Fluid therapy for acute and chronic renal failure

Animals with renal failure have a number of fairly predictable metabolic abnormalities. They are commonly presented to the veterinarian in a state of negative water balance, although prior fluid therapy in an oliguric patient may result in overhydration. Animals with oliguric ARF have sodium retention; those with polyuric ARF have increased urinary sodium loss. Chronic renal failure does not necessarily affect the ability of the renal tubule to conserve or excrete sodium, although the response to changes in sodium load is much slower than in the normal animal. Potassium retention occurs in oliguric ARF and potassium wasting in polyuric ARF; potassium balance is approximately normal in animals with CRF. Both ARF and CRF cause metabolic acidosis, although the acid-base status in a given animal will be affected by respiratory compensation, as well as other problems such as vomiting. Calcium levels are usually normal to slightly decreased in renal failure, whereas phosphorus levels are generally increased. The basic principles of fluid therapy should be used when constructing a plan for such therapy in an animal with renal failure. Intravenous administration of fluids is almost always necessary. The choice of the type of fluid, solutes, and electrolytes to be administered is based on the predicted abnormalities associated with renal failure as well as the laboratory abnormalities in the animal. Careful monitoring of the patient and periodic assessment of various laboratory parameters are necessary in order to make appropriate adjustments in fluid therapy.     

Anesthetic management in feline renal transplantation

Objective To document perioperative and anesthetic management of 30 feline renal transplant recipients (1996–1998). Study design Retrospective clinical study. Animals Thirty adult cats in end‐stage renal failure that underwent heterotopic renal transplantation. Materials and methods The medical records were reviewed from 30 feline heterotopic renal transplant recipients. Cases were included only if they had been treated for hypertension using a beta‐adrenergic antagonist, a calcium channel blocker or hemodialysis. Data regarding signalment, preoperative management, surgical technique, type and doses of anesthetics administered, perioperative hemodynamics and intra‐ and postoperative complications, postoperative analgesia, morbidity and early mortality were recorded. Data were expressed as mean ± SD. Results Preanesthetic medication included a combination of an anticholinergic and an opioid (oxymorphone). Anesthesia induction was performed mostly with isoflurane and oxygen delivered by mask. Anesthesia maintenance was primarily achieved with isoflurane in 100% oxygen. Nitrous oxide was often used as part of the anesthetic technique. The mean duration of anesthesia was 4.6 hours ± 27 minutes. The mean renal allograft ischemic time was 60 minutes. During the anesthetic period, the majority of the recipient cats received either fresh whole blood (FWB) (N = 25, 83%), cross‐matched packed red blood cells (PRBC) (N = 3, 10%) or fresh frozen plasma (FFP) (N = 2, 7%) combined with a balanced electrolyte solution. Blood products administered averaged 63 ± 34 mL and crystalloid 94 ± 62 mL. The most common treated intraoperative complications were hypotension (N = 14, 47%), hypothermia (N = 13, 43%), metabolic acidosis (N = 11, 37%), hypocalcemia (N = 5, 17%), hypoglycemia (N = 4, 13%), hypertension (N = 2, 7%), bradycardia (N = 1, 3%), and ventricular premature contractions (N = 1, 3%). All cats received opioid analgesics postoperatively. Complications observed in the first 24 hours postoperatively were hypertension (N = 20, 67%), hematuria (N = 14, 47%), electrolyte disturbances (N = 9, 30%), temperature imbalances (N = 5, 17%), decreased PCV requiring blood transfusion (N = 5, 17%), decreased perfusion of a foot associated with external iliac anastomosis technique (N = 5, 17%), seizures associated with hypertension (N = 3, 10%), uroabdomen (N = 2, 7%), acute graft rejection (N = 1, 3%) and, corneal ulceration (N = 1, 3%). Survival rates in the perioperative period were 100, 96.7, and 93.4% intraoperatively, at 24 hours, and 7 days following surgery. Conclusion Successful anesthesia can be performed in critically ill renal transplant recipients. However, for optimal graft function and patient survival, normothermia, normovolemia, normotension, and normal acid–base and electrolyte balance should be carefully maintained. Successful anesthetic management requires understanding of the pathophysiology of end‐stage renal disease and the maintenance of homeostasis during the different stages of the perioperative period.     

