Experimental infection of vaccinated slaughter ostriches in a natural, open-air feedlot facility with virulent Newcastle disease virus.

The presence of virulent Newcastle disease virus (NDV) since the 1993-94 epidemic in southern Africa holds major implications for the export of ostrich products from this region. A challenge experiment with this field strain was conducted in open-air feedlot facilities under strict biosecurity measures. The experiment was designed to follow vaccination and preslaughter quarantine regulations currently enforced in South African export ostrich facilities in order to determine the viremia period and immune response under these specific circumstances. One hundred forty-three slaughter ostriches were allocated into three test groups, according to the time period between pretrial vaccination and challenge (1-2 mo, 2-4 mo, 4-6 mo), and an unchallenged control group. All birds in the test groups were challenged by oral, tracheal, and ocular routes with a field isolate of NDV. They were slaughtered over the next 4 wk on nine separate occasions and bled on 12 occasions. Virus isolation was attempted from seven sets of pooled samples from each bird to determine the viremia period and the serum antibody concentrations were measured by hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) methods to establish an immune response curve. NDV could be back-isolated only up to day 9 postinfection and from only six ostriches with poor immune response titers and corresponding to a rise in antibody levels above an indirect ELISA optical density reading of 0.33. Virus could be recovered only from brain and respiratory tract tissue. The HI test was less sensitive than the ELISA. Immune response curves did not differ significantly between the groups and peaked on day 14 post-infection. From these data, ELISA titers would appear to be a good indicator of the probability that an ostrich will be clinically infected after velogenic NDV challenge. These results also suggest that the current vaccination schedule enforced by the South African Veterinary Authorities results in protective immunity in up to 95% of slaughter ostriches from export approved facilities. The standard 30-day preslaughter quarantine period introduced as part of Crimean-Congo hemorrhagic fever virus control measures also appears sufficient to encompass the determined NDV viremia period of 9-11 days in slaughter ostriches.     

Survival of Salmonella in the crop contents of market-age broilers during feed withdrawal.

Recent studies have indicated that crop contamination increases during preslaughter feed withdrawal and that contaminated crop contents may serve as an important source of Salmonella entry into poultry processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on crop pH and Salmonella crop contamination in broilers from three commercial broiler flocks. The effect of experimental feed withdrawal on crop pH, lactic acid concentration, and Salmonella crop contamination was also evaluated in market-age broilers challenged experimentally with Salmonella typhimurium. Crop pH increased significantly (P < 0.05) from 3.64 +/- 0.25 before feed removal to 5.14 +/- 0.72 after 8 hr of feed withdrawal in broilers from commercial flocks. The incidence of Salmonella crop contamination in the commercial broilers increased (P < 0.05) from 3.3% before feed removal to 12.6% after 8 hr of feed withdrawal. Similarly, crop pH increased (P < 0.05) by a magnitude of approximately 1 unit in broilers after 8 hr of experimental feed withdrawal. The population of S. typhimurium in the crops of the experimentally challenged broilers increased (P < 0.05) by approximately 1 log unit during the 8-hr experimental feed withdrawal. The concentration of lactic acid in the crop of the broilers during experimental feed withdrawal decreased (P < 0.01) from a range of 119-135 mumol/ml before feed removal to a range of 22-32 mumol/ml after 8 hr of feed withdrawal. The results indicated that feed withdrawal resulted in a decrease in lactic acid in the crop, accompanied by an increase in crop pH, and an increase in Salmonella crop contamination.     

Assessment of the respiratory actions of intramuscular morphine in conscious dogs.

The actions on the respiratory system of 0.25, 0.5 and 1.0 mg kg(-1) morphine given intramuscularly were studied in conscious dogs. Dogs breathed oxygen with 0, 2 and 4 per cent CO(2), in that order, through a mask attached to a flow sensor and connected to a respiratory mechanics monitor. When a steady state period of respiration was reached breathing pure oxygen, respiratory rate, tidal volume, respiratory minute volume, peak expiratory flow rate and end tidal CO(2)(PetCO(2)) were measured. The respiratory minute volume and PetCO(2) were measured when the dogs breathed 2 and 4 per cent CO(2) in oxygen, the points plotted onto a graph and the gradient of the line, describing the PCO(2)/ventilation response, plus the intercept with the y-axis were determined. Measurements for each morphine dose were taken before injection and at 30 minutes, 1, 2, 3, 4, 6 and 8 hours post injection.The incidence of panting after morphine was dose related and it occurred in all dogs given the high dose. Morphine reduced the gradients of the PCO(2)/ventilation response lines and raised the intercept. Other changes were increased respiratory minute volume and peak expiratory flow and decreased PetCO(2) and tidal volume.     

Evaluation of iodophor skin preparation techniques and factors influencing drainage from ventral midline incisions in horses.

