COMPARISON OF THE ULTRASONOGRAPHIC APPEARANCE OF OSTEOCHONDROSIS LESIONS IN THE CANINE SHOULDER WITH RADIOGRAPHY, ARTHROGRAPHY, AND ARTHROSCOPY

Osteochondrosis lesions in 29 shoulder joints (from 20 dogs) were evaluated with ultrasound (US) and the results were compared with survey radiography, arthrography, and arthroscopy. US was performed with a 7-12 MHz linear matrix transducer which was placed in cranio-caudal direction just distally to the acromion while the joint was adducted and maximally endorotated to visualize the caudal aspect of the humeral head. With US, the subchondral defect was completely visible in 21 joints and partially visible in 8 joints. The length of the subchondral defect measured on US was comparable with the length measured on survey radiographs. In two joints, the cartilage flap was mineralized and thus already visible on survey radiographs. The mineralized flap was visible on US as a straight hyperechoic line above the subchondral defect. In the other joints, survey radiographs could not assess the status of the articular cartilage. In 17 joints, the presence of a cartilage flap or cartilage fissuring was suspected based on the presence of a second hyperechoic line at the base of the subchondral defect, and this suspicion was confirmed by arthroscopic examination in 16 joints and also by arthrographic examination in 15 joints. One joint that was suspected of having a cartilage flap on US was normal on arthroscopy and arthrography. When US revealed only focal thickening of the anechoic cartilage layer (5 joints), the joints appeared normal on arthroscopic and arthrographic examination. Of the four joints where the subchondral defect was irregular and covered by heteroechogeneous material on US, arthroseopy revealed the presence of a lesion resembling chondromalacia in two joints, the presence of a small cartilage flap in one joint and the presence of scar tissue underneath the flap at the level of the subchondral defect in one joint. In conclusion, US is a helpful imaging modality in the identification of osteochondritic lesions in the canine shoulder joint. US also appears to be a satisfactory imaging tool for identifying lesions such as joint mice, joint effusion, and distinct new bone formation.     

Rabbit model for estimating relative bioavailability, residues and tissue tolerance of intramuscular products: comparison of two ampicillin products

A rabbit model for simultaneous investigation of the bioavailability, tissue residues and tissue tolerance of intramuscularly administered veterinary medicines is described. The bioavailability of ampicillin from two intramuscular products, which had been found to be different in calves, were compared in a two-way crossover design. The ampicillin levels in plasma, ampicillin residues in tissues, the plasma creatine kinase activity and the tissue damage at the injection sites were studied. The absolute bioavailabilities for the products were 100% and 40%. Differences in pharmacokinetics of ampicillin between sexes were observed after intravenous and intramuscular administration. Only slight tissue damage could be detected at the injection sites after intramuscular administration of these products. The results were compared with those obtained previously in calves and were found to be similar. Further investigations with other intramuscular drug products to validate this model are under way.     

Focus expansion of bean rust in cultivar mixtures

Radial expansion of foci in mixtures of susceptible and resistant bean cultivars was studied at two sites in Ethiopia. The foci expanded in a wave-like fashion. At Ambo (1990), radial expansion velocity ranged from 6 cm per day in mixtures with 20% susceptible plants to 15 cm per day in plots with the susceptible plants only. At Debre Zeit, the velocity ranged from 3 cm per day in a mixture with 20% susceptible plants to 16 cm per day in plots with 100% susceptible plants. At both sites the radial expansion velocity of foci correlated linearly with the logarithm of the fraction of susceptible plants in the mixture. Velocities of focus expansion at Ambo and Debre Zeit were approximately equal in plots consisting of susceptible plants only. At lower proportions of susceptible plants the velocities at Debre Zeit were lower than at Ambo. Indications were given as to the environmental factors responsible for the observed difference between sites. At each site, the variation between plots showed a clear spatial pattern, probably due to environmental factors.     

