Congenital Spinal and Vertebral Malformations in Dogs
Congenital spinal and vertebral malformations are prevalent in dogs, often stemming from genetic inheritance rather than fetal developmental issues. Notably, sacrococcygeal dysgenesis, indicating defective development, is a dominant trait, while thoracic hemivertebra, observed in German shorthaired pointers, is recessive.
Typically, spinal malformations become apparent at birth or within the first few weeks of life. However, vertebral malformations may remain latent until a dog experiences a growth spurt, usually around five to nine months of age. Observable indicators of a distorted spinal column include lordosis, a curvature at the lower back, and kyphosis, a posterior curvature of the spine. Scoliosis, characterized by a lateral curvature of the spine, is also easily recognizable.
In cases where malformations result in secondary spinal cord compression and trauma, affected dogs may exhibit symptoms such as ataxia and paresis. Unfortunately, medical interventions often fail to alleviate neurological symptoms associated with spinal and vertebral malformations. In severe and untreatable instances, euthanasia becomes a consideration.
Symptoms
- Malformation of the occipital bones – atlas and axis (the first and second cervical vertebrae at the base of the skull)
- Results in compression of the upper spinal cord, potentially leading to paralysis or sudden death
- More prevalent in small-breed dogs
- Hemivertebra (half a vertebra)
- Manifests as kyphosis, scoliosis, or lordosis
- Wedge-shaped vertebrae cause an angular spine
- Primarily affects the neurological system
- Symptoms may include rear limb weakness (paraparesis) or paralysis
- Can remain asymptomatic
- Common in breeds with short skulls and “screw-tailed” breeds, which may be desired in certain breeds like Pugs, Boston Terriers, French Bulldogs, and English Bulldogs
- Transitional vertebra
- Exhibits characteristics of two types of vertebrae
- May lead to cord compression and disc changes
- Block vertebra
- Results from fused vertebrae due to improper segmentation
- Animals may live normally without symptoms
- Butterfly vertebra (vertebra with a cleft through the body and a funnel shape at the ends)
- Identified by a cleft through the body and a funnel shape at the ends, resembling a butterfly on X-ray examination
- Causes instability of the vertebral canal and, rarely, spinal cord compression resulting in paralysis
- Sacrococcygeal dysgenesis
- Involves defective formation of the lowest vertebrae in the spine
- Associated with spina bifida, characterized by a lack of vertebral arches in the spinal column
- Spina bifida
- Entails variable spinal dysplasia, dysraphism, syringomyelia, hydromyelia, and myelodysplasia
- Dogs may not exhibit symptoms and is commonly found in Bulldogs, Pugs, and Boston Terriers
- Myelodysplasia
- Signifies defective development of the bone marrow, often seen in Weimaraners
- Congenital spinal stenosis
- Represents a narrowing of the spinal canal from birth, typically hereditary
- Common in chondrodystrophic (dwarf) breeds like Basset Hounds, Beagles, Dachshunds, Lhasa Apsos, Shih Tzus, Pekingese, and genetically disposed Doberman Pinschers.
Causes
- Genetic inheritance
- Potential exposure of pregnant bitches to:
- Compounds known to cause birth defects during fetal development
- Toxins
- Nutritional deficiencies
- Stress
Diagnosis
To assist your veterinarian in diagnosing your dog’s condition, provide a detailed history of its health and when symptoms first appeared. A comprehensive physical examination will be conducted. X-rays of the spinal column, encompassing all vertebrae, are typically employed to identify the specific malformation. If neurological symptoms such as paralysis are evident, myelography may be employed to precisely pinpoint the level at which the spinal cord is compressed. This diagnostic method involves injecting a radiopaque substance into the spine or the membranous space surrounding the spinal cord, rendering spinal defects visible on X-ray images.
Computed tomography (CT) and magnetic resonance imaging (MRI) can also offer valuable insights and are sometimes more sensitive than X-rays. However, myelography is generally preferred as the primary diagnostic imaging technique.
Treatment
Surgery can be beneficial for addressing cases characterized by a narrowed spinal canal and the compression of the spinal cord. Early surgical intervention may prevent secondary damage resulting from spinal compression. However, if the spinal compression is widespread or persistent, surgery may not yield favorable outcomes. In instances where dogs exhibit neurological symptoms such as dizziness, seizures, or paralysis after surgery, a combination of restricted activity and physical therapy may prove beneficial.
