Assessment and Management of Proteinuria in Dogs and Cats: 2004 ACVIM Forum Consensus Statement (Small Animal)

The incidence and trends of proteinuria, azotemia and hypertension in cats receiving toceranib phosphate

OBJECTIVES

This retrospective study aimed to determine the incidence and trends of proteinuria, elevations in serum creatinine and urea, and systolic blood pressure in cats undergoing treatment with toceranib.

METHODS

In total, 32 cats treated with toceranib for malignancies were analyzed. Cats were included if urinalysis and urine protein:creatinine ratio (UPC) measurements were available at 28 days (T1) and 56 days (T2) after starting the treatment. Cats with concurrent lower urinary tract disease, including urinary tract malignancy, were excluded. Friedman's ANOVA compared variables between time points, and the Spearman test assessed the correlation between treatment duration and UPC.

RESULTS

The median starting dose of toceranib was 2.68 mg/kg (range 1.7-3.9). In total, 15 (46.9%) cats received concurrent non-steroidal anti-inflammatory drugs. The most commonly treated tumors were oral squamous cell carcinoma (n = 10) and mast cell tumor (n = 5). None of the 32 cats developed progressive proteinuria or azotemia during the follow-up period (median 56 days; range 56-336). Notably, UPC and serum creatinine were significantly lower at T2 compared with baseline (P = 0.012 and 0.001, respectively). Among the four cats with baseline proteinuria, UPC decreased over time with or without concurrent telmisartan treatment (n = 2). All four of these cats experienced a reduction in tumor size with toceranib concurrently with their decreased UPC. There was no significant correlation between UPC and the duration of toceranib treatment (P = 0.089). Blood pressure was not significantly different over the assessed time points.

CONCLUSIONS AND RELEVANCE

The incidence of proteinuria, renal azotemia and hypertension in cats treated with toceranib for neoplasia appears to be low. Toceranib may be a viable treatment option even in cats with pre-existing proteinuria or renal disease, with careful monitoring of trends recommended.

Association of proteinuria at time of diagnosis with survival times in dogs with lymphoma

BACKGROUND

Lymphoma has been implicated as a possible cause of proteinuria in dogs. However, information about the potential importance of proteinuria in dogs with lymphoma is limited.

HYPOTHESIS

To determine if the presence of proteinuria at diagnosis was associated with median survival times in dogs with lymphoma and if lymphoma stage (I-V) or type (B vs T) were associated with the presence of proteinuria.

ANIMALS

Eighty-six client-owned dogs with a new diagnosis of lymphoma between 2008 and 2020.

METHODS

This was a retrospective cross-sectional study with dogs divided into proteinuric or nonproteinuric groups based on dipstick urine protein (protein ≥30 mg/dL classified as proteinuric) or a ratio of dipstick protein to urine specific gravity (ratio ≥1.5 classified as proteinuric). Dogs were excluded for: (1) treatment within 2 months with glucocorticoid, anti-neoplastic, or anti-proteinuric therapies, (2) diagnosed hypercortisolism or renal lymphoma, (3) active urine sediment, or (4) urine pH >8. Survival analysis utilized a Kaplan-Meier estimator and log-rank testing.

RESULTS

There was a significant difference in median survival between proteinuric and nonproteinuric dogs classified by urine dipstick (245 days [91, 399] vs 335 days [214, 456]; P = .03) or UP : USG (237 days [158, 306] vs 304 days [173, 434]; P = .03). No difference in prevalence of proteinuria was identified between stages (I-V) or types (B and T).

CONCLUSIONS AND CLINICAL IMPORTANCE

Proteinuria appears to be negatively associated with survival time in dogs newly diagnosed with lymphoma.

Characterization of the circulating markers of the renin-angiotensin-aldosterone system in telmisartan- or enalapril-treated dogs with proteinuric chronic kidney disease

BACKGROUND

Effects of the renin-angiotensin-aldosterone system (RAAS) inhibitors enalapril and telmisartan on circulating RAAS in dogs with proteinuric chronic kidney disease (pCKD) are undescribed.

OBJECTIVES

To characterize the RAAS in untreated dogs with pCKD compared to healthy, life-stage- and sex-matched controls, and in dogs with pCKD after 30 days of treatment with enalapril or telmisartan.

ANIMALS

Dogs with pCKD (n = 36) and healthy controls (n = 20).

METHODS

Retrospective study of banked samples and previously collected data. Day 0 serum equilibrium concentrations of angiotensin I, II, III, IV, 1-5, and 1-7, and aldosterone, and urinary aldosterone-to-creatinine ratio (UACR) from pCKD dogs were compared to values on day 30 of treatment with enalapril (0.5 mg/kg PO q12) or telmisartan (1 mg/kg PO q24h) and to those of healthy dogs. Data were analyzed using linear mixed models.

RESULTS

Compared with healthy dogs, pCKD dogs had significantly higher Ang I, III, 1-5, and 1-7 concentrations, and UACR. Relative to pretreatment values, day 30 Ang II concentrations were significantly increased and decreased in telmisartan- and enalapril-treated pCKD dogs, respectively (both P < .001). Mean (95% confidence interval) percentage change from pretreatment value in serum Ang 1-7 concentration was significantly greater in telmisartan- (753% [489%-1134%]) versus enalapril-treated (149% [69%-268%]) dogs (P < .001). Serum aldosterone decreased with treatment (P = .02 for enalapril, P < .001 for telmisartan), with no difference between groups at day 30.

CONCLUSIONS AND CLINICAL IMPORTANCE

Circulating RAAS activity is higher in dogs with pCKD. Compared with enalapril, treatment with telmisartan caused significantly greater increases in the presumed beneficial peptide Ang 1-7.

A review of renal tubular acidosis

OBJECTIVE

To review the current scientific literature on renal tubular acidosis (RTA) in people and small animals, focusing on diseases in veterinary medicine that result in secondary RTA.

DATA SOURCES

Scientific reviews and original research publications on people and small animals focusing on RTA.

SUMMARY

RTA is characterized by defective renal acid-base regulation that results in normal anion gap hyperchloremic metabolic acidosis. Renal acid-base regulation includes the reabsorption and regeneration of bicarbonate in the renal proximal tubule and collecting ducts and the process of ammoniagenesis. RTA occurs as a primary genetic disorder or secondary to disease conditions. Based on pathophysiology, RTA is classified as distal or type 1 RTA, proximal or type 2 RTA, type 3 RTA or carbonic anhydrase II mutation, and type 4 or hyperkalemic RTA. Fanconi syndrome comprises proximal RTA with additional defects in proximal tubular function. Extensive research elucidating the genetic basis of RTA in people exists. RTA is a genetic disorder in the Basenji breed of dogs, where the mutation is known. Secondary RTA in human and veterinary medicine is the sequela of diseases that include immune-mediated, toxic, and infectious causes. Diagnosis and characterization of RTA include the measurement of urine pH and the evaluation of renal handling of substances that should affect acid or bicarbonate excretion.

CONCLUSIONS

Commonality exists between human and veterinary medicine among the types of RTA. Many genetic defects causing primary RTA are identified in people, but those in companion animals other than in the Basenji are unknown. Critically ill veterinary patients are often admitted to the ICU for diseases associated with secondary RTA, or they may develop RTA while hospitalized. Recognition and treatment of RTA may reverse tubular dysfunction and promote recovery by correcting metabolic acidosis.

Determination of the reference interval for urine kidney injury molecule-1 in 50 healthy cats

OBJECTIVES

The aim of the present study was to establish a reference interval (RI) for urine kidney injury molecule-1 (KIM-1) in healthy cats.

METHODS

History, physical examination, blood pressure, and feline immunodeficiency virus and feline leukemia virus serology status were determined. A complete blood cell count, serum biochemical profile, urinalysis and kidney ultrasound were performed, and N-terminal pro-brain natriuretic peptide, total thyroxine (TT4) and urine KIM-1 were measured. An RI was calculated and the effect of age, sex, body condition score (BCS), blood pressure, symmetric dimethylarginine (SDMA), serum creatinine concentration (SCr), phosphorus, TT4, urine specific gravity (USG) and mid-sagittal kidney length on urine KIM-1 was evaluated using a general linear model.

RESULTS

Of 69 recruited cats, 50 met the inclusion criteria. There were 35 male cats and 15 female cats, with a median age of 4.3 years (range 1.0-12.3), median weight of 5.11 kg (range 2.52-8.45) and median BCS of 6/9 (range 3-8). The median serum concentrations were SDMA 11.0 µg/dl (range 2-14), SCr 88.5 µmol/l (range 47-136), phosphorus 1.41 mmol/l (range 0.8-2.2) and TT4 32.0 nmol/l (range 17-51). Median USG was 1.057 (range 1.035-1.076), mid-sagittal left kidney length was 3.50 cm (range 2.94-4.45) and mid-sagittal right kidney length was 3.70 cm (range 3.06-4.55). The derived RI for urine KIM-1 was 0.02-0.68. USG was a significant (P <0.001) predictor of urine KIM-1. Individually, age, sex, blood pressure, BCS, SDMA, SCr, phosphorus, TT4 and mid-sagittal kidney length were not significant predictors of urine KIM-1. In a multivariate model, if combined with USG, SDMA concentration was predictive (P = 0.030) of urine KIM-1.

CONCLUSIONS AND RELEVANCE

Urine concentration was significantly correlated with urine KIM-1, which will be an important consideration when interpreting findings in cats with potential kidney injury.

