OBJECTIVE To determine whether passage of whole blood through a microaggregate filter by use of a syringe pump would damage canine erythrocytes. SAMPLE Blood samples obtained from 8 healthy client-owned dogs. PROCEDURES Whole blood was passed through a standard microaggregate filter by use of a syringe pump at 3 standard administration rates (12.5, 25, and 50 mL/h). Prefilter and postfilter blood samples were collected at the beginning and end of a simulated transfusion. Variables measured at each time point included erythrocyte osmotic fragility, mean corpuscular fragility, RBC count, hemoglobin concentration, RBC distribution width, and RBC morphology. In-line pressure when blood passed through the microaggregate filter was measured continuously throughout the simulated transfusion. After the simulated transfusion was completed, filters were visually analyzed by use of scanning electron microscopy. RESULTS Regardless of administration rate, there was no significant difference in mean corpuscular fragility, RBC count, hemoglobin concentration, or RBC distribution width between prefilter and postfilter samples. Additionally, there were no differences in in-line pressure during the simulated transfusion among administration rates. Echinocytes were the erythrocyte morphological abnormality most commonly observed at the end of the transfusion at administration rates of 12.5 and 25 mL/h. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that regardless of the administration rate, the microaggregate filter did not alter fragility of canine RBCs, but may have altered the morphology. It appeared that the microaggregate filter would not contribute to substantial RBC damage for transfusions performed with a syringe pump.

Power spectral analysis and digital filtering of brain stem auditory evoked potentials (BAEP) were performed in dogs. The BAEP were recorded in 7 dogs, using alternating clicks at frequency of 20 Hz. The clicks were delivered monaurally at intensity of 90-dB normal hearing level. Power spectral analysis indicated that the frequency compositions of the averaged responses were divisible into 4 frequency bands: A (30 to 390 Hz), B (390 to 680 Hz), C (680 to 910 Hz) and D (910 to 1960 Hz). The frequency limits of digital high-pass (HP) and low-pass (LP) filters, at which neither peak-to-peak nor absolute amplitudes were reduced, were 1,170 and 1,270 Hz for P1, 290 and 1,170 Hz for P2, 290 and 980 Hz for P3, 290 and 980 Hz for P4, and 200 and 880 Hz for P5, respectively. The dual structure of BAEP was confirmed in dogs. Below 200 Hz for the HP filter, peak-to-peak and absolute amplitudes of afl waves were not significantly reduced. Therefore, this frequency may be a boundary frequency between low- and high-frequency components of BAEP in dogs. The main source for the high- frequency components that constituted each positive peak and the following trough was derived from frequency bands C and D. The frequency limits of 200 Hz for a digital HP filter and of 1,270 Hz for a digital Lp filter, at which amplitudes of aU waves were not reduced, support the analog filter settings recommended for dogs (ie, less than and qual to 53 and 3,000 Hz for analog HP and LP filters, respectively).

Effects of analog filter frequency on brain stem auditory-evoked potentials (BAEP) were investigated in 7 non-sedated dogs. The BAEP were recorded successively at various low-pass (LP) and high-pass (HP) filter frequency settings. The analog filters had a rolloff of 6 dB/octave. Decrease of LP filter frequency from 30 khz to 100 Hz caused prolongation of the peak latency and reduction of the peak-to-peak (from a positive peak to the following trough) and absolute (from a positive peak to the baseline) amplitudes for aU peaks, except the peak latency for P5 and the absolute amplitude for P4. Changes in these variables were statistically significant (P < 0.05) at different cutoff frequencies specific for the individual peaks. The inter-peak latency between P1 and P4, and P4/P1 peak to-peak amplitude ratio were not changed significantly. At the lowest LP filter frequency of 100 Hz, positive peaks (fast waves) seemed to be superimposed on a slow positive wave (slow wave). In contrast, increase of HP filter frequency from 0.53 to 160 Hz did not result in significant changes for any peaks, except for reduction in the absolute amplitude of P4. The various effects of LP filter frequency and negligible effects of Hp filter frequency on individual peaks may be attributable to their frequency composition and/or elimination of the slow wave at higher HP filter frequency settings. On the basis of our results, LP filter setting of 3 kHz and HP filter setting of less than or equal to 53 Hz are recommended for recording of BAEP in dogs. These settings sufficiently attenuate unwanted high-frequency artifacts, are adequate for recording of fast and slow waves, and have only slight effects on configurations, peak latencies, and amplitudes.

