Continuous renal replacement therapy in dogs and cats

Nephrology in Veterinary Medicine

Veterinary nephrology is a specialized field of veterinary medicine providing a high level of care for animals with all types of kidney disease. Veterinarians complete extensive training to become board-certified in veterinary nephrology-urology. Companion animal nephrology is the most advanced field; however, all species are afflicted by a variety of renal disorders. Most naturally occurring animal kidney diseases have similar disorders found in people; where veterinary research is lacking, clinical management is often modified from standard of care in people. Veterinarians have become adept at scaling down procedures to safely perform them on dogs and cats weighing only a few kilograms. Advanced diagnostics (renal biopsy, cystoscopy, fluoroscopic studies, etc. ) and therapeutics (renal replacement therapy, interventional endourology, etc. ) are commonly performed within the practice of veterinary nephrology-urology. Collaboration between veterinary and human nephrologists may advance both disciplines and improve care for people and animals alike.

Continuous renal replacement therapy is a safe and effective modality for the initial management of dogs with acute kidney injury

OBJECTIVE

To describe the management of dogs with acute kidney injury (AKI) by continuous renal replacement therapy (CRRT), and to investigate the relationship between a prescribed CRRT dose, the hourly urea reduction ratio (URR), and the overall efficacy.

ANIMALS

45 client-owned dogs diagnosed with severe AKI, receiving 48 CRRT treatments at a veterinary teaching hospital.

PROCEDURES

Retrospective study. Search of medical records of dogs with AKI managed by CRRT.

RESULTS

Median serum urea and creatinine at CRRT initiation were 252 mg/dL [Inter quartile range (IQR), 148 mg/dL; range, 64 to 603 mg/dL] and 9.0 mg/dL (IQR, 7 mg/dL; range, 4.3 to 42.2 mg/dL), respectively. Median treatment duration was 21 hours (IQR, 8.8 hours; range, 3 to 32 hours). Systemic heparinization and regional citrate anticoagulation were used in 24 treatments each (50%). The prescribed median CRRT dose for the entire treatment was 1 mL/kg/min (IQR, 0.4 mL/kg/min; range, 0.3 to 2.5 mL/kg/min). The median hourly URR was 4% (IQR, 1%; range, 2% to 12%), overall URR was 76% (IQR, 30%; range, 11% to 92%) and median Kt/V was 2.34 (IQR, 1.9; range, 0.24 to 7.02). The CRRT dose was increased gradually from 0.9 mL/kg/min to 1.4 mL/kg/min (P < .001) and the hourly URR decreased from 6.5% to 5.5% (P = .05). The main complication was clotting of the extra-corporeal circuit, occurring in 6/48 treatments (13%). Twenty-four dogs (53%) survived to discharge.

CLINICAL RELEVANCE

CRRT is safe when the prescription is based on the current veterinary guidelines for gradual urea reduction. Treatment efficacy can be maximized by gradually increasing the dose according to the actual URR.

Extracorporeal Therapies in the Emergency Room and Intensive Care Unit

Extracorporeal treatments create opportunity for removing disease causing solutes within blood. Intoxications, renal failure, and immune-mediated diseases may be managed with these treatments, often providing new hope for patients with severe or refractory disease. Understanding solute pharmacokinetics and the limitations of each type of extracorporeal technique can allow for the selection of the optimal treatment modality.

Hematological and Hemostatic Alterations Associated With a Single Extracorporeal Renal Replacement Therapy in Dogs With Acute Kidney Injury Associated Leptospirosis: A Pilot Study

Extracorporeal renal replacement therapy (ERRT) used in dogs with acute kidney injury (AKI) may be associated with hematological and hemostatic disorders. However, its characteristics are not fully described in dogs. The purpose of this pilot study was to characterize the impact of ERRT on hematological, hemostatic, and thromboelastometric parameters in dogs with AKI. We conducted a prospective observational single cohort study in 10 client-owned dogs with AKI associated leptospirosis undergoing ERRT. Results from the CBC, coagulation tests (prothrombin and activated partial thromboplastin times [aPTT]) and rotational thromboelastometry (TEM; intrinsic TEM [inTEM] and heparinase-based TEM [hepTEM]) were recorded before and after the first ERRT session. Blood abnormalities observed before the ERRT session included thrombocytopenia (10/10), anemia (8/10), leukocytosis (4/10), prolonged aPTT (4/10) and leukopenia (1/10). After ERRT, the platelet count decreased (-25%; P = .012) whereas leukocytes (+15%; P = .046) and aPTT (+24%; P = .006) increased. The clotting time (CT) on inTEM assay and the relative variation of CT based on inTEM and hepTEM profiles increased after the ERRT session (P = .037 and P = .048, respectively). Seven dogs, 2 dogs, and 1 dog were defined as having a normal, hypocoagulable, and hypercoagulable inTEM profile after ERRT, respectively. After ERRT, no hepTEM parameter was significantly different from before treatment. Platelet count, leukocytes, aPTT and CT were altered after the first ERRT session. Beyond the hemostatic abnormalities expected by the use of UFH, thrombocytopenia appears as the only hemostatic change after a single ERRT session in dogs with AKI.

