Proteinuria in the dog: a pathomorphological study of 51 proteinuric dogs

Renal cortical biopsies of 51 dogs with spontaneous proteinuria were examined by histology, electron microscopy and immunofluorescence. Glomerular lesions were classified in four groups: mesangioproliferative, membranoproliferative and membranous glomerulonephritis and amyloidosis. The glomerular and the tubulointerstitial lesions were graded, using a semiquantitative system. The results were used for the calculation of correlation coefficients between several parameters. A positive correlation was found between the severity of glomerular and tubulointerstitial lesions. Fibrin detection by immunofluorescence and histochemical methods appeared not to be correlated. The presence of electron dense deposits correlated only with the fluorescence for IgG and C3. Fluorescence for IgA and IgM was frequently observed in cases with or without dense deposits.     

Membranous nephropathy in the dog

Membranous nephropathy, a disease syndrome characterized by severe proteinuria and often accompanied by the nephrotic syndrome, was identified in 29% of a population of 46 proteinuric dogs. Renal lesions were characterized by the presence of subepithelial immunoglobulin deposits distributed diffusely along the glomerular capillary wall. Advanced stages were associated with progressive thickening of capillary basement membranes and incorporation of the immune deposits. These changes were followed by either glomerulosclerosis or recovery. Characteristic morphologic stages were correlated with clinical pathologic findings which showed that the level of proteinuria, hypoalbuminemia, and consequent nephrotic syndrome was most severe in the initial stages of membranous nephropathy while the level of azotemia increased in the more advanced stages of the syndrome.     

Clinical considerations on canine visceral leishmaniasis in Greece: a retrospective study of 158 cases (1989-1996).

The medical records of 158 dogs with visceral leishmaniasis confirmed cytologically and/or serologically were reviewed. Ages of affected dogs varied from nine months to 15 years, with a male-to-female ratio of 1.3. The most common clinical manifestations of the disease were variable cutaneous lesions such as exfoliative dermatitis and skin ulcerations, chronic renal failure, peripheral lymphadenopathy or lymph node hypoplasia, masticatory muscle atrophy (i.e., chronic myositis), ocular lesions (i.e., conjunctivitis, keratoconjunctivitis sicca, blepharitis, and uveitis), and poor body condition. Ascites, nephrotic syndrome, epistaxis, polyarthritis, and ulcerative stomatitis were seen only in a small number of cases. Clinical splenomegaly was not a common finding. The clinicopathological abnormalities were nonregenerative anemia, hyperproteinemia, glomerular proteinuria, and symptomatic or asymptomatic azotemia. In this study, an indirect immunofluorescence assay's diagnostic sensitivity was found to be higher than that of lymph node aspiration cytology.     

Azotemia and mortality among Babesia microti-like infected dogs

Babesia microti-like piroplasms are a recently recognized cause of illness in dogs in northwest Spain. Our objective was to describe the clinical characteristics and investigate the risk factors for azotemia and death among 58 B microti-like infected dogs. Twenty-one of the 58 (36%) dogs were azotemic at the time that the infection was diagnosed. The case fatality rate during the following week was 22%. Dogs with azotemia at the time of diagnosis were 10 times (95% CI, 3.26-28.8) more likely to die during the following week. Azotemia was the main cause of death for B microti-like infected dogs (attributable fraction = 90%). Severe anemia was present in 45 of the 58 (78%) dogs. Azotemic dogs also presented with hyperphosphatemia, hypoalbuminemia, hypercholesterolemia, proteinuria, and high urine protein: creatinine ratios, suggesting a glomerular component to the disease. Age was the only factor significantly associated with the risk of azotemia (P = .042): on average, a 4-year age increase doubled the risk of an infected dog being azotemic. The only factor significantly associated with mortality was azotemia (P = .001). We concluded that B microti-like infection is associated with a high risk of azotemia and mortality.     

