Equine neutrophil antibody was raised in rabbits inoculated with equine neutrophils isolated to purity > 99.0%, using Percoll density-gradient sedimentation. Neutrophil antibody was detected by use of agar gel diffusion, leukoagglutination, indirect immunofluorescence, staphylococcal protein A and streptococcal protein G binding, and phagocytic inhibition techniques. Precipitin lines and leukoagglutination were seen in antiserum dilutions of 1:4 and 1:64, respectively. The specific nature of leukoagglutination was characterized by the formation of rosette-like clumps of neutrophils. Specific bright membranous fluorescence was seen in neutrophils treated with the antiserum and exposed to fluorescein-conjugated goat anti-rabbit immunoglobulin, and staphylococcal protein A and streptococcal protein G. Whereas the indirect immunofluorescence and protein G-binding tests were equally sensitive and resulted in titer of 1:256, the protein A-binding test was less sensitive and resulted in titer of only 1:32. Nonspecific binding of protein A and protein G was noticed as uniform or patchy cellular fluorescence in a small number of neutrophils. Treatment of neutrophils with antiserum up to dilution of 1:8 resulted in a significant (P < 0.05) suppression of phagocytosis of opsonized zymosan particles. Thus, protein G-binding and indirect immunofluorescence tests are highly sensitive to detect neutrophil antibody and may be used to diagnose immune-mediated neutropenias in horses and, possibly, in other animal species.

Serum concentration of ampicillin, a semisynthetic penicillin, was measured in mares at various time intervals up to 24 hours after intrauterine infusion of 3 g of ampicillin. Blood samples were drawn immediately before infusion and at l-, 4-, 10- and 24-hour intervals after infusion. At postinfusion hour 24, two endometrial biopsy specimens were obtained to measure endometrial concentrations of ampicillin. Blood was drawn twice as part of the 24-hour postinfusion sample collection, once before removal of the biopsy specimens and again 5 minutes after removal of the biopsy specimens. After drug infusion, more diestrous mares had detectable serum ampicillin concentration than did estrous mares for all samples, except the 24-hour prebiopsy sample. None of the 24-hour prebiopsy serum samples had detectable ampicillin concentration, but ampicillin was detected in the serum of 4 of 5 diestrous mares after endometrial biopsy. Endometrial concentrations of ampicillin were detectable at postinfusion hour 24 in estrous and diestrous mares, but were not different. All 24-hour biopsy specimens had ampicillin concentrations greater than the ampicillin minimal inhibitory concentration.

Immunoglobulin reactions to Salmonella dublin in serum and milk from 4 groups of lactating cows were measured by an indirect ELISA. The groups consisted of (1) cows that were natural carriers of S dublin in the mammary gland, (2) experimentally infected cows that did not become carriers, (3) cows inoculated with a commercial S dublin bacterin, and (4) cows used as S dublin-negative controls. Milk and serum samples were obtained at monthly intervals. Models for predicting carrier status were developed by use of stepwise logistic regression. Independent variables consisted of serum and milk IgG and IgM titers to S dublin lipopolysaccharide and a ratio of IgG to IgM. The utility of a single sample vs multiple samples obtained at 1-month or 2-month intervals was tested by comparison of goodness-of-fit X2 P values for 8 models predicting carrier status. Immunoglobulin reactions specific to S dublin were a significant predictor of carrier status (P < 0.001). Serum IgG titers specific for S dublin were the most important variable for predicting carrier status. Two serum IgG titers to S dublin obtained 2 months apart was a better predictor of carrier status than measurement of the IgG:IgM ratio from a single serum sample. Immunoglobulin recognizing S dublin epitopes also were detected in milk samples. In milk, performing 2 ELISA 60 days apart to determine IgG and IgM reactions to S dublin appeared to be useful for the prediction of carrier status, but was not as accurate as models for serum immunoglobulin reactions.

