Mammary uptake, portal-drained visceral flux, and hepatic metabolism of free and peptide-bound amino acids in cows fed steam-flaked or dry-rolled sorghum grain diets.

Our objectives were to measure net fluxes of free AA (FAA) and peptide-bound AA (PBAA) across portal-drained viscera, liver, splanchnic tissues, and mammary tissues, and milk AA output of lactating Holstein cows (n = 8, 86 +/- 8 d in milk). Cows were fed an alfalfa-based total mixed ration containing 40% steam-flaked (SFS) or dry-rolled (DRS) sorghum grain. The total mixed rations were offered at 12-h intervals in a crossover design. Blood samples were obtained from indwelling catheters in portal, hepatic, and mammary veins and from mesenteric or costoabdominal arteries every 2 h from each cow and diet. Intake of dry matter was 17.9 and 18.6 kg/d of the SFS and DRS diets, respectively, but dropped to 16.3 kg/d for cows fed the SFS diet in the last 3 experimental days, sampling day included. Milk and milk crude protein yields (kg/12-h sampling) were 13.85 vs. 13.25 and 0.425 vs. 0.396 for cows fed SFS or DRS, respectively, and were not affected by the considerable drop in dry matter intake of cows fed the SFS diet during the last 3 experimental days. The portal-drained visceral flux of total essential FAA was 417 and 442 g/12 h (SEM 63) in cows fed SFS and DRS, respectively. However, the portal-drained visceral flux of 7 essential PBAA out of the 9 determined was numerically greater in cows fed the SFS diet, and total essential PBAA in that treatment was 77.4 +/- 22.2 compared with 35.4 +/- 50.2 g/12 h for cows fed the DRS diet. This phenomenon was again observed in a greater total splanchnic flux (FAA + PBAA) of 462 and 371 g/12 h in SFS- and DRS-fed cows, respectively. Mammary uptake of essential AA from both pools (free and peptide bound), and recovery of essential AA in milk, was again numerically higher in SFS-fed cows. In addition to FAA, quantifying the contribution of PBAA may improve our understanding of tissue use of AA substrates, and this may ultimately lead to improved diet formulations with respect to intestinal absorption and mammary uptake of AA.

An instrumented scaffold can monitor loading in the knee joint.

No technique has been consistently successful in the repair of large focal defects in cartilage, particularly in older patients. Tissue-engineered cartilage grown on synthetic scaffolds with appropriate mechanical properties will provide an implant, which could be used to treat this problem. A means of monitoring loads and pressures acting on cartilage, at the defect site, will provide information needed to understand integration and survival of engineered tissues. It will also provide a means of evaluating rehabilitation protocols. A "sensate" scaffold with calibrated strain sensors attached to its surface, combined with a subminiature radio transmitter, was developed and utilized to measure loads and pressures during gait. In an animal study utilizing six dogs, peak loads of 120N and peak pressures of 11 MPa were measured during relaxed gait. Ingrowth into the scaffold characterized after 6 months in vivo indicated that it was well anchored and bone formation was continuing. Cartilage tissue formation was noted at the edges of the defect at the joint-scaffold interfaces. This suggested that native cartilage integration in future formulations of this scaffold configured with engineered cartilage will be a possibility.

Correlation between initial and long-term responses of spontaneous pet animal tumors to heat and radiation or radiation alone.

Most early-phase testing of new therapeutic modalities involves analysis of initial tumor response as opposed to estimation of long-term response. In this study, the validity of initial response rates to predict long-term responses was examined for tumors treated with radiotherapy alone compared with heat combined with radiotherapy. A total of 130 pet animals with either squamous cell carcinomas, melanomas, fibrosarcomas, mammary adenocarcinomas, or mast cell sarcomas were randomized to receive either radiation alone (XRT) or heat + radiation (delta + XRT). Responses to treatment were evaluated by response rates and response duration. The complete response (CR) rates were consistently higher for delta + XRT than for XRT across different histology groups. The combined therapy led to prolonged tumor response in all histological subgroups except melanomas, which had a longer response duration when treated with XRT alone (p = 0.043). This was in spite of a relatively high CR rate in that group (100% versus 12.5% for delta + XRT and XRT, respectively). In contrast, while no significant improvement in CR rate was observed for dermal squamous cell carcinomas treated with delta + XRT (XRT = 52.9%; delta + XRT = 68.8%), a significant improvement in response duration was noted (p = 0.002). These are two examples where CR rate did not predict long-term response. When all histological subgroups were combined (except melanomas), the CR rate was higher (p less than 0.001), and response duration was prolonged (p = 0.031) for delta + XRT compared to XRT alone.