Renal dysfunction in dogs with pyometra

Renal function and pathologic changes in 27 dogs with pyometra were studied. Evaluation included CBC; serum biochemical evaluation; urinalysis; urine and uterine bacteriologic culture; uterine morphologic features; and light, electron, and immunofluorescent microscopic evaluation of renal tissues. Measurements of 24-hour creatinine clearance, protein excretion, Na excretion, and urine volume were made in 12 dogs without azotemia. Of 27 dogs, 26% were azotemic and 89% had a urine sp gr less than 1.035. Glomerular filtration rate was reduced in 75% of 12 dogs without azotemia. None of these 12 dogs was proteinuric. Examination of renal biopsy specimens revealed a high prevalence of mild tubulointerstitial nephritis, but few specific glomerular lesions. Minimal immunofluorescence was detected within the mesangium in 18% of the dogs. Immunofluorescence was not associated with the interstitium or tubules. Urinary tract infection was detected in 22% of the dogs. Escherichia coli and Klebsiella were recovered from the uterus in 59 and 15% of the dogs, respectively. Low urine specific gravity values were obtained from dogs without azotemia and from dogs with uterine cultures considered negative for E coli and other gram-negative bacteria. The reduction in glomerular filtration rate was a functional abnormality not correlated with structural damage in the glomerulus.     

Glomerular lesions in dogs infected with Leishmania organisms

OBJECTIVE: To histologically identify glomerular lesions in dogs infected with Leishmania organisms. ANIMALS: 41 dogs (17 sexually intact males and 14 sexually intact and 10 ovariohysterectomized females) that had positive results when tested for leishmaniosis as determined by use of serologic evaluation (indirect fluorescent antibody test, titers of 1:80 to 1:640) and direct microscopic identification of the protozoal organisms. PROCEDURE: Urine samples were collected by use of cystocentesis and examined by qualitative SDS-agarose gel electrophoresis (AGE). All dogs had non-selective (glomerular) or mixed (glomerular and tubular) proteinemia. Specimens were obtained from each dog during ultrasound-assisted renal biopsy and used for histologic examination. Each specimen was stained with H&E, periodic acid-Schiff, Goldner's trichrome, methenamine silver, and Congo Red stains. Specimens were adequate for evaluation when they contained at least 5 glomeruli/section, except for specimens stained with Congo Red in which 1 glomerulus/section was adequate. RESULTS: Examination of renal biopsy specimens revealed various glomerular lesions in all dogs and interstitial or tubular (or both) lesions in 23 of 41 (55%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Glomerular lesions that develop in dogs during infection with Leishmania organisms can be classified histologically as mesangial glomerulonephritis, membranous glomerulonephritis, membranoproliferative glomerulonephritis, and focal segmental glomerulonephritis. Tubulointerstitial histopathologic conditions were not observed as the primary lesion, despite being evident in 23 of 41 (55%) dogs. Use of SDS-AGE for qualitative evaluation of proteinuria and successive collection of specimens during renal biopsies following diagnosis of nonselective glomerular proteinuria provides the possibility for early identification of renal lesions.     

Comparison of signalment, clinicopathologic findings, histologic diagnosis, and prognosis in dogs with glomerular disease with or without nephrotic syndrome

