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.
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.
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.
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°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 μmol/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.
Objective—To determine the strength of the relationship between paradoxical breathing (PB) and spontaneous pleural diseases in dyspneic dogs and cats.
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.
Objective—To compare pharmacokinetics and clearances of creatinine and iohexol as estimates of glomerular filtration rate (GFR) in dogs with various degrees of renal function.
Animals—50 Great Anglo-Francais Tricolor Hounds with various degrees of renal function.
Procedures—Boluses of iohexol (40 mg/kg) and creatinine (647 mg/kg) were injected IV. Blood samples were collected before administration and 5 and 10 minutes and 1, 2, 4, 6, and 8 hours after administration. Plasma creatinine and iohexol concentrations were assayed via an enzymatic method and high-performance liquid chromatography, respectively. A noncompartmental approach was used for pharmacokinetic analysis. Pharmacokinetic variables were compared via a Bland-Altman plot and an ANOVA.
Results—Compared with results for creatinine, iohexol had a significantly higher mean ± SD plasma clearance (3.4 ± 0.8 mL/min/kg vs 3.0 ± 0.7 mL/min/kg) and a significantly lower mean volume of distribution at steady state (250 ± 37 mL/kg vs 539 ± 73 mL/kg), mean residence time (80 ± 31 minutes vs 195 ± 73 minutes), and mean elimination half-life (74 ± 20 minutes vs 173 ± 53 minutes). Despite discrepancies between clearances, especially for high values, the difference was < 0.6 mL/min/kg for 34 (68%) dogs. Three dogs with a low GFR (< 2 mL/min/kg) were classified similarly by both methods.
Conclusions and Clinical Relevance—Plasma iohexol and creatinine clearances can be used interchangeably for screening patients suspected of having chronic kidney disease (ie, low GFR), but large differences may exist for dogs with a GFR within or above the reference range.