Kinds of Nervous System Disorders That Affect Dogs
Thu, April 22, 2021

Kinds of Nervous System Disorders That Affect Dogs

 

Thomas Schubert, DVM, DACVIM, DABVP, of Merck Veterinary Manual, a trusted source of animal health information for students and practicing veterinarians, explained that a change in an animal’s ability to sense its environment can be due to disease in the central nervous system or the peripheral nervous system.

The signs of nervous system disorders are behavioral changes, tremors, pains, seizures, numbness, lack of coordination, weakness, or paralysis of one or more legs. The impacts of an injury in your dog’s sensory and motor functions depend on its location and severity. Further, some injuries to your pet’s nervous system can inflict damage that will not be evident until 24 to 48 hours after your dog is injured.

Prevalence of Neurological Disorders In French Bulldogs (2017)  

Vincent Mayousse and colleagues of open access journal portal BMC wrote that 2,846 case records of French bulldogs presented for neurological signs and spinal pain between January 1, 2002 and January 1, 2016 were studied at their institution. Only 343 French bulldogs with a confirmed neurological disease and precise diagnoses were included in the study. They found that 64.7% of the 343 dogs had a myelopathy, 19.8% had encephalopathy, 9.3% reported an unclassified condition, and 6.1% had a PNS (Peripheral nervous system)/muscle disorder.

The most common myelopathy was Hansen type I intervertebral disk herniation (70.3%). IVDH represented 45.5% of all neurological conditions and 5.5% of all dogs presented to the researchers’ institution during the study period. Cervical IVDH represented 39.8% of all IVDH, while thoracolumbar and lumbar locations accounted for 60.2% of IVDH. When taken together, cervical and thoracic/lumbic IVDH represented 80.8% of dogs that were over three years old. Therefore, the dogs’ ages were significantly associated with IVDH since 81% of French bulldogs affected by it were over three years old unlike 64% of dogs affected by another myelopathy.

Spinal arachnoid diverticulum was another common myelopathy, affecting 11.3% of French bulldogs. SAD accounted for 7.3% of all diseases. Compressive vertebral malformation was observed in 8.6% of dogs with myelopathy, along with a neoplastic condition like spinal or vertebral neoplasia (3.2%), syringomyelia (2.7%), and ischemic myelopathy (1.8%).

 

 

Brain neoplasia was suspected to be found in 36.8% of dogs affected by an encephalopathy. The most common being a glioma, either suspected or confirmed, representing 68% of all neoplasia. 20% of French bulldogs reported having a pituitary macroadenoma. Meningoencephalitis of unknown origin (MUO) accounted for 25% of the encephalopathies 94.1% of dogs less than 5.5 years old presented clinical signs related to an encephalopathy were afflicted by MUO, while 60.7% of those over 5.5 years old presented with the same clinical signs were not affected by said condition.

Idiopathic epilepsy accounted for 13.2% of encephalopathies, as well as bacterial encephalitis associated with otitis media/interna (11.8%). Among unclassified neurological disorders, 90.6% of French bulldogs showed congenital deafness. Bilateral deafness was found in 72.4% of dogs showing congenital deafness unlike 27.6% for the unilateral form of the condition. Among dogs with congenital deafness, 79.3% were white or had white in their coat.

Among PNS/muscle disorders, 66.7% of dogs exhibited otitis externa with neurological signs. 14.3% showed a myopathy, with one case reported for immune-mediated polymyositis, ischaemic neuromyopathy and corticosteroids-induced myopathy. The authors concluded that the high prevalence of neurological diseases found in the study might be due to the specific body conformation of French bulldogs.

However, this hypothesis needs to be verified by conducting comparative studies with other breeds and multicentric studies in European and North American referral centers. Future studies should also consider having larger representative populations. The authors noted that the findings of their study could be of interest among owners and breeders of French bulldogs. Practicing veterinarians, and pet insurance companies.

Congenital and Inherited Disorders of Dogs’ Nervous System

Some congenital defects or those that are present at birth are inherited from your dog’s parents, while some are caused by environmental factors in the womb-like viral infections or nutritional deficiencies, said Rebecca A. Packer of MSD Veterinary Manual, an animal health information source. But the cause is unknown for most cases.

One example is hydrocephalus (“water on the brain”), which refers to an excess cerebrospinal fluid that puts pressure on the brain, which may damage the cerebrum. This results in symptoms similar to those a cerebral injury, and may gradually worsen. Although some dogs do not show obvious signs of hydrocephalus, it is possible for them to develop blindness or impaired vision.

Another is congenital vestibular disease, which seems to be inherited among German Shepherds, English Cocker Spaniels, and Doberman Pinschers. This disorder causes permanent deafness as well as balance and posture dysfunction. Treatment for congenital vestibular disease is not available, but dogs with this condition can learn to improve their balance and posture.

 

 

Central Nervous System Disorders Caused by Parasites

Charles M. Hendrix, DVM, Ph.D., of Merck Veterinary Manual said coenurosis is caused by Taenia multiceps multiceps. An intestinal tapeworm of both humans and dogs, the larval stage of the tapeworm can invade your dog’s nervous system, causing its brain and spinal cord to swell. As an adult, the worm may grow to over two inches in diameter, increasing pressure on the brain and causing loss of muscle control, blindness, stumbling, paralysis, and head tilting. On the other hand, myiasis refers to the development of larval dipteran flies in your pet’s body tissues or organs.

The Cutebra’s larvae are deposited under your dog’s (or cat’s) skin, moving into the central nervous system and affecting either the cerebrum or cerebellum. Oftentimes, corticosteroid drugs are recommended to curb additional inflammatory damage and pressure on your pet’s brain during treatment.

 

 

Tumors of the Nervous System

Tumors are classified by the cell type affected, the tumor’s behavior, the pattern of growth, and secondary changes observed in and around the tumor. In dogs, primary tumors of the nervous system are more commonly found in the brain than the spinal cord or peripheral nerves. 

Among domestic animals, adult dogs of brachycephalic breeds such as Boxers, English Bulldogs, and Boston Terriers are more susceptible to brain tumors. Golden retrievers are also at risk of developing brain tumors. X-rays, myelography, scintigraphy, and other tests are conducted to diagnose nervous system tumors. Though the outlook among dogs with this condition is generally poor depending on the location, tumor growth rate, and other factors, there have been recent improvements with regard to radiation therapy and other procedures.

There are more nervous system disorders caused by parasites and other factors. Owners should be cognizant of any changes in their dog’s behavior for early intervention, diagnosis, and treatment.