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Abstract

Objective—To determine features of postoperative wound infection caused by Actinobacillus spp in horses undergoing clean, elective surgery and to evaluate bacterial susceptibility profiles of bacteria isolated.

Design—Retrospective study.

Animals—10 horses.

Procedure—Data were retrieved from medical records and the microbiology laboratory database.

Results—1,604 horses underwent clean, elective surgical procedures during the study period. Of these, 23 (1.43%) had postoperative wound infections, and Actinobacillus spp was isolated from 10 of these 23 (43%). Surgical procedures in these 10 horses included laryngoplasty with ventriculocordectomy (n = 3), arthroscopy (3), desmotomy of the accessory ligament of the superficial digital flexor tendon (2), removal of laryngoplasty prostheses (1), and hygroma resection (1). Seven horses survived, and 3 were euthanatized. All 10 Actinobacillus isolates were resistant to penicillin, and 6 were resistant to trimethoprim-sulfamethoxazole. All isolates were susceptible to ceftiofur and gentamicin. During the 5-year period of the study, Actinobacillus organisms were isolated from 35 of 513 (6.8%) samples from the general hospital population submitted for bacterial culture and antimicrobial susceptibility testing.

Conclusions and Clinical Relevance—During the study period, Actinobacillus spp was isolated from a higher than expected percentage of horses that developed postoperative wound infections after clean, elective surgery. Susceptibility profiles for these isolates were different from typical susceptibility profiles for Actinobacillus isolates, suggesting that a pattern of resistance may be emerging. (J Am Vet Med Assoc 2002;221:1306–1310)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether particular vaccine brands, other injectable medications, customary vaccination practices, or various host factors were associated with the formation of vaccine-associated sarcomas in cats.

Design—Prospective multicenter case-control study.

Animals—Cats in the United States and Canada with soft tissue sarcomas or basal cell tumors.

Procedure—Veterinarians submitting biopsy specimens from cats with a confirmed diagnosis of soft tissue sarcoma or basal cell tumor were contacted for patient medical history. Time window statistical analyses were used in conjunction with various assumptions about case definitions.

Results—No single vaccine brand or manufacturer within antigen class was found to be associated with sarcoma formation. Factors related to vaccine administration were also not associated with sarcoma development, with the possible exception of vaccine temperature prior to injection. Two injectable medications (long-acting penicillin and methyl prednisolone acetate) were administered to case cats more frequently than to control cats.

Conclusions and Clinical Relevance—Findings do not support the hypotheses that specific brands or types of vaccine within antigen class, vaccine practices such as reuse of syringes, concomitant viral infection, history of trauma, or residence either increase or decrease the risk of vaccineassociated sarcoma formation in cats. There was evidence to suggest that certain long-acting injectable medications may also be associated with sarcoma formation. (J Am Vet Med Assoc 2003;223:1283–1292)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the prevalence of bacterial colonization of IV catheters among young dogs suspected to have parvoviral enteritis, to identify the organisms responsible for catheter colonization, and to determine the antimicrobial susceptibility of organisms that were obtained.

Design—Case series.

Animals—100 dogs.

Procedure—Catheters were aseptically removed when fluid therapy was discontinued, the catheter was replaced, or the dog died. The distal tip of the catheter was cut off, split open, and vortexed with sterile saline (0.9% NaCl) solution. The saline solution was plated on culture plates, which were then incubated and examined for bacterial growth every 24 hours for 72 hours. All bacteria cultured were identified, and antimicrobial susceptibility was determined.

Results—Bacteria were isolated from 22 catheters. Most bacteria that were isolated were of gastrointestinal tract or environmental origin (Serratia odorifera, S liquefaciens, S marcescens, Acinobacter anitratus, Citrobacter freundii, Klebsiella pneumoniae, K oxytoca, Escherichia coli, Enterobacter spp). Only 2 gram-positive organisms were isolated (Staphylococcus intermedius and Streptococcus spp). High percentages of organisms were resistant to penicillin, lincomycin, cloxacillin, erythromycin, and cephalexin. Percentages of organisms resistant to amikacin, enrofloxacin, chloramphenicol, potentiated sulfonamides, and amoxicillin-clavulanic acid were low.

