Prevalence of Immune‐Complex Glomerulonephritides in Dogs Biopsied for Suspected Glomerular Disease: 501 Cases (2007–2012)

Abstract

Background Glomerulonephropathies are common causes of kidney disease in dogs. Objective To determine the prevalence of immune‐complex glomerulonephritis (ICGN) in North American dogs biopsied for suspected glomerular disease. Animals Renal biopsies (n = 733) submitted to the Texas Veterinary Renal Pathology Service between January 1, 2007 and December 31, 2012 were reviewed. Dogs were included if the biopsy was performed for suspected glomerular disease. Methods Specimens were evaluated by light microscopy (LM), immunofluorescence (IF), and transmission electron microscopy (TEM). Findings were retrospectively evaluated to categorize the diagnosis for each case. For the diagnosis of ICGN, TEM findings were considered conclusive when LM and IF were equivocal. Results Of the 501 dogs included in the study, 241 (48.1%) had ICGN; 103 (20.6%) had primary glomerulosclerosis; 76 (15.2%) had amyloidosis; 45 (9.0%) had nonimmune complex (IC) glomerulopathy; 24 (4.8%) had non‐IC nephropathy; and, 12 (2.4%) had primary tubulointerstitial disease. Many (66/241; 27.4%) ICGN cases required TEM for definitive diagnosis, including 14 cases (5.8%) that were not suspected on LM. Of cases not diagnosed as ICGN, a substantial proportion (60/260; 23.1%) required TEM to rule out immune complex deposits, including 14 of 189 cases (7.4%) presumptively diagnosed as ICGN on LM. Conclusions and Clinical Importance Approximately half of all dogs biopsied for suspected glomerular disease had conditions other than ICGN. Renal biopsy is needed to accurately categorize the underlying disease and direct appropriate treatment. Additionally, TEM and IF evaluations by experienced nephropathologists are necessary to obtain an accurate diagnosis in many cases.

Correlation of Urine and Serum Biomarkers with Renal Damage and Survival in Dogs with Naturally Occurring Proteinuric Chronic Kidney Disease

“…Cases with an active sediment were excluded from analysis. Renal biopsies were routinely processed for light (LM) and transmission electron microscopy (TEM) as previously described 24. Criteria for diagnosis of renal disease included persistent proteinuria, azotemia, or both.…”

Aging in the Canine Kidney

“…63 The role of estrogens is intriguing because proteinuric dogs diagnosed with FSGS were disproportionately female (74 of 103, 71.8%), almost all of which (93%) were spayed. 72 In aged Fisher 344 rats, the pattern of glomerular gene expression resembles changes observed in arteries with arteriosclerosis. Specifically, there is transcriptional regulation of cell adhesion molecules, chemotactic factors, oxidoreductases (specifically ceruloplasmin), MMPs, coagulation factors, and TGF-ß.…”

“…The WSAVA-RSSG defines FSGS as sclerosis that effaces <50% of a glomerular tuft and involves <50% of glomeruli of the sample. 13 Given that FSGS is associated with proteinuria in humans 22 and dogs, 72 its presence might indicate clinically relevant disease. Notably, FSGS was observed (but not quantified) in the 2 of the canine studies discussed above 29,57 ; however, either it was not mentioned, 11,74 or it was reported as being absent in the others.…”

“…27 There is age-associated glomerular enlargement in ad libitum-fed 20-week-old Sprague-Dawley rats, followed by GS at 2 years of age. 34 With the recent recognition of focal segmental GS (FSGS) as a disease in dogs, 72 this lesion should be identified and reported separately from global GS (Fig. 7).…”

Management of Proteinuria in Dogs and Cats with Chronic Kidney Disease

“…Nearly 60% of dogs with glomerular proteinuria will have either immune-complex mediated glomerulonephritis or amyloidosis (Schneider et al, 2013), both of which may represent an aberrant or excessive immune or inflammatory response to an infectious, neoplastic or inflammatory condition. Cats rarely get glomerulonephritis but a percentage of these cats would also be expected to have developed this secondary to a systemic disease.…”