Brice S. Reynolds

Estimation of glomerular filtration rate via 2- and 4-sample plasma clearance of iohexol and creatinine in clinically normal cats.

OBJECTIVE To compare 2 methods for estimation of glomerular filtration rate (GFR), study the effects of age and body size on GFR estimates, and provide a reference range for estimated GFR in clinically normal cats. ANIMALS 57 cats. PROCEDURES In each cat, GFR was estimated via plasma clearance of iohexol and creatinine. Results of a 1-compartmental model (CL1comp) were calibrated to a trapezoidal method estimate (CLtrap) by use of a correction formula applicable to dogs or humans and standardized to body weight; for iohexol clearance, data were also standardized to extracellular fluid volume (ECFV). For all 57 cats, method comparison was performed via agreement analysis. Reference ranges for GFR derived by the different methods were established by use of data from a subset of 51 cats after exclusion of 6 cats that were azotemic, Birman, or both. RESULTS In 57 cats, mean CLtrap of creatinine was 0.29 mL/min/kg (13%) higher than CLtrap of iohexol. In 51 nonazotemic cats, mean CLtrap was 2.26 mL/min/kg for iohexol (reference range, 1.02 to 3.50 mL/min/kg) and 2.55 mL/min/kg for creatinine (reference range, 1.27 to 3.83 mL/min/kg). Values of GFR/kg or GFR standardized to liters of ECFV did not decrease with increasing age. A negative linear relationship was detected between body weight and estimated GFR/kg or GFR standardized to liters of ECFV. CONCLUSIONS AND CLINICAL RELEVANCE Reference ranges for estimated GFR via plasma clearance of iohexol and creatinine should facilitate early detection of impaired renal function in cats, although body weight should be taken into account.

Effects of Dietary Salt Intake on Renal Function: A 2-Year Study in Healthy Aged Cats

BACKGROUND Increasing salt intake to promote diuresis has been suggested in the management of feline lower urinary tract disease. However, high dietary salt intake might adversely affect blood pressure and renal function. OBJECTIVES The objective of this study was to assess the long-term effects of increased salt intake on renal function in healthy aged cats. METHODS This study was controlled, randomized, and blinded. Twenty healthy neutered cats (10.1 ± 2.4 years) were randomly allocated into 2 matched groups. One group was fed a high salt diet (3.1 g/Mcal sodium, 5.5 g/Mcal chloride) and the other a control diet of same composition except for salt content (1.0 g/Mcal sodium, 2.2 g/Mcal chloride). Clinical examination, glomerular filtration rate, blood pressure measurement, cardiac and kidney ultrasonography, and urinary and blood tests were performed before and over 24 months after diet implementation. Statistics were performed using a general linear model. RESULTS Sixteen cats completed the 2 year study. The only variables affected by dietary salt intake were plasma aldosterone and urinary sodium/creatinine ratio, respectively, higher and lower in the control group all over the study period and urinary specific gravity, lower in the high salt diet group at 3 months. CONCLUSIONS AND CLINICAL IMPORTANCE Glomerular filtration rate (GFR), blood pressure, and other routine clinical pathological variables in healthy aged cats were not affected by dietary salt content. The results of this 2 year study do not support the suggestion that chronic increases in dietary salt intake are harmful to renal function in older cats.

Feline CKD Pathophysiology and risk factors — what do we know?

Practical relevance: Chronic kidney disease (CKD) is one of the most frequently encountered disorders in cats, having increased in prevalence in recent decades. Although the underlying cause is rarely identified, the common final outcome of feline CKD is tubulointerstitial fibrosis. Knowledge of CKD pathophysiology is necessary for optimal individualised patient management, especially with regard to diagnosis and treatment of extrarenal complications. Patient group: CKD is most common in senior and geriatric cats, but should be considered in any feline patient with ureterolithiasis, hyperthyroidism, retrovirus infection, systemic hypertension, cardiovascular disease or urinary tract infection. Evidence base: Most of our knowledge of the pathogenesis of CKD is extrapolated from human nephrology and experimental animal studies. There is, therefore, a need for further studies in cats. The prevalence of clinical signs in feline CKD is well documented. Several concurrent diseases associated with CKD have also been reported in cats, especially in the geriatric population, but there is no or only limited published evidence demonstrating a cause-and-effect relationship between most of these conditions and CKD. Studies performed over the past 15 years have nevertheless allowed identification of major risk factors (proteinuria, plasma phosphate and plasma creatinine) influencing the progression of feline CKD. Clinical challenges: Clinical signs occur in the late stages of renal disease, so populations at higher risk of CKD should be screened routinely. CKD-associated complications (systemic hypertension, secondary renal hyperparathyroidism, hypokalaemia, anaemia, metabolic acidosis) must not be overlooked as they may affect the progression of disease. Disease progression is itself unpredictable and renal function may remain stable for extended periods. Most cats with early CKD do not progress to end-stage CKD before they die. Audience: General practitioners play a major role in screening feline patients at risk of development or progression of CKD.