Background: Nephrotic syndrome (NS) develops most commonly in people with glomerular diseases associated with marked albuminuria. Hypernatremia, hypertension, and progressive renal failure are more prevalent in nephrotic than nonnephrotic human patients. Hypothesis/Objectives: Dogs with NS have higher serum cholesterol, triglyceride, and sodium concentrations, higher urine protein:creatinine ratios (UPC) and systolic blood pressure, and lower serum albumin concentrations than dogs with nonnephrotic glomerular disease (NNGD). NS is associated with membranous glomerulopathy and amyloidosis. Affected dogs are more likely to be azotemic and have shorter survival times. Animals: Two hundred and thirty‐four pet dogs (78 NS dogs, 156 NNGD dogs). Methods: Multicenter retrospective case‐control study comparing time‐matched NS and NNGD dogs. NS was defined as the concurrent presence of hypoalbuminemia, hypercholesterolemia, proteinuria, and extravascular fluid accumulation. Signalment, clinicopathologic variables, histopathologic diagnoses, and survival time were compared between groups. Results: Age, serum albumin, chloride, calcium, phosphate, creatinine, and cholesterol concentrations, and UPC differed significantly between NS and NNGD dogs. Both groups were equally likely to be azotemic at time of diagnosis, and NS was not associated with histologic diagnosis. Median survival was significantly shorter for NS (12.5 days) versus NNGD dogs (104.5 days). When subgrouped based on serum creatinine (< or ≥1.5 mg/dL), survival of NS versus NNGD dogs was only significantly different in nonazotemic dogs (51 versus 605 days, respectively). Conclusions and Clinical Importance: Presence of NS is associated with poorer prognosis in dogs with nonazotemic glomerular disease. Preventing development of NS is warranted; however, specific interventions were not evaluated in this study.     

Experimental immune complex glomerulonephritis in dogs receiving cationized bovine serum albumin

Eight 16-week-old dogs were used to induce immune complex glomerulonephritis by daily intravenous injections of 120 mg highly cationized bovine serum albumin (pI9.5). Of four control dogs, two received unmodified native anionic bovine serum albumin (pI 4.5) while the other two received only phosphate buffered saline. The renal glomeruli were examined by light, electron (transmission and scanning) and immunofluorescence microscopy at intervals from five to 11 weeks after the start of the injections. Animals receiving cationic antigen all developed generalised diffuse granular deposits of IgG and C3 along the capillary walls; these were detected as early as five weeks and continued until the termination of the experiment at 11 weeks. Ultrastructural studies revealed many electron dense deposits along the subepithelial regions of the glomerular basement membrane. The experimental disease resembled in many respects naturally occurring membranous nephropathy, the most common form of immune complex glomerulonephritis in dogs.     

Histopathologic patterns of nephropathy in naturally acquired canine visceral leishmaniasis

Although the nephropathy of visceral leishmaniasis (VL) is known both in humans and dogs, histopathologic alterations have not been thoroughly studied. We examined renal alterations in 55 dogs with naturally acquired VL compared with five noninfected dogs from an endemic area in northeastern Brazil. Glomerulonephritis was found in 55 dogs, interstitial alterations in 53 dogs, and tubular changes in 43 dogs with VL. The glomerular alterations found were minor glomerular abnormalities (n = 8, 14.5%), focal segmental glomerulosclerosis (n = 10, 18.2%), mesangial proliferative glomerulonephritis (n = 17, 32.7%), membranoproliferative glomerulonephritis, (n = 18, 30.9%), crescentic glomerulonephritis (n = 1, 1.8%), and chronic glomerulonephritis (n = 1, 1.8%). Morphometric and ultrastructural studies complemented the analysis. The five control animals exhibited no glomerular alterations. The glomerular lesions were related to functional alterations. Considering that the alterations of canine and human nephropathy in VL are very similar, the data obtained in this study constitute an important contribution to the understanding of canine and human VL nephropathy.     

Pitfalls in immunofluorescence testing in dermatology. II. Pemphigus-like antibodies in the cat, and direct immunofluorescence testing of normal dog nose and lip

Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 75 cats: 25 cats with various nonpemphigus dermatologic diseases, 25 cats with various nondermatologic diseases, and 25 normal cats. Pemphigus-like antibodies were not detected. It was concluded that neither true pemphigus antibodies, nor pemphigus-like antibodies are commonly detected by indirect immunofluorescence testing in the cat. Direct immunofluorescence testing for IgG, IgA, IgM, and C3 was performed on the nose and lip of 15 normal dogs. Granular deposition of IgM at the basement membrane zone of the nose was demonstrated in 11 of the 15 dogs. Lip was consistently negative. It was concluded that direct immunofluorescence testing of canine nose by only polyvalent immunoglobulin antisera or anti-IgM antisera may lead to misinterpretation and misdiagnosis in up to 73% of all dogs tested.     

