Vasculitis

Introduction

Vasculitis is an inflammatory disease of blood vessels.

It is characterised histologically by the accumulation of leukocytes within and around the vessel wall. It can be of neutrophilic (leukoclastic/non-leukoclastic), lymphocytic, eosinophilic, granulomatous or mixed cell type.

It is a combination of type III and type I hypersensitivity reactions.

Endothelial damage by an infectious agent, parasite infestation, eridotoxin or immune complex deposition initiates local inflammation, neutrophil accumulation and complement activation. Neutrophils release lysosomal enzymes leading to necrosis of the vessel wall, thrombosis and haemorrhage.

Any animal can be affected, and the clinical significance depends on the number, size and type of vessels affected, and the presence of thrombosis, ischaemia and infarction.

Aetiology

Idiopathic (50% of cases)

Systemic Lupus Erythematosus

Cold agglutinin disease

Frostbite

Disseminated Intravascular Coagulation

Lymphoreticular neoplasia

Drug reactions

Post-vaccine reactions

Spider bites

Immune-mediated disease

Erythema nodosum-like panniculitis

Rheumatoid arthritis

Staphylococcal hypersensitivity

Food hypersensitivity causing urticarial vasculitis

FeLV and FIV-associated vasculitis in cats

Clinical Signs

Clinical features of vasculitis are variable and depend on the vessels involved. It can present as: purpura, haemorrhagic bullae, necrosis and punched-out ulcers. It often affects the extremities such as the ear tips, tail, lips, paws and oral mucosa, and can be painful.

The systemic signs usually reflect the organ involved (hepatopathy, arthropathy, myopathy...). There may also be vague systemic signs of illness: lethargy, lymphadenopathy, vague pain, pyrexia and weight loss.

Signs associated with immmune-mediated disease include: thrombocytopaenia and polyarthropathy.

Breed-related vasculitis include: familial cutaneous vasculopathy of German Shepherd Dogs, neutrophilic leukoclastic vasculitis of Jack Russell Terriers, ear margin vasculitis/seborrhea in Dachshunds.

Differential Diagnoses

Ear margin seborrhea, chemical and thermal burns, hepatocutaneous syndrome, erythema multiforme, dermatomyositis and sepsis

Diagnosis

Immunodiagnostics to consider include: ANA titre, Coombs test, and cold agglutinin test.

Haematology, biochemistry and urinalysis may reveal a systemic disease.

Lesions should be biopsied. Histopathological findings will include: neutrophilic, lymphocytic, eosinophilic, granulomatous or mixed cells in and around the vessels. There may be vascular necrosis and fibrin thrombi. Perivascular haemorrhage and oedema can occur.

Treatment

Management depends on the underlying cause, and treatment of this is the first priority.

Antibiotics may be a first line of therapy if drug reaction is not suspected.

Immune-modulatory drugs which may help control an immune-mediated disease with concurrent vasculitis include: prednisolone, sulfasalazine, chlorambucil. These should always be used until remission and then doses decreased to the lowest possible dose for controlling clinical signs.

Prognosis is often guarded, and depends on the underlying cause.

References

Merck and Co (2008) Merck Veterinary Manual Merial

Weiss, D. (2011) Schalm's veterinary haematology John Wiley and Sons

Helton Rhodes, K. (2011) Blackwell's Five-Minute Veterinary Consult Clinical Companion: Dermatology Wiley-Blackwell

Day, M. (2010) Veterinary Immunology Manson Publishing