TGF-beta1-enhanced TCP-coated sensate scaffolds can detect bone bonding.

Porous polybutylene terephthalate (PBT) scaffold systems were tested as orthopedic implants to determine whether these scaffolds could be used to detect strain transfer following bone growth into the scaffold. Three types of scaffold systems were tested: porous PBT scaffolds, porous PBT scaffolds with a thin beta-tricalcium phosphate coating (LC-PBT), and porous PBT scaffolds with the TCP coating vacuum packed into the scaffold pores (VI-PBT). In addition, the effect of applying TGF-beta1 to scaffolds as an enhancement was examined. The scaffolds were placed onto the femora of rats and left in vivo for 4 months. The amount of bone ingrowth and the strain transfer through various scaffolds was evaluated by using scanning electron microscopy, histology, histomorphometry, and cantilever bend testing. The VI-PBT scaffold showed the highest and most consistent degree of mechanical interaction between bone and scaffold, providing strain transfers of 68.5% (+/-20.6) and 79.2% (+/-8.7) of control scaffolds in tension and compression, respectively. The strain transfer through the VI-PBT scaffold decreased to 29.1% (+/-24.3) and 30.4% (+/-25.8) in tension and compression when used with TGF-beta1. TGF-beta1 enhancement increased the strain transfer through LC-PBT scaffolds in compression from 9.4% (+/-8.7) to 49.7% (+/-31.0). The significant changes in mechanical strain transfer through LC-PBT and VI-PBT scaffolds correlated with changes in bone ingrowth fraction, which was increased by 39.6% in LC-PBT scaffolds and was decreased 21.3% in VI-PBT scaffolds after TGF-beta1 enhancement. Overall, the results indicate that strain transfer through TCP-coated PBT scaffolds correlate with bone ingrowth after implantation, making these instrumented scaffolds useful for monitoring bone growth by monitoring strain transfer.

Radiotherapy prior to cortical allograft limb sparing in dogs with osteosarcoma: a dose response assay.

Twenty-one dogs with spontaneously occurring appendicular osteosarcoma were given preoperative radiation therapy prior to a limb sparing procedure using a cortical allograft. Radiation doses were randomly assigned, ranged from 36-52 Gy in 4 Gy intervals, and were given in 10 equally-sized fractions on a M, W, F schedule. Seventeen of the 21 dogs underwent the limb sparing procedure approximately 3 weeks after completion of radiation therapy. Local tumor recurrence was documented in 4 of 17 dogs at mean and median times of 5.5 and 5.8 months, respectively, after initiation of radiation therapy. Three of 4 recurrences were in anatomic regions with sparse adjacent soft tissue which precluded wide excision. Complications were significant. Fixation device failure occurred in 9 of 17 dogs and was associated with host bone necrosis, muscle thinning and fibrosis of vessels and nerves in irradiated normal tissue. Incidence of host bone necrosis was directly related to radiation dose (Kendall's statistic, p = 0.005). Metastasis occurred in all 21 dogs. Mean and median times to metastasis in these dogs were 5.1 and 4.0 months, respectively, after initiation of radiation therapy. Local tumor control rates and survival times were higher in dogs developing allograft infection suggesting that infection acted as an immunostimulant. All local failures occurred in dogs that did not develop allograft infection and median survival times for uninfected versus infected dogs were 5 and 11 months, respectively (logrank test, p = 0.029). Increased tumor radiopacity following radiation therapy was significantly related to survival. Median survival in dogs whose tumors were characterized by decreased, unchanged or increased opacity after radiation therapy were 3.5 and 14 months, respectively (logrank test, p = 0.014). Based on the results of our study, radiation therapy can not be recommended as part of limb sparing treatments for patients with osteosarcoma at doses and dose per fraction values similar to those used herein.

Gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts.

RATIONALE AND OBJECTIVES: The authors evaluated gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts. METHODS: Ten rabbits underwent ligation of the left anterior descending coronary artery. Five animals underwent echocardiography before and after production of myocardial infarct (MI) and four animals had post-MI imaging only. In either case, images were obtained before and after injection of a single dose of 1 mL of gas-filed liposomes. Three radiologists blinded to clinical information reviewed the pre- and postcontrast images and assessed endomyocardial border definition, wall motion, confidence levels for normal versus abnormal wall motion and visualization of papillary muscle and mitral valve. RESULTS: Postcontrast scans showed significant improvement (P < .05) in endomyocardial border definition, visualization of wall motion, papillary muscle and mitral valve as well as increased reader confidence level. CONCLUSIONS: These results are encouraging and suggest that gas-filled liposomes may be a useful contrast agent for echocardiography.