Dietary management of canine and feline chronic renal failure

Nutritional therapy is the mainstay of management of chronic renal failure in dogs and cats. Diets designed for use in renal failure are typically reduced in protein, phosphorus, and sodium content. These and other dietary modifications are designed to prevent or ameliorate clinical signs of uremia, minimize disturbances associated with excesses or losses of electrolytes and minerals, arrest or retard progression of renal failure, and maintain adequate nutrition.     

Strategies for management of acute renal failure.

Acute renal failure (ARF) is often defined as the sudden inability of the kidneys to regulate water and solute balance. ARF may be more broadly defined as rapid deterioration of renal function resulting in the accumulation of nitrogenous wastes such as urea and creatinine. Clinically, oliguria is defined as urine flow of less than 2 mL/kg/h and anuria has no measurable urine production. In animals, the most common cause of ARF is nephrotoxicity; ischemia ranks second, with interstitial and glomerular diseases following.     

Pleural dialysis in the management of acute renal failure in two dogs

Pleural dialysis, as an alternative to peritoneal dialysis and hemodialysis, was shown in a limited number of cases to be an inexpensive and easily applied technique for use in dogs. It is a viable modality for the management of acute renal failure in dogs that have suffered an acute but reversible renal insult, in which volume replacement and dopamine/furosemide infusion fails to reverse the oliguric state.     

Peritoneal dialysis in the management of acute renal failure in 5 dogs with leptospirosis

Objective: To describe the use of peritoneal dialysis (PD) in the management of 5 dogs with acute renal failure (ARF) caused by leptospirosis. Case Series Summary: All dogs were treated for leptospirosis with intravenous (IV) fluids and ampicillin prior to PD. Median age of dogs was 5 years (range 2–6 years). All dogs had positive titers for Leptospira bratislava. Median duration of PD was 4 days (range 3–16 days). PD resulted in a decrease in azotemia in all dogs. Median serum blood urea nitrogen at the start of PD was 192 mg/dL (range 140–235 mg/dL) and at the end of PD was 63 mg/dL (range 48–139 mg/dL). Median serum creatinine at the start of PD and the end was 12.8 mg/dL (range 7.7–16.9 mg/dL) and 3.4 mg/dL (range 1.4–11.1 mg/dL), respectively. Complications identified during PD included hypokalemia (n=3, 60%), hypoalbuminemia (n=2, 40%), hypomagnesemia (n=1, 20%), pelvic limb edema (n=2, 40%), central nervous system signs (n=2, 40%), dialysate retention (n=1, 20%), and leakage from the catheter site (n=1, 20%). Peritonitis was not identified in any of the dogs. Four dogs (80%) survived to discharge from the hospital. PD was effective for management of uremia in dogs with ARF caused by leptospirosis.     

Use of dopamine in acute renal failure

Objective: To review the current understanding of dopamine and its use in the prevention and treatment of acute renal failure (ARF). Data sources: Original research articles and scientific reviews. Human data synthesis: Low‐dose dopamine administration has been shown to increase natriuresis and urinary output in both healthy individuals and in a few small studies in human patients with renal insufficiency. However, in several large meta‐analyses, dopamine treatment did not change mortality or the need for dialysis. Due to the potential side effects, the use of dopamine for prevention and treatment of ARF is no longer recommended in human medicine. Veterinary data synthesis: Low‐dose dopamine increases urinary output in healthy animals and animal models of ARF if given before the insult. There are no available studies looking at the effect of low‐dose dopamine therapy in naturally occurring ARF in dogs or cats. Conclusion: Due to the potential side effects of low‐dose dopamine therapy, the results from large human trials, and the lack of information in veterinary medicine, the use of dopamine for treatment of ARF in veterinary patients should be further evaluated.     

Gentamicin-associated acute renal failure in the dog

Gentamicin-associated acute renal failure was diagnosed in 10 dogs. The disease was characterized by a poor prognosis and lengthy hospitalization. Hypoalbuminemia, disorders of potassium homeostasis, proteinuria, hematuria, and cylindruria were common during therapy for renal failure. Fever and dehydration were the most commonly identified potential predisposing factors.     

