Rabbits were given T-2 mycotoxin orally at 0, 0.25, 0.5, and 0.75 mg/kg of body weight/day for 21 days. Only rabbits in the 0.75 mg/kg/day group (4 of 5 rabbits) died. Alveolar macrophages were harvested on day 22 and used for in vitro phagocytosis of killed Aspergillus fumigatus conidia. Cultures included sera from untreated rabbits or rabbits treated with T-2. Phagocytosis was significantly (P < 0.01) reduced in cultures that used serum from rabbits treated with 0.5 mg of T-2kg/day and alveolar macrophages from untreated rabbits or rabbits treated with T-2. There was little reduction in phagocytosis when alveolar macrophages from rabbits treated with T-2 and normal serum were used. Ingestion of 0.5 mg of T-2 toxin/kg/day significantly (P < 0.05) reduced weight gain, serum alkaline phosphatase activity, serum sorbitol dehydrogenase activity, and serum bacteriostasis. Similar changes were found in the 0.75 mg/kg/day group, as well as a significant (P < 0.05) reduction in PCV, total WBC, and differential leukocyte counts. Neutrophil counts decreased, but not significantly (0.05 < P < 0.10). Significant changes were not detected in alanine transaminase activity, aspartate transaminase activity, blood urea nitrogen concentration, or complement hemolytic activity. Histopathologic changes consisting of centrilobular hepatocellular swelling, mild portal and periportal fibrosis and lymphocyte necrosis within secondary lymphoid tissues developed in most rabbits treated with T-2. Thymic atrophy, bile duct reduplication, and lymphocyte depletion of secondary lymphoid tissues developed in the group given 0.75 mg/kg/day. Severity of lymphoid depletion in secondary lymphoid tissues was greatest in the appendix and decreased in the following order: appendix > sacculus rotundus > ileal Peyer patches > lymph nodes and spleen. In this study, we provide additional data showing that, at these oral doses of T-2 toxin, rabbits could be immunosuppressed, as evidenced by reduced alveolar macrophage phagocytosis and histopathologic changes in lymphoid tissues. Also, these doses caused reductions in weight gain, certain hematologic factors, and serum alkaline phosphatase and sorbitol dehydrogenase activities.

In a study to evaluate the effect of flunixin meglumine on secretory diarrhea, 11 calves were assigned to 3 groups: group 1 (n = 3) served as controls, group-2 calves (n = 4) were given 2.2 mg of flunixin meglumine/kg, IM at 7 AM and 3 PM, and group-3 calves (n = 4) were given 2.2 mg of flunixin meglumine/kg IM at 7 AM, 11 AM, and 3 PM. All calves were given approximately 200 microgram of heat stable Escherichia coli enterotoxin (STa) orally at 8 AM. Mean cumulative fecal output for groups 1, 2, and 3 was 1,331.0 +/- 317.2 g, 1,544.3 +/- 154.4 g, and 785.5 +/- 276.5 g, respectively. There was a significant (P < 0.05) reduction in mean fecal output in group-3 calves, compared with that in groups 1 and 2. Calves in group 2 tended to have a delay, but not a reduction, in their fecal output. At 12 hours, hemoconcentration was significantly (P < 0.05) greater in group-1 calves than in group-2 or group- 3 calves.

Twelve Holstein calves mere used to determine the prophylactic efficacy of ivermectin against challenge exposure with gastrointestinal and pulmonary nematodes. Two groups of 6 calves (mean body weight, 205 kg) each were formed by restricted randomization according to body weight. Group-l calves served as nonmedicated controls. Each calf of group 2 was orally given one prototype sustained-release bolus designed to deliver ivermectin at a continuous daily dose of 8 mg. Third-stage nematode infective larvae were given to the calves on posttreatment days 28 and 42. The calves were euthanatized 77 or 78 days after treatment. Ivermectin was 100% effective (P < 0.05) in preventing the establishment of infection by Haemonchus placei, Ostertagia ostertagi, Cooperia spp (C punctata, C oncophora, C surnabada), Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus and was > 99% effective against Trichostrongylus axei. Incidental infection by Trichuris spp was reduced by 94% (P = 0.08).