Evaluation of a urine dipstick protein to urine specific gravity ratio for the detection of proteinuria in dogs and cats

BACKGROUND

The utility of urine dipsticks for the quantification of proteinuria is limited because of the influence of urine specific gravity (USG). To circumvent the need for urine protein creatinine ratios (UPCR) some have proposed a calculated dipstick urine protein to USG ratio (DUR) for the detection of proteinuria. However, the performance of DUR has not been evaluated in veterinary patients.

OBJECTIVES

Evaluate the correlation between DUR and UPCR, while also assessing the effect of urine characteristics on this relationship and evaluating the performance of DUR in detecting proteinuria.

ANIMALS

Urine samples from 308 dogs and 70 cats.

METHODS

Retrospective cohort study of urinalyses and UPCRs from dogs and cats collected between 2016 and 2021.

RESULTS

Both canine and feline urine samples showed a positive moderate correlation between the UPCR and DUR. The correlation was not influenced by the presence of active urine sediment, glucosuria, or urine pH. In detecting canine urine samples with a UPCR >0.5, an optimal DUR of 1.4 had sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 89%, 83%, 96%, and 63%, respectively. In detecting feline urine samples with a UPCR >0.4, an optimal DUR of 2.1 had sensitivity, specificity, PPV, and NPV of 70%, 100%, 100%, and 75%, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Use of the DUR can be a relatively reliable method for identification of proteinuria. However, given its poor NPV, the DUR cannot be recommended for exclusion of proteinuric patients.

Association between systolic blood pressure and target organ damage in naturally occurring cases of systemic hypertension in the dog

Chronic elevation in the systolic blood pressure (SBP) adversely affects the lifespan in the dog by causing injury to the eye, heart, kidney and brain. Understanding the association between SBP and target organ damage (TOD) helps in risk categorization and treatment planning. Therefore, a prospective study was undertaken to find the association between SBP and renal resistive index (RI) in naturally occurring cases of canine systemic hypertension. Based on the ACVIM guidelines 2018, dogs (n=135) were categorized into four risk groups of SBP, viz., A (minimal), B (low), C (moderate), and D (high). Ophthalmoscopy and echocardiography were used to assess ocular and cardiac changes, respectively. Nephrosonography, urinalysis, and RI were used to assess kidney damage. Odds ratio (OR) was used to quantify the risk of TOD for different categories of SBP. One-way Anova with Tukey's post-hoc test was used to test the effect of different SBP risk groups on urine protein creatinine ratio (UPC) and RI as well as the effect of number of TOD on the RI. Pearson's correlation test was done to see the relation of SBP with UPC and RI. Tortuous retinal vessels were common in group B with an OR of 11 (95% CI: 0.59-207). Retinal hemorrhage and left ventricular hypertrophy were common in group D with an OR of 13 (95% CI: 0.67-234) and 11 (95% CI: 0.61-207), respectively. A significant strong positive correlation of SBP with UPC (R2=0.65) and RI (R2=0.58) was observed. The renal RI significantly increased when the number of TOD was ≥ 2. It was concluded that SBP and RI are associated with the number and severity of TOD and might be valuable in risk classification in hypertensive dogs.

The relationships between sediment findings and culture results and the presence of proteinuria in canine urine samples

OBJECTIVES

To assess relationships between urine sediment and microbial culture findings and the presence of proteinuria in canine urine samples, and to assess the change in the percentage of proteinuric samples and urine protein-to-creatinine ratio when urine abnormalities resolve.

MATERIALS AND METHODS

Canine urine samples collected via cystocentesis and submitted for culture and contemporaneous urinalysis (including urine protein-to-creatinine ratio) were retrospectively identified. Dogs receiving corticosteroids were excluded. Associations between haematuria (red blood cells>5/high-power field), pyuria (white blood cells>5/high-power field), presence of microorganisms on microscopy, active sediment, and positive culture and proteinuria (urine protein-to-creatinine ratio>0.5) were investigated. Patient characteristics were considered possible confounders. In dogs with repeat urinalysis, the associations between active sediment and positive culture resolution on proteinuria and urine protein-to-creatinine ratio were assessed.

RESULTS

One hundred and ninety-two of 491 samples were proteinuric (39.1%). Age was positively associated with proteinuria. In the multivariable analysis corrected for age, active sediment was the only variable significantly associated with proteinuria (adjusted odds ratio: 2.12; 95% confidence interval: 1.44 to 3.11); however, only 49.8% of samples with active sediment were proteinuric. Neither resolution of active sediment nor positive culture were associated with reduced proportions of proteinuric samples (from 57.9% to 42.1% and from 40.0% to 25.0%, respectively) or significant reductions in urine protein-to-creatinine ratio (median change: -0.16 and -0.14, respectively).

CLINICAL SIGNIFICANCE

Attributing proteinuria to urinalysis abnormalities or a positive urine culture in canine cystocentesis samples is not supported by our findings, and could result in alternative causes of proteinuria (e.g. renal proteinuria) being overlooked.

Response and survival of dogs with proteinuria (UPC > 2.0) treated with angiotensin converting enzyme inhibitors

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEi) are a recommended treatment for glomerular proteinuria. Frequency of response to ACEi and the association of achieving proposed urine protein-to-creatinine ratio (UPC) targets on survival is unknown.

OBJECTIVES

To determine response rates to ACEi therapy and whether a positive response is associated with improved survival.

ANIMALS

Eighty-five dogs with proteinuria (UPC > 2.0).

METHODS

Retrospective study including dogs (UPC > 2.0) prescribed an ACEi for treatment of proteinuria. Baseline creatinine, albumin, cholesterol, UPC, and systolic blood pressure were recorded, and cases reviewed to track UPC. Treatment response was defined as achieving a UPC of <0.5 or reduction of ≥50% from baseline within 3 months. Outcome data were collected to determine overall and 12-month survival.

RESULTS

Thirty-five (41%) dogs responded to ACEi treatment. Treatment response was statistically associated with both median survival time (664 days [95% confidence interval (CI): 459-869] for responders compared to 177 [95% CI: 131-223] for non-responders) and 12-month survival (79% responders alive compared to 28% non-responders). Baseline azotemia or hypoalbuminemia were also associated with a worse prognosis, with odds ratios of death at 12 months of 5.34 (CI: 1.85-17.32) and 4.51 (CI: 1.66-13.14), respectively. In the 25 dogs with normal baseline creatinine and albumin, response to treatment was associated with 12-month survival (92% responders alive compared to 54% non-responders, P = .04).

CONCLUSIONS AND CLINICAL IMPORTANCE

When the UPC is >2.0, achieving recommended UPC targets within 3 months appears to be associated with a significant survival benefit. Response to treatment is still associated with survival benefit in dogs with less severe disease (no azotemia or hypoalbuminemia).

Biological variation of urinary protein: Creatinine ratio and urine specific gravity in cats

BACKGROUND

Laboratory results are influenced by presence and severity of disease, as well as preanalytical factors, analytical variation, and biological variation. Biological variation data for urinary protein: creatinine ratio (UPC) and urine specific gravity (USG) in cats are lacking.

OBJECTIVES

Determine the biological variation of UPC and USG in cats.

ANIMALS

Eighty healthy client-owned cats.

METHODS

Prospective study. Urine was collected on days 0, 14, and 56 from all 80 cats to investigate the persistence of borderline or overt proteinuria or suboptimal urine concentration. In 15 of these cats, urine was collected weekly from day 0 to 42 to calculate the index of individuality (II) and reference change value (RCV), and on days 56 and 57 to evaluate day-to-day variability of UPC and USG.

RESULTS

Borderline or overt proteinuria (UPC ≥0.2) was present in 18/80 (23%) cats at baseline and persisted on 3 occasions in 2 months in 8/18 (44%) cats. Urine concentration was suboptimal at inclusion (USG <1.035) in 8/80 (10%) cats and at all 3 time points during 2 months in 3/8 (38%) cats. The II of UPC and USG indicated intermediate individuality. The 1-sided RCV was 82% for UPC and 36% for USG. Proteinuria substage was identical on 2 consecutive days in 13/15 (87%) cats, and urine concentrating ability remained the same in all 15 cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

A >82% increase in UPC in a healthy cat is not solely attributable to physiological and analytical variation. For USG, a decrease of >36% is considered clinically relevant.

Endotoxic kidney injury in Beagle dogs assessed by serum creatinine and symmetric dimethylarginine, and urinary neutrophil gelatinase-associated lipocalin and clusterin

Sepsis of Gram negative bacterial origin results in lipopolysaccharide-induced endotoxemia. This often leads to acute kidney injury (AKI) and its recognition remains a challenge and delays treatment. As renal damage occurs before a rise in serum creatinine is detected, new early biomarkers of kidney injury need to be explored. The aim of this study was to determine changes in serum parameters of renal function and urine biomarkers of renal injury. This was a descriptive study. Endotoxemia was induced intravenously in six anaesthetized Beagles (T1). To achieve normotension, dogs received fluids (T2), followed by a continuous infusion of noradrenaline and dexmedetomidine or 0.9% NaCl (T3). Ten minutes later, the dogs received fluids (T4) and noradrenaline and dexmedetomidine or 0.9% NaCl in a crossover manner (T5). At each timepoint, blood and urine were collected for serum creatinine, urea, symmetric dimethylarginine, urine protein/creatinine (UPC) ratio, urine neutrophil-gelatinase-associated lipocalin (U-NGAL), U-NGAL/creatinine ratio, urine clusterin (U-clusterin) and U-clusterin/creatinine ratio. Data were analyzed using a mixed-effect model taking into account time and stage of veterinary AKI (VAKI). Three of six dogs had a VAKI stage ≥1; one with anuria and elevated creatinine. Serum creatinine (P < 0.001), U-NGAL/creatinine ratio (P = 0.01) and U-clusterin/creatinine ratio increased over time (P < 0.01). The UPC ratio (mean (range) 0.68 (0.35-2.3) versus 0.39 (0.15-0.71) P < 0.01) and U-NGAL (3164 pg/mL (100-147,555) versus 100 (100-14,524), P = 0.01) were higher in VAKI stage ≥1 versus stage 0, respectively. Endotoxemia induced VAKI stage ≥1 in half of the dogs. Repeated measurement of selected parameters could detect AKI early.

