Genotoxicity from metronidazole detected in vitro, but not in vivo, in healthy dogs in a randomized clinical trial

Hannah M. Peterson Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI

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Colette I. Manley Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI

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Lauren A. Trepanier Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI

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Jessica C. Pritchard Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI

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Abstract

OBJECTIVE

To determine whether metronidazole (MTZ), at recommended therapeutic dosages in dogs, induces peripheral blood cell (PMBC) genotoxicity, using the γ-H2AX assay as a sensitive measure of DNA breaks. The secondary aim was to assess dose-dependent genotoxicity in vitro in dog and cat PBMCs exposed to increasing MTZ concentrations.

ANIMALS

12 healthy employee- and student-owned dogs and blood samples from 2 other healthy untreated dogs and 2 healthy untreated cats.

PROCEDURES

Screened dogs were randomized to receive lower-dose MTZ (7.5 mg/kg, PO, q 12 h) or higher-dose MTZ (20 mg/kg, PO, q 12 h) for 7 days. Blood was drawn at baseline, after the 1 week of treatment, and after a 1-week washout, for DNA damage assessment and serum MTZ concentration measurements. For in vitro studies, PBMCs from untreated healthy dogs and cats were exposed to 0 to 500 μg/mL MTZ.

RESULTS

No dogs showed a significant increase in DNA damage at these MTZ dosages for 1 week. The highest serum MTZ concentration observed 1 hour after dosing was 36 μg/mL. In vitro, MTZ led to a significant increase in DNA damage at 100 μg/mL in both canine and feline PBMCs.

CLINICAL RELEVANCE

Although MTZ was not significantly genotoxic in vivo in the healthy dogs in this study, MTZ was significantly genotoxic to canine PBMCs in vitro at 3-fold higher concentrations than those documented in vivo. The safety of MTZ in clinically ill dogs, which may have impaired MTZ clearance or DNA repair, should be assessed next.

Abstract

OBJECTIVE

To determine whether metronidazole (MTZ), at recommended therapeutic dosages in dogs, induces peripheral blood cell (PMBC) genotoxicity, using the γ-H2AX assay as a sensitive measure of DNA breaks. The secondary aim was to assess dose-dependent genotoxicity in vitro in dog and cat PBMCs exposed to increasing MTZ concentrations.

ANIMALS

12 healthy employee- and student-owned dogs and blood samples from 2 other healthy untreated dogs and 2 healthy untreated cats.

PROCEDURES

Screened dogs were randomized to receive lower-dose MTZ (7.5 mg/kg, PO, q 12 h) or higher-dose MTZ (20 mg/kg, PO, q 12 h) for 7 days. Blood was drawn at baseline, after the 1 week of treatment, and after a 1-week washout, for DNA damage assessment and serum MTZ concentration measurements. For in vitro studies, PBMCs from untreated healthy dogs and cats were exposed to 0 to 500 μg/mL MTZ.

RESULTS

No dogs showed a significant increase in DNA damage at these MTZ dosages for 1 week. The highest serum MTZ concentration observed 1 hour after dosing was 36 μg/mL. In vitro, MTZ led to a significant increase in DNA damage at 100 μg/mL in both canine and feline PBMCs.

CLINICAL RELEVANCE

Although MTZ was not significantly genotoxic in vivo in the healthy dogs in this study, MTZ was significantly genotoxic to canine PBMCs in vitro at 3-fold higher concentrations than those documented in vivo. The safety of MTZ in clinically ill dogs, which may have impaired MTZ clearance or DNA repair, should be assessed next.

Metronidazole (MTZ) is frequently prescribed in veterinary medicine for treatment of anaerobic bacterial and protozoal infections, as well as for hepatic encephalopathy, antimicrobial-responsive diarrhea, and inflammatory bowel disease.13 MTZ limits microbial infection by directly interacting with DNA to inhibit the binding of polymerases, resulting in the inability to synthesize DNA or RNA.4

Despite its important clinical uses in veterinary medicine, MTZ administration can result in DNA damage. Reversible genotoxicity induced by MTZ has been shown both in vitro and in vivo in cats.5 Drug-induced genotoxicity may prevent the cell from completing a normal cell cycle, increasing the risk for recombination errors, deleterious mutation formation, and potential tumorigenesis. MTZ has been shown to increase mutation rates in Drosophila6 and cause DNA damage in healthy human blood cells.4,79 Metronidazole is therefore considered a potential human carcinogen.4 However, it is not known whether MTZ induces genotoxicity in dogs, despite being one of the most widely used antimicrobials in companion animal medicine.