OBJECTIVE: To document natural bacterial flora on the ventral aspect of the equine abdomen, to compare 2 preparation techniques, and to identify potential risk factors that may contribute to incisional drainage. DESIGN: Prospective study. ANIMALS: 53 horses undergoing exploratory celiotomy. PROCEDURE: Group-1 horses (n = 26) were prepared with povidone-iodine and alcohol. Group-2 horses (27) were prepared with a film-forming iodophor complex. Numbers of bacterial colony-forming units (CFU) were measured before and after surgical scrub, following skin closure, and after recovery from general anesthesia. Swab specimens to identify normal skin bacterial flora and potential pathogens were obtained by swabbing a 4 x 4-cm area. Variables that might affect incisional drainage were also investigated. RESULTS: For both techniques, there was a significant reduction in bacterial numbers after skin preparation. Incisional drainage was observed in 14 (26%) horses (8 group-1 and 6 group-2 horses). Preexisting dermatitis, poor intraoperative drape adherence, high number of bacterial CFU obtained after recovery from anesthesia, and high number of CFU obtained from the surgery room environment were the main risk factors associated with subsequent incisional drainage. Bacillus spp, nonhemolytic Staphylococcus spp, Micrococcus spp, Corynebacterium spp, Streptomyces spp, other nonenteric genera, and nonhemolytic Streptococcus spp were the most common isolates obtained before surgical scrub. CONCLUSIONS AND CLINICAL RELEVANCE: Both skin preparation techniques were equally effective in reducing numbers of bacterial CFU by 99%, and a significant difference was not found in incisional drainage rate between groups. Protection of the wound during recovery from anesthesia and the immediate postoperative period may reduce incisional drainage after abdominal surgery in horses.     

Serum total and ionized magnesium concentrations and urinary fractional excretion of magnesium in cats with diabetes mellitus and diabetic ketoacidosis

OBJECTIVE: To determine magnesium (Mg) status in cats with naturally acquired diabetes mellitus (DM) and diabetic ketoacidosis (DKA), evaluate changes in Mg status after treatment for DKA, and correlate Mg status with systemic blood pressure and degree of glycemic control. DESIGN: Case series and cohort study. ANIMALS: 12 healthy cats (controls), 21 cats with DM, and 7 cats with DKA. PROCEDURE: Serum total magnesium (tMg) and ionized magnesium (iMg) concentrations and spot urinary fractional excretion of magnesium (FEmg) were determined, using serum and urine samples obtained from all cats when they were entered in the study and from cats with DKA 12, 24, and 48 hours after initiating treatment. Indirect blood pressure and degree of glycemic control were determined in 10 and 21 cats with DM, respectively. RESULTS: Initially, 2 and 13 cats with DM and 1 and 4 cats with DKA had serum tMg and iMg concentrations, respectively, less than the low reference limit (mean-2 SD) determined for controls. In cats with DKA, serum tMg concentration decreased significantly over time after initiating treatment. Urinary FEmg was significantly higher in cats with DM or DKA, compared with controls. Systemic hypertension was not detected nor was there a correlation between Mg status and degree of glycemic control in cats with DM. CONCLUSIONS AND CLINICAL RELEVANCE: Hypomagnesemia was a common finding in cats with DM and DKA and was more readily identified by measuring serum iMg concentration than tMg concentration. The clinical ramifications of hypomagnesemia in such cats remain to be determined.     

Coccygeal muscle injury in English Pointers (limber tail)

A condition colloquially referred to as "limber tail" and "cold tail" is familiar to people working with hunting dogs, primarily Pointers and Labrador Retrievers. The typical case consists of an adult dog that suddenly develops a flaccid tail. The tail either hangs down from the tail base or is held out horizontally for several inches from the tail base and then hangs straight down or at some degree below horizontal. Initially, the hair on the dorsal aspect of the proximal tail may be raised and dogs may resent palpation of the area 3-4 inches (8-10 cm) from the tail base. Most dogs recover spontaneously within a few days to weeks. Anecdotal reports suggest that anti-inflammatory drugs administered within 24 hours after onset hasten recovery. Less than one half of affected dogs experience a recurrence. Affected Pointers almost always have a history of prolonged cage transport, a hard workout the previous day, or exposure to cold or wet weather Most owners and trainers familiar with the condition do not seek veterinary assistance. In cases where people are not familiar with this disease, other conditions such as a fracture, spinal cord disease, impacted anal glands, or prostatic disease have been incorrectly diagnosed. We examined 4 affected Pointers and found evidence of coccygeal muscle damage, which included mild elevation of creatine kinase early after onset of clinical signs, needle electromyographic examination showing abnormal spontaneous discharges restricted to the coccygeal muscles several days after onset, and histopathologic evidence of muscle fiber damage. Specific muscle groups, namely the laterally positioned intertransversarius ventralis caudalis muscles, were affected most severely. Abnormal findings on thermography and scintigraphy further supported the diagnosis.     