Albuminuria and proteinuria in dogs infected with Dirofilaria repens: A cross-sectional study

BACKGROUND

It is unknown whether Dirofilaria repens is capable of causing similar glomerular lesions, as does Dirofilaria immitis.

OBJECTIVE

To determine whether D. repens infection could cause albuminuria or proteinuria.

ANIMALS

Sixty-five clinically healthy laboratory beagle dogs.

METHODS

In this cross-sectional study, dogs were tested for D. repens infection (modified Knott test, PCR test, D. immitis antigen test) and were grouped as "D. repens infected" or "control" dogs. Urinary albumin-to-creatinine ratio (UAC) and urinary protein-to-creatinine ratio (UPC) were measured from samples taken by cystocentesis.

RESULTS

Forty-three (26 infected, 17 control) dogs were included in the final study group. UAC but not UPC level was significantly higher in the infected group (UAC median 12.5; range, 0-700 mg/g and UPC median 0.15; range, 0.06-1.06) than in the control group (UAC median 6.3; range, 0-28 mg/g and UPC median 0.13; range, 0.05-0.64; P = .02 and P = .65). Overt proteinuria (UPC > 0.5) was present in 6/26 (23%) of the infected dogs and 1/17 (6%) of the control dogs. Albuminuria (UAC > 19 mg/g) was detected in 9/26 (35%) dogs in the infected group, and 2/17 dogs (12%) in the control group.

CONCLUSIONS AND CLINICAL IMPORTANCE

D. repens might cause similar glomerular lesions to those caused by D. immitis.

Proteinuria and Electrophoretic Pattern in Dogs with Comorbidities Associated with Chronic Kidney Disease

In animals with chronic pathologies, the detection of proteinuria via the proteinuria: creatininuria ratio (UPC) and urinary protein electrophoresis allows for the early diagnosis of chronic kidney disease (CKD). The objective of this work was to identify and determine the magnitude of proteinuria and its electrophoretic pattern characterization in dogs with chronic diseases pathophysiologically related to proteinuria. With the studied patients, five groups were formed. The control group (CG) contained non-proteinuric cases. The cases with proteinuria were classified into four groups according to the concurrent disease: chronic inflammatory diseases (IG), neoplasms (NG), heart diseases (HG), and endocrine diseases (EG). For the statistical analysis, descriptive statistics and non-parametric tests were used. Data from 264 dogs were obtained; in the disease groups, proteinuria was observed in more than 30% as the only finding of kidney disease, evidencing a greater risk factor for proteinuria in the HG group (OR 4.047, CI 1.894-8.644, p < 0.0001). In the HG, NG, and EG groups, a higher frequency of glomerular pattern (GEP) related to glomerular hypertension was observed; in the IG, a higher frequency of mixed pattern (MEP) was observed. These findings are secondary to the hyperfiltration process that affects the glomerulus and the renal tubule.

Effect of laboratory and sample storage factors on urinary protein:creatinine ratios and clinical decision making in cats

BACKGROUND

Urinary protein:creatinine ratio (UPC) results affect the diagnosis, prognosis, and therapy of chronic kidney disease in cats.

OBJECTIVES

To investigate the interlaboratory and intralaboratory variability and the effect of storage on UPC and International Renal Interest Society (IRIS) proteinuria substaging in cats.

ANIMALS

Healthy and diseased client-owned cats.

METHODS

Prospective study. Urine of 60 cats was randomly sent to 4 (of 9) participating laboratories (to assess interlaboratory variability) and per cat, 2 laboratories each received 2 aliquots (to determine intralaboratory variability). Samples of 23 cats were analyzed in the same laboratory the day of collection, after preservation at 22°C for 1 day and at 4°C during 1-7 days (short-term storage) and at -24°C and -80°C for 6-12 months (long-term storage). Storage conditions were compared by equivalence testing.

RESULTS

UPCs showed good interclass correlation (ICC-inter, 0.90) and excellent intraclass correlation (ICC-intra, 0.99). However, in 30/60 (50%) cats at least 1 of 4 laboratories assigned a different IRIS proteinuria substage. Urinary protein:creatinine ratio remained stable with short-term storage, but not after 6 months storage at -24°C and after 12 months storage at -24°C or -80°C. Long-term storage caused a change in IRIS proteinuria substage in 27% of cats, whereas a shift occurred only in 4% of cats during short-term storage.

CONCLUSIONS AND CLINICAL IMPORTANCE

Laboratory choice for UPC measurement can result in different IRIS substaging for the same cat, whereas urine storage at room temperature for 1 day or in the refrigerator for up to 7 days does not clinically affect UPC.

The ultrasonographic appearance of renal medullary striations and their association with renal disease and renal histopathology in domestic cats

Medullary striations (MS) have been anecdotally observed on ultrasound of feline kidneys; however, their significance is unknown. Aims of this retrospective, case control, pilot study were to describe the appearance, prevalence, and clinicopathological correlates of MS in a referral feline population. Still images from 1247 feline abdominal ultrasound studies performed between 2011 and 2021 were reviewed. Cats with MS were identified and compared with age-matched controls. Serum urea, creatinine, calcium, phosphate, and calcium-phosphate-product, plus urine specific gravity, urine protein: creatinine ratio (UPC), prevalence of active sediment (defined as > 5 red (RBC) or white blood cells (WBC) per high-power field) and prevalence of positive urine culture were compared between MS and control groups using the Mann-Whitney U test or Fisher's Exact test. Data are presented as median [range]. 27 cats were identified as having MS, giving a prevalence of 2.2% with a significantly higher proportion being seen in males (P = 0.018). Medullary striation cats had significantly higher UPC values than controls (0.46 [0.16-7.57] vs. 0.16 [0.07-2.27]; P = 0.006). Cats with MS were more likely to have active urinary sediments (39% vs 8%, P = 0.023), but no difference in prevalence of positive urinary cultures was observed between groups. There was no significant difference in other parameters between MS and control cats. Renal histopathology performed in three MS cats revealed focal regions of linear medullary fibrosis. Medullary striations are associated with proteinuria and urinary tract inflammation in cats, which may reflect renal tubular dysfunction and/or inflammation. Hence identification might allow for earlier detection of renal pathology.

Use of urinalysis during baseline diagnostics in dogs and cats: an open survey

OBJECTIVES

To describe how veterinarians utilise and perform urinalyses for dogs and cats.

MATERIALS AND METHODS

A survey, developed and distributed through the Veterinary Information Network, enlisted veterinarians who perform urinalyses for dogs and cats. Participants were directed to question banks based on whether urinalyses were performed in-house, by an outside diagnostic laboratory, or using an in-house automated instrument. Participants using multiple methods were directed to questions that related to the chosen methods.

RESULTS

A total of 1059 predominantly first-opinion clinicians from the USA and Canada completed the survey. Participants performed urinalyses much less frequently than blood work during a routine examination. The most common factors preventing participants from performing a urinalysis with blood work included clients' financial constraints, difficulty obtaining urine and lack of perceived diagnostic need. The most common reasons for submission to a diagnostic laboratory included efficiency, more trusted results and convenience. Speed of obtaining results was the most common reason for performing urinalyses in-house. Of the participants who performed in-house urinalyses, fewer always performed a manual sediment examination (79%) as compared with urine-specific gravity (99%) and manual dipstick (87%).

CLINICAL SIGNIFICANCE

This survey documents that urinalysis is often not used in senior patients as recommended by recent clinical guidelines for dogs and cats which can result in decreased diagnosis and impaired management of subclinical disease. There is significant variability in urinalysis methods despite veterinary guidelines promoting standardisation, and this could lead to inaccurate results.

Establishment of a reference interval for urinary albumin-to-creatinine ratio in dogs

BACKGROUND

Albuminuria is an important marker of renal damage and can precede proteinuria; thus, it can be a useful analyte in the early diagnosis of kidney diseases. Albuminuria has also been found in dogs with hypertension, inflammatory, infectious, and neoplastic diseases.

OBJECTIVES

The aim of this study was to establish a reference interval (RI) for albuminuria in dogs.

METHODS

One hundred sixty-four clinically healthy dogs were enrolled in the study. Urinary albumin was determined by the immunoturbidimetric method, and albumin excretion was expressed as the urinary albumin-to-creatinine (UAC) ratio. The RI for UAC was established.

RESULTS

After exclusions, 124 dogs from 32 breeds remained. The median UAC of the study population was 3.0 mg/g (range: 0-48). The RI was defined as 0-19 mg/g (with a 90% CI for the upper limit of 13-28 mg/g). No significant difference was found between male and female dogs or between different age and body weight groups. The results of Sighthounds (n = 30) and Beagle dogs (n = 23) did not differ from the other breeds.

CONCLUSION

The canine RI of UAC is similar but somewhat narrower than the human RI.

Urinary phoretograms performed by capillary electrophoresis in dogs with chronic disease with or without Leishmania infantum infection

INTRODUCTION

The study of early markers to detect kidney malfunction has increased in recent years since serum markers, such as creatinine increase when there is a 75% loss of renal mass. Urinary capillary electrophoresis (UCE) is an available laboratory technique that provides an easily interpretable electrophoretic pattern. This pattern in our study has been divided into five fractions as it is done in serum: fraction 1 migrating in the albumin zone, fraction 2 in the alpha₁-globulins zone, fraction 3 in the alpha₂-globulins zone, fraction 4 in the beta-globulins zone, and fraction 5 in the gamma globulins zone. UCE can be useful in the early diagnosis of renal disease.

