Pathology and residues in veal calves treated experimentally with clenbuterol

Six veal calves were medicated with clenbuterol at 20 μg kg bodyweight⁻¹ day⁻¹ for 42 days before they were slaughtered, to evaluate the lesions and residues in target organs. Compared with six unmedicated calves the most noticeable changes were tracheal dilatation, decreased uterine weight, slight mucous hypersecretion in the uterus and vagina and depletion of liver glycogen. The highest concentrations of clenbuterol (62 to 128 ng/g⁻¹) were recorded in the choroid/retina, and the aqueous humour had the lowest concentration (0·5 to 2·4 ng ml⁻¹). The residue concentrations were higher than the maximum residue level set for clenbuterol (0·5 ng g⁻¹)     

Changes in lymphocyte glucocorticoid and beta-adrenergic receptors in veal calves treated with clenbuterol and steroid hormones for growth-promoting purposes

In order to identify possible peripheral markers of illegal treatments with growth-promoting agents in veal calves, beta-adrenergic receptor (beta-AR) and glucocorticoid receptor (GR) concentrations were measured in lymphocytes of 12 male Friesian crossbred calves (six controls and six treated). The animals received a cocktail of anabolic and re-partitioning agents [17beta-oestradiol: 3 x 10 mg intramuscular (i.m.) doses at 17-day intervals; dexamethasone sodium phosphate: 4 mg/day for 6 days and 5 mg/day for six further days dissolved in milk; and clenbuterol: 20 microg/kg/day dissolved in milk for the last 40 days before slaughter]. Blood samples were collected by venipuncture at different time points and lymphocytes were isolated by density gradient centrifugation. Lymphocyte beta-AR and GR levels were measured by binding assays. Treatment with re-partitioning agents caused a significant down-regulation of lymphocyte beta-ARs 19 days after the beginning of clenbuterol administration and at day 55 (after dexamethasone withdrawal, just before slaughter). This phenomenon was partially reversed at day 50, after dexamethasone administration, at which time a significant decrease in GR concentrations also occurred. For both types of receptors, no significant changes in the dissociation constant values were observed at any time point. Lymphocytes express measurable concentrations of beta-ARs and GRs and the measurement of receptor levels highlights the fluctuation of receptor expression due to the dynamic interaction of the drugs used in combination. Lymphocyte receptor determination could therefore be included in a battery of biological assays to detect illegal treatments with anabolic agents in veal calves in the light of a multivariate approach.     

Effects of clenbuterol on haemocoagulation process in calves

The aim of this investigation was to study the effects of clenbuterol treatment (1 mug/kg b.w. i.m. for 10 consecutive days) on haemocoagulation process in seven calves. From each animal, blood samples were taken before (basal sample) and 24, 72, 144, 216, 264, 336 and 360 h after the end of treatment and some parameters were evaluated: coagulation process [prothrombin (PTT) and thrombin times (PT)], a complete blood count and plasmatic levels of 3'5'-monophosphatocyclic-adenosine (c-AMP) . A comparison of the values in each time group during the whole course of the experiments shows a significant increase (P < 0.03, P < 0.01) in PT and PTT at 72, 144, 216 and 264 h. Significant increase (P < 0.01) in c-AMP plasma levels were observed at 144, 216 and 264 h. All these values returned to normal levels after 360 h.     

Effect of clenbuterol on the incidence of abomasal ulcers in veal calves

The effect of clenbuterol on the incidence of abomasal lesions in veal calves was studied in two fattening units. Some of the calves in each unit were treated with 1.6 micrograms clenbuterol/kg bodyweight/day from the seventh until the 23rd week of the fattening period. In one unit the calves were fed milk replacer only and 176 of the 236 calves were treated with clenbuterol. In the other unit the calves were fed roughage pellets in addition to milk replacer and 92 of the 194 calves were treated with clenbuterol. Only in the second unit did the calves treated with clenbuterol have significantly fewer abomasal lesions.     

The pharmacokinetics and residues of clenbuterol in veal calves.

