Therapies for feline chronic kidney disease. What is the evidence?

Supplementation of vitamin E as an addition to a commercial renal diet does not prolong survival of cats with chronic kidney disease

BACKGROUND

The aim of this double-blind, placebo-controlled study was to investigate the effect of vitamin E supplementation as an addition to a commercial renal diet on survival time of cats with different stages of chronic kidney disease (CKD). In addition, we were interested whether vitamin E supplementation affects selected oxidative stress and clinical parameters. Thirty-four cats with CKD and 38 healthy cats were included in the study. Cats with CKD were classified according to the IRIS Guidelines; seven in IRIS stage 1, 15 in IRIS stage 2, five in IRIS stage 3 and seven in IRIS stage 4. Cats with CKD were treated according to IRIS Guidelines. Cats with CKD were randomly assigned to receive vitamin E (100 IU/cat/day) or placebo (mineral oil) for 24 weeks in addition to standard therapy. Plasma malondialdehyde (MDA) and protein carbonyl (PC) concentrations, DNA damage of peripheral lymphocytes and plasma vitamin E concentrations were measured at baseline and four, eight, 16 and 24 weeks thereafter. Routine laboratory analyses and assessment of clinical signs were performed at each visit.

RESULTS

Vitamin E supplementation had no effect on the survival time and did not reduce the severity of clinical signs. Before vitamin E supplementation, no significant differences in vitamin E, MDA and PC concentrations were found between healthy and CKD cats. However, plasma MDA concentration was statistically significantly higher (p = 0.043) in cats with early CKD (IRIS stages 1 and 2) than in cats with advanced CKD (IRIS stages 3 and 4). Additionally, DNA damage was statistically significantly higher in healthy cats (p ≤ 0.001) than in CKD cats. Plasma vitamin E concentrations increased statistically significantly in the vitamin E group compared to the placebo group four (p = 0.013) and eight (p = 0.017) weeks after the start of vitamin E supplementation. During the study and after 24 weeks of vitamin E supplementation, plasma MDA and PC concentrations and DNA damage remained similar to pre-supplementation levels in both the placebo and vitamin E groups.

CONCLUSIONS

Vitamin E supplementation as an addition to standard therapy does not prolong survival in feline CKD.

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 Multicomponent, Multitarget Therapy SUC in Cats with Chronic Kidney Disease: A Multicenter, Prospective, Observational, Nonrandomized Cohort Study

BACKGROUND

We compared the natural multicomponent, multitarget therapy SUC (Solidago compositum ad us. vet., Ubichinon compositum and Coenzyme compositum, Heel GmbH, Baden-Baden, Germany) to the well-known angiotensin-converting enzyme inhibitor benazepril in a prospective, observational, nonrandomized, two-arm cohort study of cats with chronic kidney disease (CKD). The objective was to assess the tolerability and the effectiveness of SUC in cats with CKD.

MATERIAL AND METHODS

One hundred thirty-six cats were screened for CKD, and 70 cats were eligible for the study. Thirty-three cats were assigned to the SUC treatment, and 35 cats received benazepril. All cats were diagnosed with CKD. The follow-up period was 168 days. Response was assessed as an improved or stable serum creatinine from baseline to the end of the study. Additionally, a clinical summary score, as measure of quality of life, was evaluated.

RESULTS

Serum creatinine remained close to baseline in both study groups with slightly improved values in the SUC group. The clinical summary score improved significantly in the SUC group on days 3, 7, 28, 56 and 112, but not on day 168.

CONCLUSIONS

Within the limitations of the study, the results carry implications for the usefulness of SUC as an interesting new treatment option for feline CKD. The results indicate that SUC might be more effective if given at least twice weekly.

Concurrent Infection with Cryptococcus Neoformans/Gattii Species Complex and Mycobacterium Avium Affecting the Subcutis and Bone of a Pelvic Limb in a Cat

This paper describes a cat with severe localised infections with Cryptococcus neoformans/gattii species complex and Mycobacterium avium affecting the subcutis and underlying fascia and bone of the right pelvic limb. The simultaneous isolation of both pathogens in this patient was unexpected and posed unique issues concerning both diagnosis and clinical management. The aetiopathogenesis of this infection is discussed in relation to aspects of diagnosis and therapy.

