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Abstract

Objective—To identify the Moraxella bovis cytotoxin gene.

Procedure—Hemolytic and nonhemolytic strains of M bovis were compared by use of western blotting to identify proteins unique to hemolytic strains. Oligonucleotide primers, designed on the basis of amino acid sequences of 2 tryptic peptides derived from 1 such protein and conserved regions of the C and B genes from members of the repeats in the structural toxin (RTX) family of bacterial toxins, were used to amplify cytotoxin-specific genes from M bovis genomic DNA. Recombinant proteins were expressed, and antisera against these proteins were produced in rabbits.

Results—Several proteins ranging in molecular mass from 55 to 75 kd were unique to the hemolytic strain. An open reading frame encoding a 927-amino acid protein with a predicted molecular mass of 98.8 kd was amplified from M bovis genomic DNA. The deduced amino acid sequence encoded by this open reading frame was homologous to RTX toxins. Antisera against the recombinant carboxy terminus encoded by this open reading frame neutralized hemolytic and cytolytic activities of native M bovis cytotoxin.

Conclusions and Clinical Relevance—A gene was identified in M bovis that encodes a protein with sequence homology to other RTX toxins. Results of cytotoxin neutralization assays support the hypothesis that M bovis cytotoxin is encoded by this gene and belongs in the RTX family of bacterial exoproteins. Identification of this gene and expression of recombinant cytotoxin could facilitate the development of improved vaccines against infectious bovine keratoconjunctivitis. (Am J Vet Res 2001;62:1222–1228)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether dietary supplementation with ammonium chloride would affect urine pH or urinary fractional excretion (FE) of electrolytes in goats fed grass hay.

Design—Clinical trial.

Animals—15 yearling castrated male goats.

Procedures—In the dose response study, 3 yearling goats fed orchard grass hay and water ad libitum were administered ammonium chloride at either 200, 400, or 500 mg/kg (91, 182, or 227 mg/lb), PO, every 24 hours. In the FE study, 8 goats fed orchard grass hay were randomly divided into either a treatment (n = 4) or a control group (4). In the treatment group, ammonium chloride was administered at 450 mg/kg (2.25% of dry matter intake [DMI]), PO, every 24 hours for 8 days. The FE of electrolytes was compared between groups; FE measurements were also determined for 4 client-owned goats fed alfalfa hay.

Results—Ammonium chloride administered at 450 mg/kg (2.25% of DMI) achieved and maintained urine pH < 6.5 for 24 hours. Goats fed orchard grass hay with ammonium chloride supplementation had significantly higher FE of calcium and chloride than did goats fed orchard grass hay without supplemental ammonium chloride.

Conclusions and Clinical Relevance—Dietary ammonium chloride supplementation at a dose of 450 mg/kg may be necessary to achieve a urine pH < 6.5 in goats. Further studies of ammonium chloride supplementation and urolithiasis in goats fed low-calcium diets are indicated.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To describe disorders of performance-age bucking bulls.

DESIGN Retrospective case-control study.

ANIMALS 78 bucking (cases) and 236 nonbucking (controls) beef bulls.

PROCEDURES The medical record database of a referral hospital was reviewed to identify beef bulls > 1 year old that were examined for a medical or musculoskeletal disorder between January 1, 2000, and April 1, 2014. Bucking bulls were designated as cases, and nonbucking bulls were designated as controls. For each bull, the signalment, history, physical examination and diagnostic test results, and clinical diagnosis were recorded. The frequency of each disorder was compared between cases and controls.

RESULTS Fifteen of 78 (19%) cases and 132 of 236 (56%) controls had medical disorders; however, the frequency did not differ between the 2 groups for any medical disorder. Musculoskeletal disorders were identified in 55 (70.5%) cases and 109 (46%) controls. Cases were 10.55 times as likely as controls to have horn and sinus disorders. Of the 43 (55%) cases examined because of lameness, the thoracic limb was affected in 19 (44%). Compared with controls, cases were 13.37 and 3.31 times as likely to have a musculoskeletal disorder of the vertebral region and pelvic limb, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated bucking bulls were more likely than nonbucking bulls to develop horn and sinus disorders and musculoskeletal disorders of the vertebral region and pelvic limbs. The limb distribution of lameness for bucking bulls may differ from that for nonbucking bulls.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the immunogenicity of a Moraxella bovis cytolysin-enriched vaccine for prevention of infectious bovine keratoconjunctivitis (IBK).

Animals—104 mixed-breed beef calves ranging between 4 and 8 months of age.

Procedure—Vaccines were prepared by the diafiltration of broth culture supernatant from hemolytic M bovisor or sterile media. The diafiltered retentate was combined with Quil A adjuvant. Calves were randomly assigned to receive either the cytolysin vaccine (n = 35) or, as controls, adjuvant (35) or saline (0.9% NaCl) solution (34). Eyes of all calves were examined weekly for signs of IBK for 15 weeks. Calves that developed severe IBK were treated SC with florfenicol.