Four virgin heifers were experimentally inoculated intravaginally with 7 X 10(6) Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 x 10(5) T foetus, transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determined by culturing of reproductive tract secretions. The lag times of antibody responses during this reinfection were shorter than in the initial infection, and ELISA optical densities were at least as high as during the primary infection, suggesting an anamnestic response.

An ion chromatographic method was used to simultaneously determine nitrate and nitrite ions in biological samples. Ultrafiltration was used to produce a protein-free filtrate. Chloride interferences were eliminated by precipitation as the silver salt. Detection limits and average recoveries were 0.5 mg/L and 102% for nitrate and 0.2 mg/L and 78% for nitrite, respectively. Nitrate concentration was 2.1 +/- 1.8 mg/L and 4.9 +/- 0.8 mg/L in serum and ocular fluid of healthy cattle, respectively; nitrite was not detected. A severe case of nitrate poisoning in cattle was described and used to study the concentrations of nitrate and nitrite in samples obtained under natural conditions. Nitrate concentration of acutely poisoned cattle was 35% lower in ocular fluid at 158.1 +/- 51.4 mg/L, than in serum at 256.3 +/- 113.4 mg/L. Nitrite was not detected, because of the long processing time (> 3 hours) required for samples obtained in the field. A gradual decrease in ocular fluid nitrate of 29.4% at 24 hours, 25.9% at 36 hours, 51.6% at 48 hours, and 73.2% at 60 hours was observed; however, concentrations remained diagnostically significant (73.2 mg/L) 60 hours after death. Twenty-four hours after poisoning, the serum nitrate concentration of severely ill (52.7 +/- 51.9 mg/L) and moderately affected (12.4 +/- 5.7 mg/L) cattle that survived was indicative of the severity of clinical signs previously observed. Nitrate in serum and ocular fluid was stable in samples stored for 24 hours at 23 C, 1 week at 4 C, and 1 month at -20 C.

Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2',5'-oligoadenylate (2',5'-oligo[A]) synthetase activity sufficient to synthesize 186 +/- 82 pmol of 2',5'-oligo(A)/h/10(6) cells. Calves had no measurable serum interferon (IFN) activity. Five calves were given IM injections of 10(4), 10(5), 5 x 10(5), 10(6), and 10(7) U of bovine IFN-alpha 1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 x 5 Latin square design so that each calf received each dose once. Activity of 2',5'-oligo(A) synthetase increased at 24 hours in response to all dosages of IFN and then declined following first-order kinetics, with an apparent half-life (t1/2) of 2.1 +/- 0.5 days. The area under the concentration-time curve for 2',5'-oligo(A) synthetase increased with dose of IFN more rapidly than did peak response. Serum IFN that was measured at 1-day intervals following administration of IFN was consistently measurable only at dosages above 10(6) U of IFN/kg. The t1/2 for circulating IFN was 12.4 +/- 1.0 hours. Over all dosages, increases in 2',5'-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in IFN following IM injection of IFN. None of the calves developed detectable anti-IFN antibodies.

The disposition of doxycycline hyclate after IV administration of 20 mg/kg of body weight was studied in 6 pigs. Median elimination half-life, estimated in 4 pigs, was 3.92 hours. Mean (+/- SEM) total body clearance was 1.67 +/- 0.18 ml/min/kg, and mean apparent volume of distribution at steady state was 0.53 +/- 0.04 L/kg. In 2 pigs, secondary peaks in the logarithmic serum concentration-time profile suggested discontinuous enterohepatic cycling, and precluded using these pigs in the pharmacokinetic analysis. The extent of doxycycline binding to serum protein was 93.1 +/- 0.2%. Serum or urine from 3 of the pigs was analyzed by use of photodiode array detection and mass spectrometry of a high-performance liquid chromatographic column effluent. These procedures documented lack of doxycycline biotransformation in pigs. It is concluded that, despite an elimination half-life shorter than that reported in other species, doxycycline may be a valuable antimicrobial drug for use in swine practice, pending the development of appropriate formulations.