Effect of gonadal hormones on the plasma clearance and metabolite formation of antipyrine in the dwarf goat

The effect of gonadal hormones on the plasma elimination and urinary metabolite profile of antipyrine was studied in dwarf goats. Female goats were treated with testosterone and male goats were treated with 17β-oestradiol. Castrated males were treated with either testosterone or 17β-oestradiol. Antipyrine (25 mg/kg, i.v.) was given both before and after the hormonal treatments. The effects of the hormonal status on the plasma elimination of the parent compound were not consistent. This was possibly due to the fact that formation of the main metabolite of antipyrine in the goat, 4-hydroxy antipyrine (OHA), was not affected by sex or hormonal treatment. On the other hand, there were clear effects of hormonal status on urinary excretion of the three other metabolites. In females and castrated males testosterone suppressed the formation of norantipyrine (NORA), 3-hydroxymethylantipyrine (HMA) and 4,4'-dihydroxyantipyrine (DOHA). Intact males produced smaller amounts of these metabolites than females. It is concluded that distinct xenobiotic metabolizing pathways exist in the dwarf goat, which are influenced in their activity by gonadal hormones. This confirms previous findings in rats and mice. The possibility that sex hormones influence drug metabolism in food-producing animals could have consequences for veterinary therapeutics and public health. This study also demonstrates that, when using the antipyrine test for the assessment of hepatic drug metabolism, it is very important to include the determination of metabolites.     

Regulation of bronchomotor tone in conscious calves

The purpose of this study was to investigate the effects of some a and β sympathomimetic and sympatholytic drugs on respiratory impedance in healthy conscious calves. Ten Friesian calves were investigated in this study. The forced oscillation technique was used to measure the resistance ( R _rs) and the reactance ( X _rs) of the respiratory system at frequencies ranging from 4 to 26 Hz. Isoprenaline (1 μg/kg i.v.), propranolol (3 μg/kg i.v.), noradrenaline (2 μg/kg i.v.), xylazine (20 μg/kg i.v.) and yohimbine (0.25 mg/kg i.v.) were administered. Isoprenaline induced a significant decrease of R _rs. An increase of R _rs after administration of propranolol was observed but without any change of the frequency dependence of R _rs. A small increase in the resonant frequency was also recorded. A decrease of R _rs was recorded after yohimbine injection. Noradrenaline and xylazine administration increased the resistances and the resonant frequency and induced a negative frequency dependence of R _rs. These results suggest that (1) the major effects of β adrenergic drugs are on the central airways, (2) the a adrenergic system may play a role on the regulation of bronchomotor tone in calves, (3) the effects of a adrenergic drugs are on both central and peripheral airways and (4) the forced oscillation technique allows the differentiation of calibre changes occurring in small and large airways.     

ULTRASOUND APPROACH TO THE CANINE DISTAL TIBIA AND TROCHLEAR RIDGES OF THE TALUS

The aim of the present study was to evaluate to what extent the distal tibia and the trochlear ridges of the talus can be examined with ultrasound (US) in the dog and to establish a protocol for an optimal US examination of these ridges. Six hind limbs of deceased adult mixed-breed dogs were used. In two limbs, needles were placed using US guidance on the trochlea of the talus, just dorsal to and plantar to the distal tibia: one with the tarsal joint in extension and one with the joint in flexion. Then mediolateral (ML) radiographs of both joints were made with the needle in place to determine the percentage of the trochlear ridge of the talus that can be seen using US imaging. An US examination of the tarsal joint was performed on the four other limbs using microconvex (8 MHz) and linear (12 MHz) transducers (Logiq 7) and compound imaging. A three-step protocol was performed including a dorsal approach with the limb extended and the linear transducer (step I), a plantar approach with the limb flexed and the linear transducer (step II), and a plantar approach with the limb flexed and the microconvex transducer (step III). After the US examination, the four limbs were frozen and sectioned, two in a transverse and two in a sagittal plane. Bony structures on the US images were matched with the corresponding anatomic sections. The distal tibia and both trochlear ridges of the talus were easily recognized on the US images using the proposed protocol. When combining the dorsal and plantar approaches, it was possible to visualize up to 75% of the trochlear ridges of the talus in the dog.     

Trypanosomatid flagellate in the Phloem of diseased coconut palms

Ultrastructural observations of the phloem of coconut palms affected by "hartrot" disease in Suriname have revealed the presence of the plant-infecting flagellate Phytomonas in mature sieve tubes. The occurrence of these flagellates during the earliest symptoms of the disease and the correlated increase and spread of the flagellates in the phloem as the disease progresses suggest that the organisms may be pathogenic to the palms.