The primary aim of the study reported here was to determine whether MTZ, at recommended therapeutic dosages in dogs, induces peripheral blood cell genotoxicity, using the γ-H2AX assay as a sensitive measure of DNA breaks. The secondary aim was to assess dose-dependent genotoxicity in vitro in dog PBMCs exposed to increasing MTZ concentrations.

Materials and Methods

Animals

Healthy and employee- and student-owned pet dogs were recruited at the University of Wisconsin-Madison School of Veterinary Medicine. For inclusion, dogs were required to be > 1 year of age, > 10 kg, and healthy as determined by history, physical examination, CBC, and serum biochemical analyses. Dogs could not be currently receiving any prescription medications, over-the-counter medications, or supplements aside from standard flea, tick, and heartworm preventatives, have had a previous adverse reaction to MTZ, or exposure to MTZ or other genotoxic agents (eg, chemotherapy) within 30 days of the study.

Ethics approval

This study design was approved by the Institutional Animal Care and Use Committee (Animal Use Protocol No. V006190) at the University of Wisconsin-Madison. The owners of each dog provided written consent before enrollment. Recruitment incentives included free physical examination, standard CBC, and serum biochemical analyses, with results available to the owner and their primary care veterinarian.

Study design

A prospective, randomized, interventional study was conducted from May to August 2019 in 12 healthy pet staff- and student-owned dogs. On day 0, 5 mL of blood in EDTA was drawn from the cephalic vein for baseline plasma MTZ concentrations and DNA damage assessment using the γ-H2AX assay. The dogs were randomized, using a random number generator, into 2 treatment groups of 6 dogs each: “lower-dose” MTZ (7.5 mg/kg PO q12h, commonly used for hepatic encephalopathy)2 and “higher-dose” MTZ (20 mg/kg, PO, q 12 h, in the range of 15 to 25 mg/kg, PO, q 12 h, used for anaerobic or protozoal infections).10 All dogs were treated with MTZ for 7 days to approximate clinical courses used for protozoal or soft tissue infections.10

Dogs returned on day 7, received their last morning MTZ dose in the hospital, and 1 hour later had blood collected in EDTA (5 mL) for plasma MTZ concentrations and DNA damage assessment. Owners were asked to report any new clinical signs or perceived adverse reactions to MTZ administration. Dogs returned on day 14, 7 days after discontinuing MTZ, for final blood collection for plasma MTZ concentrations and DNA damage assays.

Blood collection and processing

Whole blood collected in EDTA was immediately centrifuged at 500 X g for 5 minutes to harvest at least 1ml of plasma, which was frozen at –80°C for batched analysis of plasma MTZ concentrations by ultra-performance liquid chromatography-tandem mass spectrometer at a fee-for-service academic laboratory (Kansas State University) using a published method.11 The remaining blood sample was used for preparation of peripheral blood mononuclear cells (PBMCs) by standard density centrifugation at 400 X g for 30 minutes in Histopaque 1077. Cell pellets were washed and resuspended in 1X phosphate buffered saline (PBS).

PBMC exposures to metronidazole in vitro

Whole blood in EDTA was also collected from 2 healthy pet dogs, not treated with MTZ, for in vitro experiments. PBMCs were prepared as for dogs treated in vivo and were pooled for in vitro assays. PBMCs were also prepared from 2 healthy adult domestic short-hair pet cats, not treated with MTZ, and pooled for in vitro DNA damage assays to compare findings to a previous report of metronidazole genotoxicity in cats.5 In vitro experiments were performed from January 2020 through December 2021.