Evaluation of parameters for the differentiation of acute from chronic renal failure in the dog

The differentiation of acute (ARF) from chronic (CRF) renal failure is important for therapeutic and prognostic reasons and should be established as soon as possible. In practice this differentiation is often based on history, physical examination and laboratory results. In this retrospective study the diagnostic accuracy of parameters to differentiate ARF from CRF was tested in 19 dogs with ARF and 49 dogs with CRF. The diagnostic accuracy of body condition was 65%, of the hematocrit 78%, of serum potassium levels 28%, of total CO2 48%, of urinary casts 77%, of glucosuria 90% and of the urine protein-to-urine creatinine ratio 43%. Of all the parameters evaluated only glucosuria revealed an acceptable discriminating quality with a sensitivity of 92% and a specificity of 89%. A limitation of this factor is, that glucosuria depends on the cause of ARF. The single parameters tested are not very useful and the diagnosis of ARF or CRF is based on a combination of parameters from history, physical examination, laboratory results and diagnostic imaging. If a diagnosis can't be established immediately, treatment for ARF is recommended. With an immediate, aggressive treatment the possibility of total recovery from ARF is increased.     

Dietary management of renal senescence and failure in dogs

SUMMARY The need for dietary management of renal senescence and the beginning of chronic renal failure should be evaluated in all middle-aged dogs. One survey found that 35% were overweight and 10% underweight; another that 25% were mildly azotaemic, with 5% showing slight clinical signs of chronic renal failure. Dogs in prime condition or overweight are candidates for a diet low in energy (for example 3.0–3.3 kcal/g dry matter, DM), but thin dogs need a higher caloric density (such as 4.0–4.5 kcal/g DM). Healthy older dogs need higher dietary protein than the minimum for maintenance (about 20% on a metabolisable energy basis, ME) of young mature dogs. Thin older dogs showing signs of renal insufficiency may benefit from moderate protein and near-minimal phosphorus in the diet. In dogs with chronic renal failure, clinical, haematological and biochemical responses to the combination of low protein (13–16% ME) and low phosphorus (0.4% DM) were positive in one clinical trial but not in three others. Only beneficial responses, such as less proteinuria, less renal impairment and lower mortality, have been reported for diets containing low phosphorus and moderate protein (20–31% ME). Individual dietary goals for energy, protein and phosphorus should be chosen for each middle-aged or older dog; these goals may be met by a single product or mixtures of products.     

Survival of cats with naturally occurring chronic renal failure: effect of dietary management

Fifty cats with naturally occurring stable chronic renal failure (CRF) were entered into a prospective study on the effect of feeding a veterinary diet restricted in phosphorus and protein with or without an intestinal phosphate binding agent on their survival from initial diagnosis. Twenty-nine cats accepted the veterinary diet, whereas compliance (due to limited intake by the cats or owner resistance to diet change) was not achieved in the remaining 21. At diagnosis, both groups of cats were matched in terms of age, bodyweight, plasma creatinine, phosphate, potassium and parathyroid hormone (PTH) concentrations, packed cell volume and urine specific gravity. Feeding the veterinary diet was associated with a reduction in plasma phosphate and urea concentrations and prevented the increase in plasma PTH concentrations seen in cats not receiving the diet. Cats fed the veterinary diet survived for longer when compared with those that were not (median survival times of 633 versus 264 days). These data suggest that feeding a diet specifically formulated to meet the needs of cats with CRF, together with phosphate binding drugs if required, controls hyperphosphataemia and secondary renal hyperparathyroidism, and is associated with an increased survival time.     

The anemia of chronic renal failure revisited

The mechanisms of the anemia of chronic renal failure are reviewed. Ineffective erythropoiesis is undoubtedly the major cause of this anemia. The contributions of inadequate erythropoietin secretion by the diseased kidneys, suppressive effects of uremic "toxins" on erythropoiesis and red cell survival, excess blood loss, and plasma concentrations of parathyroid hormone, calcium and phosphate are discussed.     