Thirty-six Staphylococcus aureus isolates recovered from 35 of 204 young goats at slaughter were characterized. All isolates were susceptible to cephalothin, clindamycin, chloramphenicol, gentamicin, kanamycin, and amikacin. All but 2 were susceptible to erythromycin and tetracycline, and 19 and 20 were susceptible to penicillin and ampicillin, respectively. Thirteen isolates were classified as biotype A, 9 isolates were classified as biotype B, 8 isolates were clssified as biotype C, and 6 isolates were classified as intermediate between B and C or were not biotypable. Six biotype A isolates were enterotoxigenic; 4 produced enterotoxin B, 1 produced enterotoxin C, and 1 produced enterotoxin D. Two biotype B strains produced enterotoxin B, and all 8 biotype C isolates produced enterotoxin C and the toxic shock syndrome toxin-1.

Experiments reported here were directed at 2 questions: (1) Can the stable fly (Stomoxys calcitrans) tansmit enzootic bovine leukosis? (2) Could early viremia augment the probability of transmission by this insect? In one vector experiment, calves and bovine leukemia virus (BLV)-infected cows were housed with and without stable flies. The calves were monitored serologically during a 3-month postexposure period, using the agar gel immunodiffusion test. All fly-infested and fly-free calves remained BLV-seronegative. For a second vector experiment, donor calves, newly injected with blood from BLV-infected cows with high virus expression, were tethered alternately between uninoculated, weaned BLV-seronegative calves. These groups were housed with or without flies in 2 replicate trials. The inoculated calves from the first replicate seroconvert at 16 and 23 days after inoculation; the inoculated calves from the second replicate seroconverted at 11, 16, 16, and 37 days after inoculation. All uninoculated calves remained BLV-seronegative. In a manual transmission experiment, 50 unfed stable flies were allowed to complete a meal on each of 3 BLV-seronegative calves after feeding on a BLV-seropositive cow with high (42%) virus expression. One control calf was injected with blood from the cow. Seroconversion occurred in the control calf and 1 calf on which flies were given access. A scanning electron microscopic study was made of the everted and closed mouth parts of the stable fly. Given the lymphocyte count in blood from the cow used in the manual vector transmission experiment, it was calculated that 3,950 mouth part volumes would be necessary to transmit BLV. This estimate and our negative transmission results indicated that the stable fly is not a BLV vector of consequence.

Morphologic changes developing during bovine mammary involution were examined. Quarter biopsy specimens were obtained weekly from 5 cows beginning the day milking was discontinued through parturition. Light and electron microscopic examination of mammary tissue indicated a gradual reduction in synthetic and secretory activity of alveolar epithelium as involution progressed. Light microscopic morphologic analysis revealed increases in stroma and nonactive secretory epithelium, with concomitant decreases in epithelium, lumen, and fully active secretory epithelium during the first 2 weeks of involution. Electron microscopic analysis of alveolar epithelium revealed decreased number of organelles associated with milk synthesis and secretion during this time. These changes reversed gradually beginning 2 weeks before parturition, and by the time of calving, cell structure was typical of lactating glands. Tissue from infected quarters had less synthetic and secretory ability as indicated by significantly higher percentages of stroma and nonactive cells, but lower percentages of lumen and moderately active cells, compared with uninfected quarters. Infected quarters also had more leukocytes infiltrating the epithelium, lumen, and stroma, compared with uninfected quarters. Microscopic examination of macrophages and neutrophils suggested these cells removed milk components and cellular debris during involution. Large numbers of plasma cells, with distended cisternae of rough endoplasmic reticulum, suggested local antibody production during the periparturient period.

