Structure and Function of the Brain and Spinal Cord in Dogs

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Below is information about the structure and function of the canine brain and spinal cord We will tell you about the general structure, how the brain and spinal cord works, common diseases, and common diagnostic tests performed to evaluate the brain and spinal cord in dogs. 

What Are the Brain and Spinal Cord?

The brain and the spinal cord comprise the central nervous system in a dog and other pets. The brain is the center for interpreting and integrating information from all over the body. The spinal cord acts as a conducting system to relay information from the brain to various areas of the body.

Where Are the Brain and Spinal Cord Located in Dogs?

The brain is located within the bony cranium or the skull. The spinal cord is located within the spinal canal that runs through the vertebral column (neck and back bone), and extends from the base of the skull down the middle of the tail.

What Is the General Structure of the Brain and Spinal Cord?

The brain is a mass of soft, pinkish gray nerve tissue divided into three major compartments: the brain stem, cerebrum and cerebellum.

  • Brain stem. The brain stem is located at the base of the brain and is connected to the spinal cord and cerebellum. Almost all of the cranial nerves (nerves that control various functions on the head) arise from the brain stem.
  • Cerebrum. The cerebrum, which forms the bulk of the brain, may be divided into two major parts: the right and left cerebral hemispheres. The hemispheres are divided by a narrow slit or cleft called the cerebral longitudinal fissure. The two sides of the brain are connected at the bottom by the corpus callosum, which delivers messages from one side to the other.
  • Cerebellum. The cerebellum is located at the back of the brain and is attached to the brain stem and cerebrum. The cerebellum functions chiefly to coordinate movement and posture.

    The spinal cord is an elongated structure, more or less cylindrical, that is made up of the major bundle of nerve tracts that carry nerve impulses to and from the brain to the rest of the body. The spinal cord is connected to all areas of the body by nerves that leave and enter the spinal column through the gaps between the bony vertebrae.

    Both the brain and the spinal cord are enclosed within the meninges, which consists of three tough membranes called the dura mater, arachnoid and pia mater. Cerebrospinal fluid (CSF) is produced within the brain in hollow channels called ventricles. This fluid surrounds the brain and spinal cord to protect them from injury. Both brain and spinal tissue can be subdivided into gray matter and white matter.

  • What Are the Functions of the Brain and Spinal Cord for Dogs?

    The brain governs various behaviors through learning, motivation and perception. It produces nerve impulses to make muscles move, to send signals to organs, and to control numerous automatic bodily functions. The brain also receives and registers sensory impulses, such as sight, sound, taste, touch, smell, and pain.

    The spinal cord acts to coordinate movement and muscular activity. It also governs both automatic and voluntary reflexes, such as blinking, scratching, twitching the ears, and wagging the tail.

    What Are the Common Diseases of a Dog’s Brain?

    Brain disorders can be subdivided into congenital abnormalities, infections, inflammations, degenerative diseases, metabolic disorders, vascular conditions, tumors, traumatic injuries, nutritional disorders, toxic conditions, and diseases of unknown cause. Some examples of brain diseases that occur in dogs are listed below:

  • Hydrocephalus is the accumulation of cerebrospinal fluid within the ventricular system of the brain. As a result, the ventricles become enlarged and the brain matter shrinks from the fluid pressure. It may be primary and congenital, resulting from either increased production of CSF or failure of absorption. Hydrocephalus may also develop secondary to obstruction of the ventricles. Congenital cases most commonly occur in toy and brachycephalic breeds of dogs, such as the pug, Chihuahua, toy poodle, Lhasa apso, etc.
  • Peripheral vestibular disease is a condition that affects both the brain and the nerves that control equilibrium. Dogs with vestibular disease have difficulty with balance and orientation. Signs include head tilt, falling and falling over. Canine idiopathic vestibular disease (also called “old dog vestibular disease”) is a common form of the disease.
  • Infectious encephalitis is inflammation of brain tissue caused by infectious organisms. In dogs it may be caused by viral diseases (canine distemper, infectious canine hepatitis, rabies), parasitic infestations, protozoal infections (toxoplasmosis, neosporosis, encephalitozoonosis), numerous bacteria, rickettsial organisms (ehrlichiosis, Rocky Mountain spotted fever, salmon poisoning), and fungal infections (blastomycosis, cryptococcosis, coccidioidomycosis).
  • Seizures are abnormal brain activity that may result in convulsions that manifest as odd behaviors, tremors, muscles contractions, salivation and defecation. There are many causes of seizures such as epilepsy, which is a condition characterized by recurrent seizures. Epilepsy is found in many pure bred and mixed breed dogs. The Belgian tervuren is listed among the breeds for which a genetic factor is either proved or highly suspected. Other breeds with increased prevalence of epilepsy include the beagle, dachshund, German shepherd dog, boxers, collie, and Labrador retriever.
  • Narcolepsy is a neurological disorder that induces extreme daytime sleepiness. It may be accompanied by cataplexy, which is characterized by sudden episodes of muscular weakness. Dogs are one of the few animals that suffer from narcolepsy.
  • Brain tumors may be primary and arise from brain tissues, or they may be secondary and develop from either surrounding or distant tissues. Many different tumors can metastasize to the brain.
  • Head trauma is a fairly common injury in dogs that are hit by cars or receive either blunt or penetrating injuries to the head. Clinical signs can vary widely depending upon the type of injury, but may include stupor, loss of consciousness, abnormalities in pupil size and the function of other cranial nerves, seizures, weakness, inability to walk, and head tilt.
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