Comparative study of chronic kidney disease in dogs and cats: Induction of myofibroblasts

We investigated the kidneys of dogs and cats to clarify whether renal myofibroblasts induction is associated with the severity of chronic kidney disease (CKD). Immunohistochemical expression of myofibroblast markers, α-smooth muscle actin (SMA) and vimentin, were evaluated quantitatively. The degrees of glomerulosclerosis, glomerular hypertrophy, interstitial cell infiltration, and interstitial fibrosis were also evaluated quantitatively. The plasma creatinine (pCre) concentrations correlated with glomerulosclerosis, cell infiltration, and fibrosis in dogs, and only with fibrosis in cats. The α-SMA expression correlated with pCre, glomerulosclerosis, cell infiltration, and fibrosis in dogs, and with pCre and fibrosis in cats. Tubular vimentin expression correlated with fibrosis in cats, but not in dogs. Interstitial vimentin expression correlated with pCre, glomerulosclerosis, cell infiltration, and fibrosis in dogs, but only with pCre in cats. In conclusion, it was suggested that the severity of CKD in dogs and cats was mediated by different pathways associated with myofibroblasts expression.     

B-mode and Doppler ultrasound of chronic kidney disease in dogs and cats

Ultrasound is the imaging test of choice for renal evaluation, because it provides information about the position, size, shape, internal architecture and hemodynamics of the kidneys without harming the patient. In chronic kidney disease, the main findings observed in B-mode ultrasound images are increased cortical echogenicity, loss of corticomedullary differentiation, reduced renal volume and irregular renal contour, and when these changes are associated, they are indicative of end-stage renal disease. However, the cause of kidney disease cannot be determined by ultrasonography, but must be confirmed by means of biopsy, although the presence of ultrasonographic changes indicative of the end-stage of the disease may contraindicate this procedure. The Doppler ultrasound test complements the ultrasonic B-mode examination and enables the assessment of renal perfusion based on a calculation of the hemodynamic indices, which are increased in cases of chronic kidney lesions, with higher values ??in the most severe cases. Thus, ultrasound examinations are not only useful in diagnostics but also play an important role in defining the prognosis of patients with chronic kidney disease.     

A case-control study of the effects of nephrolithiasis in cats with chronic kidney disease

OBJECTIVE: To determine whether nephrolithiasis was associated with an increase in mortality rate or in the rate of disease progression in cats with naturally occurring stage 2 (mild) or 3 (moderate) chronic kidney disease. DESIGN: Retrospective case-control study. ANIMALS: 14 cats with stage 2 (mild) or 3 (moderate) chronic kidney disease (7 with nephroliths and 7 without). PROCEDURES: All cats were evaluated every 3 months for up to 24 months. Possible associations between nephrolithiasis and clinicopathologic abnormalities, incidence of uremic crises, death secondary to renal causes, and death secondary to any cause were evaluated. RESULTS: There were no clinically important differences in biochemical, hematologic, or urinalysis variables between cats with and without nephroliths at baseline or after 12 and 24 months of monitoring. No associations were detected between nephrolithiasis and rate of disease progression, incidence of uremic crises, or death. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in cats with mild or moderate chronic kidney disease, nephrolithiasis was not associated with an increase in mortality rate or in the rate of disease progression. Findings support recommendations that cats with severe kidney disease and nephrolithiasis be managed without surgery.     

Prognostic factors in cats with chronic kidney disease

BACKGROUND: Chronic kidney disease (CKD) is a common cause of morbidity and mortality in cats. HYPOTHESIS: Some baseline variables are associated with shorter survival times in cats with CKD. ANIMALS: Client-owned cats. METHODS: Cats with CKD with initial plasma creatinine concentration > or =2.0 mg/dL and urine specific gravity (USG) < or = 1.025 were recruited into a prospective clinical trial that compared benazepril with a placebo. We describe baseline variables in 190 cats and their influence on renal survival time in the placebo group (95 cats), which was followed for up to 1,097 days. Renal survival time was defined as the time from initiation of therapy to the need for parenteral fluid therapy, euthanasia, or death related to renal failure. RESULTS: Of the 95 cats treated with a placebo, 58 were censored and 37 reached the renal survival end point (died, n = 0; euthanized, n = 17; parenteral fluids, n = 12; parenteral fluids followed by euthanasia, n = 8). Increased plasma creatinine concentration, increased urine protein-to-creatinine ratio (UPC), and increased blood leukocyte count were significantly (P < .01) associated with a shorter renal survival time and were independent risk factors. Increased concentrations of plasma phosphate or urea, and lower blood hemoglobin concentration or hematocrit were significantly (P < .01) associated with a shorter renal survival time and were dependent risk factors, because they also were significantly (P < .01) correlated with plasma creatinine concentration at baseline. CLINICAL IMPORTANCE: Several variables were significantly associated with a shorter renal survival time in cats with 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.     