MATERIAL AND METHODS

In this study, UCE was performed in dogs with azotemia and proteinuria due to chronic kidney disease (CKD) not related to Leishmania infantum (L. infantum) infection (G₁, n = 11) and dogs with CKD related to L. infantum infection (G₂, n = 17) and compared with reference intervals from healthy dogs (G₀, n = 123), with the aim of comparing their phoretograms and assessing changes in the fractions of the phoretograms based on the health status of individuals.

RESULTS

Fraction 2 was statistically augmented in dogs with CKD (G₁) when compared with the healthy population (G₀) and dogs infected by L. infantum (G₂). Fraction 3 was statistically increased in dogs with CKD (G₁) and dogs infected by L. infantum (G₂) compared with G_0. Fraction 4 was found to be statistically decreased in dogs with CKD (G₁) and dogs infected by L. infantum (G₂) compared with G_0. Fraction 5 was statistically higher in dogs with L. infantum (G₂) compared with G₀ and dogs with CKD (G₁). No statistical relationship was found between the protein to creatinine ratio and different fractions from the urinary phoretogram in the study population. No statistical relationship was found between serum and urine fractions in the study population.

DISCUSSION

The results of the present study suggest that UCE is a promising non-invasive technique that might be used as a part of the diagnostic and follow-up in dogs with kidney disease due to different pathologies.

Urinary Protein/Creatinine Ratio in Feline Medicine: Reasons to Perform It and Its Role in Clinical Practice-A Retrospective Study

This study aimed at understanding the reasons veterinarians conduct a urinary protein/creatinine ratio (UPCR) in cats, correlating it with signalment, dipstick proteinuria tests, and urine specific gravity (USG) and assessing its role in chronic kidney disease (CKD) diagnosis and monitoring. A retrospective study was conducted, including medical data from cats consulted between 2016 and 2018 in a veterinary teaching hospital and submitted to at least one UPCR measurement. A total of 140 cats were included: 35% non-proteinuric (UPCR < 0.2), 25% borderline proteinuric (0.2 < UPCR < 0.4), and 40% overtly proteinuric (UPCR > 0.4). In contrast to other studies, there was no association between UPCR and male reproductive status. UPCR was mainly requested for CKD diagnosis and monitoring. Correlation between UPCR and combined results from dipstick tests and USG was low and inconsistent. Proteinuric CKD cats had a worse outcome at both 6 (odds ratio (OR 4.04) and 12 months (OR 4.36)), and this finding was more pronounced for severely proteinuric cases in which the OR for death was 4.36 and 6.00 at 6 and at 12 months, respectively. In addition to reinforcing the negative prognostic value of proteinuria, this study stresses the low and the inconsistent agreement between UPCR and the combined results of dipstick tests and USG in cats.

The Relevance of Screening for Vector-Borne Diseases in Dogs with Proteinuria Living in an Endemic Region: A Retrospective Study

This study aims to assess the main causes of proteinuria in dogs from the region of Lisbon (Portugal), estimating the relevance of screening for canine vector-borne diseases (CVBDs). A cross-sectional retrospective study was conducted. Medical records from proteinuric dogs (urinary protein−creatinine ratio > 0.5) presented to a Veterinary Teaching Hospital over a two-year period were reviewed for signalment, established diagnosis, proteinuria origin, and CVBD screening results. A total of 106 dogs were included. The median age was 9.5 years old (IQR: 7−12). Proteinuria was considered of renal origin in 76% of cases (46% of them had a presumptive diagnosis of glomerulonephritis secondary to CVBD, 27% chronic kidney disease, 26% systemic disease possible to induce proteinuria, and 1% leptospirosis). Proteinuria was classified as post-renal or mixed-origin in 17% and 7% of cases, respectively. About 35% of proteinuric dogs were positive for at least one CVBD. Of them, 84% were seropositive for one CVBD, while 16% tested positive for two or more. Among dogs testing positive for CVBD, 89% were seropositive for Leishmania infantum. This study showed that about one-third of proteinuric dogs tested positive for CVBDs, highlighting the relevance of their screening in dogs with proteinuria living in endemic regions.

Evaluation of Heller's reaction and the urine dipstick method alone or in combination to detect proteinuria in sheep

BACKGROUND

Urine dipstick and Heller's reaction are easy first-line screening tests for the detection of proteinuria; however, the performance of these methods in alkaline ovine urine is largely unknown.

OBJECTIVE

The aim of this study was to evaluate the diagnostic performance of Heller's reaction alone or in combination with dipstick for the detection of proteinuria in sheep, using the urine protein to creatinine ratio (UP/C) with two cut-off values as the reference method.

METHODS

Ninety-eight urine samples were collected from sheep using the transient apnea method. Heller's reaction, the dipstick method, and the UP/C ratio were used to assess proteinuria. The results were statistically analyzed twice, based on two different UP/C cut-off values of 0.2 and 0.5. Cohen's kappa value was used to determine the agreement between the UP/C ratios and Heller's reaction, the dipstick method, or the combination of methods. Sensitivity, specificity, and positive and negative likelihood ratios were calculated. ROC curves were also generated, and the areas under the curve (AUC) were evaluated to determine the optimal threshold for the numerical values of the two methods.

RESULTS

Heller's reaction is more specific (96.67% and 96.00% when the cut-off value is 0.2 and 0.5, respectively) than the dipstick method, while the dipstick method was more sensitive (91.18% and 91.30%, when the cut-off value was 0.2 and 0.5, respectively) than Heller's reaction for the detection of proteinuria. Both tests were accurate when any grade >0 was considered positive.

CONCLUSIONS

Proteinuria can almost be excluded in ovine urine samples with negative Heller's reaction and dipstick test.

Point prevalence and clinical course of proteinuria in dogs with idiopathic non-erosive immune-mediated polyarthritis

Objectives

To describe the point prevalence and clinical course of proteinuria in dogs diagnosed with idiopathic non‐erosive immune‐mediated polyarthritis.

Materials and Methods

Cases presenting to a single referral centre with a diagnosis of idiopathic non‐erosive immune‐mediated polyarthritis were retrospectively recruited from January 2009 to August 2018. Data including signalment, urinalysis, clinicopathological results, cytology from arthrocentesis, treatment and long‐term follow‐up were analysed. Dogs were defined as: non‐proteinuric (UPC <0.2), borderline proteinuric (UPC 0.2‐0.5) or overtly proteinuric (UPC >0.5).

Results

Fifty‐eight dogs met the inclusion criteria. Twenty‐two dogs were overtly proteinuric (38%), eight dogs were borderline proteinuric (14%) and 28 dogs were non‐proteinuric (48%). Repeated urinalysis was performed in nine of 12 dogs with UPC greater than 2.0. The UPC decreased in all nine dogs, with the UPC decreasing to less than 0.5 in 44% of dogs. A greater than 50% decrease in UPC was noted in 44% of dogs, despite seven of nine (77%) receiving prednisolone as either monotherapy or in conjunction with an adjunctive immunosuppressive medication.

Clinical Significance

Proteinuria was common in this cohort of dogs diagnosed with primary idiopathic non‐erosive immune‐mediated polyarthritis. The use of prednisolone does not appear to be contraindicated in proteinuric dogs with idiopathic non‐erosive immune‐mediated polyarthritis.

Dogs with leishmaniosis: how are we managing proteinuria in daily practice? A Portuguese questionnaire-based study

Background

Proteinuria is a common finding in dogs with leishmaniosis. Although antileishmanial therapeutic protocols are widely implemented, little information is available on which treatments are most adequate for identifying proteinuria in patients with canine leishmaniosis (CanL), especially regarding the use of immunosuppressants. The aim of this study was to explore the current paradigm regarding the antiproteinuric approach adopted by veterinary practitioners in Portugal to treat dogs with CanL.

Methods

A questionnaire-based study was developed using Google Forms®. The questionnaire presented a number of different hypothetical scenarios of CanL, and the topics surveyed included the general features of the respondents and the protocols preferred by these respondents to manage proteinuria in the presented scenarios, including choice of therapeutic drugs, appropriate diet and use of immunosuppressants, in dogs with immune-mediated glomerulonephritis. The questionnaire was internally prevalidated and diffused online over a 2-month period through Portuguese veterinary social networking groups, and data were collected for descriptive analysis.

Results

A total of 86 veterinary practitioners responded to the survey. When exposed to theoretical scenarios of proteinuria in dogs with CanL at stages IIb, III and IV (LeishVet guidelines), 16.3%, 62.8% and 93.8% of the respondents, respectively, answered that they would treat it. The dog was started on a renal diet as therapy by 28.6%, 83.3% and 97.4% of respondents, respectively. Angiotensin-converting enzyme inhibitors (ACEI) were prescribed by 100%, 85.2% and 78.9% of respondents as first-choice drugs for CanL at stages IIb, III and IV, respectively, with ACEI used in monotherapy by 64.3%, 40.7% and 46.1%. In comparison, protocols using ACEI in combination with other compounds were chosen by 7.1%, 33.3% and 39.5% of respondents, and combination therapy which did not include ACEI was the choice of 0.0%, 12.9% and 14.5%. Regarding immunosuppressants, 44.2% of the respondents answered they would prescribe them, with 97.4% electing for prednisolone and 5.3% choosing mycophenolate mofetil.