PBMCs from untreated dogs and cats were exposed to MTZ in vitro at concentrations of 5, 25, 50, 75, 100, and 500 μg/mL for 1 hour at room temperature, with 1X PBS as the vehicle control. These concentrations were chosen to include the range of mean inhibitory concentrations reported for MTZ toward anaerobic isolates in dogs (up to 64 μg/mL),12 and peak plasma concentrations reached after IV administration in dogs (up to 60 μg/mL).13 PBMCs were washed with 1X PBS prior to immunocytochemistry for γ-H2AX. Each in vitro exposure experiment was performed in triplicate on 2 separate occasions.

Immunocytochemistry for γ-H2AX

PBMCs from both in vivo and in vitro MTZ exposures were counted with a hemocytometer using trypan blue; 1 X 106 cells/mL were fixed in 4% paraformaldehyde in PBS for 15 minutes at room temperature. Fixed cells were washed twice with sterile water, added to positively charged microscope slides, and dried with a slide warmer. Slides were kept overnight in a humidified chamber at 4°C and stained the following day.

Cells were permeabilized with a surfactant (0.1% Triton X-100, Sigma Aldrich) in 1X PBS for 10 minutes at room temperature and washed with 1X PBS with detergent (Tween-20; Sigma Aldrich; 1X PBST). Nonspecific binding was blocked with 5% goat serum in 1X PBST for 45 minutes at room temperature and washed 3 times with 1X PBST. PBMC were then incubated with anti-phospho-histone H2A.X [Ser139] mouse monoclonal antibody (Abcam) at a 1:1000 dilution in 1% BSA in 1X PBST for 18 hours at 4°C in a humidified chamber. After incubation, slides were washed with 1X PBST and then incubated with secondary anti-mouse IgG Fab2 antibody (Alexa Fluor 488 antibody; Cell Signaling Technology) at a 1:500 dilution in 1% BSA in 1X PBST for 1 hour at room temperature in the dark. Following additional washing, cell nuclei were counterstained with DAPI 1 mg/mL in 1% BSA in 1X PBS, for 5 minutes. Slides were then mounted with mounting medium (Vibrance; Vector Laboratories), cover slipped, and kept at 4°C until imaged.

Imaging for γ-H2AX foci

Imaging was performed with a laser scanning confocal microscope equipped with a 63X oil-immersion objective. Two channels were acquired sequentially with 488/500- to 540- and 405-nm lasers. Standard gains (%) were used (100 for DAPI and 700 for secondary antibody) while the intensities for both lasers were set at 10% to avoid oversaturation. Chosen pixel size for the images was 4,096 X 4,096. Images were analyzed with FoCo software program, available through MATLAB.14 Analysis parameters were established from a preliminary set of images to minimize noise and missed calls.14 The γ-H2AX foci were counted for a minimum of 100 PBMC nuclei per slide and were expressed as mean γ-H2AX foci/total nuclei. Laboratory personnel was masked to in vivo treatment group.

Statistical analyses

All data were reported as medians with observed ranges. For in vivo dosing, serum MTZ concentrations were compared between dosing groups using a Mann-Whitney U test. Median γ-H2AX foci/nucleus were compared at baseline, 7 days, and 14 days within each metronidazole dosing group using Friedman 2-way ANOVA. Plasma MTZ concentrations were assessed for associations with DNA damage using a Spearman rank-order correlation. For in vitro exposures, median γ-H2AX foci per PBMC nucleus were compared across metronidazole concentrations using Kruskal-Wallis and Mann-Whitney U tests. Sample size was calculated as follows: since there were no in vivo data using the γ-H2AX assay in dogs, we estimated variability from our previous study of endogenous DNA damage in healthy dogs using the comet assay.15 Using this variability, 6 dogs in each group were powered to detect a conservative 2-fold increase in DNA damage from baseline, with P < .05 and 80% power.

