. This muscle extends the head and neck and when contracted unilaterally flexes the head and neck laterally.

• Sternocleidomastoid – This can be a large muscle up to 2.5 – 3.5 cm wide and 10 -14mm thick ion large breed dogs. The mastoid part of the muscle inserts into the mastoid part of the temporal bone on the back of the dog’s skull, via a large tendon. This muscle also extends and flexes the neck and turns the head side to side.

• Splenius – This is a fleshy triangular muscle. It extends from the third thoracic vertebrae and nuchal ligament to the skull. This muscle also extends and flexes the neck and turns the head laterally.

• Obliquus capitis – This muscle arises on the lateral wing of the atlas (vertebrae) and inserts on the mastoid part of the temporal bone and the nuchal ligament. It extends the atlanto-occipital joint. (moves the dog’s head forward)

• Biventer – This muscle originates in the processes of the fourth, third and second thoracic vertebrae and inserts into the occipital protuberance of the skull. This muscle contains a high concentration of neurotenindous muscle spindles (Golgi tendon organs) which points to the role of this muscle in the coordination of the head and neck for orientation and efficient locomotion.

The study also observed the movement of the head and neck joints along the cervical vertebrae. The “head joint” comprises the atlanto-occiptal joint and atlanto-axial joint which involve C1 and C2. These joints share a joint capsule and allow the dog’s head to move independently of the neck. It is thought that 40% of axial rotation occurs at the atlanto-axial joint with the remainder occurring along the rest of the neck.

Findings

The study concluded that as the dog moved their head up and down (nodding) and from side to side, the compression forces increased gradually from C1/C2 to C4/C5 where they were the greatest. The forces gradually decreased toward C7/T1. These forces are a result of both the muscle and ligament attachments to these vertebrae and the amount of movement that occurs at the head and neck joints along the cervical spine.

Tips for preventing neck injury in dogs

The greatest forces on the dog’s neck are at the C4/C5 joint, so this area is the most prone to fatigue and injury. Here are some tips for preventing neck injury and soreness.

1. Address potential injury or strain immediately

If you think your dog has injured or strained their neck then address it immediately. Signs of potential injury include

• sensitivity to touch or the dog avoiding you handling them in the neck and upper back area

• reluctance to turn their head side to side or up and down

• shortened stride in the forelimbs

2. Rest

If your dog has exercised strenuously including galloping, jumping or participating in dog sports, ensure they exercise lightly the following day. A day of rest allows small tears in muscle fibres, that occur with normal activities, to heal.

3. Reduce stresses on the dog’s neck
Consider if you can eliminate anything physical that adds strain to the dog’s neck. Consider things like collars and harnesses. See http://www.fullstride.com.au/blog/can-dogs-pulling-on-lead-hurt-their-neck for more information.

4. Maintenance treatment

A maintenance massage treatment 3 or 4 times a year reduces muscle strain and soreness in the cervical spine and helps to prevent more serious injuries occurring from the muscles being overloaded.

Full Stride provides remedial massage therapy for rehabilitate dogs to keep them active and healthy. Please leave me a comment with your tips on preventing muscle strain in your dog’s neck.

Until next time, enjoy your dogs.

Sources:

Alizadeh, M., Knapik, G. G., Dufour, J. S., Zindl, C., Allen, M. J., Bertran, J., & Marras, W. S. (2017). An EMG-driven biomechanical model of the canine cervical spine. Journal of Electromyography and Kinesiology, 32, 101-109.

Evans, H & de Lahunta, A, 2013, Miller’s Anatomy of the Dog (4th ed), Elsevier Saunders, Missouri.