Conclusions

Among the veterinary practitioners who responded, proteinuria treatment was considered since stage IIb CanL, although implementation of a therapeutic approach was more evident in advanced CanL stages. ACEI were the first-choice drugs, particularly for the treatment of stage IIb CanL; in advanced stages, a combination of antiproteinuric drugs was more often used. Immunosuppressant use was controversial, although when applied, prednisolone was the preferred choice. These findings reinforce the small body of evidence that supports the use of such drugs and the need to further explore their role in CanL.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05222-w.

The effect of non-absorbent hydrophobic sand litter on the urine protein-to-creatinine ratio in feline urine

Background

Proteinuria can be quantified through the measurement of the urine protein‐to‐creatinine ratio (UPC). Voided urine samples in cats are often exposed to a non‐absorbable litter substrate prior to collection and urinalysis. Little is known about the effect exposure to such substrates has on pre‐analytical variability of UPC measurements.

Objectives

The aim of this study was to assess agreement between UPC measurements from urine obtained by cystocentesis before and after exposure to non‐absorbent hydrophobic sand for 24 hours.

Methods

UPCs were measured in 40 urine samples obtained by cystocentesis from 39 cats (baselineUPC). Urine was then exposed to non‐absorbent hydrophobic sand litter for 24 hours, recovered, and repeat UPCs were measured (litterUPC). Agreement between paired measurements and the presence of any bias or error was evaluated using Bland–Altman analysis Passing–Bablok regression analysis, respectively. Cohen's kappa was used to measure agreement for the International Renal Interest Society (IRIS) proteinuria classification of samples. Observed total error (TE_obs) was calculated for the laboratory analyzer and compared against absolute percentage changes in paired UPC measurements.

Results

Neither proportional nor constant error was identified using Passing‐Bablok regression between baselineUPC and litterUPC. Visual inspection of the Bland–Altman plot revealed good agreement, with 95% of paired measures falling within the limits of agreement (LOA). Cohen's kappa demonstrated almost perfect agreement for the IRIS classification of proteinuria between baselineUPC and litterUPC. Absolute percentage changes of paired UPC measurements outside of the LOAs were lower than the inter‐assay TE_obs.

Conclusions

Feline urine exposed to non‐absorbent hydrophobic sand litter appears acceptable for UPC measurements.

A Questionnaire-Based Survey on the Long-Term Management of Canine Leishmaniosis by Veterinary Practitioners

Simple Summary

Canine Leishmaniosis is a chronic and potentially fatal disease, caused by Leishmania infantum, a zoonotic microorganism. In economically disadvantaged regions, costs associated with long-term patient monitoring may determine that some owners decline veterinary follow-up of their dogs, with potentially severe implications for animal welfare and public health. This online, questionnaire-based survey aimed to assess how Portuguese veterinary practitioners perform long-term patient management and recognize relapses. More than half of the respondents stated that most dog owners declare having financial restraints, which condition the use of diagnostic tests during long-term follow-up. Allopurinol ad aeternum or until disease remission and domperidone were the most prescribed treatment, and relapses were detected by the reappearance or worsening of clinical signs by most veterinary practitioners. The rate of relapse detection was higher in the most economically favored regions, probably because of a lesser constraint on the use of the appropriate diagnostic tests. This study confirms that owner financial restraints negatively influence veterinary follow-up and relapse recognition, potentially compromising clinical decision making and favoring the maintenance of Leishmania infantum infection endemic status in Portugal.

Abstract

Canine Leishmaniosis (CanL) is a chronic and potentially fatal disease. In economically disadvantaged regions, costs associated with long-term patient monitoring may determine that some owners decline veterinary follow-up of their dogs. This online, questionnaire-based survey aimed to assess how Portuguese veterinary practitioners perform long-term patient monitoring and recognize relapses. More than 50% of respondents reported that 50–100% of dog owners declared financial restraints. Hence, in these circumstances, most veterinary practitioners only performed clinical examination and serology. However, when owners did not declare financial restriction, other tests were additionally performed, such as renal and hepatic profiles, hemogram, serum protein electrophoresis and urine protein creatinine ratio. The mean number of exams performed when owners presented financial restraints was significantly lower than the number of exams performed without economic limitations. Most veterinary practitioners prescribed allopurinol ad aeternum or until disease remission and domperidone. CanL relapses were recognized by more than half of respondents “Always”, through the reappearance or worsening of clinical signs, whereas about a quarter detected an increase in anti-Leishmania antibody levels and identified abnormalities in the serum protein electrophoresis profile. The relapse rate was higher in the Lisbon Metropolitan Area and north, the most economically favored regions of Portugal. This study confirms that owner financial restraints negatively influence veterinary follow-up and relapse recognition, ultimately compromising clinical decision making and favoring the maintenance of Leishmania infantum infection endemicity.

Immunohistochemical Expression of TGF-β1 in Kidneys of Cats with Chronic Kidney Disease

Transforming growth factor-beta 1 (TGF-β1) plays a central role in the progression of chronic kidney disease (CKD). However, in feline CKD, renal expression of TGF-β1 and how it changes as the disease progresses have not been fully studied. In the present study, we immunohistochemically assessed the renal expression levels of TGF-β1 in cats with CKD and statistically analyzed its correlation with CKD severity. Clear immunosignals were detected in the glomerular mesangial cells, Bowman’s capsules, proximal tubules, distal nephrons, platelets, and vascular smooth muscles in the kidneys of cats with CKD. Statistically, luminal signals in the distal nephrons showed positive correlations with plasma creatinine levels and glomerulosclerosis, while those in the proximal tubules and platelets showed negative correlations with plasma urea and/or creatinine levels. Therefore, it was suggested that the changes in the renal expression of TGF-β1 could be associated with progression of feline CKD.

Renal biomarkers in cats: A review of the current status in chronic kidney disease

Serum creatinine concentration, the classical biomarker of chronic kidney disease (CKD) in cats, has important limitations that decrease its value as a biomarker of early CKD. Recently, serum symmetric dimethylarginine concentration was introduced as a novel glomerular filtration rate biomarker for the early detection of CKD in cats. However, data on its specificity are still limited. The limitations of conventional biomarkers and the desire for early therapeutic intervention in cats with CKD to improve outcomes have prompted the discovery and validation of novel renal biomarkers to detect glomerular or tubular dysfunction. Changes in the serum or urinary concentrations of these biomarkers may indicate early kidney damage or predict the progression of kidney before changes in conventional biomarkers are detectable. This review summarizes current knowledge on renal biomarkers in CKD in cats, a field that has progressed substantially over the last 5 years.

Combined Untargeted and Targeted Metabolomics Approaches Reveal Urinary Changes of Amino Acids and Energy Metabolism in Canine Babesiosis With Different Levels of Kidney Function

Canine babesiosis is a tick-borne disease with a worldwide distribution, caused by the haemoprotozoan parasites of the genus Babesia. One of the most prevalent complication is acute kidney injury, and an early diagnosis of altered kidney function remains a challenge for veterinary practice. The aim of this study was to assess the urine metabolic profile from dogs with babesiosis and different degree of kidney function using untargeted and targeted MS-based metabolomics approaches. In this study, 22 dogs naturally infected with Babesia canis and 12 healthy dogs were included. Untargeted metabolomics approach identified 601 features with a differential abundance between the healthy group and groups of dogs with babesiosis and different level of kidney function, with 27 of them identified as a match to known standards; while targeted approach identified 17 metabolites with significantly different concentrations between the groups. A pattern of significantly altered metabolites referring to the inflammatory host response, oxidative stress, and energy metabolism modulation in babesiosis was presented. Our findings have demonstrated that kidney dysfunction accompanying canine babesiosis was associated with changes in amino acid metabolism, energy metabolism, fatty acid metabolism, and biochemical pathways such as urea cycle and ammonia detoxication. These findings will enable the inclusion of urinary markers for the detection and monitoring of renal damage in babesiosis, as well as in other similar diseases.

Alterations of Serum Biochemical and Urinary Parameters in a Canine Population before and after Intravenous Contrast Administration

Intravenous iodinated contrast (IVIC) medium is routinely administered to dogs. Scattered information exists regarding the serum biochemical or urinary profiles associated with the administration of IVIC in dogs. The aim of the study was to describe, compare, and discuss from the perspective of previous studies the alterations in serum biochemical and urinary parameters before (T0) and within one week (T1) of the IVIC administration during routine computed tomography (CT) scan evaluation of 22 dogs. Mature dogs presenting for CT scan evaluation for preoperative oncology staging/surgical planning were included. T1 evaluation was performed within one week of IVIC administration. Statistically significant differences in serum total protein, albumin, chloride, calcium, and phosphorus concentrations, urine protein to creatinine ratio, and urine specific gravity were found between T1 and T0. At T1, the serum creatinine concentration was within reference ranges in all dogs but one. An increase in the urine protein to creatinine ratio was observed in four samples, one of which was non-proteinuric at T0. Changes in biochemistry and urine parameters between T0 and T1 were not considered clinically significant.

Influence of preanalytical factors on feline proteinuria

BACKGROUND

To date, little information is available about the effect of preanalytical factors on the urinary protein-to-creatinine (UPC) ratio in cats.

OBJECTIVES

We aimed to evaluate the effect of a commercially available cat litter, creatinine measurements at three different dilutions of urine, and different storage conditions on the UPC ratio in cats.

METHODS

Feline urine specimens were prospectively collected. Twenty-two whole-urine specimens were placed uncovered and in contact with cat litter for 1 hour; 25 urine supernatants were diluted 1:10, 1:20, and 1:100 for creatinine measurements. The correlation, difference, agreement, and concordance in classifying specimens according to International Renal Interest Society staging were determined. Storage effects on UPC ratios were assessed in specimens stored for 6 hours at +20℃ (n = 20), 1 week at +4℃ (n = 20), and 3 months at -20℃ (n = 25). Specimens were also subjected to four freeze-thaw cycles (n = 20). Results were compared, and clinical significance was assessed by comparing each UPC ratio to the inter-assay range of the baseline value.