Pitfalls in immunofluorescence testing in canine dermatology

Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 100 dogs: 50 dogs with various nonpemphigus dermatologic diseases, 25 dogs with various nondermatologic diseases, and 25 normal dogs. One dog (generalized demodicosis) was positive for pemphigus-like antibodies at a titer of 1:10. It was concluded that canine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluorescence testing for IgG, IgA, IgM, and C3 was performed on the footpads of 11 normal dogs. Granular deposition of IgM at the basement membrane zone was demonstrated in 5 of the 11 dogs. It was concluded that direct immunofluorescence testing of canine footpads using only polyvalent immunoglobulin antisera or anti-IgM antisera may lead to misinterpretation and misdiagnosis in up to 45% of all dogs tested.     

Effects of allopurinol treatment on the progression of chronic nephritis in Canine leishmaniosis (Leishmania infantum)

Forty dogs with canine leishmaniosis (CL) participated in this study, which was designed to investigate the effect of allopurinol on the progression of the renal lesions associated with this disease. The animals were allocated into 5 groups. Group A dogs (n = 12) had neither proteinuria nor renal insufficiency, group B dogs (n= 10) had asymptomatic proteinuria, and group C dogs (n = 8) were proteinuric and azotemic. Two more groups, CA and CB, comprising 5 dogs each, served as controls for groups A and B, respectively. Group A, B, and C dogs received allopurinol PO (10 mg/kg q12h) for 6 months, whereas group CA and CB dogs were placebo-treated. Serum biochemistry profile, urinalysis, urine protein/creatinine ratio, and glomerular filtration rate (GFR) measurements were carried out at the beginning of the study, the 3rd month, and the 6th month, whereas renal biopsies were carried out only at the beginning and the end of the trial. Membranoproliferative glomerulonephritis was the most common cause of chronic renal failure. Mesangioproliferative and tubulointerstitial nephritis were detected even in group A and CA dogs. Allopurinol not only lowered proteinuria in group B dogs but also prevented the deterioration of GFR and improved the tubulointerstitial, but not the glomerular, lesions in both group A and group B dogs. Further, it resolved the azotemia in 5 of the 8 dogs admitted with 2nd stage chronic renal failure (group C). Consequently, treatment with allopurinol is advisable in CL cases with asymptomatic proteinuria or 1st-2nd stage chronic renal failure.     

Glomerulopathy with IgA deposition in the dog.

In 100 dogs autopsied, glomerular IgA deposition was examined by the immunofluorescence technique and the histopathological features of glomeruli with IgA deposition were examined by light and electron microscopy. The incidence of the IgA deposition was age-related but there were no sex and breed predisposition. Deposition of IgA was observed mainly in mesangial areas in approximately a half (47%) of dogs examined. IgG, IgM and C3 often co-deposited. Histopathology of the glomeruli with IgA deposition indicated increase of mesangial cells, crescent formation, hemispherical deposits in paramesangial areas and glomerular sclerosis. Ultrastructurally electron dense substances positive for IgA deposited in mesangial and paramesangial areas. The examination to know the relation between the severity of IgA deposition and the number of mesangial cells or percent of the cells to total glomerular cells indicated that mesangial cells increased at the early stage of the disease and subsequently epithelial and endothelial cells proliferated as the increasing amount of IgA. Dogs suffering from enteritis or liver diseases showed high incidence of glomerular IgA deposition.     

