Meningitis

Introduction | Causes & Prevention | Symptoms & Signs | Diagnosis & Test | Treatment Options

Meningitis

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Introduction

Meningitis is defined as inflammation of the meninges, which are the membrane layers that cover and protect the outer surface of the brain and spinal cord. Meningitis is not a "disease" per se. Rather, it is a serious and painful pathological condition involving inflammation and frequently infection of the delicate tissues surrounding the brain. It can be caused by a number of diseases or disorders.

Causes & Prevention

Causes of Canine Meningitis
Most cases of canine meningitis are caused by secondary complications of diseases that start elsewhere in the body, including viral, protozoan, bacterial, parasitic or fungal infections. The causative agent can be anything that triggers inflammation in a particular dog. Some known causes are infected bite wounds on the head and neck and bacterial migration to the brain from infected sinuses, nasal passages, middle ears or elsewhere. Meningitis can also be aseptic, which means that it is caused by a non-bacterial disease of unknown origin. Aseptic meningitis tends to affect young, large-breed dogs between 4 and 24 months of age. Meningitis is an extremely serious condition that should not be taken lightly.

Prevention of Meningitis
There is no way to prevent meningitis, other than preventing the underlying cause of the condition. As with most illnesses, a high-quality diet, free access to fresh water, good housing conditions and regular veterinary check-ups will support a healthy immune system in domestic dogs and reduce the risk of infectious disease.

Special Notes
Meningitis can be difficult to diagnose and to treat. The long-term prognosis for dogs with meningitis is generally poor.

Symptoms & Signs

Introduction
Meningitis is not a specific disease, but instead refers to the pathological condition of inflammation of the tissues surrounding and protecting the brain and spinal cord. The causative agent can be anything that triggers an inflammatory process in a particular dog, including bacteria, virus, fungus, chemical toxins and/or other agents. Meningitis is a very serious condition, and if a dog exhibits signs associated with this disorder it should be taken to a veterinarian immediately. Early diagnosis and treatment can lead to a successful outcome. Without treatment, the prognosis is poor.

Symptoms of Canine Meningitis
Most cases of canine meningitis happen as secondary complications of other diseases caused by bacterial infection. Dogs of any age, breed or gender can be equally affected. Newborn puppies seem to be especially at risk. With meningitis, the affected dog is almost always systemically ill. Clinical signs include one or more of the following:

High fever (elevated body temperature)
Muscle stiffness
Muscle spasms in the back (often painful)
Rigidity of the muscles of the neck and forelimbs (often painful)
Extreme sensitivity to touch (hyperesthesia); may jump or yelp when touched
Loss of appetite (anorexia; inappetence)
Lethargy
Nausea
Vomiting
Stiff, awkward stilted gait
Inability to bend legs
Head tilt
High fever
Depression
Vision impairment/ blindness
Progressive paralysis
Seizures
Confusion/disorientation
Agitation
Loss of coordination (ataxia)
Aggression
Meningitis can be fatal. Advanced cases of meningitis can cause extreme depression, blindness, progressive paralysis, seizures, confusion, agitation and/or aggression. Severe cases can also cause ataxia, which basically means lack of muscular coordination. Affected dogs may be unable to coordinate their movements. They might move in uncontrollable circles, stand up then stumble when trying to walk, or stand and walk with their front legs spread abnormally far apart. The clinical signs of meningitis can mimic those of other disorders. In order to successfully diagnose meningitis in dogs, a series of tests and examinations will need to be performed by a skilled and perceptive veterinarian.

Dogs at Increased Risk
Dogs of any age, breed or gender can be equally affected. Newborn puppies are especially at risk. Affected animals are almost always systemically ill. They develop a high fever, a stiff awkward gait, painful back spasms, rigidity of the neck and forelimbs and extreme sensitivity to touch. They become lethargic, anorexic and nauseous. Advanced meningitis causes extreme depression, blindness, progressive paralysis, seizures, confusion, agitation, ataxia and/or aggression. It can be life-threatening.

Diagnosis & Tests

Introduction
Canine meningitis involves swelling and inflammation of the tissues covering the outer layers of the brain and spinal cord. Meningitis causes neurological symptoms, fever and pain. Regardless of the cause of the condition (of which there are many), meningitis is very serious in domestic dogs. Early and accurate diagnosis is crucial to achieving a successful outcome. A conclusive diagnosis of meningitis cannot always be based solely upon a dog's clinical signs. Additional tests are necessary to rule out other causes of the same symptoms, in order to reach a correct and conclusive diagnosis.

