Diseases of the nervous system in dogs

Inflammatory diseases of the nervous system in dogs are a large group of pathologies, including meningomyeloencephalitis and meningoencephalitis of various origins.

Meningitis is an inflammation of the membranes that cover the central nervous system, myelitis is an inflammatory process in the spinal cord, and encephalitis is an inflammation of the brain tissue. In meningitis, the subarachnoid space is involved in the pathological process. Simply put, the tissues containing nerve cells become inflamed.

Inflammatory diseases of the nervous system in dogs

In veterinary practice, it is not customary to consider meningitis and encephalitis as separate diseases, as they often develop simultaneously due to the anatomical proximity of structures within the skull. Therefore, the umbrella term meningoencephalitis is used.

Although this disease cannot be called widespread, it is quite common among neurological pathologies in dogs, regardless of the cause.
An inflammatory disease such as meningoencephalomyelitis is usually divided into two types:

• non-infectious
• infectious

Typically, infectious meningoencephalomyelitis can be caused by bacteria, fungi, protozoa, parasites, rickettsia, and viruses. Signs of brain parenchyma damage are more pronounced in parasitic, viral, and protozoan infections, while bacterial infections tend to involve more pronounced meningeal damage.
If the inflammatory process is caused by rickettsia or fungi, then damage to both the meningeal membranes and the brain parenchyma can be observed, that is, diffuse symptoms are observed.

Diseases such as steroid-dependent meningitis, granulomatous meningoencephalitis, and some specific meningoencephalitis, which are common in several dog breeds, are classified as non-infectious inflammatory diseases of the nervous system. Some evidence suggests that their development is due to an immunological disorder. They are successfully treated with immunosuppressive doses of glucocorticoids.

Inflammatory process - granulomatous meningoencephalitis

A non-suppurative inflammatory process in animals is called granulomatous meningoencephalitis. As the disease progresses, diffuse or focal damage to the central nervous system occurs.
In veterinary medicine, three forms of this process are distinguished:

• Limited meningoencephalitis, which is characterized by involvement of the brainstem.
• Disseminated granulomatous meningoencephalitis, which is characterized by damage to the cerebellum and cervical spinal cord, lower brainstem and cerebrum.
• Optic granulomatous meningoencephalitis, which affects the optic nerves and eyes.

The exact cause of granulomatous meningoencephalitis remains unknown. Some evidence suggests that this disease is immune-mediated. Glucocorticoids are prescribed for treatment, but the outcome cannot be accurately determined. If the disease progresses rapidly, the prognosis is generally poor.

Myasthenia in dogs

Myasthenia in dogsMyasthenia is a neurological disorder that disrupts the transmission of nerve impulses to muscles, leading to severe muscle weakness and fatigue. Congenital and acquired forms of myasthenia are distinguished. The acquired form is most often associated with autoimmune processes, in which the immune system attacks the body's own cells.

The main symptoms of myasthenia in dogs:

• weakness of the limbs, unsteady gait, lameness;
• difficulty swallowing, risk of choking;
• muscle tremors and spasms;
• rapid fatigue even with little exertion;
• In severe cases, episodes of temporary paralysis, especially after activity.

Treatment for myasthenia in dogs is aimed at reducing symptoms and preventing complications. A veterinarian may prescribe anticholinesterase drugs, which improve nerve impulse transmission. For the autoimmune form, immunosuppressants are also used. It is recommended to provide rest and avoid excessive physical activity.

In different breeds of dogs

A severe form of steroid-dependent meningitis with polyarthritis can develop into a pain syndrome in beagles. Typically, during the course of the disease, the animal experiences severe pain in the cervical spine. Since complete remission of this disease can be achieved with steroid administration, it can be assumed that it is caused by immune disorders.

Bernese Mountain Dogs are very susceptible to diseases such as polyarteritis andnecrotizing vasculitisAs in the previous case, the exact cause of meningitis in this breed of dog has not yet been determined, but when the animal is treated with steroids, all clinical manifestations disappear.

Pugs between the ages of 9 months and 4 years are at risk of contracting meningoencephalitis. This disease typically progresses rapidly and has a poor prognosis. In the early stages of meningoencephalitis, pugs experience seizures and diffuse damage to the central nervous system. Dogs may tangle their legs when walking, move in circles, bump their heads against walls, experience neck pain, and eventually develop blindness. Such animals typically die within 2-3 weeks, and treatment with steroids and anticonvulsants is ineffective.

Depending on how severely a particular area is affected, the clinical manifestations of an inflammatory disease of the central nervous system can be very different - focal, diffuse, or rapidly developing from focal to diffuse.

The main symptoms of meningitis in dogs are fever and neck pain. An affected dog will be reluctant to walk on a leash, become hypersensitive to touch, and exhibit neck muscle rigidity. In severe cases, a lateral posture, hyperextension of the forelimbs, and opisthotonos may also be observed.

Diagnosis and treatment

When diagnosing and determining the cause of meningoencephalitis, cerebrospinal fluid analysis is considered. CSF collection is performed under anesthesia and is considered a relatively risky procedure. Non-invasive imaging techniques, such as MRI and CT, are also performed under general anesthesia. These techniques are not considered dangerous for the animal; however, unfortunately, CT scan data does not always provide an accurate diagnosis.

The animal's therapeutic treatment largely depends on the underlying cause of the disease. Typically, steroids in immunosuppressive doses, symptomatic therapy, and antibiotics are used in most cases. The prognosis always depends on the underlying cause, but for steroid-dependent encephalitis, the prognosis, unfortunately, is poor.

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