Sixteen 7-week-old Holstein male calves were inoculated with sporulated oocysts of Eimeria zuernii. Four calves (controls) were euthanatized and necropsied at 14 and 20 days after inoculation (DAI). Two calves were treated with 20 mg of dexamethasone (IM) on 13, 14, and 15 DAI and euthanatized and necropsied 17 DAI and 2 calves were given similar treatments and necropsied 20 DAI. The 8 other calves were euthanatized and necropsied 20 DAI. Two were started on the anticoccidial drug decoquinate in feed 13 DAI; 2 others were given decoquinated on the same schedule plus dexamethasone on 13, 14, and 15 DAI. Two calves were given the antibiotic narasin in feed beginning 13 DAI and 2 calves were given parasin on the same schedule plus dexamethasone on 13, 14, and 15 DAI. All calves, except 2 controls necropsied 14 DAI and 4 calves given decoquinate, discharged moderate-to-large numbers of oocysts in feces and had moderate-to-severe changes in fecal consistency. Histologic examintions revealed large numbers of endogenous stages in tissues of calves treated or not treated with dexamethasone. Few endogenous stages were observed in tissues from calves that were given decoquinate or decoquinate plus dexamethasone. Calves given narasin or narasin plus dexamethasone had moderate-to-large numbers of endogenous stages in the tissues.

This paper dealt wih the distribution of Shigella spp. on 5 piggeries in Taegu and Kyongbuk during the period from August to October 1987. Isolated Shigella were examined for serogrouping, antimicrobial drug resistance and detection of R plasmid. Genetic properties of R plasmid in Shigella were examined for fertility inhibition (F1) and gel electrophoresis was performed for the isolation of plasmid DNA. Of total 2,978 samples from 5 piggeries, 82 strains (2.8 %) of Shigella spp. were isolated from 82 samples. The isolated strains were identified as S. dysenteriae (60 strains), S. flexneri (20 strains) and S. sonnei (2 strains). Of the 82 strains examined 67 (95.1 %) were resistant to one or more antibiotics, such as ampicillin (Am), chloramphenicol (Cm), kanamycin (Km), nalidixic acid (Na), rifampicin (Rf), streptomycin (Sm), sulfademethoxine (Su), and tetracycline (Tc) and higher resistance to Su (90.2 %), Sm (63.4 %) and Tc (63.4 %). Of the 78 resistant Shigella strains 26 (33.3 %) harbored conjugative R plasmids and the transfer frequency of Sm (50.0 %), Cm (33.3 %) resistance was much higher than that of the other drug resistance. The most common resistant patterns were SmSuTc, Su and AmSmSuTc. Out of the 26 Shigella R plasmids examined for Fi, 14 (53.8 % were Fi + and the remainder were Fi-. The plasmid DNA profiles in Shigella spp. (9 strains) isolated from pigs were confirmed as being 2 to 9 fragments by the gel electrophoresis. Their molecular size ranged 2.17 to 87.62 kilobase (Kb). All strains of Shigella spp. consisted in 15.4 Kb plasmids.

Thirteen 3-week-old pigs that had been allowed to nurse for the first 16 to 18 hours after birth were orally inoculated with 1 X 10(6.5) TCID(50) of porcine rotavirus. All developed diarrhea, anorexia, and vomiting by postinoculation (PI) hour 30. These signs had abated by PI day 6. Villus blunting in the small intestine was most severe in the jejunum and ileum of pigs euthanatized between PI days 3 and 5. Villi had returned to nearly normal length by PI day 6, although fused villi were seen in a few locations in the distal portion of the jejunum and in the ileum. Virus was detected in the feces of inoculated pigs by isolation in cell cultures and by electron microscopy during the 7-day course of the experiment. There was 1 extraintestinal virus isolation from the lung of 1 pig at PI day 2. Infection and disease developed in the presence of serum-neutralizing antibody obtained by nursing seropositive sows. There was no significant change in neutralizing antibody titers in the 3-week-old pigs over the course of the experiment. In this experimental work, a model to study rotavirus infection in 3-week-old pigs has been developed.