RESULTS

Exposure to cat litter did not affect UPC ratios. A positive proportional bias was found in the 1:100 dilution compared with the 1:20 dilution; however, concordance was high for all comparisons. At +20, +4℃, and after four repeated freeze-thaw cycles, UPC ratios were stable. Compared with baseline values, UPC ratios decreased (P < .01) after 8 and 12 weeks at -20℃. However, all UPC ratios were within the inter-assay variability of the baseline value.

CONCLUSIONS

Exposure to cat litter did not affect UPC ratios, but further studies are necessary to evaluate other potential variables. The effects of the dilutions and storage conditions were clinically acceptable, although the 1:20 and 1:100 dilutions were not perfectly comparable.

Comparison of three types of analyzers for urine protein-to-creatinine ratios in dogs

BACKGROUND

Quantitation of urine protein is important in dogs with chronic kidney disease. Various analyzers are used to measure urine protein-to-creatinine ratios (UPCR).

OBJECTIVES

This study aimed to compare the UPCR obtained by three types of analyzers (automated wet chemistry analyzer, in-house dry chemistry analyzer, and dipstick reading device) and investigate whether the differences could affect clinical decision process.

METHODS

Urine samples were collected from 115 dogs. UPCR values were obtained using three analyzers. Bland-Altman and Passing Bablok tests were used to analyze agreement between the UPCR values. Urine samples were classified as normal or proteinuria based on the UPCR values obtained by each analyzer and concordance in the classification evaluated with Cohen's kappa coefficient.

RESULTS

Passing and Bablok regression showed that there were proportional as well as constant difference between UPCR values obtained by a dipstick reading device and those obtained by the other analyzers. The concordance in the classification of proteinuria was very high (κ = 0.82) between the automated wet chemistry analyzer and in-house dry chemistry analyzer, while the dipstick reading device showed moderate concordance with the automated wet chemistry analyzer (κ = 0.52) and in-house dry chemistry analyzer (κ = 0.53).

CONCLUSIONS

Although the urine dipstick test is simple and a widely used point-of-care test, our results indicate that UPCR values obtained by the dipstick test are not appropriate for clinical use. Inter-instrumental variability may affect clinical decision process based on UPCR values and should be emphasized in veterinary practice.

Reference intervals for electrophoretograms obtained by capillary electrophoresis of dialyzed urine from healthy dogs

Electrophoresis of urine to evaluate protein fractions in dogs with proteinuria to differentiate glomerular from tubular damage has increased in recent years; however, capillary electrophoresis (CE) of urine has not been reported in a study of > 40 healthy animals, to our knowledge. We aimed to establish reference intervals (RIs) for the urine protein fractions obtained by CE of urine from healthy dogs. We obtained urine samples from 123 clinically healthy dogs of both sexes between December 2016 and April 2019; urine was frozen until CE was performed. The electrophoretic patterns obtained were divided into 5 protein fractions, and RIs were established in percentages and absolute values using nonparametric methods. RIs were obtained for the fractions (F) as follows: 5.5 to 56.2% for F1, 3.2 to 16.5% for F2, 3.5 to 16.2% for F3, 17.8 to 69.8% for F4, and 5.1 to 23.9% for F5. These RIs obtained by CE might be useful clinically as a basis for comparison with pathologic samples. Age was a statistically significant factor for F2 (p = 0.01) and F3 (p = 0.02), and sex was a statistically significant factor for F1 (p = 0.03).

Evaluation of the progression of non-azotemic proteinuric chronic kidney disease in dogs

Proteinuria is a recognized risk factor for progression of canine chronic kidney disease (CKD). However, the prognosis of non-azotemic proteinuric CKD in dogs has been studied only to a limited extent. Moreover, the degree to which proteinuria should be decreased to delay CKD progression remains unknown. The purposes of this study were (1) to identify factors associated with disease progression and (2) to investigate the degree of proteinuria, albuminuria, and blood pressure during the course of treatment associated with the progression using time-averaged urine protein:creatinine ratio (UPC) and urine albumin:creatinine ratio (UAC) in canine non-azotemic proteinuric CKD. Twenty-one dogs with non-azotemic proteinuric CKD were included in the study. High UPC and UAC were associated with CKD progression (P < .05). Time-averaged high UPC and UAC were significantly related to progression (P < .05). The cutoff values of these time-averaged parameters for predicting the progression were 4.1 and 2.0, respectively. In dogs with non-azotemic proteinuric CKD, more severe proteinuria and albuminuria were associated with progression. The present study suggests that because UPC ≥ 4.1 and UAC ≥ 2.0 during treatment were associated with a faster progression of non-azotemic proteinuric CKD, therapeutic intervention is warranted.

Treatment of proteinuria in dogs with telmisartan: A retrospective study

Background

Use of telmisartan for the treatment of proteinuria in dogs has not been thoroughly investigated.

Hypothesis/Objectives

Telmisartan can be effective for the treatment of proteinuria in dogs.

Animals

Forty‐four client‐owned dogs with proteinuria.

Methods

Retrospective study. Dogs diagnosed with clinically relevant proteinuria (nonazotemic dogs with a urine protein‐to‐creatinine ratio [UPC] ≥2 and azotemic dogs with UPC ≥0.5) were separated into 3 groups: telmisartan alone, with benazepril, or with mycophenolate. The UPC was recorded before treatment and at subsequent follow‐ups (1, 3, 6, and 12 months, as available). Response to treatment was categorized as complete (UPC ˂0.5), partial (UPC decreased by ≥50% but still ≥0.5), or no response (UPC decreased by <50%). Serum creatinine and potassium concentrations and arterial pressure also were recorded.

Results

In the telmisartan group, treatment response (UPC ˂0.5 or decreased by ≥50%) was observed in 70%, 68%, 80%, and 60% of dogs at 1, 3, 6, and 12 months follow‐up, respectively. No significant changes were noted in serum creatinine or potassium concentrations, or in arterial blood pressure at all follow‐up times. Adverse effects consisted of mild self‐limiting gastrointestinal signs in 5 dogs. Two dogs developed clinically relevant azotemia that required discontinuation of the treatment before the first follow‐up.

Conclusions and Clinical Importance

Telmisartan can be considered for treatment of proteinuria in dogs, alone or in combination with other treatments for proteinuria.

Evaluation of Chronic Kidney Disease Progression in Dogs With Therapeutic Management of Risk Factors

This research was performed to describe the characteristics of the progression of naturally occurring chronic kidney disease (CKD) in dogs, together with the management of identified risk factors, following the International Renal Interest Society recommendations. Dogs diagnosed and staged with CKD, and with a longitudinal follow-up from the moment of diagnosis of up to a maximum of 730 days, were included. A total of 545 dogs that presented risk factors for the development of CKD were analyzed, out of which 36 met the inclusion criteria. Advanced age was identified in 80.6% of cases. Initiation risk factors were represented by inflammatory/infectious diseases, history of anesthetic-surgical procedures, heart disease, neoplasms, endocrinopathies, and exposure to nephrotoxic drugs. During the follow-up period, progression of CKD was identified in 47.2% of the cases, being more salient in advanced stages. Serum symmetric dimethyl arginine (SDMA) was the only glomerular filtration rate (GFR) marker which displayed differences among studied times during early stages of CKD, associated with the disease progression and decline of renal function. A significant difference between the survival curves in early and advanced CKD stages was observed. The factors related to decreased survival were hyperphosphatemia, anemia, and low body condition score (BCS). No differences were found between the presence of arterial hypertension and renal proteinuria and decreased survival. Furthermore, CKD diagnosis based on the persistent finding of abnormalities in early disease markers, such as serum symmetric dimethyl arginine increase and/or renal proteinuria, and timely therapeutic management of risk factors, allowed for CKD stabilization, reducing progression to advanced stages, and favoring higher survival rates.

Serial serum creatinine, SDMA and urinary acute kidney injury biomarker measurements in dogs envenomated by the European adder (Vipera berus)

Background

Acute kidney injury (AKI) is associated with high morbidity and mortality in dogs, but diagnosis may be impaired due the insensitivity of routine renal function biomarkers to detect earlier or milder forms of injury. Snake envenomation is one of several causes of AKI in dogs and humans. Dogs are commonly envenomated by the European adder (Vipera berus) between April and October each year, but few studies exist examining serial serum creatinine (sCr) and symmetric dimethylarginine (SDMA) measurements and AKI biomarkers in these dogs. Novel urinary biomarkers could improve clinical outcome by allowing earlier diagnosis of and intervention in AKI. The aim of this study was to assess the presence of AKI in dogs envenomated by V. berus at 12, 24 and 36 h after bite, as well as 14 days later, using sCr, SDMA and a panel of urinary AKI biomarkers normalised to urine creatinine (uCr), compared to a group of healthy control dogs.

Results

Thirty-five envenomated dogs and 35 control dogs were included. Serum creatinine did not exceed the upper reference limit at any time point in any dog after envenomation. Serum SDMA did not exceed 0.89 μmol/L in any dog. Compared to controls, urinary albumin/uCr, neutrophil gelatinase-associated lipocalin/uCr and monocyte chemotactic protein-1/uCr were significantly elevated 12 h (P <  0.0001, P <  0.0001, P = 0.01), 24 h (P <  0.001, P <  0.001, P = 0.002) and 36 h (P <  0.001, P <  0.001, P = 0.0008) after bite. Osteopontin/uCr was higher 24 and 36 h after bite (P < 0.0001), kidney injury molecule-1/uCr, interleukin-8/uCr and γ- glutamyl transferase/uCr were significantly higher 36 h after bite (P = 0.003, P = 0.0005, P = 0.001). Urinary cystatin C/uCr was not significantly different to controls at any timepoint. Biomarker/uCr ratios were not significantly different 14 days after envenomation compared to controls.

