Sonographic features of drug-induced splenic congestion

Drug-induced splenic congestion has been reported in dogs secondary to barbiturate administration. This research attempted to verify and quantify size changes associated with drug-induced splenic congestion in dogs. Transverse plane ultrasound images of the spleen in normal dogs were collected to determine the maximum diameter in the minimum dimension prior to, and 15 min after, administration of acepromazine, thiopental, or propofol. Significant splenic enlargement was seen after administration of acepromazine (P<0.01) and thiopental (P=0.02), but no enlargement was seen after administration of propofol. Significantly increased attenuation (P<0.01) and a trend of increased backscatter (P=0.09) were measured after administration of acepromazine. These results indicate that measurable splenomegaly occurs after acepromazine and thiopental administration. This represents the first report of a condition causing measurable diffuse increased attenuation in the spleen. Propofol does not cause measurable splenic enlargement under the conditions of this research.     

TECHNICAL PARAMETERS AFFECTING IMAGE CHARACTERISTICS IN IN VIVO MR MICROSCOPY OF THE MOUSE

The aim of the study was to assess the effects of changing acquisition parameters used for high-resolution in vivo magnetic resonance (MR) microscopy on image quality and scan time. The head or abdomen of 11 normal and 1 glioblastoma-bearing anesthetized BALB/c mice were imaged using a high-resolution 7.0-Tesla magnet. Scan parameters such as matrix size (MTX), slice thickness (ST), number of excitations (NEX), pulse sequence type including repetition time (TR) and echo time (TE), respiratory gating, and intraperitoneal contrast medium administration were altered to assess their actual effect on signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) as compared to calculated effects. As expected, SNR increased with increasing ST or NEX and with decreasing MTX. However, although the empirical increase in SNR was similar to that expected for increased ST, it was less than that anticipated for increasing NEX or decreasing MTX. Increasing NEX and applying respiratory gating both increased SNR and reduced the image degradation associated with respiratory motion in images of the abdomen. Intraperitoneal contrast medium administration produced a marked increase in CNR in the subject with the implanted glioblastoma, suggesting that this route is satisfactory for the enhancement of lesions disrupting the blood-brain barrier. The consequence of improving image quality in terms of spatial and contrast resolution is increased scan time. However, the actual increase in SNR when altering acquisition parameters may not be as much as predicted by theory.     

Effects of Feeding Distiller's Dried Grains with Solubles on Growth and Feed Efficiency of Weanling Horses

The effects of replacing corn and soybean meal with distiller's dried grains and solubles in the weanling horse diet were examined. Sixteen weanling horses, 12 fillies and four colts, were fed completely pelleted diets consisting of 50% alfalfa in addition to 50% of a concentrate containing either corn and soybean meal (CS), or 30% of the concentrate replaced with distiller's dried grains with solubles (DDGS). There were no significant differences (P > .05) between the two diets in either average daily gain or gain-to-feed ratio. The CS diet had a higher apparent dry matter digestibility (P < .0001), and higher apparent digestibility of crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) (P < .01). It was concluded that replacing a portion of the corn and soybean meal with distiller's dried grains with solubles in the weanling horse diet did not lead to significant growth depression. However, the diet containing DDGS had reduced apparent digestibility of dry matter, CP, and fiber. Therefore, it was concluded that it may not be advisable to replace more than 30% of the concentrate portion or 15% of the total diet with distiller's dried grains and solubles when alfalfa is used as the forage source constituting 50% of the weanling diet. Even less DDGS may be desirable to substitute for corn and soybean meal in weanling horse diets if the forage source is one with lower protein quality than alfalfa. It is possible that using DDGS for less than 30% of the concentrate portion of the diet along with high-quality alfalfa forage may produce comparable gain and feed efficiency results with less depression of apparent digestibility of dry matter, crude protein, and fiber.     