Regional hyperthermia by magnetic induction in a beagle dog model: analysis of thermal dosimetry.

We have investigated magnetic induction heating techniques for achieving normal tissue hyperthermia in a beagle dog model to clarify the physics and physiology of "regional heating," to develop an animal model of regional heating in humans, and to develop a method of rapid regional heating in dogs for a normal visceral tissue toxicity study. Heating was done with a concentric coil or a coaxial pair of coils applied to the abdominal region, and with or without surface cooling blankets in each case. Thermometers were placed at multiple visceral and subcutaneous sites including an intraarterial thermocouple at the aortic arch level. With either electrode arrangement and no surface cooling, whole-body hyperthermia ( WBH ) at 42 degrees C was produced within 30 to 55 min with 250 W applied power; the 42 degrees C state could be maintained with 40 to 60 W of power. Thermal gradients in these cases reflected nonuniform power deposition superimposed upon arterial temperature elevation. With surface cooling blankets added, systemic heating was significantly reduced, and temperature gradients again reflected the nonuniform power deposition. Regional heating in a dog produces WBH unless sufficient surface cooling is used to provide a heat dissipation rate balancing the heat absorption rate; this latter case best models the use of inductive techniques in humans. The coaxial pair of coils, without surface cooling, produced rapid WBH and the visceral temperature maximum and minimum were within Tesoph + 0.21 degrees C and Tesoph - 0.07 degrees C, respectively (95% confidence index; Tesoph = esophageal temperature). This is an appropriate technique for the proposed toxicity study.

An evaluation of the effectiveness of alcohol treatment, driver license actions and jail terms in reducing drunk driving recidivism in California.

AIM: There has been long-standing interest in determining which sanctions work best to reduce drunk driving. This study examines the effectiveness of alcohol treatment, driver license actions and jail terms in reducing drunk-driving recidivism. DESIGN: This quasi-experimental study examines the relationships between the sanctions that drivers convicted of driving-under-the-influence (DUI) receive and their subsequent reconviction of DUI, while statistically controlling for pre-existing differences among groups receiving different sanctions. Separate analyses were conducted for subjects having 0, 1 or 2 or more prior DUI convictions on their driving record. SETTING: The study analyzes drunk driving reacidivism throughout the state of California. Participants. All drivers holding a California driver license who were convicted of DUI by a California court during 1990 and 1991 were selected for inclusion in the study. MEASUREMENTS: A number of demographic, prior personal driving history and surrogate traffic environment measures were collected and used as covariates in the analyses. Data were also gathered on subsequent DUI reconvictions, and the number of days to first subsequent DUI reconviction, and used as outcome variables in the study. FINDINGS: Results of the analyses showed that for all levels of prior DUI convictions, combining alcohol treatment with either driver license restriction or suspension is associated with the lowest DUI recidivism rates. CONCLUSIONS: Based on this research, and the results of prior studies, it can be persuasively argued that combining license actions with alcohol treatment represents the most effective sanction combination for combating DUI recidivism.

In vivo strain measurements collected using calcium phosphate ceramic-bonded strain gauges.

Identification of the strains and the strain changes caused by implants is critical to the understanding of bone remodeling and can identify design changes needed to prevent bone loss near orthopedic implants. Calcium phosphate ceramic (CPC) coated strain gauges have been developed to allow long-term in vivo strain measurements. Previously used cyanoacrylate-bonded gauges have uncharacterizable sensing accuracy because the adhesive is resorbed from the instant it is placed in vivo. In this study CPC-coated strain gauges were used to measure physiologically "normal" bone strains collected from the proximal femora of dogs at a series of gait speeds and the postmortem sensing accuracy of the gauges was evaluated. Three male dogs were surgically implanted with up to six wired CPC-coated strain gauges placed around the circumference of their proximal femora. The dogs were trained to run on a treadmill, and in vivo strain measurements were collected following a 12-week period. The animals were tetracyline labeled and then euthanized and their femora explanted. Gauges were attached with cyanoacrylate to the intact contralateral control femora in the same position as the CPC-coated gauges on the test femora. Both femora were tested in cantilever bending to assess the functionality of the gauges and quality of the CPC-bone bond. After testing, all bones were embedded, sectioned, and ground. Sections from each femur were stained with mineralized bone stain and examined with transmitted and ultraviolet light to assess bone formation. Additional sections were examined with backscattered electron microscopy to confirm bone bonding to coatings. Wired gauges attached with the CPC coatings measured strain patterns during gait at several treadmill speeds. Patterns were similar and peak strains the same over a 2-week period. Mechanical testing showed bonding of CPC-coated gauges, and histologic examination showed intimate contact between gauge coatings and bone surfaces. Further development of CPC-bonded strain gauges is expected to result in a measurement system that provides ease of placement, and consistent longer term bone strain measurements with characterizable accuracy.