Comparison of a new device for blood sampling in cats with a vacuum tube collection system—Plasma biochemistry, haematology and practical usage assessment

Using paediatric devices to collect venous blood from a cephalic vein in cats offers numerous practical advantages over traditional jugular venepuncture and vacuum closed systems: minimal restraint is required; there is minimal risk of serious injury to the cat; the discomfort associated with venepuncture is reduced by the use of small diameter (25 gauge) needles; very small volumes (200 μl) of blood are extracted; and the risk of vein collapse or haematoma is low. The aim of this study was to compare the haematological and plasma chemistry results obtained from six healthy cats using the two sampling techniques. Five plasma biochemical analytes were measured and a complete haematological examination was performed on each specimen. No clinically relevant difference between the two blood sampling techniques was observed for any variable, indicating that paediatric devices provide a useful alternative to vacuum tubes for venous blood collection in the cat.

Effects of intravenous, low-dose ketamine-diazepam sedation on the results of hematologic, plasma biochemical, and coagulation analyses in cats

OBJECTIVE To evaluate the effects of an IV, low-dose ketamine-diazepam combination used for short-duration chemical restraint on the results of clinicopathologic testing in cats and to assess its practicality and tolerance. DESIGN Prospective case series. ANIMALS 42 client-owned cats of various breeds, ages, and health status. PROCEDURES Blood samples were obtained just prior to and just after IV injection of ketamine chlorhydrate (10 mg) and diazepam (0.5 mg). A CBC, plasma biochemistry panel, and coagulation profile were performed on each sample (ie, before and after chemical restraint). Practicality of the procedure was assessed, and cats were monitored for immediate and delayed effects. RESULTS Significant changes were observed for most of the analytes tested. However, the magnitude of the observed changes was notably low and likely not of clinical relevance. The chemical-restraint procedure appeared effective, safe, and well tolerated. CONCLUSIONS AND CLINICAL RELEVANCE The IV, low-dose ketamine-diazepam combination used for short-duration chemical restraint in the present study may be suitable to assist physical restraint for blood sampling for assessment of hematologic, serum biochemical, and coagulation parameters in cats.

Within-day and between-day variability of blood pressure measurement in healthy conscious Beagle dogs using a new oscillometric device

OBJECTIVES The main objective of this study was to determine the within- and between-day variability of blood pressure measurement in dogs using an oscillometric device, pet-MAP. ANIMALS, MATERIALS AND METHODS Five healthy conscious adult Beagle dogs were used. The dogs were presented in a random order for examinations and the investigators were blinded to the dogs. Blood pressure was measured using a standardized procedure. Three investigators with the same level of experience, trained for 1 h with pet-MAP the day before starting the study, performed 480 blood pressure measurements in 5 healthy conscious dogs on two different days. RESULTS The within- and between-day CVs for systolic blood pressure were 9.0-10.1% and 12.8-16.4%, respectively. The corresponding SD values were 14.7-16.6 mm Hg and 21.0-27.1 mm Hg respectively. For diastolic blood pressure, the within- and between-day CVs were 10.3-14.4% and 14.2-24.9% respectively. The corresponding SD values were 9.7-13.9 mm Hg and 13.0-24.0 mm Hg. CONCLUSIONS The within- and between-day CVs for systolic blood pressure, measured with pet-MAP by investigators with a minimal period of training, seem to be acceptable in Beagle dogs without hypertension or hypotension. This study suggests that, using this device, one investigator can be replaced by another under the described circumstances.

Determination of reference intervals for plasma biochemical values in clinically normal adult domestic shorthair cats by use of a dry-slide biochemical analyzer

OBJECTIVE To establish reference intervals of plasma biochemical values in healthy adult domestic shorthair (DSH) cats by use of controlled conditions. ANIMALS 95 healthy client-owned cats. PROCEDURES Food was withheld from the cats overnight. All blood samples were obtained on the same day, at the same location, and by the same investigator. Blood samples were collected from a cephalic vein into lithium heparin tubes. After centrifugation of blood samples, plasma supernatants were harvested and stored at -20 degrees C until assayed for total proteins, albumin, creatinine, urea, glucose, calcium, phosphates, sodium, chloride, potassium, and CO2 concentrations and alkaline phosphatase and alanine aminotransferase activities. RESULTS Reference intervals in healthy adult DSH cats were 65 to 85 g/L for total proteins, 27 to 39 g/L for albumin, 89 to 207 micromol/L for creatinine, 6.6 to 11.3 mmol/L for urea, 4.1 to 8.2 mmol/L for glucose, 2.4 to 2.9 mmol/L for calcium, 1.1 to 2.1 mmol/L for phosphates, 153 to 161 mmol/L for sodium, 120 to 127 mmol/L for chloride, 3.3 to 4.2 mmol/L for potassium, 15 to 21 mmol/L for CO2, 32 to 147 U/L for alkaline phosphatase, and 34 to 123 U/L for alanine aminotransferase. CONCLUSIONS AND CLINICAL RELEVANCE This study provided reference intervals for plasma analytes in adult DSH cats. The influence of potential confounding factors was minimized through use of controlled preanalytic and analytic conditions. However, these results cannot be extrapolated to other feline breeds or used to interpret results from other biochemical analyzers.