Controversies in Veterinary Nephrology: Renal Diets Are Indicated for Cats with International Renal Interest Society Chronic Kidney Disease Stages 2 to 4: The Pro View

Renal diets have been the mainstay of therapy for cats with chronic kidney disease (CKD) for many decades. Clinical trials in cats with CKD have shown them to be effective in improving survival, reducing uremic crises, and improving serum urea nitrogen and phosphorous concentrations. It has shown that, when food intake is adequate, renal diets can maintain body weight and body condition scores for up to 2 years. Although some have questioned whether renal diets provide adequate protein and have advocated feeding higher-protein diets to cats with CKD, there is currently no convincing evidence in support of this proposal.

ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease

PRACTICAL RELEVANCE

Chronic kidney disease (CKD) is one of the most commonly diagnosed diseases in older cats. In most cats, CKD is also a progressive disease and can be accompanied by a wide range of clinical and clinicopathological changes. These ISFM Consensus Guidelines have been developed by an independent panel of clinicians and academics to provide practical advice on the diagnosis and management of this complex disease.

CLINICAL CHALLENGES

Although CKD is a common clinical problem in cats, the manifestations of disease vary between individuals. Thus there is a need for careful and repeat evaluation of cats with CKD and adjustment of therapy according to individual needs. In addition to addressing problems arising from CKD and improving quality of life (QoL) for the patient, therapy may also target slowing the underlying progression of disease and hence prolonging life. While maintaining QoL is of paramount importance in our patients, this can be challenging when multiple therapies are indicated. In some cases it is necessary to prioritise therapy, given an understanding of what is likely to most benefit the individual patient.

EVIDENCE BASE

In preparing these Guidelines, the Panel has carefully reviewed the existing published literature, and has also graded the quality of evidence for different interventions to help to provide practical recommendations on the therapeutic options for feline CKD. This is a field of veterinary medicine that has benefited from some excellent published clinical research and further research findings will undoubtedly modify the recommendations contained in these Guidelines in the future.

Oral Manifestations of Chronic Kidney Disease and Renal Secondary Hyperparathyroidism: A Comparative Review

Recent epidemiological studies have demonstrated that significant associations exist between oral disease and diseases involving non-oral tissues. Occasionally, the roles may be reversed and the oral cavity can be severely affected by systemic disease originating in another part of the body. Renal secondary hyperparathyroidism is a common endocrinopathy that occurs as a consequence of chronic azotemic kidney disease. Renal osteodystrophy, the most dramatic clinical consequence of renal secondary hyperparathyroidism is uncommon, but can result in demineralization of maxillofacial bones, loosening of teeth, and pathological jaw fractures. The purpose of this report is to update the current understanding of the pathophysiology of this endocrine disease and to compare the oral manifestations of renal secondary hyperparathyroidism in humans and companion animals. A 50-year review of the veterinary literature was undertaken to examine the clinical presentation of renal osteodystrophy in dogs, and to determine what clinical consequences of renal secondary hyperparathyroidism have been reported in domestic cats.

Acceptance and effects of a therapeutic renal food in pet cats with chronic kidney disease

Introduction

Renal foods are used to manage chronic kidney disease (CKD) in dogs and cats, but their effectiveness may be limited by the ability to transition animals to them.

Material and Methods

In a prospective study, pet cats with previously undiagnosed kidney disease (20 International Renal Interest Society (IRIS) 1, 61 IRIS 2, 14 IRIS 3/4, 33 at risk for CKD) were transitioned to a renal food. Markers of renal function were measured and owners answered questionnaires about their pet over one year.

Results

All but eight cats (120/128; 94 per cent) successfully transitioned to the renal food. Most of the time, cats moderately or extremely liked the food (89 per cent), ate at least half (73 per cent) and were moderately or extremely enthusiastic while eating (68 per cent). Cats rarely disliked the food (2 per cent) or refused to eat it (1 per cent). Markers of renal function were unchanged in IRIS 1 and 2 cats and changed little in IRIS 3/4 cats. In all groups, owner-assessed quality of life improved initially and then remained stable. Mean bodyweight did not change in cats with CKD.

Conclusions

Most cats with CKD successfully transitioned to the renal food. The results also support previous studies that the renal food can help stabilise cats with CKD.

Relationship among serum creatinine, serum gastrin, calcium-phosphorus product, and uremic gastropathy in cats with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) in cats is associated with gastrointestinal signs commonly attributed to uremic gastropathy. Consequently, patients often are treated with antacids and gastrointestinal protectants. This therapeutic regimen is based on documented gastric lesions in uremic humans and dogs, but the nature and incidence of uremic gastropathy in cats are unknown.

HYPOTHESIS/OBJECTIVES

Evaluate uremic gastropathy in CKD cats to facilitate refinement of medical management for gastrointestinal signs.

