Effects of additives on in vitro ruminal fermentation: a comparison of monensin and bacitracin, another gram-positive antibiotic

Mixed ruminal bacteria (n = 4) were incubated in anaerobic media for 24 h in vitro with either hay, corn meal, protein hydrolyzate or hydrogen gas as the substrate. The ionophore monensin and the polypeptide antibiotic bacitracin were added to the incubation flasks at concentrations ranging from 0 to 10 or 40 mg/liter. As was expected, monensin decreased methane production, increased the ratio of propionate to acetate and decreased the deamination of amino acids. Monensin had little effect on methane production, however, if hydrogen gas was the fermentation substrate. Bacitracin, another gram-positive antibiotic with a distinctly different cellular target, was somewhat less potent than monensin, but it produced strikingly similar responses. This similarity of fermentation patterns suggested that monensin action in the rumen is probably due to its activity as a gram-positive antibiotic, and that any gram-positive antibiotic not suppressed by resistance may produce fermentation effects similar to those of monensin. The cellular action of monensin as an ionophore in membranes is probably little more than a means of inhibiting sensitive species. Many gram-positive antibiotics have little affect on ciliate protozoa or coccidia.     

Cerebrospinal Fluid Myelin Basic Protein as a Prognostic Biomarker in Dogs with Thoracolumbar Intervertebral Disk Herniation

Background: Release of myelin basic protein (MBP) into the cerebrospinal fluid (CSF) is associated with active demyelination and correlates with outcome in various neurological diseases. Hypothesis/Objectives: To describe associations among CSF MBP concentration, initial neurological dysfunction, and long‐term ambulatory outcome in dogs with acute thoracolumbar intervertebral disk herniation (IVDH). Animals: Five hundred and seventy‐four dogs with acute thoracolumbar IVDH and 16 clinically normal dogs. Methods: Prospective case series clinical study. Signalment, initial neurological dysfunction as determined by a modified Frankel score (MFS), and ambulatory outcome at >3‐month follow‐up were recorded. Cisternal CSF MBP concentration was determined by an ELISA. Associations were estimated between CSF MBP concentration and various clinical parameters. Results: Dogs with thoracolumbar IVDH that did not ambulate at follow‐up had a higher CSF MBP concentration (median, 3.56 ng/mL; range, 0.59–51.2 ng/mL) compared with control dogs (median, 2.22 ng/mL; range, 0–3.82 ng/mL) (P= .032). A CSF MBP concentration of ≥3 ng/mL had a sensitivity of 78% and specificity of 76% to predict an unsuccessful outcome based on receiver‐operating characteristics curve analysis (area under the curve =0.688, P= .079). Affected dogs with a CSF MBP concentration ≥3 ng/mL had 0.09 times the odds of ambulation at follow‐up compared with affected dogs with CSF MBP concentration <3 ng/mL when adjusted for initial MFS (95% confidence interval 0.01–0.66, P= .018). Conclusions and Clinical Importance: These results would suggest that CSF MBP concentration may be useful as an independent prognostic indicator in dogs with thoracolumbar IVDH.     

MENSURATION OF THE NORMAL PITUITARY GLAND FROM MAGNETIC RESONANCE IMAGES IN 96 DOGS

The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy.     

Do dogs use a mirror to find hidden food?

Dog (Canis familiaris) cognition research that examines whether dogs are able to use a mirror as a problem-solving tool is rare. The aim of this study was to explore whether dogs could find food that was visible only via a mirror at the beginning of the experiment. In a laboratory setting, we exposed 44 dogs to a large mirror, attached at a 90° angle to an opaque barrier for 10 minutes. Dogs were allowed complete freedom of movement. For the first minute of the exposure phase, the owner and experimenter stood against a wall, ignoring the dog; afterward, both walked around the room for 9 minutes. The dogs could observe their movements in the mirror. Then, dogs were taught to associate a bowl with food, after which the bowl was surreptitiously placed behind the barrier, and the dogs were positioned so that they could see the reflection of the food in the mirror. Dogs were pseudorandomly assigned to the experimental group (n = 22) as described or a control group (n = 22), which was identical except that the mirror was covered during the testing phase. In the testing phase, dogs that could see the mirror were more likely to find the treat than dogs that could not (P = 0.032). Although fewer dogs in the control condition found the food, those that did were just as likely as those in the mirror condition to locate it within 3 minutes. This suggests that, although dogs' food-searching behavior can be triggered by the mirror's visual cues to locate food, some dogs used other cues that we were unable to control.     