Conclusion

Urinary biomarker/Cr ratios are indicative of mild transient, non-azotaemic AKI in dogs envenomated by V. berus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02851-8.

Effect of telmisartan, angiotensin-converting enzyme inhibition, or both, on proteinuria and blood pressure in dogs

Background

The use of telmisartan (TEL), an angiotensin‐receptor blocker, for the control of systemic hypertension and proteinuria in dogs has not been reported extensively in a clinical setting.

Objectives

To determine the effects of an angiotensin‐converting enzyme inhibitor (ACEi) alone, ACEi in combination with TEL, or TEL alone on systolic blood pressure and proteinuria in dogs with protein losing nephropathy (PLN).

Animals

Forty‐two client‐owned dogs being treated for PLN.

Methods

Retrospective observational study of medical records of dogs at a university teaching hospital from 2012 to 2018 with the use of benazepril or enalapril alone, TEL alone, or both modalities for the management of PLN. Noninvasive blood pressure and urine protein to creatinine ratio (UPC) were compared among the treatment groups over time. A multivariable mixed‐effects linear regression model followed by post hoc analysis was used to estimate the marginal means and differences between the treatment groups.

Results

In comparison to group ACEi alone, combination treatment of an ACEi with TEL significantly reduced (P = .007) systolic blood pressure by 13 mm Hg (95% confidence interval [95% CI]: 4‐22 mm Hg). Angiotensin‐converting enzyme inhibitor + TEL in comparison to ACEi alone showed significant (P = .01) reduction in UPC of 2.5 (95% CI: 0.6‐4.4). The UPC of group ACEi + TEL was significantly lower (P = .01) in comparison to TEL alone by 3.8 (95% CI: 0.8‐6.8).

Conclusions and Clinical Importance

Telmisartan can be used to treat systemic hypertension and proteinuria in dogs.

Associations between biochemical parameters and referral centre in pet rabbits with urolithiasis

OBJECTIVES

To determine the association between signalment, selected haematologic and biochemical parameters and referral centre in pet rabbits with imaging evidence of urolithiasis presented to two veterinary teaching hospitals in North America.

MATERIALS AND METHODS

The medical record database of two veterinary teaching hospitals was searched from 2009 to 2019 for records of pet rabbits that received both imaging studies and plasma biochemistry profiles. Information regarding signalment, bodyweight, packed cell volume, total solids, and plasma biochemistry profiles was obtained. Univariable and multivariable logistic regression models were performed to identify statistically significant parameters associated with imaging evidence of urolithiasis.

RESULTS

Of the 324 examined rabbits, 33 (10.2%) had confirmed evidence of urolithiasis on imaging. Increasing plasma calcium and sodium concentrations and referral centre were significantly associated with the presence of urolithiasis on the univariable logistic regression model. However, only plasma calcium concentration and the referral centre demonstrated significant associations on the multivariable logistic regression model.

CLINICAL SIGNIFICANCE

Results indicate that urolithiasis in pet rabbits that receive imaging is associated with mildly increasing plasma calcium concentration and referral centre. The association with referral centre may indicate there are geographic influences on urolithiasis or on imaging. However, the identified associations have low predictive value for the diagnosis of urolithiasis, indicating the need for additional diagnostic modalities.

Development and progression of proteinuria in dogs treated with masitinib for neoplasia: 28 cases (2010-2019)

OBJECTIVES

To describe the incidence, severity and progression of proteinuria over the first 6 months of masitinib treatment in tumour-bearing dogs without pre-existing proteinuria. To describe the effect of treatment on urine protein:creatinine and renal parameters in patients with pre-existing proteinuria.

MATERIALS AND METHODS

Records were reviewed from patients receiving masitinib for neoplasms between June 1, 2010, and May 5, 2019. Patients without pre-treatment and at least one urine protein:creatinine after ≥7 days treatment were excluded. Signalment, tumours and concurrent diseases, treatments, haematology, biochemistry and urinalysis results before, during and after treatment for up to 202 days were collected. Patient visits were grouped into six timepoints for analysis.

RESULTS

Twenty-eight dogs were included. Eighteen percent of dogs non-proteinuric at baseline (four of 22) developed proteinuria during treatment, all within 1 month of treatment initiation. One dog developed hypoalbuminaemia, none developed oedema or ascites, azotaemia or were euthanased/died due to proteinuria. Masitinib was immediately discontinued in both dogs in which urine protein:creatinine greater than 2.0 was detected and in both, proteinuria improved. Six dogs with pre-treatment proteinuria were treated with masitinib, significant worsening of proteinuria did not occur. Neither azotaemia nor severe hypoalbuminaemia occurred.

CLINICAL SIGNIFICANCE

Proteinuria, when it occurs, tends to develop within 1 month of masitinib commencement and may progress rapidly. Weekly proteinuria monitoring should be considered for the first month and a urine protein:creatinine greater than 0.5 should prompt reassessment within 1 week. Masitinib treatment can be considered in patients with pre-treatment proteinuria and does not inevitably cause worsening of proteinuria.

Proteinuria in dogs with gallbladder mucocele formation: A retrospective case control study

Background

Proteinuria is an independent risk factor for morbidity and mortality in dogs. An association between proteinuria and gallbladder mucocele formation in dogs is unknown.

Objective

Determine if gallbladder mucocele formation or clinicopathologic comorbidities are associated with proteinuria.

Animals

Twenty‐five dogs with mucocele formation and 25 breed and age‐matched control dogs from a prior study.

Methods

Retrospective case control study. Proteinuria defined by calculated urine dipstick protein concentration (mg/mL) to urine specific gravity (USG) ratio. Clinicopathologic findings, postcosyntropin cortisol concentration, thyroid function profile, and illness severity score were recorded.

Results

Median urine dipstick protein concentration to USG ratio and number of dogs having a ratio ≥1.5 were significantly higher for dogs with mucocele formation compared to control dogs. Proteinuria was not significantly associated with CBC or serum biochemistry profile abnormalities but increased in relation to severity of illness.

Conclusions and Clinical Importance

Gallbladder mucocele formation is significantly associated with proteinuria in dogs. Diagnosis and treatment of proteinuria in dogs with mucocele formation might minimize long term kidney morbidity in these patients.

Noninvasive sampling method for urinalysis and urine protein profile in captive giraffes

Urinalysis could be helpful to investigate the health status of giraffes held in captivity using noninvasive methods to avoid animal handling or anesthesia. We collected 52 voided urine samples from 20 giraffes of different ages, sexes, and subspecies from the ground. To evaluate potential interference by soil contaminants, a pilot study was performed using 20 urine samples obtained from 10 cows. All bovine and 29 giraffe samples were subjected to routine urinalysis including urine specific gravity (USG). All samples were analyzed for urine total protein (uTP), urine creatinine (uCrea) concentration, and urine protein-to-urine creatinine ratio (UPC). Urinary proteins were separated by SDS-PAGE electrophoresis. No significant differences were determined between free-catch and urine sampled from the ground in cows. Giraffe urine was pale-yellow, with alkaline pH (>8.0) and a mean USG of 1.035 ± 0.013. The uTP, uCrea, and UPC expressed as median (range) were 0.20 (0.08-0.47) g/L, 2.36 (0.62-5.2) g/L, and 0.08 (0.05-0.15), respectively. SDS-PAGE allowed the separation of protein bands with different molecular masses, including putative uromodulin at 90 kD, putative albumin at 64 kD, and putative immunoglobulin heavy and light chains at 49 kD and 25 kD, respectively. Urine collection from the ground appears to be a reliable technique for urinalysis and urine electrophoresis in giraffes.

Efficacy of telmisartan for the treatment of persistent renal proteinuria in dogs: A double-masked, randomized clinical trial

BACKGROUND

Information regarding efficacy of the angiotensin II receptor blocker, telmisartan, for treatment of proteinuria in dogs is limited.

OBJECTIVE

To evaluate the antiproteinuric efficacy of telmisartan, as compared to enalapril, in dogs with chronic kidney disease and persistent, renal proteinuria.

ANIMALS

Thirty-nine client-owned dogs with chronic kidney disease and urinary protein-to-creatinine ratio (UPC) > 0.5 (if azotemic) or ≥ 1.0 (if nonazotemic).

METHODS

In this prospective, randomized, double-masked clinical trial, dogs were block randomized, according to presence or absence of azotemia and systemic arterial hypertension, to receive telmisartan (1.0 mg/kg PO q24h), or enalapril (0.5 mg/kg PO q12h), and followed for 120 days. Up-titration of study drug dosage on days 30 and 60, and addition of the other study drug at day 90, were performed if UPC > 0.5 was noted at these visits. Percentage change in UPC relative to baseline was calculated for all time points. Data are presented as median (range).

RESULTS

Thirty-nine (20 telmisartan-treated, 19 enalapril-treated) dogs were included. At day 30, percentage change in UPC was greater for telmisartan-treated (-65% [-95% to 104%]) vs enalapril-treated (-35% [-74% to 87%]) dogs (P = .002). Among dogs persistently proteinuric at earlier visits, telmisartan remained superior to enalapril at days 60 (P = .02) and 90 (P = .02). No difference in percentage change in UPC between study groups was observed at day 120, when combination therapy was allowed. Combination therapy resulted in relevant azotemia in 4/13 (31%) dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Telmisartan might be a suitable first-line therapy for dogs with renal proteinuria.