Seven female Brown Swiss calves were used to study the pharmacokinetics of clenbuterol after an effective anabolic dosage of 5 micrograms/kg of BW was given twice daily for 3 wk. Analyses of clenbuterol concentrations in different tissues was done by enzyme immunoassay (EIA). Tissue samples were taken from three calves on the last day of administration and from two more after 3.5 or 14 d of clenbuterol withdrawal. The rate of clenbuterol elimination was dependent on time and tissue. Clenbuterol concentrations in the lung dropped from a mean of 76 ng/g to a level of less than .08 ng/g after 14 d, whereas in the liver the clenbuterol concentrations decreased from 46 ng/g to .6 ng/g within 14 d of withdrawal. Highest levels were always found in the eye: 118 ng/g, 57.5 ng/g, and 15.1 ng/g after 0, 3.5, and 14 d of withdrawal, respectively. These data reveal that different compartments contribute to the elimination of clenbuterol; therefore, concentrations in urine do not follow first order kinetics. An initial rapid decline in the concentration of clenbuterol in urine with a half-life of 10 h is followed by a slower elimination with a half-life of about 2.5 d. Treatments using the anabolic dose of 5 micrograms/kg of BW require longer withdrawal times than the therapeutic dose (.8 micrograms/kg BW).     

The effects of clenbuterol hydrochloride on the pulmonary function of calves with subacute and chronic bronchopneumonia

The influence of clenbuterol on some pulmonary function tests in 11 calves with subacute and chronic bronchopneumonia has been investigated. Treatment with clenbuterol caused changes only in calves with subacute bronchopneumonia; in these animals it decreased the total pulmonary resistance, the viscous work per litre and the peak to peak changes in transpulmonary pressure.     

Effects of metoclopramide, clenbuterol and butorphanol on ruminoreticular motility of calves

Rate and amplitude of contractions of the rumen dorsal sac and reticulum of 6 male Holstein calves ages 12 to 20 weeks were monitored with electromyography, strain gauges and an intraruminal pressure catheter. Heart rate and mean arterial pressure were measured with ultrasound. The effects of metoclopramide, a dopamine antagonist, clenbuterol, a beta-2 adrenergic agonist, and butorphanol, a narcotic agonist/antagonist, were observed utilizing dosages bracketing those employed clinically. Metoclopramide significantly decreased the intraruminal pressure peaks associated with cyclical contractions without changing their rate. Clenbuterol had no measurable effect on the ruminoreticulum. Butorphanol totally inhibited ruminoreticular contractions for periods of 6 to greater than 40 min depending on dosage. Only clenbuterol significantly affected cardiovascular function; it increased heart rate and decreased mean arterial pressure. Both metoclopramide and butorphanol produced behavioral changes in the calves.     

The influence of clenbuterol on prostaglandin F2 alpha-induced dyspnoea in calves

Pulmonary function tests were performed in six healthy calves. Prostaglandin F2 alpha causes severe narrowing of both upper and lower airways (total lung resistance increased, dynamic compliance decreased). Clenbuterol administered intravenously fifteen minutes prior to prostaglandin F2 alpha aerosol, and in increasing doses (0, 0.4, 0.8, 1.2 micrograms/kg), on days 1, 2, 4 and 6 of the experiment, effectively but not entirely suppressed these responses. These data indicate that beta-adrenergic receptors are present in the bovine airways and that the use of clenbuterol (0.8 micrograms/kg) may be effective in treating clinical respiratory disease such as bronchopneumonia in calves.     

Prenatal growth of the adrenal gland in sheep

From 1256 adult sheep received for clinical/post-mortem examination over an 8 1/2-year period, intestinal adenocarcinomas were diagnosed in 37 (2.9%). Mean age of the affected animals was 6.1 years. Clinical pathology and post-mortem findings are summarized.     

The effect of clenbuterol on lung function parameters in calves suffering from bronchopneumonia

Pulmonary function testing was performed in calves affected with bronchopneumonia. In these calves respiratory rate, viscous work per litre air and per minute, intrapleural pressure difference, mean inspiratory and expiratory flow rate and ventilation per minute were significantly increased. Total resistance of the lung was just not significantly increased. Dynamic compliance and tidal volume were significantly reduced. The main effect of clenbuterol was a significant increase in dynamic compliance. The reduction in the total resistance of the lung was just not significant. These results indicate that clenbuterol can antagonise, at least partly, the alterations caused by bronchopneumonia.     