An evaluation of the specific deterrent effects of vehicle impoundment on suspended, revoked, and unlicensed drivers in California.

There have been a number of studies conducted during the past two decades that convincingly demonstrate that license suspension and revocation are some of the most effective countermeasures currently available for attenuating the traffic safety risk of problem drivers. At the same time, it is also known that most suspended/revoked (S/R) drivers violate their illegal driving status and continue to drive, accruing traffic convictions and becoming involved in crashes. In an attempt to strengthen license actions and to better control S/R and unlicensed drivers, California enacted two laws effective January 1995 which provide for the impoundment and forfeiture of vehicles driven by S/R and unlicensed drivers. The study described in this paper evaluates the impact of vehicle impoundment on the 1-year subsequent driving behavior of S/R and unlicensed drivers who experience this sanction. The results show that drivers with no prior convictions for driving while S/R or unlicensed whose vehicles were impounded have, relative to similar drivers whose vehicles were not impounded: 23.8% fewer driving while suspended/revoked or unlicensed convictions; 18.1% fewer traffic convictions; and 24.7% fewer crashes. The differences between the impound and no-impound groups are even larger when the driving records of repeat offenders (i.e. drivers with prior driving-while-S/R or unlicensed convictions) are examined. Repeat offenders whose vehicles are impounded have 34.2% fewer driving-while-S/R or unlicensed convictions, 22.3% fewer traffic convictions and 37.6% fewer crashes. These findings provide strong support for impounding vehicles driven by S/R and unlicensed drivers.

Estimating the exposure and fatal crash rates of suspended/revoked and unlicensed drivers in California.

There have been a number of studies conducted during the past three decades which show that most suspended/revoked (S/R) drivers violate their license action and continue to drive during their period of disqualification. Traffic safety researchers also suspect that S/R drivers are overinvolved in traffic crashes, but this is difficult to demonstrate because of the lack of good data on their prevalence among all road users. This paper applies the quasi-induced exposure method to fatal crash data obtained from the National Highway Traffic Safety Administration's Fatal Accident Reporting System, to generate exposure and crash rate estimates for S/R drivers in California. The results show exposure rates of 8.8% and 3.3% for suspended/revoked and unlicensed drivers, respectively, and that, compared to validly licensed drivers, the former are overinvolved in fatal crashes by a factor of 3.7:1, and the latter 4.9:1. These findings provide support for efforts to better control S/R and unlicensed drivers. The paper also discusses serious limitations to using quasi-induced exposure to estimate the numbers of such drivers on California roads, and concludes that it is not suited to this task.

The impact of mail contact strategy on the effectiveness of driver license withdrawal.

The California Department of Motor Vehicles currently uses first-class mail to notify drivers of a suspension or revocation of their driving privilege. The served drivers are instructed to sign and return the order and any driver's license to the department, thereby establishing proof of the driver's knowledge of the order. The establishment of proof is considered essential in the prosecution of drivers cited for operating a motor vehicle while under a suspension or revocation (California Vehicle Code Section 14601). However, past research indicates that a majority of drivers fail to comply with the order. In an attempt to increase proof rates, the present study developed and evaluated a number of mailing strategies for various categories of suspensions and revocations. Among the mailing factors evaluated were (1) use of certified mail, (2) use of a follow-up contact, (3) use of a postage paid return envelope and (4) masking the Department of Motor Vehicles return address of the certified mail action notice. The results indicate that there are significant differences between the type of mail contact employed as well as between the different categories of suspension or revocation reason. The most effective strategies (certified mail, return receipt requested) resulted in proof rates of approximately 60-70% compared to approximately 25% for the current first-class mailing procedure. An analysis of subsequent driving records indicated that certified mail also increased the percentage of convictions which were prosecuted as 14601 violations, while decreasing the total number of entries (convictions and accidents) accumulated during suspension or revocation.

Splanchnic nitrogen metabolism by growing beef steers fed diets containing sorghum grain flaked at different densities.

