Treatment of canine aural haernatorna using an indwelling drain and corticosteroids

Aural haematomas were treated using a Pen-rose tissue drain inserted through the haematoma and left in situ for two weeks. Oral prednisolone was prescribed at a dose of 2 mg/kg for two weeks then 1 mg/kg for a further two weeks. Twenty-nine haematomas were treated in 22 dogs. Twenty-six cases resolved after a single treatment. Three ears required a second treatment two to four weeks after the initial treatment and one dog had a postoperative infection of the drain tract. No ears required more than one repeated drainage. Good cosmetic results were achieved in all cases.     

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.     

Demonstration of pseudorabies viral antigen in thick and ultrathin tissue sections of young pigs using an immunogold method

Pseudorabies (Aujeszky's) virus antigens were labeled in thick and ultrathin tissue sections of young pig brain and liver tissue, using an indirect immunogold method. Antigens were tagged with 20 nm gold particles. Controls proved the specificity of the reaction in paraffin sections and ultrathin epoxy sections. Immunogold staining was compared with immunoperoxidase staining in paraffin sections. In ultrathin sections stained with the immunogold method, the gold particles were present on viral nucleocapsids and viral envelopes, as well as on a number of other intracellular structures. These included the inner nuclear membrane, the nucleoplasm, intranuclear filaments, the endoplasmic reticulum, and free cytoplasmic polyribosomes. Gold particles were absent on mitochondria and microtubules. In paraffin sections, immunogold labeling for pseudorabies virus antigen was less sensitive than immunoperoxidase staining. Immunogold staining of ultrathin tissue sections can yield additional information on virus-host cell interactions.     

Excretion of [3H]prednisolone in clinically normal and experimentally infected bovine udders

The excretion rate of [3H]prednisolone from clinically normal and experimentally infected udders of 10 lactating cows was studied. Each quarter of 6 cows was injected with a single dose of [3H]prednisolone mixed with non-radioactive prednisolone equivalent to 10 mg in 10 ml of peanut oil base. Each of the remaining 4 cows was given 40 mg of nonradioactive prednisolone and [3H]prednisolone in 60% ethanol IV. Control and postadministration samples of blood, milk, and urine were examined for radioactivity. The effects of [3H]prednisolone were evaluated in the same cows, first in clinically normal udders, then 2 weeks later in udders experimentally infected with Streptococcus agalactiae. Absorption and elimination of prednisolone were the same before and after induced infection. Within 3 hours after intramammary injection, 95% of the labeled prednisolone was absorbed systemically, less than 5% of this dose was recovered in milk, and 29% was excreted in urine. After IV injection of [3H]prednisolone, less than 0.2% of the total radioactivity was recovered in milk and less than 46% was excreted in urine. Clinical mastitis induced by S agalactiae was moderate. Circulating blood leukocytes and somatic cells in the milk of normal cows remained essentially unchanged. The leukocyte response to induced infection was rapid in blood and milk. Large numbers of leukocytes were noticed in the milk and a severe leukopenia occurred. Prednisolone treatment did not alter the number of somatic cells in milk or reduce the inflammatory response of experimentally infected cows.     

Zearalenone intoxication of pigs

Mycotoxicosis due to ingestion of zearalenone was detected on 2 pig farms on the Atherton Tableland in northern Queensland. In one herd of 200 pigs, this resulted from feeding maize which had been stored with a high moisture content. In the other herd of 1400 pigs, it resulted from feeding sorghum grain which was rain affected before harvest. Concentrations of zearalenone in the feeds ranged up to 8 mg/kg. Most prepubertal gilts in the herds displayed enlarged teats and signs of oestrus such as having red, swollen vulvas. In several cases both rectal and vaginal prolapses occurred. On one of the farms, 25 pigs died as a direct result of prolapses. Autopsy of a 3-month-old gilt revealed apparently enlarged ovaries and uterine horns. Sows and boars seemed to be unaffected. Four gilts failed to conceive following mating during the period of zearalenone ingestion, but apart from this and the deaths from prolapses, production of the herds appeared to be unaffected.     

Growth patterns of Angus, Hereford and shorthorn cattle. I. Comparison of inbred and noninbred lines, changes in patterns over time and effects of level of inbreeding and reproductive performance

Mature weight (A) and rate of maturing (K) were estimated for 283 Angus, 140 Hereford and 280 Shorthorn cows utilizing the asymptotic regression equation Yt=A(1-Be-Kt). The Yt was weight of the individual at age t; and B was an estimate related to early life weight changes and provided for a Y-intercept (A-B). Each breed consisted of four inbred and two noninbred lines. Regression of estimated growth curve parameters on levels of inbreeding of the individuals and of their dams and effects of early reproductive performance (EREPRO) were studied as sources of variation in addition to line differences and trends in line values over years. Considered jointly with inbreeding of the dam and with EREPRO, inbreeding of the individual was negatively related (P less than .01) to estimates of A in the three breeds and unrelated (P greater than .10) to estimates of K. Each 1% increase in inbreeding of the individual was associated with about 2 kg decrease in estimated mature weight. An increase in inbreeding of the dam of an individual was negatively related to estimates of K in Angus (P less than .01) and Shorthorns (P less than .05). Inbreeding of dams was positively related to estimates of A in the three breeds, but only in Shorthorns could the relationship be declared significant. Estimates of A were about 46 kg heavier and estimates of K about .010 less for each year an individual failed to produce a calf during her first three opportunities. In general, A values declined in all three breeds during the study. Significant changes were observed in all Hereford analyses and after inbreeding was included in the Angus analysis, while inclusion of inbreeding in the Shorthorn analysis caused the change to become unimportant. The K values increased in all three breeds during the study; however, the change could be declared significant only in Herefords.     