The effect of clenbuterol on lung function parameters in calves suffering from bronchopneumonia

Pulmonary function testing was performed in calves affected with bronchopneumonia. In these calves respiratory rate, viscous work per litre air and per minute, intrapleural pressure difference, mean inspiratory and expiratory flow rate and ventilation per minute were significantly increased. Total resistance of the lung was just not significantly increased. Dynamic compliance and tidal volume were significantly reduced.The main effect of clenbuterol was a significant increase in dynamic compliance. The reduction in the total resistance of the lung was just not significant. These results indicate that clenbuterol can antagonise, at least partly, the alterations caused by bronchopneumonia.     

Blood supply of the ovine adrenal gland and its relevance in adrenal autotransplantation

SUMMARY The arterial supply and venous drainage of 62 left and 5 right ovine adrenal glands is described, and the contribution of individual arteries to successful adrenal gland autotransplantation was evaluated. Arterial flow was measured by direct collection from the draining adrenal vein. Assessment of function of the transplanted adrenal gland was made from survival of the sheep and by the cortisol response to infusion of ACTH and the aldosterone secretory response to infusion of angiotensin II or potassium. For the left adrenal, the principal arterial supply was from the renal artery in 21 (34%), a lumbar artery in 32 (52%), and the anterior mesenteric artery in 3. The total blood flow was 5.0 ± SEM 0.4 mL/min, the flow from the renal branch 2.3 ± 0.3 mL/min, and the principal lumbar branch 2.6 ± 0.3 mL/min. Venous drainage from the left adrenal was via a major adrenal vein to the left renal vein, but additional tributaries to the renal vein were present in 26% . The arterial supply to the adrenal is regional and omission of a branch at transplantation could result in infarction of portion of the gland. By defining arterial supply and measuring blood flow, selection of the appropriate artery or multiple arteries can achieve an adrenal gland autotransplant survival of 90% .     

Altered protein expression in neutrophils of calves treated with dexamethasone

The effect of glucocorticoid treatment on protein expression in bovine neutrophils was examined with a proteomic approach to address the mechanisms by which stress alters neutrophil function and predisposes to bacterial pneumonia in cattle. Calves 6 to 8 mo old were treated with dexamethasone (0.1 mg/kg), neutrophils were isolated 24 h later, and whole-cell lysates were examined by 2-dimensional electrophoresis. Differentially expressed protein spots were identified by peptide mass fingerprinting. The antimicrobial protein lactotransferrin was detected at increased amounts in the neutrophils of the dexamethasone-treated calves. Proteins detected at reduced amounts in the neutrophils of the dexamethasone-treated calves included annexin 1, phosphoglycerate mutase, Na(+) - K+ ATPase, and cathelicidin 1. These findings identify glucocorticoid-induced changes in the levels of neutrophil proteins involved in host defense, inflammation, and cellular metabolism and suggest additional mechanisms by which glucocorticoids affect neutrophil function.     

Effects of mitotane therapy in dogs with pituitary dependent Cushing syndrome on the adrenal gland size--an ultrasonographic study]

The effect of mitotane therapy on adrenal gland size was evaluated in 13 dogs with pituitary dependent hyperadrenocorticism. Ultrasonographic measurements were obtained before and during mitotane therapy. During therapy both adrenal glands were shorter and thinner (median during therapy: left adrenal gland 19.4 mm long, 5.4 mm thick, right adrenal gland 18.1 mm long, 6.1 mm thick) than before mitotane therapy (median before therapy: left adrenal gland 23.6 mm long, 8.3 mm thick, right adrenal gland 21.6 mm long, 8.1 mm thick). Statistical evaluation showed a significant reduction in size. But ultrasonographic measurement of adrenal gland size is not useful in the evaluation of adrenal reserve during mitotane therapy. Inadequate adrenal reserve was not identified and adrenal size measurement by ultrasonography was not helpful to differentiate adequate and inadequate control of adrenal cortisol secretion during mitotane therapy.     

Besnoitia cysts in the adrenal gland of a cow

Summary

An unusual finding of Besnoitia besnoiti was discovered during histopathological examination of the adrenal gland of a cow brought to slaughter.