Retrospective evaluation of the clinical course and outcome following grape or raisin ingestion in dogs (2005-2014): 139 cases

OBJECTIVE

To describe the prevalence of acute kidney injury (AKI), clinical course, decontamination procedures, and outcome in dogs following grape or raisin ingestion.

DESIGN

Retrospective case series from 2005 to 2014.

SETTING

Three university veterinary teaching hospitals.

ANIMALS

One hundred thirty-nine client-owned dogs with known grape or raisin ingestion.

MEASUREMENTS AND MAIN RESULTS

Among dogs with biochemical data, the prevalence of AKI was 6.7% (8/120). The prevalence of AKI in the early presentation (3/67) and late (5/53) presentation groups were 4.5% and 9%, respectively. The prevalence of AKI was not significantly different between groups (P = 0.27). Four dogs (3.3%) were azotemic at presentation and 4 dogs (3.3%) had increases in creatinine of ≥26.5 µmol/L (0.3 mg/dL) at recheck (3 from the early and 1 from the late group). Vomiting was the most common clinical sign (18/139). One hundred twenty-two dogs (88%) underwent gastrointestinal decontamination and significantly more dogs in the early group were decontaminated (P < 0.0001). Two dogs received continuous renal replacement therapy. One hundred thirty-eight dogs survived and 1 died.

CONCLUSIONS

The prevalence of AKI and mortality was low in dogs with confirmed grape or raisin ingestion. Due to the retrospective nature of the study, conclusions about the utility of gastrointestinal decontamination and other therapies cannot be made.

Primary hemostatic function in dogs with acute kidney injury

BACKGROUND

Bleeding tendencies can occur with uremia.

OBJECTIVES

To characterize primary hemostatic function in dogs with acute kidney injury (AKI).

ANIMALS

Ten dogs with International Renal Interest Society AKI grade III or above and 10 healthy controls.

METHODS

Prospective study comparing PCV, platelet count, platelet aggregometry (Multiplate), and von Willebrand factor antigen to collagen binding activity ratio (vWF:Ag:vWF:CBA) in 2 groups of dogs (AKI group versus controls). Buccal mucosal bleeding time was measured in the AKI group only. Data are presented as median [25th, 75th percentile] unless otherwise stated. Significance was set at P < .05.

RESULTS

Mean PCV was significantly lower in the AKI (34.7%; ±SD, 8.8) than in the control (46.1%; ±SD, 3.6; P < .001) group. Platelet count was significantly higher in the AKI (350.5 × 103 /μL [301, 516]) than in the control (241 × 103 /μL [227, 251]; P = .01) group. Collagen-activated platelet aggregometry measured as area under the curve was significantly lower in the AKI (36.9 ± 17.7) than in the control (54.9 ± 11.2; P = .05) group. vWF:Ag:vWF:CBA was significantly higher in the AKI (2.2 [1.9, 2.6]) than in the control (1.1 [1.1, 1.2]; P = .01) group. There was a strong correlation between vWF:Ag:vWF:CBA and creatinine (r = 0.859; P < .001), but no other variables.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with AKI had decreased collagen-activated platelet aggregation and appear to have a type II von Willebrand disease-like phenotype as indicated by the high vWF:Ag:vWF:CBA.

Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE): Domain 4-Refining and monitoring antithrombotic therapies

OBJECTIVES

To systematically review the evidence for therapeutic monitoring of antithrombotic drugs in small animals, develop guidelines regarding antithrombotic monitoring, and identify knowledge gaps in the field.

DESIGN

First, a standardized, systematic literature review was conducted to address predefined PICO (Population/Patient, Intervention, Control, Outcome) questions, with categorization of relevant articles according to level of evidence and quality. Preliminary guidelines were developed by PICO worksheet authors and the domain chair. Thereafter, a Delphi-style survey was used to develop consensus on guidelines regarding therapeutic monitoring of antithrombotics in dogs and cats.

SETTING

Academic and referral veterinary medical centers.

