ISSN 2398-2969      

Microscopic necrotizing vasculitis

icanis

Synonym(s): Beagle Pain Syndrome (BPS; Steroid-responsive meningo-arteritis (SRMA


Introduction

  • Microscopic necrotizing vasculitis (MNV) refers to a large heterogenous group of clinical syndromes, the multisystemic form of which, Juvenile polyarteritis syndrome (JPS), is reported in young Beagle dogs.
  • Multisystemic peripheral vascular disease.
  • Etiology suspected to be a familial (hereditary) predisposition or possibly immune-mediated condition.
  • Also known as Beagle pain syndrome, aseptic suppurative meningitis, canine pain syndrome, canine juvenile polyarteritis syndrome.
  • Steroid-responsive meningo-arteritis (SRMA Steroid-responsive meningitis-arteritis (SRMA) ) is the most accepted terminology.
  • Beagle pain syndrome (BPS) is accepted sterile inflammation of the nervous system especially of meninges and meningeal vasculature, therefore causing meningitis, also called steroid responsive meningitis-arteritis.
  • The clinical signs of this condition in Beagles can be slightly different from JPS in Beagles - primary periartertis or polyarteritis, necrotizing vasculitis affecting small and medium-sized arteries is seen in experimental Beagle colonies. Occurs in two forms - one form affecting major branches of coronary arteries and another form being more multisystemic.
  • Meningitis secondary to idiopathic polyarteritis is seen in many breeds of dogs (Boxers Pointers, Rottweilers, Bernese Mountain dogs, Akitas, Weimeraners, Nova Scotia duck tolling retrievers, and Greyhounds). The overshadowing feature of neck pain usually means that little attention is paid to the joints (however polyarthritis is not uncommon).

Pathogenesis

Etiology

  • Immune mediated or familial predisposition for peripheral vasculitis (polyarteritis) Polyarteritis nodosa characterized by inflammatory vessel wall changes and occlusion.
  • Activated T cells have been demonstrated in dogs with SRMA indicating potential contact with an antigenic stimulus.
  • A Th2-mediated immune response is most likely based on the presence of high CD4:CD8a ratios and a high proportion of B cells in peripheral blood and CSF.

Predisposing factors

General
  • Possibly immune mediated.

Specific

  • Familial, Beagle breeds.

Pathophysiology

  • Summary:
    • Disseminated peripheral vasculitis producing vague systemic and neurologic signs.
  • Pathological:
    • Vascular lesions resemble those found in experimental immune complex-mediated conditions, such as the local Arthus phenomenon Arthus reaction.
    • Part of the type III hypersensitivity reaction and is generalized rather than being a local response to an antigen.
    • In this condition, vasculitis is associated with immune complex deposition in blood vessel walls. Immune complexes are of unknown origin, although no infectious antigens have been identified. Complexes are deposited between and beneath vascular endothelial cells.
    • If immune complexes activate complement, neutrophil chemotaxis and accumulation follow.
    • Resident tissue macrophages that encounter immune complexes are stimulated to secrete TNF alpha, IL-1, platelet activating factor, nitric oxide and oxygen radicals.
    • TNF alpha and IL-1 upregulate expression of leukocyte adhesion molecules, especially E-selectin and ICAM-1, which facilitates neutrophil adherence.
    • Neutrophils attracted by C5a and C567, emigrate from blood vessels, adhere to immune complexes and promptly phagocytose them.
    • Eventually immune complexes are eliminated.
    • During process, large quantities of proteases and oxygen radicals are released into tissues, which are responsible for vascular damage.

Timecourse

  • Often acute onset signs.
  • Can be cyclical.
  • Slowly progressive (weeks).

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Rose J H & Harcourt-Brown T R (2013) Screening diagnostics to identify triggers in 21 cases of steroid-responsive meninigitis-arteritis. JSAP 54 (11), 575-578 PubMed.
  • Tipold A, Schatzberg S J (2010) An update on steroid responsive meningitis-arteritis. JSAP 51 (3), 150-154 PubMed.
  • Lowrie M, Penderis J et al (2009) The role of acute phase proteins in diagnosis and management of steroid-responsive meningitis arteritis in dogs. Vet J 182 (1), 125-130 PubMed.
  • Scott-Moncrieff J C et al (1992) Systemic necrotizing vasculitis in nine young beagles. JAVMA 201 (10), 1553-8 PubMed.
  • Albassam M A et al (1989) Polyarteritis in a beagle. JAVMA 194 (11), 1595-7 PubMed.
  • Hoff E, Vandevelde M (1981) Necrotizing vasculitis in the central nervous systems of two dogs: case report. Vet Pathol 18 (2), 219-223 PubMed.

Other sources of information

  • Fox P R (2001)Peripheral vascular disease. In:Textbook of Veterinary Internal Medicine (5th ed).Eds S J Ettinger and E C Feldman. W B Saunders, Philadelphia. p 973.

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