MAGNETIC RESONANCE IMAGING OF OCULAR AND ORBITAL DISEASE IN 5 DOGS AND A CAT

Magnetic resonance (MR) images were acquired in five dogs and one cat with ocular and orbital disease. MR images were obtained in the dorsal or oblique dorsal, and oblique sagittal planes. Pathologic changes identified in MR images included inflammatory lesions, cystic structures, and neoplasms. All abnormalities were readily apparent in TI-weighted images. MR findings in affected animals were often similar in signal intensity, location, and growth pattern to those found in people with comparable diseases. Although no MR changes were considered pathognomonic for a given disease, MR imaging provided detailed information on the homogeneity, extent and invasiveness of the lesions.     

Effect of hypocalcaemia on blood flow distribution in sheep

Cardiac output, the proportion of blood passing through arteriovenous shunts and blood flow distribution to various organs were measured and compared in five normocalcaemic and five hypocalcaemic sheep using radioactive microspheres. Hypocalcaemia was induced by infusing sodium EDTA solution intravenously for two hours. There was evidence that microspheres were leached from liver, muscle, adrenal and thyroid tissues during the induction of hypocalcaemia. Hypocalcaemia reduced blood flow rates by more than 58 per cent in all tissues examined except kidney (48 per cent), heart (53 per cent), lung (10 per cent) and bladder (47 per cent) and reduced cardiac output from 3.70 +/- 0.19 (mean +/- SE) litres min-1 to 2.39 +/- 0.14 litres min-1. Approximately 2.2 per cent of cardiac output passed through arteriovenous shunts. This percentage was unaffected by hypocalcaemia.     

A SURVEY OF CLINICAL MASTITIS IN SOUTH-EAST QUEENSLAND DAIRY HERDS

SUMMARY A survey of clinical mastitis in 26 South-East Queensland dairy herds supplying more than 300,000 litres of milk annually, revealed a quarter incidence of 2.6% with a cow incidence of 9% over a 3-month period. Secretion samples from cows yielded Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, Pseudomonas spp and other bacteria in 38.5%, 12.5%, 6.6%, 3.4%, 2.6%. 0.6% and 2.0% of cases respectively. Samples from 38% of the cases were culturally negative while at least 38% of the clinical quarters had shown a previous clinical episode of mastitis. There was a significant association (P < 0.025) between herd and the likelihood of a negative culture result on samples from clinical cases. Twenty-one percent of cases occurred in the first month of lactation and 10.3% in the first week. There was a significant association (P < 0.005) between the age of cow and the stage of lactation in which clinical cases occurred in that cows in the 2 to 5 year age group were more likely to suffer attacks in the earlier part of lactation. There was a highly significant relationship (P < 0.005) between cow age group and the proportion of affected quarters and it was calculated that the change with each year of age was a 55% increase over the previous year. Forty-five percent of the isolates of S. aureus were resistant to penicillin.     

Per Rectal Portal Scintigraphy Using 99mTechnetium Pertechnetate to Diagnose Portosystemic Shunts in Dogs and Cats

Per rectal portal scintigraphy using 99mTechnetium pertechnetate (99mTcO4-) was used to diagnose portosystemic shunts (PSS) before surgical confirmation in seven dogs and two cats. Shunt fractions, representing the percent of portal blood that bypasses the liver, were determined by computer analysis of the scintigraphic images. Animals with portosystemic shunts had a mean preoperative shunt fraction of 84.02% (n = 9). The mean postoperative shunt fraction in four animals was 58.22%. The mean shunt fraction in ten control dogs was 5.00%. Per rectal portal scintigraphy is an innovative, easily performed, inexpensive method to diagnose congenital portosystemic shunts in dogs and cats.     

Resistance in mutagen-induced mutants of Ustilago maydis to fungicides which inhibit ergosterol biosynthesis

Resistance to a number of inhibitors of sterol C-14 demethylation, (clotrimazole, imazalil, miconazole, fenarimol, nuarimol and triadimefon), as well as resistance to inhibitors of sterol C-14(15) double bond reduction, (tridemorph and fenpropi-morph), was readily induced in Ustilago maydis. Resistant mutants were obtained after mutagenic treatment by ultraviolet irradiation, or by treatment with 1-methyl-3-nitro-1-nitrosoguanidine, of sporidia of the wild-type strain, followed by selection in the presence of the toxicant. The level of resistance of these mutants varied appreciably. Although not always reciprocal, cross-resistance to fungicides which inhibit ergosterol biosynthesis (EBIs) appeared to be present in most cases. Several of the U. maydis mutants which were resistant to inhibitors of sterol C-14 demethylation lacked cross-resistance to tridemorph and fenpropimorph, or displayed increased sensitivity to fenpropimorph (negatively correlated cross-resistance). Cross-resistance between EBIs and the antimicrobial agents climbazole and lombazole was also established. It is suggested that fungal mutants that possess a resistance mechanism based on a deficiency in sterol C-14 demethylation or sterol C-14(15) double bond reduction, have a greatly reduced chance of survival.     

Factors affecting red-winged blackbird response to methiocarb,an avian repellent

Two physiological responses (heart rate and respiration rate) and a behavioral response (keypecking rate) were measured to determine whether or not bait from and/or gastrointestinal content would influence the efficacy of an avian repellent on red-winged blackbirds. Methiocarb was administered under four conditions (i.e., cracked corn or pellet baits and food deprivation or nondeprivation). Results show that both physiological and behavioral responses to methiocarb are much more pronounced when it is administered in pellet form to food-deprived birds. These findings help explain some inconsistencies in results of field evaluations of methiocarb and illustrate the significance of formulation and the timing of treatment application as important factors in development of bird damage control agents and techniques.     

Prevalence of Fasciola hepatica in dairy herds in England and Wales measured with an ELISA applied to bulk-tank milk

An ELISA developed to diagnose Fasciola hepatica infection in cattle by detecting serum antibodies was adapted and validated for use with samples of bulk-tank milk. The prevalence of the infection in 61 dairy herds was established by using serum antibody levels or faecal egg counts measured in a proportion of the cows in each herd. The correlation between the results of the ELISA and the herd seroprevalence was 0.83. Using a cut-off value of 27 per cent positive, the bulk-tank ELISA identified herds in which more than 25 per cent of the cows were infected with a diagnostic sensitivity of 96 per cent (95 per cent confidence interval 89 to 100 per cent) and a diagnostic specificity of 80 per cent (95 per cent confidence interval 66 to 94 per cent). By applying the ELISA to 623 herds in England and 445 herds in Wales, the prevalence of F hepatica infection in England was estimated to be 48 per cent (95 per cent confidence interval 46 to 54 per cent), and in Wales 86 per cent (95 per cent confidence interval 84 to 90 per cent).