Comparison of Three Methods of Ulnar Fixation in Horses

Objective- This study compares the mechanical properties of three methods of equine ulnar fixation: dynamic compression plating, pins and wires tension band, and a prototype grip system.
Study Design- The mechanical properties of dynamic compression plating, pins and wires tension band, and a prototype grip system repair of equine ulnar fractures were evaluated in a cadaveric osteotomy model.
Animals or Sample Population- Fifteen pairs of the radius and ulna from equine cadavers.
Methods- The three repair techniques were evaluated to mimic the pull of the triceps brachii muscle in single cycle to failure and in cyclic fatigue loading. Single cycle results were evaluated as the axial and angular displacement. Cyclic fatigue results were evaluated as the number of cycles to failure.
Results- Dynamic compression plate fixation and pins and wires tension band had significantly less axial displacement of the proximal fragment than the grip system ( P <.05). No significant difference in angular rotation of the proximal fragment was present between the three techniques. Dynamic compression plating had significantly greater fatigue resistance than the grip system ( P <.05). Cyclic failure was characterized by screw loosening or breakage and wire breakage.
Conclusions- Dynamic compression plates were better than the other techniques at maintaining compression of a transverse ulnar osteotomy at the level of the anconeal process just proximal to the trochlear notch.
Clinical Relevance- Knowledge of fixation technique mechanical properties is essential for surgeons to select the proper method of fracture repair.     

Effects of dietary yeast culture supplementation during the conditioning period on equine exercise physiology

Two groups of previously unconditioned young adult horses participated in 6 weeks of gradually increasing exercise on an inclined plane treadmill while receiving a cornoats-hay diet with or without a commercially available dietary yeast culture preparation. Forced treadmill exercise at a workload of 11.98 j/kg/m, equivalent to a workrate of 18.34 j/sec/kg and an estimated ground speed of 5.36 m/sec, began at 5 minutes per day (2.75 Mjoules/500 kg body-weight) and was increased by 5 minutes per week to a maximum of 35 minutes per day (19.25 Mjoules/500 kg) after 6 weeks. Treadmill exercise increased venous plasma lactate concentrations in direct proportion to the duration of an exercise bout, but the increases tended to be smaller after a given amount of work as the horses became conditioned. At the end of 35 minutes of exercise, plasma lactate concentrations averaged 30.08 mg/dl in the supplemented horses and 41.29 mg/dl in the unsupplemented horses (p<.01). Plasma glucose concentrations decreased significantly and triglyceride concentrations increased significantly in both groups as exercise duration exceed 10 minutes. Changes in plasma glucose concentrations were not significantly affected by yeast culture supplementation, while the supplemented horses exhibited somewhat slower rates of increased plasma triglyceride concentrations. During the 35-minute exercise bouts, significantly lower heart rates were recorded in the supplemented horses during the first 5 and the final 10 minutes of the workouts (p<.01), suggesting an enhanced state of athletic fitness. The digestible energy required for work (Mcal/500 kg bodyweight) was calculated to be 0.454 (Mcal/Mjoule) (Mjoules of work/500 kg bodyweight) + 0.024 Mcal/500 kg bodyweight (r²=0.95), with an efficiency of converting dietary DE to work of 53% for both groups of horses. Although the exercise challenges to these horses were not severe, these results suggest that dietary yeast culture supplementation of horses entering into conditioning programs may well enhance athletic training.     

Non-equivalence of canine tissue and intraluminal PCO2 responses at different sites during hemorrhage and during resuscitation

Objective: The purpose of this study was to measure and compare the hemorrhage and resuscitation partial pressure of CO₂ (PCO₂) responses at a variety of sites, predominantly intraluminal gastrointestinal, in the same dog and among different dogs. Design: Observational study. Setting: Association for Assessment and Accreditation of Laboratory Animal Care accredited research laboratory. Animals: Pound source mongrel dogs being used in 4 separate hemorrhage and resuscitation studies, the objectives of which were unaffected by the PCO₂ monitoring. Interventions: Fiber‐optic PCO₂ monitoring systems were used to simultaneously monitor subcutaneous (n=8), sublingual (n=8) PCO₂, and intraluminal esophageal (n=10), gastric (n=27), duodenal (n=16), jejunal (n=8), and ileal (n=7) PCO₂ of 28 dogs used in 4 hemorrhage and resuscitation studies. Measurements and main results: The tissue or intraluminal PCO₂ at all sites increased in response to hemorrhage. The rate and magnitude of esophageal, gastric, duodenal, jejeunal, and ileal intraluminal PCO₂ varied widely between dogs for the same site and between sites in the same dog. Different gastrointestinal sites also responded differently to resuscitation. The rate and magnitude of changes in subcutaneous and sublingual PCO₂ values were lower than those in the other tissues examined. The mean and maximum coefficients of variation for each site were as follows: subcutaneous 9%, 31%; sublingual 10%, 23%; esophageal 15%, 40%; gastric 26%, 90%; duodenal 25%, 70%; jejunal 25%, 95%; and ileal 34%, 87%. Conclusions: At different tissue sites, PCO₂ values do not respond equivalently to either hemorrhage or resuscitation. One site cannot, therefore, be reliably used to indicate the energy status of an alternate site.