Field trials of an immunization procedure against hemorrhagic enteritis of turkeys

The efficacy of oral vaccination for hemorrhagic enteritis of turkeys was assessed by comparing flocks raised on the same premises, under the same management, with and without vaccination. The immunizing virus, a strain of marble spleen disease virus of pheasants, was administered via the drinking water. Vaccinated and unvaccinated turkeys differed significantly in feed conversion rates and spleen weights after challenge.     

Influence of ambient temperature on prolactin concentrations in serum of Holstein and Brahman x Hereford heifers

Four Holstein and four Brahman x Hereford heifers about 8 mo of age were used in a study to determine whether breed influences the effects of ambient temperature on concentrations' of prolactin in serum. Two heifers of each breed were stanchioned in each of two environmental chambers at 21 C for 7 d, after which chamber temperatures were changed to 7 or 31 C during 6 h. After 5 d at 7, 21 or 31 C, heifers were injected with 60 micrograms thyrotropin-releasing hormone (TRH). A switch-back design was used and each heifer was exposed to all treatments. Concentrations of prolactin in serum of heifers during exposure to 7, 21 or 31 C for 5 d were related to ambient temperature (9.0, 20.9 and 29.5 ng/ml, respectively; P less than .001), but the response was not influenced by breed. Heifers of both breeds responded similarly to treatment with TRH, and prolactin in serum increased (P less than .001) within 5 min from 7.0 +/- 3.2 to 45.7 +/- 8.2 ng/ml in heifers at 7 C, from 13.1 +/- 1.6 to 97.2 +/- 9.6 ng/ml in heifers at 21 C and from 18.2 +/- 3.5 to 96.2 +/- 11.3 ng/ml in heifers at 31 C. We conclude that concentrations of prolactin in serum of heifers are positively associated with ambient temperature and that the effects of temperature on basal and TRH-stimulated concentrations of prolactin do not differ significantly between Holstein and Brahman x Hereford heifers. Thus, differences in tolerance to heat were not related to differences in prolactin secretion.     

EFFECT OF STRESS ON STEROID HORMONE LEVELS IN RACEHORSES

SUMMARY Cortisol and testosterone were measured by radioimmunoassay in plasma samples from race horses. None of 6 stressed male horses had Iow cortisol levels but testosterone levels (0.81 ± 0.15 nmol/l) were significantly lower than in healthy horses (1.86 ± 0.31 nmol/l). The conclusion was made that adrenocortical insufficiency is not a common association of stress in race horses. The reduction in testosterone levels is probably a nonspecific response similar to that seen in other species.     

The pharmacokinetics and tissue levels of polymyxin B, colistin and gentamicin in calves

Following a single intravenous injection of polymyxin B, colistin (5 mg/kg, each) and gentamicin (3 mg/kg) to calves, the decline in serum antibiotic concentration generally suggested a three-compartment (open system) pharmacokinetic model. Tissue binding is a dominant factor in the distribution and elimination kinetics of the drugs. Less than 65% of the dose of polymyxin B and colistin was recovered in the urine during 48 h after treatment. Concentrations of nonbound polymyxin B and colistin in the kidney, liver, lung, heart, and skeletal muscles were similar to total (free and bound) serum drug levels, but considerably higher concentrations were found, in bound form, in chloroform-ethanol extracts of these organs.
At 24 h after treatment, more than 50% of the doses of polymyxin B and colistin were present bound to the tissues; the largest amount was in the skeletal muscles. Gentamicin was concentrated in the kidney, predominantly in the free form. At 48 h after treatment the amount of gentamicin in the kidney was 6.3% of the administered dose, being more than five times greater than the corresponding amounts of polymyxin B and colistin.
The extent of tissue uptake of polymyxin B and colistin limits the usefulness of kinetic values, which are derived from the analysis of serum drug levels, for the purpose of designing dosage schedules. The strong affinity of the polymyxins to the muscle tissue, and gentamicin to the kidney, can result in drug residues persisting in the body for several weeks.     

Papillomatosis of the bovine teat (mammary papilla)

A 4th of 667 cattle examined at a Wisconsin abattoir had teat papillomas. Excised teat papillomas were sorted by gross morphologic characteristics into 3 groups: (i) atypical filiform, (ii) atypical flat, and (iii) typical fibropapilloma. Bovine papilloma virus capsid antigen was detected in thin-section slides of the 3 groups of teat papillomas by peroxidase-antiperoxidase assay. The bovine papilloma virus involved with the atypical papillomas could not be characterized by molecular hybridization, because enough pure virus could not be harvested. Homogenates of the 3 groups of teat papillomas were inoculated on 2 ponies and 4 calves. Typical fibropapillomas were produced on the 4 calves, and fibromas, on the 2 ponies. Atypical papillomas were produced only in 2 heifers.     

