Vasculitis is
an inflammation of the blood vessels. The vessels become damaged, and small
holes in the vessels allow for tiny amounts of blood to leak from the vessel.
This is often seen as pinpoint sized red spots (petechiae) on the gums
or the whites of the eyes. Vasculitis may be caused by a variety of infectious
diseases or by immune mediated disease where the body's own immune system
begins to attack the body instead of attacking germs.
********************
Necrotizing Vasculitis
Origin and Development:
Necrotizing vasculitis of the
extradural and intradural spinal meningeal arteries has been reported to
occur in young dogs of several breeds. Pathologic changes that have been describe
include fibrinoid generation, intimal and medial necrosis, inflammatory cell
infiltration, periadventitial accumulation of inflammatory cells, meningeal
fibrosis, and hyalinization and mineralization of meningeal arterial walls.
Neurologic deficits may result from the rupture of structurally weakened
blood vessels causing extensive meningeal hemorrhage, and compression of the
spinal cord. Thrombosis of vessels and infarction of the spinal cord my also
be contributing factors. Subsequent meningeal fibrosis around nerve roots
and spinal cord also may result in axonal degeneration. Pathologic changes
are seen throughout the spinal cord. Similar lesions also have been found
in the cardiac arteries of several dogs. The origin of this disease has not
been determined.
The occurrence of this disease in three Bernese Mountain dog litter mates
suggests a genetic predisposition to the disease. This disease has also
been recognized in an inbred colony of beagle dogs. Immune-mediated mechanisms
are suspected in the pathogenesis of the disease. Lymphocytic thyroiditis
and renal amyloidosis, which are also thought to have an immunologic basis,
were found in several dogs. Infectious agents have not been isolated, although
a viral-induced immune-mediated reaction is a possible cause. Antinuclear
antibody was not present in three dogs tested. Vasculitis of spinal arteries
has also been reported as part of polysystemic necrotizing vasculitis in
an older dog.
Clinical Findings:
Affected dogs are four to 12 months of age. Clinical signs include fever,
anorexia, cervical rigidity, hunched posture, apparent spinal pain, shifting
lameness, apparent pain on opening the mouth, and in some animals, neurologic
deficits, including paraparesis, tetraparesis, and paraplegia. Clinical
finds usually are indicative of meningitis and, in some animals, of multifocal
or diffuse myelopathy.
Diagnosis:
Affected animals may have peripheral mature neutrophilic leukocytosis.
Cerebrospinal fluid (CSF) generally has a marked pleocytosis (may be greater
than 10,000 WBC/microliter) with predominantly mature nontoxic netrophils
present. Bacterial or fungal organisms have not been identified in white
blood cells of CSF. Cerebrospinal fluid protein concentration is also elevated.
Blood and CSF bacterial (aerobic and anaerobic) cultures are negative.
This disease cannot be distinguished from other meningitides (including
viral, bacterial, or fungal meningitis, GME or aseptic suppurative meningitis)
on the basis of clinical and CSF findings.
Treatment:
Treatment with corticosteroids usually results in rapid improvement in
clinical signs. However, relapses commonly occur when treatment is discontinued.
Neurologic deficits may persist despite treatment in dogs with severe neurologic
abnormalities. Treatment for longer than six months may result in permanent
resolution of clinical signs. A dose of cortiosteroids sufficient to produce
a a remission of clinical signs (1-2 mg/lb Prednisone) is given initially,
followed by maintenance oral therapy at a dose tapered slowly to be the
lowest dose possible that controls clinical signs (preferably every other
day dosage). It has been suggested that corticosteroid therapy should be
continued until clinical signs have resolved and results of CSF analysis
are normal. If signs recur, the dose should again be increased. Antibiotic
therapy does not result in improvement of clinical signs. As this condition
is often indistinguishable from septic meningitis, treatment with a broad-spectrum
antibiotic that reaches satisfactory concentrations in the CSF is suggested
initially in animals in which the diagnosis is uncertain.
Source: Textbook of Veterinary Medicine
**************************
