Lordosis, or swayback, is unnatural curvature in the spine due to congenital spinal deformity. Caused by malformed, wedge-shaped vertebrae, lordosis is often evident at birth, though sometimes it may not be evident until a puppy goes through a growth spurt around 5 to 9 months of age. Aside from an uncharacteristic curve in the back, lordosis may not cause any medical complications for your puppy; however, compression of the spinal cord is a possibility.
Normal vertebrae together as they develop, creating a relatively straight spine. Hemivertebrae are a congenital deformity whereby parts of the vertebrae do not develop correctly, resulting in wedge shapes. As these wedged vertebrae line up, the spine may form one of three conditions: lordosis, a curvature in the lower back; kyphosis, a posterior curvature; or scoliosis, a lateral curvature. In many breeds, such as pugs, hemivertebrae development is encouraged, as it is responsible for the screw tail. In cases of the tail, there is no risk for spinal injury, as the spinal cord does not extend into the tail. Unfortunately, when this development occurs in other areas of the spine, cord compression is a concern.
A swayback curvature in the spine is the most common sign of lordosis in a growing puppy. If there is no spinal cord compression, no other symptoms may occur. In cases where the deformity causes spinal compression, symptoms may include weakness or paralysis in the hind limbs, spinal instability, fecal and urinary incontinence, as well as pain when pressure is applied to the spine. Symptoms may increase as the puppy grows and compression on the spine increases. Other possible neurological symptoms due to spinal compression include dizziness and seizures.
Dogs with curled tails, such as pugs, English bulldogs and French bulldogs, puggles and Boston terriers are at greater risk of hemivertebrae and lordosis due to the encouragement of the trait for screw tail formation. By breeding for the curved tail, the risk of hemivertebrae in other areas of the spine increases. If a dog from one of these breeds develops hemivertebrae in areas other than the tail, removal from the breeding pool is necessary. In addition to these screw-tail breeds, German shepherds and German shorthair pointers are at increased risk for this condition through autosomal recessive traits.
Treatment of lordosis and hemivertebrae depends on the severity of the malformation and whether spinal cord compression occurs. Rest and injections of corticosteroids may be enough to reduce symptoms in mild cases of spinal compression. In severe cases, surgery such as a hemilaminectomy may be necessary.