Effects of grain type, roughage level and monensin level on finishing cattle performance

Interactions among grain type (grain sorghum, corn or wheat), roughage level and monensin level were studied in four feedlot trials using pen-fed crossbred yearling cattle. In Trial 1, cattle fed high-moisture corn (HMC) were more efficient (.1537 vs .1406 for gain/feed; P less than .01) than cattle fed dry-rolled grain sorghum (DRGS). As level (0, 3, 6, 9%) of dietary roughage was increased, feed efficiency (gain/feed) decreased (.1566, .1461, .1479, .1382; linear, P less than .01). In Trial 2, a grain type (DRGS; dry-rolled corn, DRC; dry-rolled wheat, DRW) x roughage level interaction was observed for daily gain and feed efficiency. Feed efficiency (gain/feed) was decreased when roughage was added to diets containing DRC (.1608 vs .1750) or DRGS (.1674 vs .1465), but not to the diet containing DRW (.1664 vs .1607). In trial 3, a grain type x roughage level x monensin level interaction (P less than .08) was observed for feed efficiency. The addition of 27.5 mg of monensin per kilogram of the 0% roughage-DRC diet tended to improve feed efficiency (.1633 vs .1531), but the addition of monensin to the 7.5% roughage-DRC diet tended to depress feed efficiency (.1476 vs .1575). The addition of either roughage (.1493 vs .1420) or monensin (.1500 vs .1413) to the DRW diet improved feed efficiency. In Trial 4, cattle fed a combination of 75% DRW and 25% DRC were more efficient (.1618 vs .1591; P less than .06) than cattle fed DRC. As level of roughage (0, 3.75, 7.5%) increased, feed efficiency decreased linearly (.1645, .1599, .1569; P less than .0001). Monensin had no effect on feed efficiency. The value of feeding roughage and monensin was variable both across grain types and within similar grain types.     

Long-term anaesthesia with propofol and alfentanil in the dog and its partial reversal with nalbuphine

Prolonged surgical anaesthesia in the dog was induced with propofol (6.5 ± 1.3 mg/kg) followed by alfentanil (25.5 ± 5 μg/kg) (mean ± 1 sd) and maintained with a continuous infusion of propofol (0.14 to 0.18 mg/kg/min) and alfentanil (2 to 3 μg/kg/min). Neuromuscular blockade was produced with vecuronium (0.1 mg/kg). After induction of anaesthesia with propofol, administration of alfentanil to dogs which had received no pre-anaesthetic medication produced cardiac arrest and apnoea. Administration of atropine intravenously immediately prior to alfentanil prevented these cardiac depressant effects. The cardiac depressant effect of alfentanil was not as severe in a second group of dogs in which anaesthesia was induced with thiopentone. After commencing the continuous infusion anaesthetic regime and establishment of IPPV, blood pressure and heart rate remained stable during the remaining 4 to 6 h period of anaesthesia. Recovery from anaesthesia was smooth and uneventful. The depressant effects of alfentanil on respiration and on consciousness were reversed rapidly by administration of nalbuphine (10 mg total dose). The smooth recovery and the integration of anaesthesia and post operative analgesia attained by the reversal of alfentanil with nalbuphine make this an attractive anaesthetic regime for major surgery in dogs, provided that facilities for IPPV are available.     

Pyloric obstruction in a dog related to a gastrotomy incision closed with polypropylene

A five-year-old male, West Highland terrier was treated for a gastrointestinal foreign body via a gastrotomy incision and enterotomies. The dog was asymptomatic for several months but was eventually re-presented because of vomiting. Endoscopic and surgical evaluation confirmed a large mass within the pyloric canal that probably resulted from a reaction to the polypropylene suture material used to close the original gastrotomy incision. The mass was excised via a Y-U pyloroplasty incision and the dog has been free of vomiting for over a year.     

Influence of Cholinergic Blockade on the Development of Epinephrine-Induced Ventricular Arrhythmias in Halothane- and Isoflurane-Anesthetized Dogs

The arrhythmogenic effects of anesthetic drugs are assessed using the arrhythmogenic dose of epinephrine (ADE) model. The purpose of this study was to determine the influence of cholinergic blockade (CB) produced by glycopyrrolate (G) on ADE in 1.5 minimum alveolar concentration (MAC) halothane (H)- and isoflurane (I)-anesthetized dogs. Eight dogs (weighing between 12.5 and 21.5 kg) were randomly assigned to four treatment groups (H, HG, I, and IG) and each treatment was replicated three times. Anesthesia was induced and maintained with H (1.31%, end-tidal [ET]) or I (1.95%, ET) in oxygen. Ventilation was controlled (carbon dioxide [PCO₂] 35 to 40 mmHg, ET). G was administered 10 minutes before ADE determination at a dose of 22 μg/kg (11 μg/kg, intravenous [IV] and 11 μg/kg, intramuscular [IM]). The ADE was determined by IV infusion of epinephrine at sequentially increasing rates of 1.0, 2.5, and 5.0 μg/kg/min; and defined as the total dose of epinephrine producing at least four ectopic ventricular contractions (EVCs) within 15 seconds during a 3-minute infusion and up to 1 minute after the end of the infusion. Total dose was calculated as the product of infusion rate and time to arrhythmia. Data were analyzed using a randomized complete block analysis of variance. When significant (P < .05) F values were found a least significant difference test was used to compare group means. Values are reported as means ± standard error. The ADE (μg/kg) for H, HG, I, and IG were 1.53 ± 0.08, 3.37 ± 0.46, 1.61 ± 0.21, and > 15.00, respectively. Heart rates (HRs) (beats/min) and systolic pressures (mmHg) at the time of arrhythmia formation for H, HG, I, and IG were (60.3 ±4.0 and 142.0 ± 7.6), (213.0 ± 13.1 and 239.2 ± 7.1), (62.9 ± 4.5 and 151.9 ± 6.3), and (226.3 ± 6.1 and 323.5 ± 3.4), respectively. The H and I ADE were not different. The HG ADE was significantly less than the IG ADE. The H and I ADE were significantly less than the HG and IG ADE. We conclude the following from the results of this study of epinephrine infusion in halothane- and isoflurane-anesthetized dogs: (1) two distinct mechanisms are responsible for the development of arrhythmias, (2) CB produced by G significantly increases ADE but is associated with higher rate pressure products (RPP) and myocardial work, and (3) ADE methodology could be improved by determining ADE with and without CB.