The objective of this study was to determine effects of processing method, dry-rolled (DR) vs steam-flaked (SF), and degree of processing (flake density, FD) of SF sorghum grain on splanchnic (gut and liver) N metabolism by growing steers. Diets contained 77% sorghum grain either DR or SF at densities of 437, 360, and 283 g/L (SF34, SF28, and SF22, respectively). Eight crossbred steers (340 kg initial BW), implanted with indwelling catheters into portal, hepatic, and mesenteric veins and the mesenteric artery, were used in a randomized complete block design. Blood flows and net output or uptake of ammonia N, urea N (UN), and alpha-amino N (AAN) were measured across portal-drained viscera, hepatic, and splanchnic tissues. Plasma arterial, portal, and hepatic concentrations of individual amino acids were also measured. Decreasing FD linearly increased (P = .04) net absorption of AAN (51, 73, and 78 g/d for SF34, SF28, and SF22, respectively) and transfer (cycling) of blood UN to the gut (49, 48 and 64 g/d; P = .02). Net UN cycling averaged 38% of N intake across all diets. Hepatic uptake of AAN or UN synthesis, and splanchnic output of AAN and UN, were not altered by FD. Lowering FD linearly increased (P < or = .02) portal-arterial concentration differences for blood AAN and UN and plasma arterial concentrations for alanine. Steers fed SF compared to DR tended to have greater (P = .11) blood UN cycling (percentage of hepatic synthesis; 64 vs 50%) and decreased (P = .03) net splanchnic UN output (30 vs 50 g/d), but other net fluxes of N were not altered across splanchnic tissues. Steam-flaking compared to dry-rolling tended to decrease (P = .12) portal, but not hepatic, blood flow and increased (P < .01) hepatic-arterial concentration differences for blood UN. Except for a decrease (P = .01) in hepatic-arterial concentration differences of glutamine, plasma amino acid concentrations were not altered by feeding SF vs DR sorghum. Processing method (steam-flaking vs dry-rolling) or increasing the degree of processing (by decreasing FD) of SF sorghum grain resulted in greater transfer of blood UN to the gut. Reducing FD also linearly increased the absorption of AAN by growing steers, which explains (in part) published responses of superior performance by steers fed SF grains.

Net absorption and hepatic metabolism of glucose, L-lactate, and volatile fatty acids by steers fed diets containing sorghum grain processed as dry-rolled or steam-flaked at different densities.

We determined the effect of processing method (dry-rolled [DR] vs steam-flaked [SF]) and degree of processing (flake density; FD) of SF sorghum grain on splanchnic (gut and liver) metabolism of energy-yielding nutrients by growing steers. Diets contained 77% sorghum grain, either DR or SF, with SF at densities of 437, 360, or 283 g/L (SF34, SF28, or SF22). Eight multicatheterized steers (340 kg initial BW) were used in a randomized complete block design. Net output or uptake of glucose, L-lactate, VFA, and beta-hydroxybutyrate (BHBA) were measured across portal-drained viscera (PDV), liver, and splanchnic (PDV plus liver) tissues. Net absorption of glucose across PDV was negative and similar for all treatments (average of -104 g/d). Decreasing FD of SF sorghum grain linearly increased (P < or = .04) net absorption and splanchnic output of L-lactate by 20 and 130%, respectively, and hepatic synthesis (P = .06) and splanchnic output (P = .01) of glucose by 50%. Reducing FD did not alter output or uptake of acetate or n-butyrate by gut and liver tissues, but linearly decreased (P = .06) splanchnic output of BHBA by 40%. Net absorption (P = .18) and splanchnic output (P = .15) of propionate tended to be increased linearly by 50% with decreasing FD. Neither processing method (SF vs DR) nor degree of processing (varying FD) altered hepatic nutrient extraction ratios or estimated net absorption and splanchnic output of energy. Maximal contribution of propionate, L-lactate, and amino acids (alpha-amino N) to gluconeogenesis averaged 49, 11, and 20%, respectively. Feeding steers SF compared to DR diets did not alter net output or uptake of energy-yielding nutrients across splanchnic tissues, except net absorption of acetate tended to be greater (P = .13) for steers fed DR. Increasing degree of grain processing in the present study, by incrementally decreasing FD, tended to linearly increase the net absorption of glucose precursors (propionate and lactate), resulting in linear increases in synthesis and output of glucose by the liver to extrasplanchnic tissues (e.g., muscle).

Attempts to produce salivary cysts in the dog.

