Familial nephropathy in Bernese mountain dogs

Area of Science:

• Veterinary Pathology
• Immunology
• Canine Genetics

Background:

• Nephropathies were frequently diagnosed in Bernese Mountain Dogs between 1988 and 1992.
• 20 dogs (16 female, 4 male) aged 2-5 years presented with renal insufficiency.

Purpose of the Study:

• To investigate the cause of frequent renal lesions in Bernese Mountain Dogs.
• To determine if the observed membranoproliferative glomerulonephritis (MPGN) has a hereditary basis.

Main Methods:

• Morphologic diagnosis of renal lesions using light microscopy, immunohistochemistry (IgM, C3, IgA, IgG), and electron microscopy.
• Pedigree analysis to assess hereditary genesis.
• Serological testing for Borrelia burgdorferi IgG titers.

Main Results:

• All 20 dogs exhibited membranoproliferative glomerulonephritis (MPGN) with interstitial nephritis.
• Immunohistochemistry revealed consistent glomerular deposits of immunoglobulin-M (IgM) and the third complement component (C3).
• Electron microscopy showed glomerular basement membrane reduplication, mesangial interposition, and subendothelial immunocomplex deposits. Pedigree analysis supported a hereditary cause for MPGN.
• 17 dogs had high IgG titers against Borrelia burgdorferi.

Conclusions:

• The MPGN observed in these Bernese Mountain Dogs is of hereditary genesis and should be classified as a familial nephropathy.
• The findings suggest a potential genetic predisposition to MPGN in this breed.
• The role of Borrelia burgdorferi infection in the pathogenesis warrants further investigation.