Objective-To compare the recovery rates of Campylobacter fetus subsp venerealis (Cfv) from preputial scrapings of infected bulls with passive filtration on selective medium versus nonselective medium, with and without transport medium. Samples-217 preputial scrapings from 12 bulls (4 naturally and 8 artificially infected with Cfv). Procedures-Preputial scrapings were collected in 2 mL of PBS solution and bacteriologically cultured directly on Skirrow medium or passively filtered through 0.65-μm filters onto blood agar, with or without 24 hour preincubation in modified Weybridge transport enrichment medium (TEM). After 72 hours, plates were examined for Cfv and bacterial and fungal contamination or overgrowth. Results-Passive filtration of fresh preputial scrapings onto blood agar yielded significantly higher recovery rates of Cfv (86%) than direct plating on Skirrow medium (32%), whereas recovery from TEM was poor for both media (35% and 40%, respectively). Skirrow cultures without TEM were significantly more likely to have fungal contamination than were cultures performed with any other technique, and fungal contamination was virtually eliminated by passive filtration onto blood agar. Bacterial contamination by Pseudomonas spp was significantly more common with Skirrow medium versus passive filtration on blood agar, regardless of TEM use. Conclusions and Clinical Relevance-The use of transport medium and the choice of culture medium had significant effects on Cfv recovery and culture contamination rates from clinical samples. Both factors should be considered when animals are tested for this pathogen.

Objective: To determine whether standard manual frequency filters in the ON and OFF settings affected P-QRS-T voltages, discover whether recorded P-QRS-T voltages vary between commercial electrocardiographs, assess effects of frequency filters on base-line artifact, and evaluate ECG frequency content by high-fidelity recordings subjected to digital filters with variable frequencies. Design: Sequential 10-lead ECG were recorded in 30 cats, using 3 commercial electrocardiographs to assess effects of manual frequency filters on the P-QRS-T wave forms. Three clinically normal cats were evaluated for ECG frequency content. Animals: Thirty cats (13 with hypertrophic cardiomyopathy; 4 with restrictive cardiomyopathy; 3 hyperthyroid; 1 with ventricular septal defect; 1 with aortic stenosis; and 8 with no detectible cardiovascular disease). Three additional clinically normal cats were studied for effects of frequency filters on the ECG frequency content. Procedure: Ten-lead ECG were recorded on each cat by use of 3 commercial electrocardiographs sequentially. For each machine, a recording was made with manual filters ON, immediately followed by a recording with manual filters OFF. High-fidelity lead-II ECG recordings were made with filters set with their rolloff frequency at 0.1 Hz and 3.0 kHz; output voltage (0.2 mV/V) was fed to an analog-to-digital converter, then to attendant software, which sampled the signal at 6 kHz with a 12-bit sampler, and were digitally filtered at various corner frequencies. Results: Voltages recorded by all 3 electrocardiographs were greatest when filters were OFF (most prominent on R- and S-wave voltages). In all recorded leads, it-wave voltage was significantly greater when filters were OFF than ON. Comparison of voltages indicated significant (P < 0.05) differences between R-wave voltages recorded in all leads with manual filters ON, but not with filters OFF. With filters ON, each electrocardiograph produced a smaller percentage of recordings with moderate to severe baseline artifact than with filters OFF. R-Wave amplitudes of high-fidelity lead-II ECG were significantly decreased with digital filters set at corner frequencies < 150 Hz. Conclusion: Significant (P < 0.05) voltage attenuation was recorded by each of the 3 commercial electrocardiographs when frequency filters were ON, compared with OFF. Comparison of waveform voltages among electrocardiographs with filters ON indicated significant variation in R-wave amplitudes in all leads. With manual filters ON, each electrocardiograph recorded a smaller percentage of recordings with baseline artifact than with filters OFF. Substantial frequency components greater than or equal to 150 Hz are present in the feline ECG waveform. Thus, filters with frequencies < 150 Hz markedly attenuate the feline R wave. Clinical Relevance: Attenuation of feline ECG signals occurs with use of commercial electrocardiographs and varies greatly between manufacturers. This is attributable largely to internal manual frequency filters. These consequences may be important when applying standard feline reference values or when equivocal voltage measurements are recorded.