Congenital vertebral anomaly
Encyclopedia
Congenital vertebral anomalies are a collection of malformations of the spine
in animals. Most are not clinically significant, but they can cause compression of the spinal cord
by deforming the vertebral canal or causing instability. This condition occurs in the womb. Congenital vertebral anomalies include alterations of the shape and number of vertebrae.
problems. They are wedge shaped vertebrae, and therefore can cause an angle in the spine (such as kyphosis
, scoliosis
, and lordosis
). The most common location is the midthoracic vertebrae
, especially the eighth (T8). Neurologic signs result from severe angulation of the spine, narrowing of the spinal canal, instability of the spine, and luxation or fracture of the vertebrae. Signs include rear limb weakness or paralysis, urine or fecal incontinence, and spinal pain. Most cases of hemivertebrae have no or mild symptoms, so treatment is usually conservative. Severe cases may respond to surgical spinal cord decompression and vertebral stabilization.
The probable cause of hemivertebrae is a lack of blood supply causing part of the vertebrae to not form. Hemivertebrae in dog
s are most common in the tail, resulting in a screw
shape, but can also occur in the thoracic vertebrae. Affected dog breeds include Bulldog
s and French Bulldog
s, Pug
s, and Boston Terrier
s. It is inherited in Yorkshire Terrier
s and German Shorthaired Pointer
s. The condition can cause death in very young Bulldog
puppies.
is a normal block vertebrae.
on an x-ray
. It is caused by persistence of the notochord
(which usually only remains as the center of the intervertebral disc
) during vertebrae formation. There are usually no symptoms. Butterfly vertebrae occur most often in Bulldogs, Pugs, and Boston Terriers.
, disk changes, or spinal cord compression. One study found that male German Shepherd Dog
s with a lumbosacral transitional vertebra are at greater risk for cauda equina syndrome
, which can cause rear limb weakness and incontinence.
is characterized by a midline cleft in the vertebral arch. It usually causes no symptoms in dogs. It is seen most commonly in Bulldogs and Manx
cats. In Manx it accompanies a condition known as sacrocaudal dysgenesis that gives these cats their characteristic tailless or stumpy tail appearance. It is inherited in Manx as an autosomal dominant trait.
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
in animals. Most are not clinically significant, but they can cause compression of the spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
by deforming the vertebral canal or causing instability. This condition occurs in the womb. Congenital vertebral anomalies include alterations of the shape and number of vertebrae.
Hemivertebrae
Among the congenital vertebral anomalies, hemivertebrae are the most likely to cause neurologicNeurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
problems. They are wedge shaped vertebrae, and therefore can cause an angle in the spine (such as kyphosis
Kyphosis
Kyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
, scoliosis
Scoliosis
Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
, and lordosis
Lordosis
Lordosis is a medical term used to describe an inward curvature of a portion of the lumbar and cervical vertebral column. Two segments of the vertebral column, namely cervical and lumbar, are normally lordotic, that is, they are set in a curve that has its convexity anteriorly and concavity...
). The most common location is the midthoracic vertebrae
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
, especially the eighth (T8). Neurologic signs result from severe angulation of the spine, narrowing of the spinal canal, instability of the spine, and luxation or fracture of the vertebrae. Signs include rear limb weakness or paralysis, urine or fecal incontinence, and spinal pain. Most cases of hemivertebrae have no or mild symptoms, so treatment is usually conservative. Severe cases may respond to surgical spinal cord decompression and vertebral stabilization.
The probable cause of hemivertebrae is a lack of blood supply causing part of the vertebrae to not form. Hemivertebrae in dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s are most common in the tail, resulting in a screw
Screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
shape, but can also occur in the thoracic vertebrae. Affected dog breeds include Bulldog
Bulldog
Bulldog is the name for a breed of dog commonly referred to as the English Bulldog. Other Bulldog breeds include the American Bulldog, Olde English Bulldogge and the French Bulldog. The Bulldog is a muscular heavy dog with a wrinkled face and a distinctive pushed-in nose...
s and French Bulldog
French Bulldog
The French bulldog is a small breed of domestic dog, related to the English bulldog and American bulldog.-History:The origin of the modern French Bulldog breed descends directly from the dogs of the Molossians, an ancient Greek tribe. The dogs were spread throughout the ancient world by Phoenician...
