Focal Segmental Glomerulosclerosis in Related Miniature Schnauzer Dogs

Focal segmental glomerulosclerosis (FSGS) recently has been recognized as a common cause of proteinuria in dogs in general, and in Miniature Schnauzer dogs in particular. This study describes the morphologic features present in the kidneys of 8 related proteinuric Miniature Schnauzer dogs. The FSGS, characterized by solidification of portions of the capillary tuft, affected 32% to 49% of examined glomeruli in these dogs. Synechiae, often accompanied by hyalinosis, were present in 13% to 54% of glomeruli and were more prevalent in older dogs. Seven of 8 dogs had arteriolar hyalinosis. Ultrastructurally, all dogs had evidence of a podocytopathy in the absence of electron-dense deposits, glomerular basement membrane splitting, or fibrils. All dogs had multifocal to extensive podocyte foot process effacement. Other podocyte changes included microvillous transformation, the presence of vacuoles or protein resorption droplets, cytoplasmic electron-dense aggregates, and occasional binucleation. Variable amounts of intraglomerular lipid were present in all dogs. All dogs were proteinuric, with measured values for the urine protein-to-creatinine ratio ranging from 1.2 to 6.5. Azotemia was mild to absent and dogs were euthanatized at 5.1 to 14 years of age, in all cases due to nonrenal diseases. The underlying cause of FSGS in these Miniature Schnauzer dogs has yet to be determined, but contributors likely include genetic podocytopathy, lipid abnormalities, and glomerular hypertension.

Incidence of and mortality from kidney disease in over 600,000 insured Swedish dogs

Kidney disease is an important cause of morbidity and mortality in dogs. Knowledge about the epidemiology of kidney disease in the dog population is valuable and large-scale epidemiological studies are needed. The aim of the present study was to use insurance data to estimate kidney-related morbidity and mortality in the Swedish dog population. Insurance company data from insured dogs during the years 1995-2006 were studied retrospectively. Incidence and mortality were calculated for the whole group of dogs as well as divided by sex and breed. The total number of veterinary care insured dogs was 665,245. The total incidence of kidney disease in this group of dogs was 15.8 (15.3-16.2) cases/10,000 dog-years at risk. The number of dogs in the life insurance was 548,346 and in this group the total kidney-related mortality was 9.7 (9.3-10.2) deaths/10,000 dog-years at risk. The three breeds with the highest incidence of kidney disease were the Bernese mountain dog, miniature schnauzer and boxer. The three breeds with the highest mortality caused by kidney disease were the Bernese mountain dog, Shetland sheepdog and flat-coated retriever. In conclusion, the epidemiological information provided in this study concerning kidney disease in dogs can provide valuable information for future research.

Consensus guidelines for immunosuppressive treatment of dogs with glomerular disease absent a pathologic diagnosis

BACKGROUND

In certain situations, veterinarians must decide whether or not to recommend immunosuppressive therapy for dogs with suspect glomerular disease in the absence of renal biopsy-derived evidence that active immune mechanisms are contributing to glomerular injury. The purpose of this report is to provide guidelines for the use of immunosuppressive drugs under these conditions.

ANIMALS

Animals were not used in this study.

METHODS

Recommendations were developed by a formal consensus method.

RESULTS

Four recommendations were developed and accepted at a high level of consensus (median 92.5% agreement). Renal biopsy should not be performed when contraindications are present or when results will not alter treatment or outcome. Immunosuppressive drugs should not be given when the source of proteinuria is unknown, they are otherwise contraindicated, or a familial nephropathy or amyloidosis is likely. However, they should be considered when dogs are already being given standard therapy and the serum creatinine is >3.0 mg/dL, azotemia is progressive, or hypoalbuminemia is severe. Thorough client communication regarding pros and cons of such treatment as well as close and careful patient monitoring is required.

CONCLUSION AND CLINICAL IMPORTANCE

These recommendations can help guide the decision about renal biopsy in patients with proteinuria as well as the use of immunosuppressive drugs in those patients where the decision was made not to perform renal biopsy.

Lyme nephritis

OBJECTIVE

To review what is known and highlight knowledge gaps regarding Lyme nephritis (LN).

DATA SOURCES

Publications identified via PubMed using the keywords "Borrelia burgdorferi," "Borreliosis," "glomerulonephritis," "protein-losing nephropathy," "autoimmunity," and "retriever," and as generated by investigators working in the fields of Borreliosis and immune-mediated glomerulonephritis.

HUMAN DATA SYNTHESIS

Postborrelial immune-mediated glomerulonephritis was described recently in 6 people; 3 responded to antimicrobials/steroids, 1 to antimicrobials/angiotensin-converting enzyme inhibitor/warfarin, 1 required hemodialysis but became hemodialysis independent after 5 months and treatment with antimicrobials, steroids, plasmapheresis, immunoglobulin, and 1 did not respond to steroids and angiotensin-converting enzyme inhibitor and still requires hemodialysis.

VETERINARY DATA SYNTHESIS

Lyme nephritis is seen in <1-2% of Lyme seropositive dogs, with an average onset at 5-6 years. Labrador and Golden Retrievers are predisposed to this condition. Prior or concurrent lameness is described in 9-28% cases. Historical presentations include acute progressive protein-losing nephropathy with membranoproliferative glomerulonephritis, tubular necrosis/regeneration, and interstitial nephritis, but possibly milder forms exist. Complications include thromboembolic events, hypertension, effusive disease, and oliguric/anuric renal failure. Diagnostic tests help stage disease and rule out other causes. Renal biopsy is advocated early, when intervention may help, and to prove if immune-complex disease exists. Treatment includes standard therapy for protein-losing nephropathy, long-term antimicrobials, and perhaps immunosuppressive therapy.

CONCLUSIONS

There is no experimental model of LN to study predisposing factors, pathogenesis, onset, progression, treatment, or prevention. There are no predictive tests to identify the few individuals at highest risk, therefore all seropositive dogs should be screened and monitored for proteinuria. Lyme nephritis mimics other forms of protein-losing nephropathy and sometimes Leptospirosis. Renal biopsy helps show if immune-complex disease exists, but may not prove LN specifically. More studies are warranted on dogs with Lyme-specific immune-complex deposition to evaluate risk factors, understand pathogenesis, variability of expression, and to validate treatment and prevention protocols.