Spontaneous glomerulonephritis in dogs. II. Correlation of glomerulonephritis with age, chronic interstitial nephritis and extrarenal lesions

A morphologic study of 103 dogs, including two with renal amyloidosis, showed that different types of diffuse glomerulonephritis are correlated with different age groups. Membranous and membranoproliferative glomerulonephritis were more common in middle-aged and older animals, whereas mesangial lesions were found predominantly in younger dogs and considered to be early glomerular changes. Glomerulonephritis largely occurred independently of interstitial nephritis. The incidence of interstitial lesions was 71%. Chronic interstitial nephritis was rare in dogs under 1 year old. Glomerulonephritis did not seem to induce interstitial nephritis. Glomerulonephritis occurred not only in kidneys with severe interstitial damage, but also in those with slight damage. The indicated that glomerulonephritis occurred independently of interstitial nephritis. In end-stage kidneys with severe fibrosis, mesangial changes seemed to predominate.     

Immune complex-mediated glomerulonephritis associated with bacterial kidney disease in the rainbow trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss) developed a post-infectious chronic membranous glomerulonephritis 15 months after they had been experimentally infected with Renibacterium salmoninarum. Histologically, peritubular and periglomerular fibrosis, hypercellular glomeruli with occluded Bowman's space, and partial or complete adhesion to Bowman's capsule were constant features. Electron microscopy revealed thickened glomerular basement membranes with spikes accompanied by finely granular electron-dense deposits at the epithelial side and dense material in the mesangial matrix. Indirect immunofluorescence indicated linear immunoglobulin deposits along the glomerular basement membrane. The presence of R. salmoninarum was demonstrated by culture and by indirect immunofluorescence. Low serum hemagglutination-inhibiting antibody titers were demonstrated.     

Immunoperoxidase staining for the detection of autoantibodies in canine autoimmune skin disease; comparison to immunofluorescence results

Skin sections from 22 dogs with autoimmune skin disease were stained with anti-canine IgG, IgM and IgA using an immunobridge immunoperoxidase method. Eight cases of lupus erythematosus, three cases of pemphigus vulgaris, and 11 cases of pemphigus foliaceus were included. Results of previously performed, direct immunofluorescence tests for the detection of canine immunoglobulin on skin were available on 17/22 cases. The immunoperoxidase method yielded an overall positive result in 59% (5/8 lupus erythematosus, 2/3 pemphigus vulgaris and 6/11 pemphigus foliaceus) versus an overall positive result of 47% for direct immunofluorescence (3/5 lupus erythematosus, 2/2 pemphigus vulgaris and 2/10 pemphigus foliaceus). The immunobridge immunoperoxidase method compared favorably to direct immunofluorescence testing of canine skin for autoantibody in cases of lupus erythematosis and pemphigus vulgaris, and was superior in cases of pemphigus foliaceus. This method should prove useful as an aid in the diagnosis of canine autoimmune skin disease.     

Suppurative, nonseptic polyarthropathy in dogs

The goals of this study were to determine the historical, physical examination, and clinicopathologic findings in dogs with suppurative, nonseptic polyarthropathy and to identify concurrent disorders associated with this syndrome. Medical records of 52 dogs with cytologic evidence of suppurative inflammation in two or more joints were examined retrospectively. Age of dogs was 4.8 years (median, range: 0.5-12 years). There was no clear breed or sex predilection, but most were large-breed dogs (body weight > or = 20 kg [44.4 lbs] in 40/52). Body temperature was 103.0 degrees F (39.4 degrees C) (median, range: 100.0-105.9 degrees F), with 29 of 52 dogs having a body temperature > or = 103 degrees F (39.4 degrees C). Lameness was identified in 42 of 52 dogs. Erosive changes were found in only 1 of 37 dogs that had radiography performed. A clear underlying disease process was not identified in 34 of 52 dogs. Seven dogs had evidence of infectious or inflammatory processes at extra-articular sites; 4 dogs were diagnosed with systemic lupus erythematosus (SLE); 2 dogs had gastrointestinal disease; 2 dogs had been vaccinated within 1 month before onset of polyarthritis; 1 dog had cancer; 1 dog had polyarthritis and meningitis; and 1 dog had erosive polyarthritis. Of the 44 dogs tested, 25 had antibodies to Borrelia burgdorferi, detected by an ELISA assay, which was significantly greater than the general hospital population (P = .007). Antibodies against Rickettsia rickettsiae and Ehrlichia canis were not definitively identified in the sera of any dog tested in this study (45 and 44 dogs, respectively). We conclude that an underlying disease process is not identified in most cases of suppurative polyarthropathy in dogs and that intestinal disease, neoplasia, and SLE are uncommon causes of polyarthritis. While seropositivity against the causative agent of Lyme disease was common and possibly a cause of polyarthritis in some dogs of our study, evidence of other vector-borne infection was not identified.     

