Your dog's meninges are structures your dog may hopefully never have a problem with, but as with other dog body parts, there are always some fascinating things to discover. For instance, did you know that your dog's brain, on top of being protected by the skull, is also protected by several layers of tissue? These layers of tissue are basically your dog's meninges. Meninges have several functions and just as other dog body parts they are predisposed to medical conditions and problems. So today, let's discover more about a dog's meninges, what their purpose is and when things go wrong.
I am Your Dog's Meninges
Hello, it's your dog's meninges talking! Our name comes from the ancient Greek word "meninx" which means membrane. As our name implies, we are membranes that envelop your dog's brain.
Imagine your dog's brain as being an onion while we are the layers. There are three layers of us actually covering the brain: the dura mater, the arachnoid mater and the pia mater. Let's take a closer look at these layers individually, shall we?
Coming from the Latin word for "tough mother," the dura mater is a thick membrane that is found closest to the skull.
The arachnoid mater, discovered in 1664 by the Dutch anatomist Gerardus Blasiusm, is the layer that is sandwiched in the middle. Its name derives from the the Greek word "Arachne" ("spider") because of its spider-web like appearance.
Finally, the last layer is the pia mater, coming from the Latin word for "tender mother." This is the most delicate membrane. This structure adheres to the surface and contours of the brain and spinal cord.
In between the layers of the arachnoid and pia mater, there is a space that is filled with cerebrospinal fluid.
We Protect the Central Nervous System
As you can imagine, we play an important protective role. Together, we protect your dog's central nervous system including the brain and the spinal cord. The dura mater is quite thick, and as the name implies, this "tough mother" acts like a mother protecting her child (the brain.)
The arachnoid mater also provides cushioning for the central nervous system, while the pia mater on the other hand, contains blood vessels and small capillaries which are meant for providing nourishment to the dog's brain.
When Things Go Wrong
We are susceptible to the effects of trauma. When the trauma is forceful enough, affected dogs may develop a subrachnoid hemorrhage, meaning that there is bleeding under the arachnoid.
A hematoma, a collection of blood from torn veins, may also form between the arachnoid layer and the dura mater layer.
As with other structures, we are also prone to getting inflamed. Fortunately, though this doesn't happen as often as in other body parts courtesy of the protective barriers of the nervous system such as the blood brain barrier.
However, when these barriers weaken and we do get inflamed, the condition is known as meningitis. This inflammatory condition can be caused by viruses, protozoa, rickettsia, and fungi. Affected dogs develop an elevated temperature, neck pain, muscular spasms and rigidity. Left untreated, meningitis can progress and cause serious neurological problems such as seizures, paralysis and even death.
In some cases, we can also develop tumors, and these are referred to meningiomas. Meningiomas are likely the most common cause of seizures affecting dogs over the age of six, explains veterinarian Wendy C. Brooks. On top of causing seizures, these tumors can cause a dog to walk in circles, drag toes, and walk in a drunk-like gait. Since, most meningiomas in dogs develop in the front part of the skull, where the olfactory lobes are located, an altered sense of smell may also occur.
Meningioma tumors grow from the skull inward, which makes them more advantageous for surgical removal compared to growths set deep in the brain. Not all meningiomas are malignant, actually most tend to be benign, meaning that they do not spread to other areas. However, any growths in this area can be problematic, considering the limited amount of space within the dog's skull. For this reason, prednisone is often prescribed to reduce the problematic swelling. Anti-seizure meds are also often prescribed, but these are only palliatives, a more definitive treatment involves surgical removal of the growth and/or radiation therapy.
As seen, we are quite important structures! Think about what a good job we do in preserving your dog'a brain and spinal cord!
Your dog's meninges.
Disclaimer: this article is not meant to be used as a substitute for veterinary advice. If your dog is sick, please see your vet for proper diagnosis and treatment.
- Merck Veterinary Manual, Meningitis and Encephalitis in Dogs, retrieved from the web on November 20th, 2016