ANIMALS

Thirty-seven CKD cats; 12 nonazotemic cats

METHODS

Stomachs were evaluated for the presence of classic uremic gastropathy lesions. Histopathologic lesions were compared with serum creatinine concentrations, calcium-phosphorus product (CPP), and serum gastrin concentrations.

RESULTS

Gastric ulceration, edema, and vascular fibrinoid change were not observed. The most important gastric lesions in CKD cats were fibrosis and mineralization. Sixteen CKD cats (43%) had evidence of gastric fibrosis of varying severity and 14 CKD cats (38%) had gastric mineralization. CKD cats were more likely to have gastric fibrosis and mineralization than nonazotemic controls (P = .005 and P = .021, respectively). Only cats with moderate and severe azotemia had gastric mineralization. CPP was correlated with disease severity; severely azotemic CKD cats had significantly higher CPP when compared with nonazotemic controls, and to mildly and moderately azotemic cats (P < .05). Gastrin concentrations were significantly higher in CKD cats when compared with nonazotemic controls (P = .003), but increased concentrations were not associated with gastric ulceration.

CONCLUSIONS AND CLINICAL IMPORTANCE

Uremic gastropathy in CKD cats differs from that described in other species and this difference should be considered when devising medical management.

Intrarenal distributions and changes of Angiotensin-converting enzyme and Angiotensin-converting enzyme 2 in feline and canine chronic kidney disease

Angiotensin-converting enzyme (ACE) is a key enzyme in the renin-angiotensin system (RAS). ACE2 is a newly identified member of the RAS. The present immunohistochemical study focused on changes in intrarenal ACE and ACE2 immunoreactivity in feline and canine chronic kidney disease (CKD). ACE immunoreactivity was predominantly observed in the brush border of the proximal tubules in dogs and cats. ACE immunoreactivity was lower in CKD kidneys than in normal kidneys, and quantitative analysis demonstrated negative correlations between ACE and renal tissue damage in dogs. ACE2 immunoreactivity was also detected in the proximal tubules; it increased or decreased with CKD in dogs, depending on the renal region assessed. The changes in ACE and ACE2 in CKD were associated with the plasma creatinine concentration in dogs. Findings from dogs with glomerulonephritis were similar to those from dogs with non-glomerulonephritis. The present study suggests that changes in the intrarenal expression of ACE and ACE2 contribute to the pathological mechanisms of canine CKD, but not to the mechanisms of feline CKD.

Feline CKD: Current therapies - what is achievable?

PRACTICAL RELEVANCE

Treatment of feline chronic kidney disease (CKD) tends to focus on minimising the adverse effects of reduced renal function, rather than addressing an underlying cause. Despite this, and the progressive nature of CKD, treatment can improve quality of life and enable many cats to have long survival times.

EVIDENCE BASE

Strong evidence supports the provision of renal diets, which are protein and phosphorus restricted; compliance is improved by gradual dietary transition. Additional phosphorus restriction is achieved by the use of phosphate binding agents, although it is unknown if these yield similar survival benefits to those provided by renal diets. Interventions to control hypokalaemia and hypertension in affected cats are important to prevent serious complications. Administration of benazepril to cats with proteinuric kidney disease has been shown to significantly improve their appetite but not their survival. As CKD progresses, many cats will benefit from treatment to control clinical signs of uraemic gastroenteritis and anaemia.

Evidence-based step-wise approach to managing chronic kidney disease in dogs and cats

OBJECTIVE

To provide a framework for successfully managing chronic kidney disease (CKD) over an extended period of time with the goal of optimizing clinical outcomes by fostering a veterinarian-client relationship that facilitates successful application of evidence-based treatment.

ETIOLOGY

Ultimately, CKD results from loss of functional nephrons; however, the specific disease process responsible for this loss usually cannot be determined due to development of chronic changes (eg, fibrosis) and compensatory adaptations that have occurred in the kidneys of patients with CKD. Earlier diagnosis may foster a better understanding of the etiologies of CKD.

DIAGNOSIS

Diagnosis of CKD is based on establishing loss of kidney function(s) due to primary kidney disease that have been present for an extended time (typically 3 months or longer).

THERAPY

The goals of therapy are to: (1) slow progressive loss of kidney function, (2) ameliorate clinical and biochemical consequences of CKD, and (3) maintain adequate nutrition. These goals are achieved by: (1) managing adaptive processes that promote progression of CKD, (2) controlling intake of water, nutrients, minerals and electrolytes, and (3) correcting hormonal deficiencies.