Sera and tracheal washings (TW) were used to identify antigens of Bordetella avium recognized during experimentally induced bordetellosis in young turkeys. Pooled sera and TW were examined for antibody by a microtitration agglutination test and by western immunoblotting. In addition, comparable samples collected from 1-day-old turkeys and uninoculated control turkeys also were examined. At least 8 outer membrane proteins of B avium were recognized in immunoblots of sera and TW from infected turkeys. Reactivity of TW in immunoblots was qualitatively similar but less intense, compared with reactivity of corresponding sera collected on postinoculation (PI) weeks 2, 3, and 4. Molecular weights of the major outer membrane proteins of B avium recognized by sera and TW at PI week 4 were 100,000, 97,000, 36,000, 31,000, 21,000, 18,000, 14,000, and < 14,000. A protein with a molecular weight of 55,000 reacted nonspecifically in all samples tested. Antibody, detectable by microtitration agglutination, was in sera of 1-day-old turkeys and in sera and TW of B avium-infected turkeys during PI weeks 2 to 4.

The range of neutralizing activity to bovine viral diarrhea (BVD) virus and viral protein specificity of antibodies induced by 3 inactivated vaccines were evaluated by use of samples of sera obtained from 13 cattle 14 days after vaccination. Viral neutralizing antibodies were detected in all cattle to each of 10 noncytopathic and 10 cytopathic isolates of BVD virus. A viral-induced polypeptide (53,000 to 56,000 daltons) was detected by radioimmunoprecipitation with serum from all vaccinates. Other viral-induced polypeptides of 115,000, 80,000, 48,000, and 25,000 daltons were precipitated with sera from some vaccinates. Precipitation of those polypeptides was related to the vaccine used. When multiple viral polypeptides were precipitated, the 53,000- to 56 000-dalton polypeptide appeared immunodominant.

Disposition kinetics of cloxacillin were examined in calves after topical administration of benzathine cloxacillin and single IV administration of sodium cloxacillin, and the susceptibility of 17 field isolates of Moraxella bovis was measured. For the IV pharmacokinetic phase, sodium cloxacillin was administered at dosage of 10 mg/kg of body weight to male Holstein calves (n = 6, weighing 146 to 170 kg), and serum concentration of cloxacillin was measured thereafter for 10 hours. For the ocular pharmacokinetic phase, 6 calves were given either of 4 benzathine cloxacillin topical formulations consisting of 50-, 125-, 250-, or 375-mg doses. Treatment was repeated every 10 days until all 4 benzathine cloxacillin dosages were tested in the same 6 calves. Blood and tears were collected for 72 hours after each benzathine cloxacillin formulation was administered, and the concentration of cloxacillin in each specimen was measured, using a bioassay. The minimal inhibitory concentration of cloxacillin for 17 field isolates of M bovis was determined by use of an agar pour-plate dilution assay. After single IV administration of sodium cloxacillin, its half-life, body clearance, and volume of distribution were 19.5 +/- 12.8 minutes, 18.3 +/- 2.2 ml/min.kg, and 496 +/- 290 ml/kg, respectively. After topical administration of benzathine cloxacillin, cloxacillin concentration in lacrimal fluid peaked between 30 and 45 minutes and ranged between 963 microgram/ml and 3,256 microgram/ml for the 125- and 375- mg doses, respectively. There was no detectable cloxacillin activity in the lacrimal fluid of any calf by 36 hours after topical administration of benzathine cloxacillin, and cloxacillin was not detected in the serum at any time. The mean lacrimal fluid cloxacillin concentration for the 4 groups during the first 8 hours was not significantly different; however, by 12 hours, the cloxacillin concentration in tears from calves of the 250- and 375-mg groups was significantly (P < 0.05) greater than that in calves of the 50- and 125-mg groups. Cloxacillin concentration greater than or equal to 3.13 microgram/ml was maintained for a significantly (P < 0.05) longer time after treatment, using the 375-mg dose, compared with the 50-mg dose of benzathine cloxacillin. The minimal inhibitory concentration of cloxacillin for 1 isolate was 6.25 microgram/ml, but was less than or equal to 3.13 microgram/ml for 16 other M bovis isolates.