An ELISA has been developed for measurement of milk and serum IgG concentrations directed against Salmonella dublin. Four groups of cows were studied: group A-7 experimentally challenge-exposed cows (infected, recovered group); group B-6 normal uninfected randomly selected control cows; group C-7 naturally occurring S dublin carrier cows; and group D-6 normal uninfected S dublin negative cows from the same herd as group C. Group-A cows were inoculated orally, or inoculated orally and then IV, but none became a S dublin carrier. As expected, all 7 group-A cows responded with a marked increase in ELISA titer after oral exposure to virulent S dublin, starting with a mean serum titer of 17.7% and reaching a peak mean serum titer of 79.3% approximately 76 days after initial exposure. As determined by necropsy and organ culturing of the remaining cows, none of the group-A cows became carriers. The mean serum ELISA titer for group-B uninfected control cows was 14.1% (SD +/- 12.8%). The mean milk ELISA titer was -1.0% (SD +/- 5.5%). Colostrum and then milk gave false-positive results for up to 2 weeks after onset of lactation. Group-B cows were culture negative for S dublin in feces and milk during lactation, and when tissues were cultured after euthanasia. Milk and serum samples for ELISA, and milk and fecal samples for culturing were taken from all group-A and -B cows twice a week for 6 months. Statistical correlation (P less than 0.05) was found between serum and milk ELISA titers. A highly significant (P less than 0.001) difference in serum ELISA titers was demonstrated between control (group B) and infected cows (group A). Milk and feces from group-C carrier cows were cultured for S dublin 5 days a week for 11 to 13 months. Six of the 7 cows calved during this period. Fecal shedding was sporadic in 7 cows. Milk shedding was frequent in certain quarters of 4 of the cows and was sporadic or absent in other quarters of these cows and it was sporadic in 2 cows, and 1 cow had culture-positive milk only twice. The overall milk-shedding rate was 46% (792 positives/1,733 samples), whereas the overall fecal-shedding rate was 4% (65 positives/1,733 samples). Shedding in the 4 weeks after parturition was 28% in milk and 5% in feces. Six group-C cows had strongly positive ELISA titers in serum and milk, whereas 1 cow (the cow that had only 2 positive milk cultures) had relatively low ELISA titers. Group-C cows had a mean serum titer of 85.2% (SD +/- 19%) and mean milk titer of 70.6% (SD +/- 35.5%). These results indicate that IgG ELISA may be useful in detection of S dublin milk shedding (mammary gland infection) carrier cows. Milk shedding in the 4 persistent shedders ranged from 10(1) to 10(5) organisms/ml, and was associated with evidence of chronic active mastitis. Group-D cows, culture-negative herd mates of group-C carrier cows, were monitored in a manner identical to that used for group-C cows. All cows remained culture-negative for S dublin in feces and milk and results of organ culturing were negative for S dublin after euthanasia. The ELISA titers remained negative, with a mean group-D titer of 8 +/- 7.7% on serum, and 0.6 +/- 5.5% on milk. A highly significant difference in serum (P less than 0.0001) and milk (P less than 0.0001) ELISA titers was demonstrated between group-C carrier cows and group-D uninfected herd mates.

The prevalence and intensity of Cryptosporidium infection were examined in 445 Holstein calves at 10 dairy farms in western Washington, near Seattle. Fifty-one percent (176) of calves in the 7- to 21-day-old age group (n = 342) were positive for oocysts in the feces by carbolfuchsin staining. Prevalence and intensity of infection were highest in calves 8 to 14 days old; prevalence was 60% in this group, and 48% of the Cryptosporidium-positive calves had oocyst shedding at a 4+ level. A seasonal pattern in prevalence was not evident.