How Meningitis is Diagnosed in Domestic Dogs
The signs of meningitis are often easy to detect. If a veterinarian sees a dog with fever, stiffness, painful spasms in the back, rigidity of the muscles of the neck and forelimbs and extreme sensitivity to touch (called "hyperesthesia"), she probably will begin her diagnostic process by running blood and urine tests to detect possible causes of those signs. If the results of those tests are normal, she may prescribe medications on the assumption that the signs are caused by meningitis. This is called diagnosis by response to treatment. If the medication works, then the dog probably was suffering from meningitis.

In some cases, the veterinarian or owner wants at least a tentative diagnosis before treatment begins. Very few tests are available to diagnose meningitis. They ones that are available include computed tomography (CT or CAT scan), magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) tap and sample assessment. Blood tests can also help to narrow down or possibly identify the actual cause of a dog's neurological condition. A CT/CAT scan or MRI, if available, will allow the veterinarian to visualize inflammation of the meninges, which are the tissue layers surrounding the brain and spinal cord. If inflammation is not seen, this will almost always rule out meningitis as a cause of the dog's clinical signs. Analysis of cerebrospinal fluid obtained by a spinal tap can be diagnostic as well. A sample of the cerebrospinal fluid which coats the brain and spinal cord can help with the diagnosis. This procedure involves collecting cerebrospinal fluid through a needle inserted between several of the vertebrae in the dog's back. The fluid is analyzed microscopically for evidence suggestive of meningitis. During this procedure, the dog will be under general anesthesia. These tests are expensive, and they are not widely available. The only way to truly definitively diagnose canine meningitis is by histopathologic examination of affected brain and/or spinal cord tissue, which is not normally done in a clinical setting. It usually is done post-mortem.

Special Notes
Meningitis is a life-threatening condition. If a dog displays signs consistent with meningitis, its owner should please make an immediate visit to a veterinarian. Early diagnosis is essential for successful treatment and recovery.

Treatment Options

Introduction
Meningitis, which refers to inflammation of the several tissue layers that cover and protect the brain and spinal cord, is potentially fatal. Accurate diagnosis and prompt proper treatment are essential to the successful resolution of this dangerous condition.

Treatment Options
Meningitis can be difficult to diagnose. If a veterinarian suspects that a dog has meningitis, she may recommend prophylactic treatment immediately, even before confirmatory diagnostic assessments are performed. The goals of treating canine meningitis are to suppress the inflammatory process, recover functional neurological abilities, relieve and manage pain and prevent or control seizures.

The standard treatment protocol begins with immunosuppressive doses of glucocorticoids ("steroids"), usually administered orally, to reduce swelling and inflammation of and around the brain. The most common form of meningitis in dogs is called "steroid responsive meningitis." It occurs most frequently in young adult, large-breed dogs. The cause of steroid responsive meningitis is unknown, but the disorder responds positively to oral steroid administration. How well a dog recovers depends upon the severity of the condition and whether it was treated before permanent damage to its body occurred. Dogs suffering seizures from meningitis can also be treated with anticonvulsants.

Other types of meningitis, including bacterial meningitis, are more difficult to treat. In those cases, high doses of antibiotic medications that cross the blood-brain barrier and achieve therapeutic concentrations within the cerebrospinal fluid must be administered in an attempt to kill the organisms causing the condition. Treatment for bacterial meningitis normally is long-term. It also is expensive and can be taxing on both the dog and its owner. If the dog has seizures associated with meningitis, antiepileptic drugs can be used. These also must be managed carefully.

Supportive care is extremely important in the treatment of meningitis. Intravenous or subcutaneous fluid therapy, nutritional supplementation, comfortable bedding, managed activity, free access to fresh water and appropriate pain medications are normally necessary to manage dogs with advanced cases of meningitis.

Owners of dogs that have been diagnosed with meningitis should have a frank discussion with their dog's veterinarian about available treatment and management options. In some instances, dogs recovering from meningitis need life-long physical therapy and medical treatment.

Prognosis
The prognosis for dogs with meningitis is variable, and can be guarded depending upon the dog's response to antibiotic treatment. Some dogs die despite treatment, while others recover completely. Of course, early diagnosis and aggressive treatment can dramatically improve a dog's chances of successful recovery.

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