PROGNOSIS

The short-term prognosis for dogs with CKD varies from good to poor, while the long-term prognosis for dogs with CKD is generally guarded to poor depending on the International Renal Interest Society (IRIS) CKD stage of the patient. Both short-term and long-term prognosis for cats with CKD may vary from good to poor depending on the IRIS CKD stage. However, prognosis is more variable and unpredictable in cats.

Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease

OBJECTIVE

To evaluate recipes of diets recommended for animals with chronic kidney disease (CKD), compare nutritional profiles for those recipes to requirements for adult dogs and cats, and assess their appropriateness for the management of CKD.

DESIGN

Evaluation study.

SAMPLE

Recipes of 67 home-prepared diets promoted for use in dogs (n = 39 recipes) and cats (28) with CKD.

PROCEDURES

Recipes were analyzed with computer software to determine calories, macronutrient calorie distribution, and micronutrient concentrations and were assessed for appropriateness for the management of CKD.

RESULTS

Assumptions were required for the analysis of every recipe, and no recipe met all National Research Council nutrient recommended allowances (RA) for adult animals. Compared with RAs, concentrations of crude protein or at least 1 amino acid were low in 30 of 39 (76.9%) canine recipes and 12 of 28 (42.9%) feline recipes. Choline was most commonly below the RA in both canine (37/39 [94.9%]) and feline (23/28 [82.1%]) recipes; selenium (34/39 [87.2%] canine and 9/28 [32.1 %] feline recipes), zinc (24/39 [61.5%] canine and 19/28 [67.9%] feline recipes), and calcium (22/39 [56.4%] canine and 7/28 [25.0%] feline recipes) concentrations were also frequently below recommendations. The median phosphorus concentration in canine and feline recipes was 0.58 and 0.69 g/1,000 kcal, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Many problems with nutritional adequacy were detected, and use of the recipes could result in highly variable and often inappropriate diets. Many recipes would not meet nutritional and clinical needs of individual patients and should be used cautiously for long-term feeding.

Interaction of clarithromycin with cyclosporine in cats: pharmacokinetic study and case report

Clarithromycin (CLM) has been known to increase the cyclosporine (CsA) trough levels in human transplant patients. However, the interaction of CLM with CsA has not been reported in cats. In this study, the effects of oral dosing of CLM on the pharmacokinetics and dosing of CsA in cats were investigated. Co-administration of CLM with CsA resulted in significant increases of oral bioavailability of CsA. In addition, CLM reduced the CsA dosage required to maintain the therapeutic CsA trough levels to almost 35% of the initial CsA therapy and the dose frequency was successfully replaced from a twice a day schedule to once a day in a feline kidney transplant patient. The addition of CLM to the regular CsA-based immunosuppression could be used as an effective alternative to classical ketoconazole treatment in feline kidney transplant patients and may result in substantial cost saving and convenience for the cat owners.

Evaluation of intrarenal mesenchymal stem cell injection for treatment of chronic kidney disease in cats: a pilot study

The feasibility of autologous intrarenal mesenchymal stem cell (MSC) therapy in cats with chronic kidney disease (CKD) was investigated. Six cats (two healthy, four with CKD) received a single unilateral intrarenal injection of autologous bone marrow-derived or adipose tissue-derived MSC (bmMSC or aMSC) via ultrasound guidance. Minimum database and glomerular filtration rate (GFR) via nuclear scintigraphy were determined pre-injection, at 7 days and at 30 days post-injection. Intrarenal injection did not induce immediate or long-term adverse effects. Two cats with CKD that received aMSC experienced modest improvement in GFR and a mild decrease in serum creatinine concentration. Despite the possible benefits of intrarenal MSC injections for CKD cats, the number of sedations and interventions required to implement this approach would likely preclude widespread clinical application. We concluded that MSC could be transferred safely by ultrasound-guided intrarenal injection in cats, but that alternative sources and routes of MSC therapy should be investigated.

An evidence-based review of therapies for canine chronic kidney disease

Successful treatment and prevention of kidney disease in dogs requires a multi-dimensional approach to identify and eliminate causes or exacerbating factors, provide professional evaluation on a regular basis and implement a comprehensive treatment programme when necessary. Over the years, many therapeutic and preventive interventions have been developed or advocated for chronic kidney disease in dogs, but evidence of efficacy or effectiveness is often lacking or highly variable. Accordingly, the main objective of this systematic review was to identify and critically appraise the evidence supporting various aspects of managing canine chronic kidney disease.