Isolation and characterization of the eighth component of the bovine complement system

OBJECTIVE: To isolate and characterize the eighth component of the complement system (C8) in cattle. SAMPLE POPULATION: Fresh plasma obtained from beef cattle. PROCEDURES: Plasma samples were fractionated, using sequential precipitation and ion-exchange and gel-filtration chromatography, to yield C8. The protein was identified throughout the procedure on the basis of its hemolytic function. Electrophoresis in polyacrylamide gels was used to determine molecular weight and composition of polypeptide chains. Reconstitution of classical and alternative complement pathways was used to characterize the hemolytic function of bovine C8. RESULTS: The bovine C8 protein consisted of a disulfide-bonded alpha-gamma heterodimer that was noncovalently associated with a beta chain. Apparent molecular weight of the alpha, beta, and gamma chains under reducing conditions were 66, 61, and 23 kd, respectively. In the classical pathway of activation, bovine C8 and the ninth component of the complement system (C9) had species incompatibility with human C8 and C9 on sheep erythrocyte target cells. CONCLUSIONS: A simple 4-step fractionation procedure provided good yield of bovine C8 from plasma. The isolated protein was structurally comparable to C8 from other species. Purified bovine C8 may be useful in functional hemolytic assays to investigate the roles of complement-mediated lysis in the pathogenesis of inflammatory diseases and the killing of susceptible microorganisms.     

Neurotoxicity in calves induced by the plant, Nierembergia hippomanica Miers var. violacea Millán in South Africa

The plant Nierembergia hippomanica var. violacea has been incriminated in field outbreaks of neurotoxicity in calves in the Free State Province. Hepatotoxicity and electrocardiogram (ECG) deviations were induced in a sheep dosed with 5 g/kg dried plant material on four consecutive days. A calf dosed with 2.5 g/kg dried plant material, on two consecutive days, did not show overt clinical changes. Voluntary ingestion of approximately 30 g/kg fresh flowering plants by a second calf resulted in nervous signs characterized by chewing motions, protrusion of the tongue, dysphagia, hypermetria, ataxia, paresis and lateral recumbency. Salivation, dehydration and cardiac irregularities completed the clinical picture. Clinical chemistry changes revealed muscle damage and increased serum urea and creatinine concentrations indicative of kidney involvement. This is the first confirmed outbreak of Nierembergia hippomanica var. violacea intoxication of stock in South Africa.     

Immobilization of babirusa (Babyrousa babyrussa) with xylazine and tiletamine/zolazepam and reversal with yohimbine and flumazenil.

Twelve babirusa (Babyrousa babyrussa) (four females/eight males) were immobilized 30 times during a 4-yr interval. Significantly higher premedication and immobilizing doses were needed for females than for males (P < 0.05). An i.m. preanesthetic xylazine dose of 1.88 +/- 0.37 mg/kg (range = 1.20-2.12 mg/kg) was used for females and 1.22 +/- 0.16 mg/kg (range = 0.82-1.43 mg/kg) for males. After xylazine, the animals were induced with i.m. tiletamine/zolazepam; females received 2.20 +/- 0.47 mg/kg (range = 1.78-3.33 mg/kg) and males received 1.71 +/- 0.34 mg/kg (range = 1.08-2.05 mg/kg). Anesthesia was reversed with yohimbine (0.14 +/- 0.03 mg/kg; range = 0.07-0.20 mg/kg) and flumazenil (1 mg flumazenil/20 mg zolazepam) either i.m. or i.v. This anesthetic combination produced smooth induction, good relaxation, and sufficient immobilization to perform routine diagnostic and therapeutic procedures (venipuncture, hoof and tusk trims, transportation, radiographs, ultrasound examination, weight determinations, and skin biopsies). Supplemental ketamine HCl or isoflurane was administered to two animals to effectively deepen or prolong the anesthetic plane, with no resultant adverse effects.     

Risk assessment and surveillance for bovine spongiform encephalopathy (BSE) in Argentina

An assessment was made of the risks of bovine spongiform encephalopathy (BSE) occurring in Argentina. Most of the factors associated with the origin and development of the BSE epidemic in the UK are essentially absent. For example, Argentina's large sheep and cattle industries are based on low-cost production systems using grass. Concentrated feeds are not used for sheep, rarely for beef cattle and to a comparatively modest extent for dairy cows. Particularly important are the facts that scrapie (and BSE) has never been reported in Argentina—very small amounts of waste tissues from sheep are rendered to produce meat and bone meal (MBM)—and MBM is not used in concentrated feeds for cattle. We conclude that Argentina has an exceptionally low risk of BSE due to scrapie. There is a very small risk of BSE having been introduced via live animals imported from countries with BSE, but this could only give rise to isolated cases because MBM is not fed to cattle.

A surveillance programme has been carried out based largely on a histological examination of brains from three categories of old dairy cows: animals reported on the suspicion of having neurological disease; animals in poor condition at slaughter; healthy animals randomly selected in the abattoir. No evidence of transmissible spongiform encephalopathy was seen in several sections from each of a total of 1019 brains. We conclude that, for most practical purposes, Argentina may be considered to be free from BSE.