Results—Cytolysin vaccine contained 4 proteins with molecular masses ranging between 65 and 90 kd. Cytolysin-vaccinated calves had fewer instances of IBK than control calves. The time of onset of corneal lesions in cytolysin-vaccinated calves that developed IBK was delayed, compared with that of calves in either control group. The cytolysin-Quil A vaccine contained endotoxin, but calves did not have clinical signs of illness after vaccination.

Conclusions and Clinical Relevance—Calves that were vaccinated with a cytolysin-enriched vaccine had some resistance to IBK. Vaccines containing concentrated diafiltered M bovis cytolysin could protect beef calves against IBK. (Am J Vet Res 2005;66:136–142)

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in American Journal of Veterinary Research

Abstract

Objectives—To compare stability, antigenicity, and aggregation characteristics of Moraxella bovis cytolysins among isolates from geographically diverse areas.

Study Population—8 isolates of M bovis.

Procedure—Filter-sterilized broth culture supernatants of M bovis were concentrated, diafiltered, and chromatographed. The endotoxin and cytolysin activities in samples were measured. Chromatographed cytolysins of M bovis were examined by immunoblotting. Hemolytic and leukotoxic activities were measured from samples collected at each step of purification and before and after storage. Hemolysis was measured directly by use of washed bovine erythrocyte targets. Leukotoxicity was measured by use of a 51Cr release assay.

Results—Cytolysin was retained by a filter with 100-kd nominal molecular weight limit. Hemolytic activity, leukotoxic activity, and endotoxin were eluted together in void volume of a gel-filtration column (molecular mass exclusion limit = 4 × 107 d). Gel-column chromatographed diafiltered retentate had the greatest specific cytolytic activity and the highest endotoxinto- protein ratio. Frozen diafiltered retentate(–80°C, 4 months) was cytolytic after thawing. Immunoblots of gel-column chromatographed cytolysin contained 4 proteins with molecular masses between 90 and 68 kd. Fractions with high lytic activities also had additional protein bands with molecular masses of 98 and 63 kd. Immunoblots of gel-column chromatographed diafiltered retentate revealed proteins with molecular masses between 90 and 68 kd.

Conclusions and Clinical Relevance—Diafiltered M bovis cytolysin is aggregated with endotoxin. Antigenicity and cytolytic activities in diafiltered retentate are conserved among M bovis isolates. Diafiltration could be useful for bulk semipurification of M bovis cytolysin. Cytolysin-enriched vaccines of M bovis could be contaminated by endotoxin. ( Am J Vet Res 2004;65:977–983)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate efficacy of a recombinant Moraxella bovis pilin-cytotoxin-Moraxella bovoculi cytotoxin subunit vaccine to prevent naturally occurring infectious bovine keratoconjunctivitis (IBK).

Animals—107 beef steers.

Procedures—2 groups of calves were inoculated SC with an immunostimulating complex (ISCOM) matrix adjuvant (control group; n = 54) or a recombinant M bovis pilin-cytotoxin–M bovoculi cytotoxin subunit antigen with the ISCOM matrix adjuvant (vaccine group; 53); calves received booster injections 21 days later. Calves were examined once weekly for 16 weeks. Investigators and herd managers were not aware of the inoculum administered to each calf throughout the trial. Primary outcome of interest was the cumulative proportion of calves that developed IBK. Serum samples were obtained before inoculation (day 0) and on days 42 and 112. Serum hemolysin-neutralizing titers against native M bovis and M bovoculi cytotoxin were determined.

Results—No difference was detected between groups for the cumulative proportion of calves that developed IBK at weeks 8 and 16 after inoculation. Non–IBK-affected calves in the vaccine group had a significantly higher fold change in serum hemolysin-neutralizing titer against native M bovoculi cytotoxin from day 0 to 42 compared to control calves.

Conclusions and Clinical Relevance—The M bovis pilin-cytotoxin-M bovoculi cytotoxin subunit vaccine with the ISCOM matrix adjuvant was not effective at preventing naturally occurring IBK. It is likely that the incorporation of additional protective antigens in a recombinant Moraxella spp subunit vaccine will be required to yield a product that can be used for effective immunization of cattle against IBK.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate changes in systemic and ocular antibody responses of steers following intranasal vaccination with precipitated or partially solubilized recombinant Moraxella bovis cytotoxin (MbxA).

ANIMALS 13 Angus steers with ages ranging from 318 to 389 days and weights ranging from 352 to 437 kg.

PROCEDURES Steers were assigned to receive 500 μg of a precipitated (MbxA-P; n = 5) or partially solubilized (MbxA-S; 5) recombinant MbxA subunit adjuvanted with polyacrylic acid. A control group (n = 3) received the adjuvant alone. Each steer received the assigned treatment (1 mL/nostril) on days 0 and 28. Serum and tear samples were collected on days 0 (before vaccination), 14, 28, 42, and 55. Changes in MbxA-neutralizing antibody titers and MbxA-specific IgG concentrations in serum and tears and changes in MbxA-specific IgA concentrations in tears were measured.

