Definition

Inflammation of blood vessel walls

Pathophysiology

Primarily type III (immune complex), but type I and type II reactions possible.

Systems Affected

• Skin/Exocrine
• Renal/Urologic-some greyhounds

Genetics

• Familial pyogranuloma and vasculitis of Scottish terriers possibly autosomal dominant
• Proliferative arteritis in St. Bernards; unknown mode of inheritance

Signalment

Signs

Causes

• Idiopathic
• Drug-induced
• Vaccine-induced
• Adverse food reaction
• Tick-borne diseases (e.g., Rickettsia rickettsii)
• Infectious
• Underlying metabolic process (e.g., diabetes)
• Auto-immune
• Neoplasia

Differential Diagnosis

• See “Causes”
• Deep pyoderma
• Ear margin seborrhea
• Chemical and thermal burn
• Hypersentitivity reaction
• Dermatomyositis
• Cryoglobulinemia
• Toxic epidermal necrolysis
• Erythema multiforme
• Eosinophilic dermatitis
• Systemic lupus erythematosus
• Bullous pemphigoid
• Pemphigus vulgaris
• Sepsis

CBC/Biochemistry/Urinalysis

Normal unless due to underlying metabolic process or infection.

Other Laboratory Tests

• Serologic testing for parasitic and infectious disease in high-risk areas.
• Immunodiagnostics-ANA titer, Coombs' test, and cold agglutinin tests.

Diagnostic Procedures

• Skin scrapings-demodicosis.
• Biopsy of early lesion-submit to a dermatopathologist; findings depend on the underlying cause but usually include neutrophilic (leukocytoclastic/non-leukocytoclastic), lymphocytic, eosinophilic, or granulomatous mixed cells in and around the vessels; vascular necrosis and fibrin thrombi may be prominent; perivascular hemorrhage and edema may occur.
• Representative cultures (e.g., blood, urine, skin) if suspicious of infectious issues.
• Titers for rickettsial infections.
• Immunoassay for fungal organisms.

Pathologic Findings

• May vary according with stage and etiology.
• Intramural inflammation of vessels, endothelial cell swelling, pale collagen, faded hair follicles, hemorrhage, and edema of surrounding tissue.

Appropriate Health Care

• Underlying disease-first priority in clinical management.
• No systemic abnormalities-treat as outpatient.
• Systemic disease-inpatient care recommended.

Nursing Care

Adequate wound care may be necessary for cases with severe and extensive ulceration.

Activitiy

• No limitation unless infectious agent suspected.
• Isolate if contagious or zoonotic agent suspected.

Client Education

• Inform client that the prognosis is guarded until a cause is found.

Surgical Considerations

Individual (focal) lesions may be surgically excised. Otherwise, dependent on underlying etiology.

Drug(s) Of Choice

• The underlying disease process should be identified and appropriately treated; if drugs or drug-like substances are suspected, they should be discontinued.
• First-line therapy while awaiting histopathology results, if no drug reaction is suspected-antibiotics.
• Immune-mediated disease with concurrent vasculitis-prednisolone (0.5–4 mg/kg q24h and taper according to response).
• Pentoxifylline 10–20 mg/kg PO q8h.
• Cyclosporine may be considered.
• Tetracycline and niacinamide each 500 mg q8h for dogs >10 kg or 250 mg PO q8h for dogs <10 kg or doxycycline 5 mg/kg PO q12h with niacinamide as with tetracycline.

Precautions

• Do not use any medications suspected of causing hypersensitivity.
• Do not administer tetracycline/doxycycline to pregnant or young animals.

Alternative Drugs

• Chlorambucil 0.1–0.2 mg/kg every 1–2 days PO initially and taper according to response.
• Azathioprine 1–2 mg/kg every 1–2 days PO initially and taper according to response.
• Dapsone (1 mg/kg PO q24h) or sulfasalazine (15–22 mg/kg PO q8–12h).

Patient Monitoring

• Monitor appropriately during treatment of specific etiology.
• Pentoxifylline-may decrease blood pressure; may cause excitation; monitor blood pressure if concerned.
• Doxycycline or tetracycline-possible increased liver enzymes, possible esophageal strictures in cats (doxycycline); monitor liver chemistries.
• Patients receiving prednisolone, azathioprine, chlorambucil, sulfasalazine, or dapsone-monitor appropriately with CBC, chemistry screen, and urinalysis.
• Sulfasalazine or dapsone-may decrease tear formation; Schirmer tear test every 2 weeks initially and then routinely.
• Immuno-suppressive therapies should be reduced to the lowest possible therapeutic dose.

Possible Complications

Sepsis and death from primary cause and/or sequelae if severe.

Expected Course and Prognosis

If no underlying disease is found, vasculitis may be difficult to treat and the prognosis is guarded.

Pregnancy/Fertility/Breeding

• Corticosteroids, sulfasalazine, tetracycline/doxycycline, and dapsone-do not use in pregnant animals.
• All drugs should be used with caution in pregnant and breeding animals.

Abbreviation

ANA = antinuclear antibody