The objective of this study was to determine whether subacute ruminal acidosis (SARA) could be diagnosed by continuous measurements of the reticular pH, as compared with the ruminal pH, using healthy cows fed a control diet and SARA cows fed a rumen acidosis-inducing diet. The reticular and ruminal pH were measured simultaneously by a radio transmission pH measurement system. The mean reticular pH at 1-h intervals decreased gradually from the morning feeding to the next feeding time in both healthy and SARA cows, though the decrease in the ruminal pH was observed to be more drastic as compared with that observed in the reticular pH. The threshold of the 1-h mean pH in the reticulum for a diagnosis of SARA was considered to be 6.3, and a significant positive correlation was observed between the reticular and ruminal pH. No differences in the concentrations of lactic acid, ammonia nitrogen, and volatile fatty acids were noted between the reticular and ruminal fluids in SARA cows. These results demonstrate that the reticular pH can be used to detect SARA in cows, as opposed to using the ruminal pH.

Background: Application of a multisample method using inulin to estimate glomerular filtration rate (GFR) in cats is cumbersome.Objectives: To establish a simplified procedure to estimate GFR in cats, a single-blood-sample method using inulin was compared with a conventional 3-sample method.Animals: Nine cats including 6 clinically healthy cats and 3 cats with spontaneous chronic kidney disease. Methods: Retrospective study. Inulin was administered as an intravenous bolus at 50 mg/kg to cats, and blood was collected at 60, 90, and 120 minutes later for the 3-sample method. Serum inulin concentrations were colorimetrically determined by an autoanalyzer method. The GFR in the single-blood-sample method was calculated from the dose injected, serum concentration, sampling time, and estimated volume of distribution on the basis of the data of the 3-sample method.Results: An excellent correlation was observed (r = 0.99, P = .0001) between GFR values estimated by the singleblood-sample and 3-sample methods.Conclusions and Clinical Importance: The single-blood-sample method using inulin provides a practicable and ethical alternative for estimating glomerular filtration rate in cats.

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The isotonic, nonionic, contrast medium iodixanol, as a test substance, was compared with the conventional glomerular filtration rate (GFR) tracer inulin to establish a simplified procedure for estimating the GFR in Holstein dairy cows. First, inulin and iodixanol were coadministered as a bolus intravenous injection to clinically healthy cows at 30 mg/kg and 10mg of I/kg of body weight, respectively, followed by blood collection for multisample strategies. Serum iodixanol and inulin concentrations were separately determined by using HPLC and colorimetry, respectively, and blood urea nitrogen and creatinine concentrations in sera were measured. In the multisample method, the GFR values estimated by iodixanol were consistent with those estimated by inulin. No effects of body weight, age, or parity on GFR estimates were noted with either protocol used. No difference was observed between the GFR values obtained from nonlactating and lactating cows, suggesting that no transfer of iodixanol to milk occurred. An equation for calculating the GFR in the single-sample method was derived from the injected dose, sampling time, serum concentration, and estimated volume of distribution based on data from the multisample method in clinically healthy cows and cows with reduced renal function. The GFR values estimated by the single-sample method were in good agreement with those calculated by using the multisample method. These results demonstrate that the single-sample method using iodixanol can be applied as an alternative procedure for screening GFR in dairy cows.

In contrast to Piaget’s formulation of the development of causality, adults often generate precausal reasoning in an attempt to understand natural phenomena. Such precausal reasoning is characterized in terms of agency, a concept that plays a central role in our understanding of causality. In this context, three issues are examined – the normative model of causality and heuristics, the distinction between causes and enabling conditions, and the perception of causality. It is proposed that causal reasoning is triggered by the detection of anomaly, presupposing the recognition of an ordinary pattern in natural phenomena. This anomaly is interpreted in terms of agency. The proposal is supported through reference to research on students’ misconceptions. Finally, the implications for conceptual change with respect to causal reasoning are discussed. It is proposed that it is not a causal understanding mechanism that changes with development but, rather, the perception of anomalies that changes as we acquire knowledge of causal relations, producing developmental changes in causal reasoning.