Renal amyloidosis in a family of beagles.

Renal amyloidosis was confirmed in 6 related male and female Beagles, ranging in age from 5 to 11 years. The most commonly reported signs of illness included lethargy, anorexia, vomiting, and weight loss. Common clinicopathologic abnormalities were normocytic, normochromic anemia; hypoalbuminemia; azotemia; hypercholesterolemia; proteinuria; and urine specific gravity values below the normal range. Histologic examination of renal tissue from the 6 Beagles revealed moderate to severe glomerular amyloidosis with inconsistently observed mild medullary interstitial amyloidosis. Congo red-stained kidney sections from 4 of 4 affected dogs were potassium permanganate-sensitive, suggestive of reactive amyloidosis. Hereditary predisposition for renal amyloidosis was suspected in these Beagles.     

Development of canine nephrotic syndrome model

To develop an experimental animal model for immune-mediated glomerulonephritis and nephrotic syndrome, nine healthy dogs were sensitized by intravenous injection with 1 microg of endotoxin and 5 mg of native bovine serum albumin. After 1 week, 120 mg of cationized bovine serum albumin was injected intravenously 5 times a week. Among nine dogs, five dogs were confirmed as having developed glomerulonephritis and nephrotic syndrome by increase of urine protein-to-creatinine ratio (>1.0), hypoalbuminemia (<1.5 g/dl), hypercholesterolemia (>240 mg/dl), and edema. This model should be useful for studying immune-mediated glomerulonephritis and nephrotic syndrome.     

Development and evaluation of a flow cytometry microsphere assay to detect anti-histone antibody in dogs

Anti-nuclear antibody (ANA) is one of the diagnostic parameters that support a diagnosis of autoimmune disorders in humans, dogs, and horses, particularly the condition systemic lupus erythematosus (SLE). The most commonly used method for detecting ANA in canine serum is the indirect immunofluorescence antibody assay (IFA) that detects dog IgG with reactivity towards mammalian cell nuclei. Interpretation of the IFA results is very subjective and dependent on the source of tissue/cellular substrate. We have developed a flow cytometry based assay to detect canine serum antibodies specific to histones. Histones were chosen as the target antigen because these nuclear proteins are the most common nuclear substrate for ANA in dogs with SLE. Microsphere beads were coated with histones and incubated with canine sera. Bound anti-histone antibodies were detected by FITC-conjugated rabbit F(ab')2 anti-dog IgG. Sera from four groups of dogs (47 dogs total) were tested for anti-histone antibodies and compared with the traditional IFA assay. The groups included 15 healthy dogs, 15 dogs with noninflammatory diseases, 9 dogs with polyarthritis and positive ANA, and 8 German shepherds with perianal fistulas. The microsphere assay results indicated that only one dog in the noninflammatory group and four out of nine dogs in the polyarthritis group had mean fluorescent intensity values above our established cut-off (defined as 2 S.D. above the mean of healthy controls). There was moderate agreement between the anti-histone assay and the traditional ANA (kappa statistic=0.54). Absorption of ANA positive serum with total histones dramatically diminished the fluorescent signal detected by flow cytometry and the speckled nuclear pattern observed by IFA, whereas preabsorption did not change the diffuse nuclear staining pattern. These findings indicate that the anti-histone assay will not replace the ANA test and that other nuclear proteins, such as ribonucleoproteins may contribute to the diffuse ANA patterns.