A dog’s ability to move around and perform its daily activities depends on the ability of the brain, spine, nerves and muscles to coordinate in assembly. This complex communication system involves nerves in the brain sending messages about the outer environment to the body, and the body sending messages to the brain regarding what it is actually experiencing in the environment. These messages are transmitted through nerves in the spinal cord, which is embedded in the vertebral, or spinal, column. Together, the nerves in the brain and spinal cord make up the body's central nervous system. A trauma to any part of the nerve pathway can result in miscommunication or complete lack of communication to the brain or body, and an inability to coordinate the body's movements.
The spinal column itself consists of a set of 24 bones called the vertebrae, which are separated from each other by small cushions called intervertebral discs. Together the vertebrae and intervertebral discs protect the spine from damage. Trauma to the vertebrae or disks can create a vulnerability to the nerves within the spinal cord, resulting in further trauma to the neural pathway.
When a dog is experiencing paralysis, it is often because communications between the spinal cord and the brain have been disrupted. In some cases, the dog will not be able to move its legs at all, a condition of total paralysis, and in other cases, there may still be some communication between the brain and spine and the dog will only appear to be weak, or will have difficulty moving its legs, a condition called paresis – partial paralysis. There are also cases where a dog may be paralyzed in all four legs (tetraplegia), and in others, the dog may be able to control the movement in some of its legs but not all. This is determined by the location in the brain, spine, nerves, or muscles that the trauma has occurred.
Some breeds are more prone than others. Dogs that are low to the ground with long backs, such as the dachshund and basset hound, are commonly affected by ruptured vertebral disks putting pressure on the spinal cord, a condition called intervertebral disc disease. Some breeds are genetically predisposed to a condition called degenerative myelopathy (DM), a disease that attacks the nerves in the spines of older dogs (above seven years). This is a slow acting, progressive disorder that eventually leads to paralysis of the hind legs. Breeds affected by this disease include the Welsh Corgi, boxer, German shepherd, Chesapeake Bay retriever, and Irish setter.
You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have led to this condition, such as recent tick bites, or injuries die to jumping or falling. During the examination, your veterinarian will pay close attention to how well your dog is able to move its legs, and how well it is able to respond to reflex tests. The veterinarian will also test your dog's ability to feel pain in all four legs, checking the head, spine, and legs for signs of pain and alertness to touch.
All of these things will help your veterinarian to locate where in your dog's spine, nerves, or muscles it is having a problem. Basic laboratory tests, including a complete blood count, biochemical profile and urine analysis will be conducted, and may determine if your dog has an infection - bacterial, viral, or toxin based - that is interfering with the nerve pathway. X-ray images of your dog's spine may show evidence of an infection or malformation of the vertebrae, or a slipped disc that is pressing against the spinal cord. Other conditions that can lead to disruption of the nerve pathways may be apparent on an x-ray, such as tumors, blockages, or inflamed nerves.
In some cases, your veterinarian may order a special x-ray called a myelogram. This process uses injection of a contrasting agent (dye) into the spinal column, followed by x-ray images which will allow the doctor to see the spinal cord and vertebrae in more detail. If these imaging techniques are not helpful, your veterinarian may order a computed tomography (CT) or magnetic resonance image (MRI) of your dog's brain and spine, both of which give an extremely detailed picture of your dog's brain and spine. In some cases, your veterinarian may take a sample of the fluid from around your dog's spine for analysis, or samples from the muscles or nerve fibers for biopsy. These analyses may determine the presence of an infection in the brain or spine.
A bundle of fibers that are used in the process of sending impulses through the body
A disease of the bone marrow or of the spine
Paralysis of the legs in humans; paralysis of the hind limbs in quadrupeds
A type of paralysis that may be only slight; affects the way that an animal is able to move
The paralysis of an animal’s four limbs; quadriplegia
A picture that is taken of the spinal cord after dye is injected; may also be used to take a count of white blood cells
Any growth or organ on an animal that is not normal
The exiting of excrement from the body; bowel movements.
The blockage of a vessel by an object, like air or fat
The collection of something in a blood vessel
The padding found between the vertebrae that keeps them from rubbing together
The process of removing tissue to examine it, usually for medical reasons.