Relationship between latency of brainstem auditory‐evoked potentials and head size in dogs

Summary

Cranium and brainstem dimensions were measured in 32 postmortem dog heads. Positive correlations were found between cranium length (CL) and brainstem length (BL) (r=0.87), between cranium width (CW) and brainstem width (BW) (r=0.83), and between cranium distance (CD = CL CW/2) and brainstem distance (BD = BL+BW/2) (r=0.91). Positive correlation coefficients were also found between CL and CW (r=0.90), and between BL and BW (r=0.85). It was concluded that head size accurately reflected brainstem size. A least squares estimation of the brainstem distance (BD) from CL and CW values was BD = 10.9 + 0.16 (CL CW/2) (BD, CL and CW in mm).

Brainstem auditory evoked potentials (BAEPs) and cranium dimensions were measured in 43 dogs (86 ears) with different head size, body size, sex and age. Wave form, absolute and interpeak latencies and correlation coefficients, relating latencies to cranium dimensions and body weight, were analysed CL, CW, and CD were positively correlated with body weight (r=0.93, 0.70 and 0.93, respectively), and CL, CW, and CD were correlated with age (r=0.33, 0.52 and 0.40, respectively). BAEPs consisted of five distinct positive peaks (I to V). Secondary positive peaks following peaks I and II were seen in 60% (I') and 90% (II') of the recordings. Late waves were recorded in 90% (VI), 50% (VII), and 25% (VIII) of the recordings. Latencies increased with decreasing stimulus intensity level (from 90 dB to 10 dB hearing level, HL),especially for peaks I, II, V, and the I‐V interpeak interval Absolute and interpeak latencies were positively correlated with cranium distance and body weight. Correlation coefficients increased as wave latencies increased At 90 dB HL, the highest correlation coefficients, relating cranium distance to peak V and the I‐V interpeak latency, were 0.55 and 0.53 (P < 0.00001), respectively. Regression analysis showed that each 1 cm increase in cranium distance was accompanied by an increase of 0.006 ms in the latency of wave I, 0.03 ms for wave III, 0.05 ms for wave V, and 0.05 ms for the I‐V interpeak interval Regression analysis showed that an increase of 1 kg in body weight was accompanied by an increase of 0.001 ms in the latency of wave I, 0.005 ms for wave III, 0.011 ms for wave V, and 0.01 ms for the I‐V interpeak interval. It is concluded that head size, which accurately reflects brain size, is a relevant source (25%) of intersubject variance of BAEP latencies in the dog.     

Apparent zinc absorption and zinc status of weanling rats fed moderately zinc‐deficient diets enriched with beef tallow or sunflower oil

The aim of the study was to compare apparent Zn absorption and Zn status of weanling rats fed diets that differed in Zn level, fat level and fat source. Semi‐synthetic diets, which were about isoenergetic and contained 3% soyabean oil, were supplemented with 7 or 100 mg Zn/kg to create a mild Zn deficiency (LZ) or a high Zn supply (HZ) and with 0 (LF), 22% beef tallow (BT) or 22% sunflower oil (SF) according to a 2 × 3 factorial design of treatments. They were fed ad libitum to 6 × 8 rats for 28 days. Energy intake and growth rates were comparable among the HZ groups. Weight gains in the LZ‐LF, LZ‐BT and LZ‐SF groups averaged 5.54, 4.95 and 4.15 g/day, and apparent Zn absorption averaged 79.4, 60.3 and 48.0 μg Zn/day, respectively, whereas faecal Zn excretion was comparable among these groups. Apparent Zn absorption, and plasma and femur Zn concentrations were lower in the high‐fat groups than in the LF group, possibly due to the high cellulose content of the BT and SF diets. Plasma Zn concentrations were higher in the animals fed the BT‐based than in the SF‐based diets, whereas femur and soft tissue Zn concentrations were comparable among these groups. The differences between the LZ‐BT and LZ‐SF groups in growth rate, Zn absorption rate and Zn status were confirmed in a second experiment. The results indicate that moderately Zn‐deficient diets enriched with SF in relation to BT affect Zn metabolism of weanling rats by a yet unknown mechanism.     