RESULTS Mean fold changes in MbxA-specific IgG concentration in serum and tears and MbxA-neutralizing antibody titer in tears for the MbxA-P group were significantly greater than those for the MbxA-S and control groups. Mean serum MbxA-neutralizing antibody titer did not differ among the 3 groups. Although the mean fold change in tear MbxA-specific IgA concentration differed significantly among the groups in the overall analysis, post hoc comparisons failed to identify any significant pairwise differences.

CONCLUSIONS AND CLINICAL RELEVANCE Systemic and ocular immune responses induced by intranasal administration of the MbxA-P vaccine were superior to those induced by the MbxA-S vaccine. Additional research is necessary to determine whether the MbxA-P vaccine can prevent naturally occurring infectious bovine keratoconjunctivitis.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate the use of a percutaneous transabdominal catheter (PTC) for urinary bladder drainage in goats, sheep, and potbellied pigs with obstructive urolithiasis.

DESIGN Retrospective case series.

ANIMALS 43 goats, 10 sheep, and 16 potbellied pigs (all males) with obstructive urolithiasis evaluated at the University of California-Davis Veterinary Medical Teaching Hospital.

PROCEDURES Medical records of goats, sheep, and potbellied pigs examined because of obstructive urolithiasis from January 2000 through December 2014 were reviewed. Records of animals for which a standard PTC had been placed into the urinary bladder as part of disease management were selected. Data were collected regarding signalment, complications associated with PTC placement, and duration of PTC placement prior to removal.

RESULTS 42 of 43 goats, 5 of 10 sheep, and all potbellied pigs were castrated. Median (range) duration of PTC placement was 2 (1 to 4) days for goats, 1 (1 to 4) day for sheep, and 1 (1 to 3) day for potbellied pigs. Complications associated with PTC placement included blockage of the catheter by urine sediment, perforation of the cecum, and migration of the catheter out of the urinary bladder.

CONCLUSIONS AND CLINICAL RELEVANCE Placement of a PTC into the urinary bladder allowed for effective stabilization of goats, sheep, and potbellied pigs with obstructive urolithiasis while acid-base and electrolyte imbalances were corrected. Use of a PTC should be considered for urinary bladder drainage during medical management or prior to surgical management of obstructive urolithiasis for these species.

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in Journal of the American Veterinary Medical Association

Abstract

Case Description—6 lactating dairy goats were examined because of acute mastitis.

Clinical Findings—Goats were considered to have endotoxemia on the basis of physical examination and clinicopathologic findings. The affected udder halves had gangrenous discolored distal portions with sharp demarcations from grossly normal tissue proximally. Udder secretions from the affected sides were serosanguineous in all cases. A Bacillus sp was isolated in pure cultures in all cases. In 1 case, the Bacillus sp was identified as Bacillus cereus.

Treatment and Outcome—Goats were treated for mastitis and endotoxemia with polyionic IV fluid therapy, systemic and intramammary antimicrobial administration, anti-inflammatory drug administration, and other supportive treatment. All goats survived to discharge. All except 1 goat had follow-up information available. The affected udder halves sloughed in 1 to 2 months following discharge. In subsequent lactations after the mastitis episodes, milk production in 2 of 5 goats was above the mean, as determined on the basis of Dairy Herd Improvement records, and 3 of 5 goats were voluntarily withdrawn from lactation. All 5 goats had successful kiddings after the Bacillus mastitis episode.

Conclusions and Clinical RelevanceBacillus sp should be considered as a causative agent in goats with gangrenous mastitis, especially when the Bacillus sp is isolated in a pure culture. Antimicrobial sensitivity testing is recommended for selection of an appropriate antimicrobial for treatment. Prognosis for survival appears to be good, although milk production may be decreased.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the pharmacokinetics of ceftiofur crystalline-free acid (CCFA) following SC administration of a single dose to sheep.

Animals—9 healthy adult female Suffolk-crossbred sheep.

Procedures—Each sheep was administered 6.6 mg of CCFA/kg, SC, in the cervical region once. Serial blood samples were collected at predetermined intervals for 14 days. Serum concentration of ceftiofur free-acid equivalents (CFAE) was determined by high-performance liquid chromatography. Pharmacokinetic parameters were determined by compartmental and noncompartmental methods.

Results—Pharmacokinetics for CCFA following SC administration in sheep was best described with a 1-compartment model. Mean ± SD area under the concentration-time curve from time 0 to infinity, peak serum concentration, and time to peak serum concentration were 206.6 ± 24.8 μ•h/mL, 2.4 ± 0.5 μg/mL, and 23.1 ± 10.1 h, respectively. Serum CFAE concentrations ≥ 1 μg/mL (the target serum CFAE concentration for treatment of disease caused by Mannheimia haemolytica and Pasteurella multocida) were maintained for 2.6 to 4.9 days. No significant adverse reactions to CCFA administration were observed.

Conclusions and Clinical Relevance—Results indicated that adequate therapeutic serum concentrations of CFAE for treatment of disease caused by M haemolytica and P multocida were achieved in sheep following SC administration of a single dose (6.6 mg/kg) of CCFA. Thus, CCFA might be useful for the treatment of common respiratory tract pathogens in sheep.

Full access
in American Journal of Veterinary Research