Influence of the Expert Effect on Cultural Models

We examined hunters’ perceptions of fauna to see if expert hunters and other hunters perceive wildlife abundance similarly. We used cultural consensus analysis (CCA) to assess the knowledge of 25 hunters in the Bolivian Amazon about the abundance of 38 animals. CCA indicated highly shared beliefs among hunters concerning wildlife abundance (average agreement = .62). However, expert hunters (as judged by their reported successful hunts of rare species, having hunted recently, and consuming more game in their diet) perceived more animals as abundant than did non-experts, although they all shared the same model. Since the expert hunters did not always agree on which species was more abundant, they had low cultural knowledge scores in CCA results. These experts may be unwilling to curtail hunting efforts on key species that they perceive to be abundant.     

Dactylaria gallopava encephalitis in two grey-winged trumpeters (Psophia crepitans)

Encephalitis caused by Dactylaria gallopava is reported in two 17-to-18-day-old grey-winged trumpeters (Psophia crepitans). One of the chicks was housed in a tropical exhibit, and the other was in an adjacent room. Fir bark litter and aerosol infection were the suspected source and route of infection. The occurrence of this disease in a species other than the domestic chicken and turkey suggests the presence of a broader avian population at risk than previously indicated. Adult trumpeters and both young and old passerines housed in the same exhibit were not affected.     

Liver biopsy techniques for adult horses and neonatal foals to assess copper status

Objective To evaluate standing, percutaneous, ultrasound-guided, transthoracic liver biopsy in mares, and transabdominal, laparoscopically-guided, liver biopsy under general anaesthesia in foals, as techniques for obtaining tissue for assessment of copper status. The techniques were evaluated with respect to ease of use and effect on the animal.
Procedure Twenty of 24 Thoroughbred mares and 21 of their foals were biopsied. The animals were part of a larger study of the effect of copper supplementation on copper status and the prevalence of developmental orthopaedic disease. Livers were also collected from unrelated horses and sampled to investigate the variability in the distribution of copper in liver tissue.
Result The biopsy technique caused no lasting effect on the mares, but there was an increased risk of viscus penetration associated with taking multiple biopsy cores. The use of ultrasonography to scan the target area for the liver identified four cases that were not appropriate candidates for liver biopsy, because of large intestine being located in the biopsy area. In the foals there were no serious postoperative adverse effects, nor was there any evidence of problems caused by the procedure when the abdomen was examined post-mortem at 5 months of age. In livers collected to investigate the variability of copper concentration, copper appeared to be relatively evenly distributed through the liver.
Conclusion Standing, percutaneous, ultrasound-guided, transthoracic liver biopsy in mares, and transabdominal, laparoscopically-guided, liver biopsy under general anaesthesia in foals are convenient procedures for obtaining liver tissue for assessing copper status in horses. The use of ultrasound to identify liver tissue is recommended, especially in older mares.     

Observer variation in field data describing foot shape in dairy cattle

A qualitative scoring method was devised to describe foot shape in dairy cattle, which relied solely on visual observations. Four independent trained observers used the method to assess the foot shape of 248 cows located on three farms on two different occasions, and the percentages of agreement and near-agreement for intra-observer and interobserver variation on scores for foot shape were calculated. Score assessment methods were suitable for describing features with a broad variation within one score value; reducing the number of observers did not improve best agreement between separate observations by more than 80 per cent.