The effects of fungicides on certain chemical and microbial properties of soils

Field application of six fungicides at twice the normal rate resulted in increases in bacterial and fungal numbers after 28 days. Members of the fungal genera Gliocladium. Penicillium and Trichoderma predominated. Fungicides when applied at the field rate decreased the concentration of NO₃^? -N in soils. while the level of exchangeable NH₄⁺ -N, K, Mn and Na were generally increased. Addition of the fungicides to soil incubated in the laboratory consistently increased exchangeable Mn and K, and occasionally increased exchangeable Cu, Na and Zn. The results are discussed in relation to the microbial changes which occur, and in relation to soil fertility.     

Conjunctival lesions caused by Moraxella bovis in gnotobiotic calves

Hemolytic Moraxella bovis was instilled into the conjunctival sac of gnotobiotic calves, and conjunctivae were sampled serially after infection. Bilateral lesions developed in seven of eight infected calves. Histologically, M. bovis was first seen within swollen epithelial cells near the lid margins and occasionally within superficial epithelium in other areas. Conjunctival erosions and ulcers were seen in later stages. Scanning electron microscopy showed M. bovis in pits on surfaces of epithelial cells and in erosions on palpebral conjunctivae; lesions were prominent near lid margins. By transmission electron microscopy, M. bovis was seen within swollen epithelial cells near lid margins; many epithelial cells had undergone cytolysis. This study demonstrates that virulent M. bovis can invade bovine conjunctival epithelial cells and cause conjunctivitis in the absence of injurious ultraviolet irradiation or other predisposing environmental factors.     

ULTRASONOGRAPHIC EXAMINATION OF ABDOMINAL LYMPH NODES IN THE DOG

Ultrasonography is a valuable diagnostic tool for examination of the abdomen. Normal lymph nodes are often indistinct during routine abdominal ultrasonographic examination. Lymph nodes altered by infiltrative or inflammatory processes may become sonographically visible due to enlargement and/or altered echogeńicity. A working knowledge of the anatomic distribution of lymph nodes and the scheme of lymphatic drainage is important for increasing the sensitivity and specificity of abdominal lymph node assessment during ultrasonographic examination.     

ULTRASONOGRAPHY OF THE EQUINE BICIPITAL TENDON REGION: A CASE HISTORY REPORT AND REVIEW OF ANATOMY

The equine shoulder region is difficult to investigate by conventional imaging modalities. Diagnostic ultrasound has proven valuable for investigation of soft tissue injuries of the human shoulder. In a horse with shoulder lameness, the authors employed diagnostic ultrasound to augment the use of conventional radiography. A defect in the subchondral bone layer of the medial humeral tuberosity, with adjacent bony fragments were clearly identified with ultrasound. Ultrasound was used for initial evaluation of the bicipital tendon and bursa. The technique was subsequently used to follow and evaluate the post-operative condition of the proximal cranial humerus, bicipital tendon and bursa in this patient. The bicipital regions of 2 immature and 3 adult normal horses were also examined with to illustrate the normal ultrasonographic anatomy of the cranial shoulder region.     

Use of subcutaneously implanted chambers in calves for in vivo study of isolates of Moraxella bovis

Selected cultures of Moraxella bovis were studied in calves, using chambers fabricated from a semipermeable membrane supported and protected by perforated plastic golf balls. Plain balls, semipermeable membrane-covered balls, and balls that contained bags fabricated from semipermeable membranes were surgically implanted subcutaneously in calves at a site approximately 25 cm ventral to the paralumbar fossa and cranial to the prefemoral lymph node. After calves recovered from surgery, chambers were inoculated with different cultures of M bovis. Cultural examination of samples taken from inoculated chambers indicated that M bovis cultures were maintained within the chambers for variable times, depending on the characteristics of the culture inoculated. A smooth (piliated) culture dissociated into a rough (nonpiliated) culture after 4 weeks of incubation within a chamber but none of the rough cultures became smooth. The technique offers a method to study the in vivo variations in a series of cultures or strains of microorganisms under the influence of the same host factors. The selective permeability of the chamber may be controlled by using membranes of different porosities to control the flow of entering or exiting dialysate.     

Experimentally induced infectious bovine keratoconjunctivitis: resistance of vaccinated cattle to homologous and heterologous strains of Moraxella bovis.

In studies to determine whether vaccination with one strain of Moraxella bovis would protect against challenge with virulent homologous or heterologous strains, calves were intramuscularly inoculated 3 times with formalin-killed M bovis, with 14 days between inoculations. Fourteen days after the 3rd vaccinal dose was given, all calves were exposed to homologous or heterologous virulent cultures of M bovis. The results indicated that vaccination with one strain of M bovis may induce protective immunity against homologous and heterologous challenge exposure; however, because vaccinated cattle resisted infection and disease produced by a homologous strain to a greater extent than they resisted those produced by heterologous strains, polyvalent vaccines or highly immunogenic common antigens may be needed to protect cattle against the numerous strains they might encounter under natural field conditions. There was minimal correlation between the presence of precipitating antibodies against the heterologous strains and the establishment of infection and disease.