Results

Patient demographics

Twelve dogs were enrolled in the study. The 6 dogs in the low-dose MTZ group were reported as mixed breed (n = 3), Pembroke Welsh Corgi (1), Great Dane (1), or Australian Shepherd (1) and included 3 castrated males, 2 spayed females, and 1 sexually intact male. Dogs in the high-dose MTZ group were reported as Labrador Retriever (n = 2), mixed breed (1), pit bull–type dog (1), Catahoula (1), or Australian Shepherd (1) and included 5 spayed females and 1 castrated male. Ages and body weights for the 2 groups were comparable (Table 1). Dogs in the lower-dose MTZ group were treated with a median of 8.8 mg/kg, PO, q 12 h MTZ, while dogs in the higher-dose MTZ group were treated with a median of 18.8 mg/kg, PO, q 12 h. Owners of 3 dogs in each group reported soft stools during treatment, with no other adverse effects reported. Soft stools continued during the washout period in only the higher-dose group (n = 3).

Table 1

Median (range) age, body weight, and metronidazole (MTZ) dosage for 12 healthy student-owned or employee-owned dogs in a randomized clinical trial conducted from May to August 2019 to determine whether MTZ at targeted recommended therapeutic dosages (7.5 mg/kg [low-dose MTZ group] vs 20 mg/kg [high-dose MTZ group], PO, q 12 h for 7 days) induces in vivo genotoxicity in peripheral blood mononuclear cells.

Variable Lower-dose MTZ group (target, 7.5 mg/kg, PO, q 12 h) Higher-dose MTZ group (target, 20 mg/kg, PO, q 12 h)
Age (y) 5 (1–8) 5 (2–12)
Body weight (kg) 25.4 (13.4–57.6) 25.1 (14.3–38.1)
Actual dosage administered (mg/kg, PO, q 12 h) 8.8 (6.9–9.3) 18.8 (16.4–21.2)

Metronidazole concentrations

After 7 days of dosing, plasma MTZ concentrations ranged from 5.0 to 12.6 μg/mL (median, 8.2 μg/mL) in the lower-dose group, and 2.6 to 36.0 μg/mL (median, 18.8 μg/mL) in the higher-dose group (Figure 1). There was substantial interindividual variability in plasma MTZ concentrations in the higher-dose group, which were not statistically higher than the lower-dose group in this small population (P = .065).

Figure 1
Figure 1

Individual-value plots of plasma metronidazole (MTZ) concentrations in healthy student-owned or employee-owned dogs at day 0 (baseline before treatment), 7 (1 hour after last treatment), and 14 (completion of a 1-week washout period) during a randomized clinical trial conducted between May and August 2019 to determine whether MTZ at targeted recommended lower (7.5 mg/kg PO, q12 h, n = 6, open circles) or higher (20 mg/kg PO, q12 h, 6, filled circles) therapeutic dosages for 7 days induces genotoxicity in peripheral blood mononuclear cells (PBMCs) in dogs. Each circle represents data for 1 dog, and the horizontal lines represents the medians.

Citation: American Journal of Veterinary Research 84, 1; 10.2460/ajvr.22.07.0112

In vivo DNA damage

We did not detect an increase in DNA damage in circulating PBMCs after 7 days of lower-dose MTZ administration (median, 35.3 foci/nucleus; range, 15.3 to 101.7 foci/nucleus) when compared to baseline (median, 66.5 foci/nucleus; range, 28.2 to 171.5 foci/nucleus) or after a 1-week washout (median, 64.5 foci/nucleus; range, 37.1 to 111.9 foci/nucleus; P = .43; Figure 2). We found similar negative results for higher-dose MTZ when comparing DNA damage after 7 days of dosing (median, 109.3 foci/nucleus; range, 41.9 to 234.8 foci/nucleus) to baseline (median, 100.6 foci/nucleus; range, 47.3 to 153.7 foci/nucleus) or after a 1-week washout (median, 93.3 foci/nucleus; range, 66.8 to 112.8 foci/nucleus; P = .69). For individual dogs in the higher-dose group, the median increase in DNA damage from baseline to 7 days was 6% (range, –12% to 53%). There was no detectable correlation (r = 0.07, P = .83) between plasma MTZ concentrations and DNA damage across all dogs on day 7.

