Spinal and Vertebral Birth Defects in Dogs

There are a number of spinal and vertebral defects that can cause problems in dogs. The spine is made up of vertebrae separated by intervertebral disks that act as shock absorbers. This structure provides both support and flexibility, so your dog can move easily without injury. The spinal or vertebral canal running through the center of each vertebra contains and protects the spinal cord. The spinal cord passes messages to and from the brain, and helps to regulate many involuntary muscle processes, so it is a very important part of your dog’s nervous system. Spinal vertebrae are divided into three sections: the cervical or neck area, the upper thoracic spine, and the lower lumbar region. Each vertebra is numbered according to its placement in the section. Some abnormalities will affect the shape of vertebrae. Hemivertebra are shortened and misshapen with a wedge or triangular shape on one side, while butterfly vertebrae have a cleft on one side so their shape resembles a butterfly. Other abnormalities affect the way vertebrae are joined together. Several vertebrae may be fused or the vertebrae transitioning between different parts of the spine may be improperly differentiated. Many of these conditions may have no symptoms, or only mild gait or posture abnormality. Any problem that puts pressure on the spinal cord is more serious. Some types of vertebral malformations can cause neurological symptoms, paralysis, or even death. 

Birth defects that affect the spine are a fairly common problem in some breeds of dogs. Veterinarians call this congenital vertebral malformations. Symptoms can vary depending on the type and location of the abnormality. Problems that cause compression or injury to the spinal cord are much more serious.

These are the symptoms you might notice in a dog with spinal and vertebral malformations. Some dogs may have symptoms from birth while others may develop them after a growth spurt causes weakness in the spine.

• Sway back (lordosis) – curvature of the spine downward
• Arching spine (kyphosis) – curvature of the spine upward
• Awkward or wobbly gate
• Uncoordinated movements
• Paresis – musculature weakness or partial paralysis
• Paralysis
• Incontinence of urine or bowel movements

Types

These are some of the different types of spinal and vertebral defects in dogs, as well as the breeds they frequently affect.

Atlantoaxial luxation

• Malformation of the occipital bone – instability that may cause the spinal cord to become pinched between the first and second vertebrae
• Small and toy breeds (Yorkshire Terrier, Chihuahua, Poodle, Pomeranian, and Pekinese)

Hemivertebra 

• Vertebrae that are underdeveloped and wedged shaped on one side
• Screw-tailed breeds (Pugs, Bulldogs, and Boston Terriers), German Shorthaired Pointers, German Shepherds

Butterfly vertebra 

• Underdeveloped vertebrae with a cleft shape that resembles a butterfly
• Brachycephalic and screw-tailed breeds

Transitional Vertebra

• Abnormally differentiated vertebrae between the different parts of the spine
• Screw-tailed breeds

Block vertebra 

• Several vertebrae fused together
• Screw-tailed breeds

Meninges or spina bifida 

• Malformation or the spine that leads to exposure of the spinal cord
• Screw-tailed breeds especially bulldogs

Myelodysplasia (spinal dysraphism

• Lesions on the lower spinal cord that are present from birth
• Weimaraners

Spinal Stenosis

• A congenital narrowing of the spinal canal. In the cervical spine this is also called caudal cervical spondylomyelopathy or wobbler syndrome
• Doberman pinschers, Great Danes, Borzois, Old English Sheep Dogs, St. Bernard’s, Pointers and Basset Hounds

Spinal and vertebral malformations are usually inherited. The mode of inheritance is only understood in a few cases. German shepherds inherit hemivertebra as an autosomal recessive trait. In Weimaraners, myelodysplasia appears to be co-dominant; dogs with the gene from only one parent have mild symptoms, while puppies with two defective genes usually don’t survive. In many cases, several genes may be involved, as well as other factors like nutritional deficiency in the womb. Breeding dogs with any form of spinal birth defect is not recommended, even if your dog isn’t showing symptoms. This can help to reduce incidence in a breed.

An X-ray is needed to diagnose any vertebral malformation. If your dog is not showing symptoms, the veterinarian may notice the abnormality on an X-ray for another purpose. Dogs with an unusually swayed or arched back should be evaluated by a veterinarian, especially if the problem causes weakness or difficulty controlling movements. Other symptoms, such as paralysis or pain can help the veterinarian locate the abnormality.

Your dog’s age and breed will be relevant, as well as any recent injuries that could suggest a different diagnosis. Several X-rays may be needed to find the angle that shows the malformation. Your dog may need anesthetic, especially if moving the spine is painful. A CT scan or an MRI could also be ordered to show the spine in more detail.

Treatment will depend on the severity of the problem. Dogs that are not symptomatic don’t need to be treated. If your dog has only a mild gait or posture abnormality, the veterinarian may also not recommend treatment, unless the symptoms seem to be getting progressively worse.

Problems that affect the spinal cord are usually treated with surgery. Veterinarians will recommend a specialist for this type of surgery. The affected vertebrae will need to be decompressed and often pins or bone plates may be inserted to stabilize the area and prevent the spinal cord from becoming pinched. Dogs will usually need 6-8 weeks of rest or reduced activity after surgery to recover. A brace may be necessary to stabilize the area during healing.

Some conditions like myelodysplasia and spina bifida are not treatable. These conditions don’t get progressively worse, and dogs with only mild symptoms will live still fulfilling lives, but dogs with very severe symptoms may need to be euthanized. Some other malformations may not be untreatable, if your dog is not healthy enough for surgery, or if there is no way to correct the abnormality surgically. Steroids or painkillers may be prescribed to manage the symptoms. Depending on the severity of the problem, the veterinarian may recommend euthanasia also.

Your dog’s chance of recovery will vary greatly depending on the specific type of defect and where it is located. Some dogs will make a full recovery after surgical treatment. Others may still have neurological disabilities.  Some mobility problems can be managed with adaptive equipment, such as rear wheel carts or dog wheelchairs. You may need to rearrange the house so your dog doesn’t need to climb stairs. If your dog has continued incontinence after surgery this may need to be managed with a catheter and/or assistance emptying the bladder.