Nutritional management of chronic renal disease in dogs and cats.

Chronic renal disease is a leading cause of death in dogs and cats. Recent clinical studies show that nutrition plays a key role in improving quality of life and life expectancy of these patients. Typical nutritional interventions include modifying the protein, phosphorus, and lipid concentrations. Nutritional therapy, however, does not simply mean changing the diet; consideration must also be given to ensuring adequate caloric intake and to the method of feeding. Monitoring the effects of the dietary therapy is also crucial to ensure that the patients are responding appropriately to the selected nutritional modifications. Nutritional management must be coordinated with medical management for long term successful treatment.     

Tolerability and efficacy of benazepril in cats with chronic kidney disease

The objective of the study was to test the effect of the angiotensin-converting enzyme inhibitor (ACEI) benazepril in cats with chronic kidney disease (CKD). A total of 192 cats with CKD with an initial plasma creatinine concentration > or = 2 mg/dL (> or = 177 micromol/L) and urine specific gravity < or = 1.025 were recruited into a double-blind, parallel-group, prospective, randomized clinical trial. Cats received daily (q24h) PO placebo (n = 96) or benazepril x HCl at a dosage of 0.5-1.0 mg/kg (n = 96) for up to 1,119 days. Most cats were fed exclusively a diet containing low amounts of phosphate, protein, and sodium. Benazepril produced a significant reduction in proteinuria, assessed by the urine protein-to-creatinine ratio (UPC, P = .005). This effect of benazepril was present in all subgroups tested, including cats with UPC <0.2, although the effect was largest in cats with higher UPCs. Plasma protein was maintained at higher concentrations with benazepril as compared with placebo during treatment in cats with initial UPC <1 (P = .038 versus P = .079 for all cats). There was no difference in renal survival time between the 2 groups when all 192 cats were compared. Mean +/- SD renal survival times were 637 +/- 480 days with benazepril and 520 +/- 323 days with placebo (P = .47). Mean +/- SD renal survival times in the 13 cats with initial UPC > or = 1 were 402 +/- 202 days with benazepril and 149 +/- 90 days with placebo (P = .27). Cats with initial UPC > or = 1 treated with benazepril had better appetite (P = .017) as compared with those treated with placebo. Benazepril was well tolerated. In conclusion, benazepril decreased proteinuria in cats with CKD.     

Diagnosis of hyperthyroidism in cats with mild chronic kidney disease

OBJECTIVES: In cats with concurrent hyperthyroidism and non-thyroidal illnesses such as chronic kidney disease, total thyroxine concentrations are often within the laboratory reference range (19 to 55 nmol/l). The objective of the study was to determine total thyroxine, free thyroxine and/or thyroid-stimulating hormone concentrations in cats with mild chronic kidney disease. METHODS: Total thyroxine, free thyroxine and thyroid-stimulating hormone were measured in three groups. The hyperthyroidism-chronic kidney disease group (n=16) had chronic kidney disease and clinical signs compatible with hyperthyroidism but a plasma total thyroxine concentration within the reference range. These cats were subsequently confirmed to be hyperthyroid at a later date. The chronic kidney disease-only group (n=20) had chronic kidney disease but no signs of hyperthyroidism. The normal group (n=20) comprised clinically healthy senior (>8 years) cats. RESULTS: In 4 of 20 euthyroid chronic kidney disease cats, free thyroxine concentrations were borderline or high (> or =40 pmol/l). In the hyperthyroidism-chronic kidney disease group, free thyroxine was high in 15 of 16 cats, while thyroid-stimulating hormone was low in 16 of 16 cats. Most hyperthyroidism-chronic kidney disease cats (14 of 16) had total thyroxine greater than 30 nmol/l, whereas all the chronic kidney disease-only cats had total thyroxine less than 30 nmol/l. CLINICAL SIGNIFICANCE: The combined measurement of free thyroxine with total thyroxine or thyroid-stimulating hormone may be of merit in the diagnosis of hyperthyroidism in cats with chronic kidney disease.     

Renal transitional-cell carcinoma in two cats with chronic kidney disease

Two 12-year-old cats were diagnosed with chronic kidney disease (CKD) based on physical examination, clinicopathologic data and, in one case, abdominal ultrasound findings. Approximately 1 year after the initial diagnosis of CKD both cats developed renal transitional cell carcinoma (TCC)--bilateral in one cat. Based on post-mortem examination, one cat had no evidence of metastasis and the other had metastasis to the large intestine, heart and lungs. This is the first report of de novo bilateral renal TCC in a cat, as well as the first report of renal TCC developing in cats with previous history of confirmed CKD.