Conclusions and Clinical Relevance—Results suggest that IV catheters may be colonized with bacteria in 22% of young dogs suspected to have parvovirus infection. (J Am Vet Med Assoc 2002;220:1321–1324).

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether foals with pneumonia that were treated with erythromycin, alone or in combination with rifampin or gentamicin, had a higher risk of developing adverse effects, compared with foals treated with trimethoprim-sulfamethoxazole (TMS), penicillin G procaine (PGP), or a combination of TMS and PGP (control foals).

Design—Retrospective study.

Animals—143 foals < 240 days old.

Procedure—Information on age, sex, breed, primary drug treatment, total days of treatment with the primary drug, and whether the foal developed diarrhea, hyperthermia, or respiratory distress was obtained from the medical records. Relative risk (RR) and attributable risk (AR) were calculated to compare risk of adverse reactions between foals treated with erythromycin and control foals.

Results—Only 3 (4.3%) control foals developed diarrhea; none developed hyperthermia or respiratory distress. Foals treated with erythromycin had an 8-fold risk (RR, 8.3) of developing diarrhea, compared with control foals, and increased risks of hyperthermia (AR, 25%) and respiratory distress (AR, 15%).

Conclusion and Clinical Relevance—Results suggest that use of erythromycin to treat foals with pneumonia was associated with an increased risk of diarrhea, hyperthermia, and respiratory distress, compared with use of TMS or PGP. (J Am Vet Med Assoc 2000;217:68–73)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine types and doses of injectable medications given to periparturient sows and reasons for administering those medications, and to compare medication practices among farms of different sizes.

Design—Survey.

Sample Population—301 farms; 231,016 periparturient sows.

Procedure—A survey was used to obtain information regarding medications given to sows during the farrowing period. State and federal veterinary medical officers completed surveys during their final interview with producers who had participated in the National Animal Health Monitoring System's (NAHMS) Swine 95 study. Data were summarized and treatment regimens compared among farms of different sizes.

Results—More than a third of the sows received medications during the farrowing period. The most common reasons for administering medications were routine preventive treatment and treatment of dystocia, uterine discharge, and poor appetite. The most commonly used medications for treatment of sick sows were oxytocin, procaine penicillin G, and B vitamins. A high percentage of medications were either not indicated for the specific condition or used at greater or less than the approved dose. In general, treatment rates and medications used did not differ among farms of different sizes.

Conclusion and Clinical Relevance—Better treatment protocols are needed to provide more appropriate treatment of sick sows. (J Am Vet Med Assoc 2000;216:510–515)

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Objective

To determine the resistance and susceptibility to antimicrobial compounds of Fusobacterium necrophorum isolates from bovine hepatic abscesses.

Procedure

37 isolates of F necrophorum (21 subsp necrophorum and 16 subsp funduliforme) isolated from bovine hepatic abscesses were obtained from cultures grown and maintained in anaerobic brain heart infusion broth. A broth dilution method was used as an initial screening to determine general susceptibility to 31 antimicrobial compounds. The minimal inhibitory concentrations (MIC) of 19 of the antimicrobial compounds that inhibited growth in the initial test were determined by use of the broth microdilution method.

Results

Fusobacterium necrophorum isolates were generally susceptible to penicillins, tetracyclines (chlortetracycline and oxytetracycline), lincosamides (clindamycin and lincomycin), and macrolides (tylosin and erythromycin), and were resistant to aminoglycosides (kanamycin, neomycin, gentamicin, and streptomycin), ionophores (except narasin), and peptides (avoparcin, polymyxin, and thiopeptin). The 5 antimicrobials (bacitracin, chlortetracycline, oxytetracycline, tylosin, and virginiamycin) that have FDA approval for prevention of liver abscesses in feedlot cattle were inhibitory to F necrophorum. Differences in antimicrobial susceptibility patterns were observed between the 2 subspecies only for clindamycin and lincomycin. The MIC of F necrophorum isolates from antibiotic-fed cattle were similar to those for isolates from nonantibiotic-fed cattle.

Conclusions

The MIC of FDA-approved antibiotics were not reflective of the efficacy of antibiotics in preventing liver abscesses in feedlot cattle. Also, continuous feeding of tylosin did not appear to select resistant F necrophorum. (Am J Vet Res 1998;59:44–47)

Free access
in American Journal of Veterinary Research

Objective—

To determine whether treating cows with antimicrobials at the end of lactation would lower the incidence of clinical mastitis, improve milk production, and decrease somatic cell count (SCC) in the subsequent lactation.