Ultrasonographic assessment of abdominal aortic elasticity in hypertensive dogs

Background

Systemic hypertension (SH) is a persistent and pathological increase in arterial blood pressure (BP). Chronic SH leads to an increase in aortic (Ao) stiffness, and measuring Ao elasticity is useful for estimating Ao stiffness in humans. Currently, no literature in veterinary medicine describes noninvasive assessment of abdominal Ao elasticity in dogs with SH.

Objective

Compare ultrasonographic‐derived abdominal Ao strain (AoSt) between hypertensive (HT) and normotensive (NT) dogs.

Animals

Fifty privately‐owned dogs with clinical signs, conditions, or both potentially associated with SH.

Methods

Prospective observational case‐control study. Aortic stiffness was estimated by calculating AoSt as follows: AoSt = ([AoDs − AoDd]/AoDd) × 100, where AoDs and AoDd are the Ao diameter in systole and in diastole, respectively. Aortic stiffness was calculated from 2 different Ao transverse sections, the first caudal to the left renal artery (K_AoSt), and the second cranial to the external iliac arteries (I_AoSt).

Results

Thirty‐two dogs were included in the HT group and 18 in the NT group. Both K_AoSt and I_AoSt in HT dogs were significantly lower (P < .05) than in NT dogs (7.4 ± SD 3.6) vs 10.3 (±3.8) and 5.7 (interquartile range [IQR], 3.9‐7.5) vs 8.1 (IQR, 7‐10.3), respectively. Only K_AoSt was significantly influenced by age.

Conclusions and Clinical Importance

Ultrasonographic Ao elasticity assessment was feasible to compare HT and NT dogs. Results indicated that K_AoSt and I_AoSt indices can be used to assess SH‐related Ao stiffness, especially when indirect BP measurements are inconsistent or inaccurate. Additional studies to assess the AoSt in healthy dogs of various ages are needed.

Changes in renal parameters and their association with subclinical vector-borne infections in Bernese Mountain dogs

Background

An increased risk for glomerulonephritis and a higher prevalence of antibodies to Borrelia (B.) burgdorferi sensu lato have been reported in Bernese mountain dogs (BMDs). The aim of the study was to determine the prevalence of laboratory abnormalities suggestive of kidney disease in clinically healthy BMDs compared to a control population and to investigate if there is a correlation with the occurrence of antibodies to B. burgdorferi sensu lato, Ehrlichia canis, and Anaplasma (A.) spp. and with the occurrence of Dirofilaria (D.) immitis antigen.

A total of 197 BMDs and 57 control dogs were included in the study. Laboratory evidence of kidney disease was defined as renal azotemia and/or proteinuria with a urine protein creatinine ration of more than 0.5 in an inactive urine sediment. A SNAP®4Dx® ELISA (IDEXX, Laboratories, Inc., Westbrook, ME, USA) was used to detect antibodies to B. burgdorferi sensu lato, E. canis and Anaplasma spp. and antigen of D. immitis.

Results

Laboratory evidence of kidney disease was significantly more common in BMDs than in control dogs (17.8% versus 1.8%) (p = 0.005). The proportion of BMDs with anti-B. burgdorferi sensu latu antibodies and anti-A. phagocytophilum antibodies was significantly higher in BMDs (p <  0.001). However, an association between these findings could not be identified.

Conclusion

BMDs are more often affected by kidney disease and have a higher prevalence of antibodies to bacterial pathogens transmitted by Ixodes ticks than control dogs. However, a causal relationship between these two variables could not be established due to a lack of association between these two findings.

Electrophoretic analysis (sds-page) of canine urinary proteins according to the stage of chronic kidney disease

ABSTRACT Glomerular proteinuria is characterized by the loss of high-molecular-weight proteins (HMWPs), while tubulointerstitial proteinuria is characterized by the loss of low-molecular-weight proteins (LMWPs). The objective was to assess the molecular weight of urinary proteins (MWUP) in dogs with naturally acquired CKD and determine the proportion of HMWPs and LMWPs according to CKD stage. Twenty-eight dogs with CKD were recruited and divided into 4 groups based on serum creatinine (Cr) levels (group1: Cr<1,4, n=8; group2: 1,4<Cr<2,0, n=6; group3: 2,1<Cr<5, n=9; group4: Cr>5,0, n=5). The control group consisted of 5 healthy dogs. The MWUP was determined by SDS-PAGE. The urinary protein-to-creatinine ratio (UP/C) was used to quantitatively assess proteinuria. The electrophoresis pattern revealed a proportionally greater loss of HMWPthan of LMWP in all groups with CKD and an increased loss of LMWP in group 4 (P<0.05). These results suggest a predominance of glomerular injuries throughout all stages of CKD in these dogs and an increase in tubulointerstitial injury towards the end-stage of the disease. The results of the present study support the recommendation of SDS-PAGE as an effective technique for the qualitative assessment of proteinuria, as well as a method for assessing the severity and location of renal injury.

The utility of combined urine dipstick analysis and specific gravity measurement to determine feline proteinuria

OBJECTIVES

To assess the utility of urine dipstick strips for detection of feline proteinuria when used in combination with urine-specific gravity, compared with urine protein-to-creatinine ratio as the gold standard.

MATERIALS AND METHODS

Retrospective analysis of clinical records of comprehensive urine examination obtained from cats presented to a referral hospital. Diagnostic agreement and test accuracy were calculated for the dipstick test alone and in combination with the urine-specific gravity, using different cut-off values for proteinuria. Receiver-operating characteristic curves were also calculated.

RESULTS

A total of 121 urine samples were included. The diagnostic agreement between dipstick and urine protein-creatinine ratio was poor. A dipstick result of equal or greater than "Trace" (0.1-0.3 g/L) had a sensitivity of 81% and a specificity of 31% to detect proteinuria. Grouping the samples by urine-specific gravity did not increase dipstick agreement with the urine protein-creatinine ratio and only resulted in a slight improvement in the accuracy of detecting proteinuria.

CLINICAL SIGNIFICANCE

The dipstick test was not accurate for detecting proteinuria when combined with urine-specific gravity in cats. Clinicians should not rely on this test and, regardless of the urine concentration, other appropriate quantitative methods such as urine protein-creatinine ratio should always be performed to detect proteinuria in cats.

Prevalence and risk factors associated with systemic hypertension in dogs with spontaneous hyperadrenocorticism

Background

Systemic hypertension (SH) is common in dogs with hyperadrenocorticism (HAC) however there are not many studies assessing its prevalence and risk factors.

Objectives

To determine the prevalence and severity of SH in dogs with HAC and its association with clinical and laboratory findings to identify potential risk factors.

Animals

Sixty‐six client owned dogs with spontaneous HAC.

Methods

Retrospective cross‐sectional study. Medical records of dogs with HAC were reviewed. Systolic blood pressure (SBP) was measured using Doppler ultrasonography. Clinical signs, physical examination findings and clinicopathologic data (CBC, serum biochemistry and electrolytes, urinalysis and urinary culture, and adrenal function tests) were reviewed for analysis.

Results

Prevalence of SH (≥150 mm Hg) was 82% (54/66) and prevalence of severe SH (≥180 mm Hg) was 46% (30/66). All dogs with thrombocytosis had SH (P = .002), and a platelet count ≥438 × 10³/μL was 100% specific and 61.1% sensitive to predict SH (AUC = .802, P = .001). Median potassium levels were lower in hypertensive dogs (4.1 mEq/L, range 3.1‐5.4 mEq/L) than in normotensive ones (4.5 mEq/L, range 4.0‐5.0 mEq/L) (P = .007). Dogs with UPC ≥ 0.5 had higher median SBP than those without proteinuria (P = .03). Dogs with concurrent diabetes mellitus seemed to have a reduced risk of SH (OR = .118, 95%CI = .022‐.626, P = .02).

Conclusions and Clinical Importance

Systemic hypertension is common in dogs with HAC and is frequently severe. Blood pressure should be routinely assessed in these dogs, especially if thrombocytosis, proteinuria or low potassium concentrations are present.

Evaluation of serum biomarkers and proteinuria for the early detection of renal damage in dogs with heartworm (Dirofilaria immitis)

Glomerulonephropathy associated with Dirofilaria immitis (heartworm) is relatively frequent in infected dogs. Given the importance and the scarcity of studies focused on its prevalence and diagnosis, the objective was to determine the prevalence of proteinuria and functional indicators of glomerular filtration rate in dogs with heartworm disease and discuss its utility in the detection of renal impairment. Sera and urine from 47 infected dogs were analyzed in a reference laboratory. Urea, creatinine, plasma proteins and serum symmetric dimethylarginine (SDMA) were analyzed in sera, while the UPC ratio was performed in urine. Dogs were further evaluated for the presence/absence of microfilariae, pulmonary and systemic hypertension, and the parasite burden was assessed. The results showed that 19.1 % of dogs showed proteinuria (UPC > 0.5) and 17 % showed borderline proteinuria (UPC 0.2-0.5). Creatinine and SDMA were high (>1.8 mg/dl and ≥18 μg/dl, respectively) in 4.2 % of dogs. UPC ratio was significantly increased in dogs with high parasite burden and in dogs with microfilariemia (p < 0.05). Dogs with pulmonary hypertension showed higher increases in proteinuria as well, which was probably due to the chronicity of the infection. No significant differences were found in serum and urine values regarding systemic blood pressure. Despite the limitations of this study, proteinuria/borderline proteinuria was present in 36.2 % of dogs with heartworm disease, and this may be due to glomerular disease. Therefore, the detection of proteinuria, along with other renal biomarkers in the diagnostic protocols, could help identify kidney alterations or risk of renal damage in heartworm disease.