Ultrasonography of the parathyroid glands as an aid in differentiation of acute and chronic renal failure in dogs

OBJECTIVE: To evaluate whether determination of parathyroid gland size by use of ultrasonography is helpful in differentiating acute renal failure (ARF) from chronic renal failure (CRF) in dogs. DESIGN: Prospective study. ANIMALS: 20 dogs with renal failure in which serum creatinine concentration was at least 5 times the upper reference limit. Seven dogs had ARF, and 13 dogs had CRF. Twenty-three healthy dogs were used as controls. PROCEDURE: Dogs were positioned in dorsal recumbency for ultrasonographic examination of the ventral portion of the neck, A 10-MHz linear-array high-resolution transducer was used. The size of the parathyroid gland was determined by measuring the maximal length of the gland on the screen when it was imaged in longitudinal section. For comparison among groups, the longest linear dimension of any of the parathyroid glands of each dog was used. RESULTS: Size of the parathyroid glands in the control dogs varied from 2.0 to 4.6 mm (median, 3.3 mm). In the dogs with ARF, gland size ranged from 2.4 to 4.0 mm (median, 2.7), which was not significantly different from controls. In dogs with CRF, the glands were more distinctly demarcated from the surrounding thyroid tissue, than those of controls and dogs with ARF. Sizes ranged from 3.9 to 8.1 mm (median, 5.7 mm), which was significantly larger, compared with controls and dogs with ARF. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with severe azotemia, ultrasonographic examination of the parathyroid glands was helpful in differentiating ARF from CRF Size of the parathyroid glands appeared to be related to body weight.     

Tumoral calcinosis in a dog with chronic renal failure

A 2-year-old male German shepherd dog in poor bodily condition was evaluated for thoracic limb lameness due to a large, firm mass medial to the left cranial scapula. Radiography revealed several large cauliflower-like mineralized masses in the craniomedial left scapula musculature, pectoral region and bilaterally in the biceps tendon sheaths. Urinalysis, haematology and serum biochemistry showed that the dog was severely anaemic, hyperphosphataemic and in chronic renal failure. The dog was euthanased and a full post mortem performed. A diagnosis of chronic renal failure with secondary hyperparathyroidism was confirmed. The mineralised masses were grossly and histopathologically consistent with a diagnosis of tumoral calcinosis. Tumoral calcinosis associated with chronic renal failure that does not involve the foot pads is rarely seen.     

Serum concentrations of 1,25-dihydroxycholecalciferol and 25-hydroxycholecalciferol in clinically normal dogs and dogs with acute and chronic renal failure

OBJECTIVE: To compare serum concentrations of 1,25-dihydroxycholecalciferol (1,25-[OH]2D3) and 25-hydroxycholecalciferol (25-[OH]D3) in healthy control dogs and dogs with naturally occurring acute renal failure (ARF) and chronic renal failure (CRF). ANIMALS: 24 control dogs, 10 dogs with ARF, and 40 dogs with CRF. PROCEDURE: Serum concentrations of 1,25-(OH)2D3 were measured by use of a quantitative radioimmunoassay, and serum concentrations of 25-(OH)D3 were measured by use of a protein-binding assay. RESULTS: Mean +/- SD serum concentration of 1,25-(OH)2D3 was 153 +/- 50 pmol/L in control dogs, 75 +/- 25 pmol/L in dogs with ARF, and 93 +/- 67 pmol/L in dogs with CRF. The concentration of 1,25-(OH)2D3 did not differ significantly between dogs with ARF and those with CRF and was in the reference range in most dogs; however, the concentration was significantly lower in dogs with ARF or CRF, compared with the concentration in control dogs. Mean +/- SD concentration of 25-(OH)D3 was 267 +/- 97 nmol/L in control dogs, 130 +/- 82 nmol/L in dogs with ARF, and 84 +/- 60 nmol/L in dogs with CRF. The concentration of 25-(OH)D3 was significantly lower in dogs with ARF or CRF, compared with the concentration in control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: The concentration of 1,25-(OH)2D3 was within the reference range in most dogs with renal failure. Increased serum concentrations of parathyroid hormone indicated a relative deficiency of 1,25-(OH)2D3. A decrease in the serum concentration of 25-(OH)D3 in dogs with CRF appeared to be attributable to reduced intake and increased urinary loss.