Effects of Bacillus subtilis B10 spores on viability and biological functions of murine macrophages

This study was conducted to investigate the effects of Bacillus subtilis B10 spores on the viability and biological functions of murine macrophage. RAW 264.7 cells were stimulated both with and without B. subtilis B10 spores for 12 h. Then cell viability was determined to evaluate the cytotoxic effect of B. subtilis B10 spores to the cells, and the activities of acid phosphatase (ACP) and lactate dehydrogenase (LDH), the production of nitric oxide (NO) and inducible nitric oxide synthase (iNOS), and the secretion of inflammatory cytokines were measured to analyze the functions of macrophages. The results showed that B. subtilis B10 spores were not harmful to RAW 264.7 cells and they also strongly enhanced the activities of ACP and LDH (P < 0.01), remarkably increased NO and iNOS production (P < 0.01), and significantly stimulated the secretion of pro‐inflammatory cytokines, including tumor necrosis factor‐alpha (TNF‐α), interferon‐gamma (IFN‐γ), interleukin‐1 beta (IL‐1β), IL‐6, IL‐8 and IL‐12 (P < 0.01) while they reduced anti‐inflammatory cytokine IL‐10 (P < 0.01). The outcomes suggest that B. subtilis B10 spores are not only safe for murine macrophages, but also can activate these cells and enhance their immune function. The above findings suggest that B. subtilis B10 spores are potentially probiotic.     

ORIGINAL ARTICLE: Fish bones – a highly available calcium source for growing pigs

In general, there is a lack of scientific documentation of nutritional value of marine by‐products. The bone fraction from fish has been regarded as waste. Due to the high mineral content of fish bones, this material can be well suitable as a natural calcium source. In the present study, apparent calcium absorption of different fish bone sources was tested using growing pigs. The experimental diets consisted of boiled salmon frames, or salmon, saithe or cod bones treated with enzymes. Calcium carbonate (CaCO₃) was used as control. The experimental diets were formulated to contain 0.7% total calcium of which the added calcium source to be tested contributed about 71% (study 1) and 86% (study 2). Except for the calcium and phosphorus sources, the animals received similar basal diets. Apparent calcium digestibility coefficient was calculated using yttrium as indicator (both studies) and was based on complete collection of faeces and urine (study 2). The experimental design was parallel and cross‐over in study 1 and study 2, respectively. In study 1, piglets getting salmon bone treated with enzymes had significantly higher calcium absorption than piglets getting boiled fish bone or calcium carbonate. Therefore, in the second study only enzymatically treated fish bones were included. The higher calcium absorption from enzymatically treated salmon bone was also found in study 2, but this time not significant. Calcium from boiled salmon bones in study I, and from enzymatically treated saithe and cod bones in study II were absorbed as well as the calcium carbonate control. The results indicate that fish bones may be a useful and well absorbed calcium source. Due to the high mineral content of the bone fraction, salmon bones can be well suitable as a natural calcium and phosphorus source in, for example, food, feed or as supplement.     

RESEARCH PAPER: Segmental dorsolumbar epidural analgesia via the caudal approach using multiple port catheters with ketamine or lidocaine or in combination in cattle

ObjectiveTo determine the analgesic and systemic effects of epidural administration of ketamine, lidocaine or a combination of ketamine/lidocaine in standing cattle.Study designProspective, randomized, experimental trial.AnimalsSix healthy male cattle weighing between 335 and 373 kg.MethodsThe animals received 0.5 mg kg^?1 of ketamine (K), 0.2 mg kg^?1 of 2% lidocaine (L) or 0.25 mg kg^?1 ketamine plus 0.1 mg kg^?1 lidocaine (KL). All the drugs were injected into the dorsolumbar epidural space via a caudal approach through a non‐styletted multiple‐port catheter. Each animal received each treatment at random. Evaluations of analgesia, sedation, ataxia, heart rate, arterial pressure, respiratory rate, skin temperature and rectal temperature were obtained at 0 (basal), 5, 10, 15, 30, 45, 60, 75, 90 minutes after epidural injection, and then at 30‐minute intervals until loss of analgesia occurred. Skin temperature was taken at these intervals up to 60 minutes. All the animals received a standard noxious stimulus; a 4‐point scale was used to score the response. A second scale was used to score ataxia and a third for sedation.ResultsThe duration of analgesia in the upper and lower flanks in cattle was 140 ± 15, 50 ± 14 and 80 ± 22 minutes (mean ± SD) after dorsolumbar epidural KL, K or L, respectively. The cardiovascular changes were within acceptable limits in these clinically healthy cattle.ConclusionsDorsolumbar epidural administration of KL to cattle resulted in longer duration of analgesia of the upper and lower flanks in standing conscious cattle, than the administration of K or L alone.Clinical relevanceFurther research is necessary to determine whether this combination using this technique provides sufficient analgesia for flank surgery in standing cattle.