Inflammatory Diseases of the Central Nervous System of Dogs and Cats

The central nervous system (CNS) consists of the brain and spinal cord, which are protected from external influences by bone. The skull protects the brain and the spinal cord is protected with backbone. Between the bones and elements of the CNS are protective covers of fibrous tissue, which are called meninges.  There are three meninges:  the dura mater, arachnoid, and pia mater.
Inflammatory disorders of the CNS which affect the brain are known as encephalitis. Concomitant diseases can be inflammation of the spinal cord (myelitis) and / or inflammation of the membranes covering the brain and spinal cord, known as meningitis. These inflammatory diseases make up 10% of all neurological diseases in dogs, and 60-90% are from an unknown cause. The causes that trigger inflammation may be a virus, bacteria or parasites.

Meningitis responsive to steroid therapy (SRMA - Steroid Responsive Meningitis-Arteritis) is an inflammatory disease that affects the spinal cord, brain and arteries. This same disease damages the blood vessels of the heart, kidney, liver and the gastrointestinal system. Some breeds of dogs, such as beagle, Bernese mountain dog, and hound breeds, have a family predisposition to this kind of disease.

Disease Symptoms and Diagnosis
SRMA is manifested by rigidity, a fever of 40 degrees Celsius or higher, throat pain, increased sensitivity to stimuli and depression. Prolonged disease may cause other neurological problems to develop, such as paralysis and hind limb weakness. The disease most often manifests itself in the acute form.  The chronic form is fortunately less common.
Diagnosis is relatively simple via blood tests for inflammatory markers.  In the case of an elevated white blood cell count and neck pain, tests of the cerebrospinal fluid are necessary.
Cerebrospinal fluid is a clear, colorless fluid that cushions the brain from impact and removes unwanted substances into the circulatory system.
The first drugs of choice are steroid hormones. If the affected dog fails to respond to steroids, then immunosuppressive medicines may be added. 
SRMA has been recorded in dogs, but not cats. However, cats may suffer from other forms of meningitis.

Meningoencephalitis (MUA)
Meningoencephalitis is an inflammatory disease affecting dogs that is manifested by impairment of the brain and meninges.

Disease Symptoms and Diagnosis
All MUA symptoms are neurological in nature. Typically they include seizures, blindness, dizziness, shaking, disorientation, pain and paralysis. Symptoms may be reversible depending on the part of the brain affected.
Diagnosis of MUA is difficult and is really a diagnosis of exclusion. Other infectious causes of the symptoms must be ruled out. In addition to blood tests, MRI and CT imaging of the brain is used and the cerebrospinal fluid is checked for elevated levels of white blood cells.
If not treated promptly, MUA is a life-threatening illness. Up to 75% of patients respond well to treatment with steroids and some patients must be treated long term.

Feline infectious peritonitis (FIP) is a serious infectious disease caused by feline coronavirus.
Up to 80% of cats test positive for antibodies to coronavirus. This does not mean, however, that all cats actually have FIP. It is believed that this disease results from a mutation of the virus combined with reduced immunity.
Disease Symptoms and Diagnosis
Only about 20 - 30% of affected cats show neurological symptoms. More often, the observable symptoms are edema or an enlarged belly. Diagnosis is difficult, but the disease is manifested by altered hematological and biochemical parameters.
FIP, unfortunately, has a 98% fatality rate and there is no effective treatment. Prevention is through elimination of the virus by preventing infected cats from breeding.

Canine distemper is a disease caused by Morbillivirus. In addition to dogs and wild animals, ferrets and felines may also be infected. Thanks to vaccination, the disease has been significantly reduced.
Disease Symptoms and Diagnosis
In the early stages of distemper there may be high temperature, red eyes and a runny nose and eyes. In later stages the virus invades other organs, especially the nervous system. Some forms of the disease cause joint thickening and enlargement. Acute distemper in dogs with weakened immune systems can lead to death within 2-4 weeks after becoming infected. Diagnosis is made based on blood tests, chest x-ray, and virus and antibody tests. Unfortunately, severe forms of canine distemper are incurable. Antibiotics are administered to prevent secondary infection and antiepileptic medications are given in the case of seizures. Only subclinical forms of the disease are curable.

Tick-borne encephalitis is caused by a flavivirus and carried by ticks in all development stages. This disease is uncommon in humans, but can be found in dogs in Slovakia.
Disease Symptoms and Diagnosis
The neurological symptoms are similar to rabies - tremors, seizures, foaming salivation and aggressiveness. There is no reliable test to diagnose the disease, and 30 percent of animals may have positive antibodies yet still be healthy. With milder forms of the disease, the dog usually spontaneously recovers, but more severe cases usually die within 7 days.

Polyradiculoneuritis is a serious autoimmune disease affecting the nerves responsible for muscle movement. During an infection, acute paralysis usually begins in the hind limbs.  This often precedes voice change due to affected vocal muscles. This also occurs due to paralysis of intercostal muscles and the diaphragm. Paralysis of these structures also carries a risk of suffocation and may necessitate the use of a mechanical ventilator. This disease can in rare cases also affect cats.
Physiotherapy to prevent muscle atrophy is a recommended treatment. Denervated muscles must be kept in good condition for recovery to occur.

Myositis (inflammation) of the masticatory muscles is an inflammatory disease that affects dogs and cats. It is one of the most common muscle diseases.
Disease Symptoms and Diagnosis
Myositis is relatively easy to diagnose. It manifests as "lockjaw" - the animal has difficulty in opening or closing its mouth. The condition can also be diagnosed via biochemical and antibody tests.
Treatment must be aggressive to prevent an acute condition from becoming chronic.  Swollen muscles can cause the connective tissue to lose elasticity. This may result in an irreversibly closed jaw. Immunosuppressive medications are usually the treatment of choice.

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