Attempts were made to create salivary cysts by ligation of the mandibular salivary duct at the angle of the mandible and near the frenulum of the tongue, by rupture of the mandibular duct at the angle of the mandible and near the frenulum of the tongue, and by direct trauma to the mandibular salivary gland. Cysts were not formed as a result of the experimental procedures, but observations are made on the results obtained.

Pharmacokinetic model for cefazolin distribution during total hip arthroplasty in dogs.

OBJECTIVES: To compare cefazolin pharmacokinetics in serum and concentrations in tissues during total hip arthroplasty in dogs with and without hip dysplasia, and to calculate the optimal dosage of cefazolin for prophylactic use during total hip arthroplasty. ANIMALS: 10 dogs with hip dysplasia and 3 clinically normal dogs. PROCEDURE: Blood samples and tissue specimens from the coxofemoral joint capsule, acetabulum, and femur were obtained during unilateral total hip arthroplasty. Cefazolin concentrations in serum and tissue specimen supernatant were determined, using high-performance liquid chromatography, for use in pharmacokinetic analysis. Mathematical simulation of serum cefazolin concentration was used to to predict the optimal dose. RESULTS: Mean pharmacokinetic constants (SEM) were 0.146 (0.013) min-1 for alpha, 4.47 min for t1/2 alpha 0.015 (0.004) min-1 for beta, 46.83 min for t1/2 beta. Significant different was not detected for cefazolin distribution and elimination between dogs with and without hip dysplasia. Additional, significant difference was not observed in pharmacokinetic parameters describing distribution and elimination between the first and second doses of cefazolin. The predicted optimal dosage regimen was 8 mg/kg of body weight, i.v. every hour or mg/kg, i.v. every 2 hours. CLINICAL RELEVANCE: For prophylactic i.v. treatment during total hip arthroplasty, use of cefazolin at a dosage of 8 mg/kg every hour or 22 mg/kg every 2 hours should maintain serum cefazolin concentrations at least 10x the minimum inhibitory concentration for 3 to 4 hours.

Passive protection of segmented swine colonic loops against swine dysentery.

Swine-ligated loops were used to demonstrate passive protection against swine dysentery. Loops inoculated with immune sera containing complement and with homologous Treponema hyodysenteriae were normal at necropsy. Loops inoculated with heat-inactivated immune sera and heterologous T hyodysenteriae were not protected. Loops inoculated with heat-inactivated immune sera and homologous T hyodysenteriae were partially protected. Positive control loops inoculated with isolate B204 (88%) or B234 (44%) T hyodysenteriae and normal sera developed lesions typical of swine dysentery, whereas negative control loops inoculated with nonexposed sera only were normal.

Conductive hearing loss in bighorn sheep.

In January 1993 we simulated a conductive hearing loss in three Mexican bighorn sheep (Ovis canadensis mexicana) by placing bone wax or saline solution in their ear canals. Our objective was to test whether lesions of the external auditory canal caused by psoroptic mites (Psoroptes ovis) may lead to conductive hearing loss in bighorn sheep. We assessed the effects of these manipulations using the auditory brainstem response test. Placing saline solution in the external auditory canal, which loads the tympanic membrane, had a more dramatic effect on the auditory brainstem response than did bone wax. We propose that decreased hearing sensitivity or alterations in resonance characteristics of the external auditory canal, due to psoroptic scabies lesions, may make bighorn sheep more susceptible to predation.

Congenital pericardial diaphragmitic hernia and multiple cardiac defects in a litter of collies.

Four Collie littermates had multiple cardiac and diaphragmatic anomalies. Ventricular septal defect was found in 3, pulmonic stenosis in 2, atrial septal defect in 1, mitral regurgitaion in 1, and pericardial diaphragmatic hernia in 3. Five additional littermates died within 72 hours of birth but were not necropsied. On the basis of available evidence, it was believed that the defects were congenital but not hereditary.

Cesarean section. Anesthetic management and surgical technique.

Cesarean section can be an elective procedure but more often it is an emergency procedure that is made necessary because of dystocia. A successful outcome for both the maternal and fetal patients is primarily dependent on a thorough understanding of the physiologic alterations during normal and abnormal pregnancy and parturition. A complete history and physical examination are necessary for assessment of the dam and planning of fluid therapy and anesthetic technique. Timely coordination of presurgical preparation, anesthesia, and the surgical procedure is crucial. Because little documentation exists to prove that any one anesthetic protocol is best, this article will stress the basic principles of obstetrical anesthesia and patient management.