Haemodynamics, blood gas and metabolic changes after anaesthesia with chloral hydrate and magnesium sulphate in camels (Camelus dromedarius)

The effects of chloral hydrate and magnesium sulphate (1:1, 10 per cent solution) were evaluated in six healthy adult camels. A dose of 1 ml kg-1 was used. These agents produced satisfactory anaesthesia with good muscle relaxation. The changes in the electroencephalogram showed that the anaesthetic effect lasted for 45 to 60 minutes. Tachycardia and hypotension were moderate and within safe limits. Electrocardiogram studies showed ST segment elevation and primary T wave changes. The acid-base status, blood gas tensions, haemoglobin concentration, blood glucose level and the plasma concentration of total protein, sodium, potassium and chloride were not altered.     

Reproductive performance in a diallel cross among lines of mice selected for litter size and body weight

Genetic factors affecting female reproductive performance in lines of mice with a known history of selection were estimated from a 5 X 5 diallel cross. Lines were selected as follows: large litter size at birth (L+); large 6-wk body weight (W+); an index for large litter size and small 6-wk body weight (L+W-); the complementary index (L-W+) and randomly (K). Partitioning of direct and correlated responses for litter size, 6-wk body weight and related traits into average direct genetic (li) and average maternal genetic (mi) effects indicated that the magnitude of differences in li exceeded those in mi. Lines having positive responses in li were W+ greater than L+ greater than L-W+ for dam body weight, L+ greater than L+W- greater than W+ for litter size and L+ greater than (W+, L+W-) for litter birth weight, whereas L-W+ responded negatively for litter size. A positive association was found between mi for litter size and dam body weight, W+ and L-W+ being high and L+ and L+W- low for both traits. Female infertility and time from male exposure to parturition had relatively small correlated responses. Line rankings in general combining ability (gi) and net line effects were similar for the respective traits. Depending upon the line and trait involved, the relative contribution of average direct genetic and line direct heterotic (hi) effects to general combining ability [gi = (1/2) li + hi] varied. Line heterosis refers to average heterosis in crosses involving that line. Direct heterosis ( hij ) for each trait differed considerably among crosses. The three crosses showing the highest hij for litter size at birth, W+ X L-W+ (1.78), L+ X W+ (1.28) and L-W+ X L+W- (1.22), possibly had loci contributing directional dominance to litter size with frequencies of parental lines deviating in opposite directions relative to mean gene frequency. The correlation between absolute difference in parental line means and hij for litter size was not significant, suggesting that the magnitudes of absolute differences in parental means were not reliable predictors of divergence in gene frequency. Crossbred performance increased linearly with midparent values for litter size at birth (b = .88 +/- .09, R2 = .92) and dam parturition body weight (b = 1.13 +/- .04, R2 = .99), the latter trait showing an increase (P less than .01) in heterosis as midparent values increased.     

Determination of the antigenic relationships within the Massachusetts (M41) type of infectious bronchitis virus using the hemagglutination-inhibition test

The antigenic relationships, antigenic spectrum, and immunogenicity of seven IBV-Massachusetts-41 isolates were investigated using the hemagglutination-inhibition (HI) test. HI titers equal to 32 are considered suspicious, titers lower than 32 are considered negative, and titers higher than 32 are considered positive immune responses to infectious bronchitis virus (IBV). Some isolates of Massachusetts-41 ( M41 ) were capable of inducing large quantities of antibodies in chickens following inoculation and demonstrated a wider antigenic spectrum than others. Variations in antigenic spectrum observed within M41 isolates in this study are in agreement with previous reports. This variation is of importance in selecting a proper vaccine strain for a successful immunization program for IBV.     

Effects of some clinically significant mycotoxins on the incorporation of DNA, RNA and protein precursors in cultured mammalian cells

The effects of zearalenone (F-2), ochratoxin A and T-2 toxins on the synthesis of DNA, RNA and proteins in mouse L cells were studied. F-2 toxin inhibited protein synthesis to a lesser extent than DNA and RNA synthesis, whereas ochratoxin A inhibited the synthesis of each equally. Exposure to the toxins for 24 hours relatively reduced the synthetic ability of the cells. T-2 toxin inhibited protein and DNA synthesis in parallel but RNA synthesis to a lesser extent. Enhanced incorporation of tritiated thymidine was found when L cells were exposed to 0.4 to 0.016 ng of T-2 toxin ml-1 for 24 hours.