s, Pug
Pug
The pug is a "toy" breed of dog with a wrinkly, short-muzzled face, and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, and a compact square body with well-developed muscle. They have been described as multum in parvo , referring to the pug's personality and...
s, and Boston Terrier
Boston Terrier
The Boston Terrier is a breed of dog originating in the United States of America. This "American Gentleman" was accepted in 1893 by the American Kennel Club as a non-sporting breed. Color and markings are important when distinguishing this breed to the AKC standard. They should be either black,...
s. It is inherited in Yorkshire Terrier
Yorkshire Terrier
The Yorkshire Terrier is a small dog breed of terrier type, developed in the 19th century in the county of Yorkshire, England to catch rats in clothing mills. The defining features of the breed are its size, to , and its silky blue and tan coat...
s and German Shorthaired Pointer
German Shorthaired Pointer
The German shorthaired pointer is a breed of dog developed in the 19th century in Germany for hunting.The breed is streamlined yet powerful with strong legs that make it able to move rapidly and turn quickly. It has moderately long floppy ears set high on the head. Its muzzle is long, broad, and...
s. The condition can cause death in very young Bulldog
Bulldog
Bulldog is the name for a breed of dog commonly referred to as the English Bulldog. Other Bulldog breeds include the American Bulldog, Olde English Bulldogge and the French Bulldog. The Bulldog is a muscular heavy dog with a wrinkled face and a distinctive pushed-in nose...
puppies.
Block vertebrae
Block vertebrae occur when there is improper segmentation of the vertebrae, leading to parts of or the entire vertebrae being fused. It can lead to an angle in the spine, but there are usually no symptoms. The sacrumSacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
is a normal block vertebrae.
Fossil record
Evidence for block vertebrae found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury. A block vertebrae has been documented in T. rex. This suggests that the basic development pattern of vertebrae goes at least as far back as the most recent common ancestor of archosaurs and mammals. The tyrannosaur's block vertebra was probably caused by a "failure of the resegmentation of the sclerotomes."Butterfly vertebrae
Butterfly vertebrae have a cleft through the body of the vertebrae and a funnel shape at the ends. This gives the appearance of a butterflyButterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
on an x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
. It is caused by persistence of the notochord
Notochord
The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes...
(which usually only remains as the center of the intervertebral disc
Intervertebral disc
Intervertebral discs lie between adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.-Structure:...
) during vertebrae formation. There are usually no symptoms. Butterfly vertebrae occur most often in Bulldogs, Pugs, and Boston Terriers.
Transitional vertebrae
Transitional vertebrae have the characteristics of two types of vertebra. The condition usually involves the vertebral arch or transverse processes. It occurs at the cervicothoracic, thoracolumbar, or lumbosacral junction. For instance, the transverse process of the last cervical vertebra may resemble a rib. A transitional vertebra at the lumbosacral junction can cause arthritisArthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....
, disk changes, or spinal cord compression. One study found that male German Shepherd Dog
German Shepherd Dog
The German Shepherd Dog , also known as an Alsatian or just the German Shepherd, is a breed of large-sized dog that originated in Germany. The German Shepherd is a relatively new breed of dog, with its origin dating to 1899. As part of the Herding Group, the German Shepherd is a working dog...
s with a lumbosacral transitional vertebra are at greater risk for cauda equina syndrome
Cauda equina syndrome
Cauda equina syndrome ' is a serious neurologic condition in which there is acute loss of function of the lumbar plexus, neurologic elements of the spinal canal below the termination of the spinal cord.-Causes:...
, which can cause rear limb weakness and incontinence.
Spina bifida
Spina bifidaSpina bifida
Spina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...
is characterized by a midline cleft in the vertebral arch. It usually causes no symptoms in dogs. It is seen most commonly in Bulldogs and Manx
Manx (cat)
The Manx cat , formerly often spelled Manks, is a breed of domestic cat originating on the Isle of Man, with a naturally occurring mutation that shortens the tail...
cats. In Manx it accompanies a condition known as sacrocaudal dysgenesis that gives these cats their characteristic tailless or stumpy tail appearance. It is inherited in Manx as an autosomal dominant trait.