Design—

Randomized blind field trial.

Animals—

233 Holstein cows from a single herd. All cows were in lactation 2 or greater.

Procedure—

Cows were randomly assigned to treatment groups. Treated cows were given procaine penicillin G and novobiocin by intramammary infusion. Control cows were not treated. Farm personnel recorded cases of clinical mastitis. Milk yield and SCC were recorded during the subsequent lactation.

Results—

Treatment did not significantly reduce the incidence of clinical mastitis when data for all cows were grouped or when data were stratified by lactation groups (lactation 2 vs lactation ≥ 3) or by last SCC (≤ 500,000 cells/ml vs > 500,000 cells/ml). Somatic cell counts (first, mean of first 5, maximum of first 5) for treated and control cows were similar, and proportions of treated and control cows with SCC > 500,000 cells/ml at least once were not significantly different. Treated cows produced 179 kg (394 lb) more milk during the first 17 weeks of lactation than did control cows.

Clinical Implications—

Treating cows with antimicrobials at the end of lactation increased 17-week milk production during the subsequent lactation and, at current milk prices, was financially preferable to not treating them. (J Am Vet Med Assoc 1997;211:207–211)

Free access
in Journal of the American Veterinary Medical Association

Summary

Equine articular chondrocytes were isolated from explant cartilage cultures by digestion in a 0.075% collagenase solution for 15 to 19 hours. Cartilage from late-term fetal and neonatal foals resulted in mean chondrocyte yield of 51.99 × 106 cells/g of cartilage (wet weight), compared with a yield of 17.83 × 106 cells/g for foals 3 to 12 months old. Propagation of chondrocytes in monolayer and 3-dimensional culture was accomplished, using Ham’s F-12 as the basal medium, with supplements of fetal bovine serum (10%), ascorbic acid, α-ketoglutarate, and l-glutamine. The medium was buffered with hepes, and penicillin and streptomycin were added for microorganism control. In primary monolayer cultures of freshly isolated chondrocytes, the population doubling time was approximately 6 days. Dedifferentiation of chondrocytes toward a more fibroblastic-appearing cell was observed after the fifth passage (subculture), but was hastened by lower cell-plating density. Chondrocytes were frozen for periods of up to 9 months, using 10% dimethyl sulfoxide as the cryoprotectant. Cell viability of late-term fetal and neonatal foal chondrocytes after storage at −196 C decreased from 86% at 3 weeks to 31% at 12 weeks. Viability of cells derived from older foals and young adult horses was considerably better than that of cells from neonatal foals. Frozen chondrocytes can be stored for extended periods and thawed for immediate implantation or can be sustained in vitro in monolayer or 3-dimensional culture. Such cultures would be suitable for cartilage resurfacing experiments or in vitro assessment of various pharmaceuticals.

Free access
in American Journal of Veterinary Research

Summary

A total of 73 breeding-age and primigravid Jersey heifers in 4 herds was randomly allotted to treatment and control groups according to expected calving date. Thirty-five heifers were injected intramammarily with a nonlactating cow product containing penicillin/streptomycin. Thirty-eight heifers served as untreated controls. Of the 35 treated heifers, 34 (97.1%) were infected at time of treatment. In the untreated control group, all 38 heifers (100%) were infected at treatment time. At parturition, prevalence of intramammary infection in treated heifers decreased to 40%, whereas in the control group, prevalence remained about the same (97.4% of heifers). Prevalence of Staphylococcus aureus mastitis in treated heifers was reduced from 17.1% to 2.9% after treatment. In the control group, prevalence of S aureus mastitis decreased from 26.3% to l5.8%. Heifers treated during the second trimester of pregnancy had the greatest reduction in prevalence of mastitis and in somatic cell count at parturition, compared with controls. Findings indicated that intramammary treatment during pregnancy in primigravid heifers was effective in reducing prevalence of mastitis and somatic cell counts at parturition.

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in Journal of the American Veterinary Medical Association

SUMMARY

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 1-, 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.

Free access
in American Journal of Veterinary Research