RESULTS

PICO questions regarding the utility of therapeutic monitoring were developed for 6 different antithrombotic drugs or drug classes, including aspirin, clopidogrel, warfarin, unfractionated heparin, the low molecular weight heparins, and rivaroxaban, The majority of the literature pertaining to therapeutic monitoring of antithrombotic drugs was either performed in experimental animal models of disease or involved studies of drug pharmacokinetics and pharmacodynamics in healthy laboratory animals. There was a paucity of high level of evidence studies directly addressing the PICO questions, which limited the strength of recommendations that could be provided. The final guidelines recommend that therapeutic monitoring should be performed when using warfarin or unfractionated heparin in dogs and cats at risk of thrombosis. There is insufficient evidence to make strong recommendations for therapeutic monitoring of aspirin or low molecular weight heparin in dogs and cats at this time.

CONCLUSIONS

As in other CURATIVE domains, significant knowledge gaps were highlighted, indicating the need for substantial additional research in this field. Ongoing investigation of the role of therapeutic monitoring of antithrombotic therapies will undoubtedly facilitate improved outcomes for dogs and cats at risk of thrombosis.

Clinical application of the American College of Veterinary Emergency and Critical Care (ACVECC) Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE) guidelines to small animal cases

OBJECTIVE

To illustrate the application of the Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE) guidelines to the management of dogs and cats at risk of developing thrombosis using a case-based approach.

ETIOLOGY

Dogs and cats become at risk of developing thrombosis from a wide range of conditions. These conditions often involve a specific insult followed by an inflammatory response and when combined with other contributing factors (eg, hypercoagulability, vascular endothelial injury, hemodynamic changes) create favorable conditions for thrombosis.

DIAGNOSIS

Development of thrombosis in small animals remains challenging to demonstrate. Compatible clinical signs, the presence of known risk factors, and supporting diagnostic tests may be highly suggestive of the development of thrombosis.

THERAPY

Therapeutic recommendations in accordance with the CURATIVE guidelines for dogs and cats are described in specific case vignettes presented. Discussion is centered on antithrombotic drug choices and dosing protocols, as outlined in Domains 2 and 3 of the CURATIVE guidelines. Where appropriate, guidelines related to therapeutic monitoring (Domain 4) and discontinuation of antithrombotics (Domain 5) were included.

PROGNOSIS

In small animals at risk of developing thrombosis, overall prognosis may be improved by following consensus-based recommendations on the use of antithrombotics as outlined in the CURATIVE guidelines. Whether such interventions have any impact on outcome requires further investigation.

Evaluation of nafamostat mesilate as an alternative anticoagulant during intermittent hemodialysis in healthy Beagle dogs

OBJECTIVE

To evaluate nafamostat mesilate (NM) as an alternative anticoagulant agent for intermittent hemodialysis (IHD).

DESIGN

Prospective randomized study.

SETTING

University teaching hospital.

ANIMALS

Eighteen healthy Beagle dogs.

INTERVENTIONS

In group 1 (n = 6), NM was administered at a dose of 0.5 mg/kg/h during IHD for 5 hours. In group 2 (n = 6), NM was administered at a low dose of 0.25 mg/kg/h during IHD. In group 3 (n = 6), which was the control group, unfractionated heparin (UFH) was administered during IHD. The evaluated parameters included: the amount of residual blood clots in the blood chamber and arterial side of the dialyzer; the levels of hemoglobin, hematocrit, and platelets; and the prothrombin time (PT), activated partial thromboplastin time (aPTT), and activated clotting time (ACT).

MEASUREMENTS AND MAIN RESULTS

Groups 1 and 2 successfully completed IHD without serious coagulation in the extracorporeal circulation. The residual blood clotting in the blood chamber and arterial side of the dialyzer did not significantly differ in groups 1 and 2 compared to group 3 (group 1 vs group 3, P = 1.000; and group 2 vs group 3, P = 1.000). No significant differences were observed between pre- and posttreatment PTs in groups 1 (P = 0.476) and 2 (P = 0.597), between pre- and posttreatment aPTTs in groups 1 (P = 0.983) and 2 (P = 0.977), and between pre- and posttreatment ACT in groups 1 (P = 0.282) and 2 (P = 0.401). In group 3, a significant elevation of ACT was observed at the posttest (P < 0.001).

CONCLUSIONS

The results of this study in healthy Beagle dogs suggest that NM at 0.25 mg/kg/h may be a valid alternative to UFH for IHD. Further studies are needed in patients at high risk of bleeding.

Treatment of ibuprofen intoxication in a dog via therapeutic plasma exchange

OBJECTIVE

To describe the treatment of ibuprofen intoxication with therapeutic plasma exchange in a dog (TPE).

SUMMARY

A 13-year-old male neutered mixed breed dog presented after ingesting approximately 200 mg/kg of ibuprofen. Treatment consisted of supportive medical therapy with IV fluids, gastrointestinal protectants, antiemetics and prostaglandin analogs, and TPE. A cycle of TPE was performed over 180 minutes, achieving 1.5 plasma volume exchanges. During therapy, heparinized blood and effluent samples were collected. Ibuprofen concentrations were determined in the samples by high-pressure liquid chromatography. Post TPE, the dog was continued on supportive medical therapy and was discharged 96 hours after the overdose.

