Just as in people, the dog's body is innervated by several branches of nerves that relay information from the brain and spinal cord to several parts of the body and organs. There are several nerves originating from the dog's spinal cord which branch off into several ramifications made of individual nerves that supply the dog's front legs. The radial nerve in particular, is a nerve that can be predisposed to several problems such as dogs having trouble moving their front legs and possibly developing muscle wasting. This is another good reason to see the vet when a dog starts limping for no obvious reason.
Introducing the Dog's Radial Nerve
Hello, it's your dog's radial nerve talking! Before introducing myself, I want to give out a little lesson in canine anatomy so that you can better understand my role. You see, just like you, your dog is blessed with a nervous system that's composed by the brain and spinal cord. The brain is your dog's command central, while the spinal cord, and its associated nerves, work as a pathway for all those messages being relayed from the dog's brain to his body and vice versa.
Your dog's brachial plexus is a network of of cervical (neck) and thoracic (thorax) nerves originating from the spinal cord and then branching off into singular nerves that reach the dog's front legs.
The brachial plexus is composed by three nerves: me (the radial nerve) and my neighboring median nerve and ulnar nerve. I basically, innervate your dog's front legs from the elbow all the way down to your's dog's wrist and toes.
I don't want to sound like I am bragging, but I am basically, the biggest nerve of your dog's front leg. Can you guess how I got my name? I am known as radial nerve for the simple fact that I run right by your dog's radius bone, the main weight-supporting bone of your dog's forelimb.
I Help With Movement and Sensation
Not many people are aware of me, but I sure do a whole lot to help your dog move about all day. I provide motor innervation to your dog's muscles in the front leg allowing your dog to romp around every time he wants to and also provide sensory innervation to the skin, in particular to the upper-outside surface of the dog's front leg and the upper surface of the dog's paw.
When all goes well with me and I am all in one piece, your dog is capable of moving around, having reflexes and feeling sensations. Problems start though when something goes wrong with me.
Did you know? Dogs tend to carry the majority of their weight in the front legs. If we were to look at proportions when it comes to weight distribution in dogs, we could expect 60 percent of weight to be carried in the front legs and the remaining 40 percent in the back legs.
When Things Go Wrong
As with other body parts, I can be prone to traumatic injury such as seen with a fall or car accident. I am one of the most common areas to be subjected to nerve injuries.
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Do Dogs Fall Off Cliffs?
Yes, dogs fall off cliffs and these accidents aren't even uncommon. As we hike with our dogs, we may sometimes overestimate our dog's senses. We may take for granted that dogs naturally know what areas to avoid to prevent falls. However, the number of dogs who fall off from cliffs each year, proves to us that it makes perfect sense to protect them from a potentially life threatening fall.
If the impact is strong enough or if the dog's foreleg is hyperextended away from the body, it may cause the nervous tissue of the brachial plexus to stretch and even forcibly detach from the spinal cord (what is known as brachial plexus avulsion), which affects my functionality just like an electric cord that is fraying or splitting in half.
When this happens, affected dogs may suffer from weakness and loss of muscle use and sensation below the elbow which can lead to toe dragging when walking and since the elbow can't be extended inability to bear weight. The use of special boots or socks may be needed in dogs with radial nerve injury to prevent injury to their paws.
In some other cases, a tumor such as a nerve sheath tumor or a tumor of neighboring tissue (fibrosarcoma, myosarcoma), on or around the brachial plexus, can affect me leading to problems with the dog's forelimbs. As soon as dog owners notice any problems such as loss of sensation, weakness or paralysis, it's important to see veterinary care immediately because muscle mass can be lost quite quickly considering that us nerves time time to regenerate. Seeing a veterinarian specializing in neurology is recommended. Physical therapy using passive range of motion exercises is important so to provide blood flow to the dog's muscles preventing them from atrophying.
Unfortunately, when us nerves sustain an injury either because of trauma or presence of a tumor, we take quite a while to heal. Need a general idea? Consider that according to Pet Education, nerve fibers generally heal at the rate of 1 mm a day (that's about 1 inch per month!). Prognosis depends on the extent of injury affecting me. I might lose function temporarily recovering within a few days or I might take weeks or even months to recover and in severe cases I may sometimes never recover. In the meanwhile as I start to repair myself, I can cause a pins and needles sensation (paraesthesia) that dogs may find hard to accept. Affected dogs may therefore lick and chew on the affected leg, and since they cannot feel pain, if not monitored, they may cause substantial damage.
"Nerve injuries are very mysterious. It can be very difficult to predict if function will return after injury."~ Dr. Foster and Smith
As seen, I am an important nerve that allows your dog to move and feel sensations. Without me, dogs would not be able to walk and use their front legs to bear weight. So make sure you keep your dog safe and off the roads, so to prevent me from getting injured, and if you notice any problems with your dog's front legs, please see your vet promptly, that means sooner than later as time is of the essence with these type of injuries. I hoped this helped understand me better!
Your Dog's Radial Nerve
- Pet Education, Radial Nerve Paralysis in Dogs and Cats, retrieved from the web on August 8th, 2016
- Dr Fosters and Smith, Dog Neurological Disorders: Radial Nerve Paralysis, retrieved from the web on August 8th, 2016
Anterior view of right brachial plexus. Illustration. Modified by Mattopaedia on 02-Jan-2006 from the 1918 Edition of Gray's Anatomy. Public Domain