Relationship between paradoxical breathing and pleural diseases in dyspneic dogs and cats: 389 cases (2001-2009).

OBJECTIVE To determine the strength of the relationship between paradoxical breathing (PB) and spontaneous pleural diseases in dyspneic dogs and cats. DESIGN Cross-sectional study. ANIMALS Dogs (n = 195) and cats (194) with a recorded diagnosis of dyspnea examined at the National Veterinary Schools of Alfort and Toulouse (France) between January 2001 and October 2009. PROCEDURES Dogs and cats were divided into 2 groups according to the presence or absence of PB. Stratified analysis by species was performed. Signalment of affected animals and occurrence of PB were recorded. The relationship between PB and pleural diseases among dyspneic dogs and cats was analyzed. RESULTS A strong relationship between PB and pleural diseases was highlighted in multivariate analysis (dogs, OR = 12.6 and 95% confidence interval = 4.6 to 31.2; cats, OR = 14.1 and 95% confidence interval = 6.0 to 33.5). Paradoxical breathing prevalence among dyspneic dogs and cats was 27% and 64%, respectively. Occurrence of pleural diseases in dyspneic animals with and without PB was 49% and 9% in dogs and 66% and 13% in cats, respectively. The sensitivity and specificity of PB as a predictor of pleural diseases were 0.67 and 0.83 in dyspneic dogs and 0.90 and 0.58 in dyspneic cats, respectively. The positive and negative predictive values of PB were 0.49 and 0.91 in dyspneic dogs and 0.66 and 0.87 in dyspneic cats, respectively. Age, sex, feline breeds, and canine morphotypes in patients with PB were not significantly different from those of other dyspneic animals. CONCLUSIONS AND CLINICAL RELEVANCE PB was strongly associated with pleural diseases in dyspneic dogs and cats. The presence of this clinical sign should prompt small animal practitioners to implement appropriate emergency procedures and guide their diagnostic strategy.

Cardiovascular Effects of Dietary Salt Intake in Aged Healthy Cats: A 2-Year Prospective Randomized, Blinded, and Controlled Study

High salt dry expanded diets are commercially available for cats to increase water intake and urine volume, as part of the prevention or treatment of naturally occurring urinary stone formation (calcium oxalates and struvites). However, chronic high salt intake may have potential cardiovascular adverse effects in both humans, especially in aging individuals, and several animal models. The objective of this prospective, randomized, blinded, and controlled study was to assess the long-term cardiovascular effects of high salt intake in healthy aged cats. Twenty healthy neutered cats (10.1±2.4 years) were randomly allocated into 2 matched groups. One group was fed a high salt diet (3.1 g/Mcal sodium, 5.5 g/Mcal chloride) and the other group a control diet of same composition except for salt content (1.0 g/Mcal sodium, 2.2 g/Mcal chloride). Clinical examination, systolic and diastolic arterial blood pressure measurements, standard transthoracic echocardiography and conventional Doppler examinations were repeatedly performed on non-sedated cats by trained observers before and over 24 months after diet implementation. Radial and longitudinal velocities of the left ventricular free wall and the interventricular septum were also assessed in systole and diastole using 2-dimensional color tissue Doppler imaging. Statistics were performed using a general linear model. No significant effect of dietary salt intake was observed on systolic and diastolic arterial blood pressure values. Out of the 33 tested imaging variables, the only one affected by dietary salt intake was the radial early on late diastolic velocity ratio assessed in the endocardium of the left ventricular free wall, statistically lower in the high salt diet group at 12 months only (P = 0.044). In conclusion, in this study involving healthy aged cats, chronic high dietary salt intake was not associated with an increased risk of systemic arterial hypertension and myocardial dysfunction, as observed in some elderly people, salt-sensitive patients and animal models.

Pseudomembranous cystitis, an unusual condition associated with feline urine outflow obstruction: Four cases

The clinical follow-up of four cats presumptively diagnosed with pseudomembranous cystitis is described. All presented with acute urine outflow obstruction and acute renal failure. Urethral catheterisation was performed without difficulty but ultrasonography and contrast radiography consistently revealed abnormal bladder wall and content. One cat was euthanased, the remaining three underwent an exploratory cystotomy. Abundant inflammatory and necrotic tissue covering an ulcerated bladder mucosa was removed. All cats recovered uneventfully. No definitive cause was identified but the clinical course of the disease was not typical of idiopathic cystitis.