NEW OR UNIQUE INFORMATION

This report describes the use of TPE as an adjunct for ibuprofen intoxication. An 85% reduction in plasma ibuprofen concentration occurred and recovery from a potentially lethal ingestion of ibuprofen was achieved with TPE and supportive care. TPE should be considered when presented with acute ibuprofen intoxication due to the rapid and efficacious nature of therapy.

Use of Renal Replacement Therapy in a Neonatal Foal with Postresuscitation Acute Renal Failure

A newborn foal was presented because it was unresponsive and in cardiopulmonary arrest. Aggressive cardiopulmonary cerebral resuscitation was administered to the foal, which revived the foal; however, acute renal failure developed. Fluid retention and azotemia occurred although the foal was alert and able to suckle. A 6‐hour renal replacement therapy session using hemodiafiltration and a continuous renal replacement therapy machine was administered to the foal at 3 days of age which lowered the foal's azotemia and facilitated removal of some of the excess body fluid. Despite therapy, the foal developed pulmonary edema and was euthanized. Although the foal in this case did not survive, this report highlights the possibility of developing postresuscitation complications such as acute renal failure and describes the use of renal replacement therapy using hemodiafiltration as a viable option in neonatal foals with acute kidney injury.

Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement

OBJECTIVES

There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised.

METHODS

Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species.

RESULTS

Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD.

DISCUSSION

The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine.

Management of acute kidney injury with continuous venovenous haemodiafiltration in a cat

Continuous renal replacement therapy is an emerging technique for the treatment of acute kidney injury (AKI). Data regarding its use in cats are limited. This report describes the use of a novel continuous renal replacement therapy (CRRT) system for the treatment of AKI in a cat. A 1.3-year-old cat developed uraemic signs following the administration of a non-steroidal anti-inflammatory agent for the treatment of a suspect traumatic episode. CRRT was provided with a Prismaflex Gambro machine used in continuous venovenous haemodiafiltration mode, with an AN-69 surface-treated membrane, synthetic colloid priming and heparin anticoagulation. Two treatment cycles were performed, totalling 51 h of CRRT. The treatment was effective in controlling uraemic signs, and no major complications were noted. Owing to financial constraints the owners declined further CRRT treatments, and on day 8 of hospitalisation, owing to the lack of significant clinical improvement, humane euthanasia was performed. The set-up detailed in this report provides a viable option for the initial treatment of cats with AKI.

Long-term outcome of cats and dogs with acute kidney injury treated with intermittent hemodialysis: 135 cases (1997-2010)

OBJECTIVE

To determine the long-term outcome for small animal patients with acute kidney injury (AKI) treated with intermittent hemodialysis (IHD).

DESIGN

Retrospective case series.

ANIMALS

42 cats and 93 dogs treated with IHD for AKI.

PROCEDURES

Medical records of cats and dogs treated with IHD for AKI from January 1997 to October 2010 were reviewed. Standard methods of survival analysis with Kaplan-Meier product limit curves were used. The log-rank, Mann-Whitney, and Kruskal-Wallis tests were used to determine whether outcome, number of IHD treatments, or duration of hospitalization was different when dogs and cats were classified according to specific variables.

RESULTS

The overall survival rate at the time of hospital discharge was 50% (21/42) for cats and 53% (49/93) for dogs. The overall survival rate 30 days after hospital discharge was 48% (20/42) for cats and 42% (39/93) for dogs. The overall survival rate 365 days after hospital discharge was 38% (16/42) for cats and 33% (31/93) for dogs. For all-cause mortality, the median survival time was 7 days (95% confidence interval, 0 to 835 days) for cats and 9 days (95% confidence interval, 0 to 55 days) for dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Cats and dogs with AKI treated with IHD have survival rates similar to those of human patients. Although there was a high mortality rate prior to hospital discharge, those patients that survived to discharge had a high probability of long-term survival.

Extracorporeal renal replacement therapy and blood purification in critical care

OBJECTIVE

To review indications methods of renal replacement therapies (RRT) and practical considerations for the creation of a RRT program.

DATA SOURCES

Current human and veterinary literature review with a focus on advanced renal physiology and clinical experience in RRT and acute/chronic kidney diseases.

DATA SYNTHESIS

Renal replacement therapies encompass intermittent hemodialysis, continuous renal replacement therapy as well as some "hybrid" techniques. Each method of RRT has practical and theoretical advantages but currently there is no evidence that one technique is superior to the other.

CONCLUSIONS

RRT is a valuable therapeutic tool for treatment of acute kidney injury and chronic kidney disease. The implementation of an RRT program needs to take into consideration multiple parameters beyond the choice of an RRT platform.