Fifty-five dogs, naturally infected with Taenia sp or Dipylidium caninum or both, were assigned to the following treatment groups for dose titration studies with epsiprantel: nonmedicated control dogs (n = 14), medicated dogs given a dosage of 2.75 mg/kg of body weight (n = 15), medicated dogs given a dosage of 5.5 mg/kg (n = 16), and medicated dogs given a dosage of 8.25 mg/kg (n = 10). Medication was given orally in a tablet formulation. Feces were examined for cestodes passed and the gastrointestinal tract was examined at necropsy for retained cestodes. Efficacy of epsiprantel was 92.9% against Taenia and 44.8% against Dipylidium for a dosage of 2.75 mg/kg, 100% against Taenia and 99.8% against Dipylidium for a dosage of 5.5 mg/kg, and 94.6% against Taenia and 100% against Dipylidium for a dosage of 8.25 mg/kg. For dose confirmation, 36 dogs naturally infected with Taenia sp or D caninum or both were allotted to 2 treatment groups: nomedicated control dogs (n = 16) and dogs medicated with epsiprantel at a dosage of 5.5 mg/kg (n = 20). Efficacy was 100% for both Taenia sp and D caninum.

Eighteen female Holstein calves, raised as natural herd additions under conditions typical of a well-managed midwestern United States dairy farm, were used in a natural-exposure study to determine the anticoccidial efficacies of lasalocid and decoquinate. Calves were allotted to 6 treatment blocks of 3 calves each as they were weaned. Within each block, calves were randomly assigned to be given either lasalocid or decoquinate or to remain as a nonmedicated control. Calves were given medication for 90 days and remained separated from other calves for 120 days. Adjusted weight gains were consistently greater in calves that were given medication; however, differences were not statistically significant. Fecal specimens were obtained from calves at weekly intervals during the study. Overall, oocyst shedding was low. During the medication period, quantitative mean fecal shedding of oocysts was reduced eightfold in calves given decoquinate and fourfold in calves given lasalocid, as compared with nonmedicated control calves. During the period following the medication period, calves that had been controls shed fewer oocysts than did calves that had previously been given medication. A pairwise comparison of the proportion of specimens that were oocyst-positive was made to assess qualitative oocyst shedding among treatment groups. During the medication period, qualitative oocyst shedding (all species, Eimeria bovis, E zuernii, species other than E bovis and E zuernii) was greater in controls than in either lasalocid-or decoquinate-treated groups. Likewise, lasalocid-medicated calves shed oocysts more frequently than did the decoquinate-medicated group. After medication, qualitative findings were reversed. Little diarrhea was noticed in treatment or control calves during the study. However, calves given either lasalocid or decoquinate had glossier coats and a healthier appearance by the end of the medication period than did nonmedicated controls. It was concluded that, under the exposure conditions of the study, trends in weight gain and oocyst shedding patterns approximated those resulting from previous studies that used experimental inoculation of oocysts.

In addition to the 3-striped blister beetles (Epicauta temexa and E occidentalis), other sources of equine cantharidin toxicosis were identified at the Texas Veterinary Medical Diagnostic Laboratory and included E albida and E attrivittata and the previously incriminated E pardalis and E pennsylvanica. Improved methods for diagnosing cantharidin or blister beetle toxicosis involve partial purification of urine and gastric content extracts, using silica cartridges, followed by analysis, using capillary gas chromatography/mass spectrometry. During a 26-month period, 53 episodes of cantharidin toxicosis in horses were confirmed at our diagnostic laboratory. Concentrations of cantharidin in urine and gastric contents ranged from 0.0003 to 3.50 microgram/g. Peak incidences were observed in late summer and early fall.

Subclinical Toxoplasma gondii infection was induced in young and adult cats by oral administration of tissue cysts. An antibody-capture ELISA to detect anti-Toxoplasma IgM-class antibodies in the serum of cats was developed. The serologic response to experimental infection was followed in the 2 groups of cats by use of anti-Toxoplasma IgM and IgG detection. This study shows that anti-Toxoplasma IgM-class antibody titers develop early in the course of experimental infection in cats and that the combination of IgM- and IgG-class antibody titer measurement can aid in the detection of recent subclinical toxoplasmosis.

A bacteriophage for Corynebacterium glutamicum strain LP-6 was isolated from swine waste. It belongs to the Siphoviridae family or Bradley morphologic group B, has a narrow host range, and is sensitive to chloroform and resistant to carbon tetrachloride. The phage is unstable (96% inactivation) in swine waste stored for 4 months at 22 C. The DNA has a molecular weight of approximately 20 Md, cohesive ends, and numerous restriction endonuclease sites. The phage differs from other known C glutamicum phages.