Intramammary devices (IMD) were abraded with medium-grade emery cloth or were left smooth. One IMD of each type was inserted into a mammary quarter of each of 5 lactating cows. The remaining 2 quarters served as controls. Quarter foremilk, bucket milk, and stripping milk samples were collected for 3 consecutive days at 2 weeks after IMD insertion, and milk somatic cell counts (SCC) were determined. Milk samples also were collected immmediately after and 0.5, 1,2,4,6,8, and 11 hours after milking. All quarters were challenge exposed with 250 colony-forming units of Streptococcus uberis at 2 months after IMD insertion. Foremilk and stripping milk samples were collected for bacteriologic culture and SCC at the next 10 milkings. Mean foremilk, bucket milk, and stripping milk SCC (X 10(6) cells/ml) were 0.18, 0.07, and 0.91, respectively, for quarters with abraded IMD; 0.06, 0.05, and 0.43, respectively, for quarters with smooth IMD; and 0.03, 0.03, and 0.15, respectively, for control quarters. Mean SCC after milking (X 10(6) cells/ml) for the various intervals were 0.70, 1.29, 0.70, 0.97, 1.15, 1.17, 0.77, and 0.85 for quarters with abraded IMD; 0.43, 0.62, 0.61, 0.45, 0.64, 0.60, 0.31, and 0.26 for quarters with smooth IMD; and 0.15, 0.24, 0.15, 0.19, 0.15, 0.15, 0.14, and 0.06 for control quarters. After challenge exposure, 2 of 5 of the quarters with abraded IMD, 4 of 5 of the quarters with smooth IMD, and 8 of 9 of control quarters became infected. Results indicated that abraded IMD increased SCC in stripping milk to concentrations that provided 60% portection against challenge eexposure with S uberis.

During the 1986 lambing season, 33 Michigan sheep producers submitted all lambs that had died before weaning to the Michigan State University Diagnostic Laboratory for necropsy. Inductively coupled argon plasma emission spectroscopy was used to measure 22 elements in the liver of 888 of the lambs submitted. Mean concentrations of each element were established and compared with literature values of established deficient, normal, and toxic concentrations. Mean values in milligrams per kilogram of wet weight were as follows: A1, 3.843; As, less than 1; Ba, 0.176; Ca, 128.2; Cr, 0.778; Cu, 56.82; Fe, 491.6; Hg, less than 2; K, 2,150; Mg, 138.4; Mn, 2.776; Mo, 0.489; Na, 1,384; P, 2,583; Pb, 1,453; Sb, less than 1; Tl, less than 5; Zn, 68.31. In only 11 lambs did the liver contain As, B, Cd, Co, Hg, Sb, Se, or Tl in detectable concentrations.

To obtain synchronous infection, 10 cats were inoculated with feline herpesvirus-1 (FHV-) on the oral, nasal and conjunctival mucosa. Swab specimens of the nasal conjunctival, and pharyngeal mucosa were obtained for virus isolation from each cat before inoculation and at 3-day intervals thereafter until postinoculation day 21. Recovery of virus and evidence of clinical signs were used to document FHV-1 infection. Serum was obtained from blood samples collected sequentially from each cat between day 0 and postinoculation day 90. Virus-neutralizing antibody titer was determined in all serum specimens. Immunoprecipitation with [35S]methionine- and [14C]glucosamine-labeled viral antigens, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was performed on each specimen. Three precipitation bands with approximate molecular weights of 105,000, 68,000, and 60,000 were separated from [14C]glucosamine- and [35S]methionine-labeled immunoprecipitates. The concurrent detection of virus-neutralizing antibody glycoprotein-specific immunoprecipitins implied that in cats, the FHV-1 glycoproteins were important in the induction of virus-neutralizing antibodies to FHV-1.

In 5 horses, 13CO2/12CO2 ratios in expired air were determined using isotope mass spectroscopy to investigate metabolism of naturally occurring [13C]glucose. Oral glucose tolerance tests (OGTT) were performed using maize or beet glucose. Maize has a higher 13C concentration than that of most plants. The 13CO2/12CO2 ratios after OGTT was performed using maize glucose were compared with 13CO2/12CO2 ratios in expired air after OGTT was performed using beet glucose. The ratio also was determined during the period horses were not fed. Using OGTT, all horses were glucose tolerant. The OGTT performed using beet glucose led to minimal changes in 13CO2/12CO2 ratios. The 13CO2/12CO2 ratios decreased significantly (P less than 0.01) when horses were not fed. After oral dosing with maize glucose, 13CO2/12CO2 ratios reached maximal increases 5 hours after dosing and reached baseline values 15 hours after dosing.