Figure 2
Figure 2
Figure 2

Individual-value plots of the number of DNA breaks identified in circulating PBMCs with the use of γ-H2AX assays (γ-H2AX foci/nucleus) on days 0, 7, and 14 for the dogs in the lower-dose (A) and higher-dose (B) MTZ treatment groups described in Figure 1. See Figure 1 for the key.

Citation: American Journal of Veterinary Research 84, 1; 10.2460/ajvr.22.07.0112

In vitro DNA damage

When PBMCs from untreated healthy dogs were exposed to MTZ in vitro, we observed a dose-dependent increase in DNA damage, with a significant increase at 100 μg/mL (median, 363 foci/nucleus) compared to either vehicle (median, 271 foci/nucleus; P = .019) or 5 μg/mL MTZ (median, 200 foci/nucleus; P = .017, Figure 3). DNA damage at 25 and 50 μg/mL MTZ (311 and 326 foci/nucleus, respectively) were observably higher than vehicle control but were not statistically different. To put these in vitro exposures in context, the highest plasma MTZ concentration observed in vivo at 1 hour after dosing was 36 μg/mL in the dogs in this study.

Figure 3
Figure 3

Bar graphs of DNA strand breaks identified with the use of the γ-H2AX assay (γ-H2AX foci/nucleus) in pooled PBMCs from 2 healthy untreated dogs (black bars) and 2 healthy untreated cats (gray bars), exposed in vitro to increasing concentrations of MTZ (0, 5, 25, 50, 75, 100, or 500 µg/mL) for 1 hour at room temperature. The top of each bar represents the mean, and the error bar represents the upper limit of the SD. *DNA damage was significantly (P = .019 [dogs] or P = .018 [cats]) higher from vehicle control.

Citation: American Journal of Veterinary Research 84, 1; 10.2460/ajvr.22.07.0112

Because a previous study5 had reported genotoxicity from MTZ in cats using a different measure of DNA damage (the comet assay), we also examined in vitro DNA damage from MTZ in feline PBMCs using the γ-H2AX assay. DNA damage was significantly increased at 100 μg/mL MTZ (median, 331 foci/nucleus) compared to vehicle (median, 156 foci/nucleus; P = .018; Figure 3) in feline cells.

Discussion

Metronidazole has been considered potentially genotoxic since the discovery of its mechanism of action against bacterial agents, namely through reduction of the nitro-group and resultant production of cytotoxic compounds.16,17 Metronidazole at therapeutic doses can lead to DNA damage in PBMCs from healthy people, as assessed by the comet assay.7,9,18 The traditional alkaline comet assay measures DNA strand breaks as changes in DNA migration during gel electrophoresis; damaged DNA migrates away from unaffected supercoiled DNA creating a “comet tail,” which can be semiquantitated. However, the comet assay may be insensitive to very low levels of DNA damage19 and had substantial interassay variability in our hands (data not shown).

For the current study, we chose the more recently developed γ-H2AX assay, which may be more sensitive to low-dose or early DNA damage than the comet assay.20,21 The γ-H2AX detects real-time histone phosphorylation in response to DNA strand breaks and replication lesions, even at the single-cell level.22 However, in our dogs given oral MTZ at 7.5 or 20 mg/kg, q 12 h, we did not detect even a 2-fold increase in vivo DNA damage after 7 days of treatment. This contrasts somewhat with human subjects given approximately 12.5 mg/kg MTZ, PO, q 12 h, in which there was a 20% increase in PBMC comet tails after 10 days of dosing.9 Unfortunately, postpill plasma MTZ concentrations were not evaluated in that study. Our data also contrast with a prior study in purpose-bred cats given 12.5 mg/kg MTZ, PO, q 12 h for 7 days, in which a significant increase in DNA damage was noted using the comet assay, which resolved after a 1-week washout.5 Direct comparisons to our results are difficult to make, because of the low numbers of cats in the previous study (n = 3 purpose-bred cats) and the lack of MTZ plasma concentrations measured at a comparable time point. However, plasma concentrations as high as 17.8 μg/mL were demonstrated in cats after a single 12.4-mg/kg oral dose of MTZ,5 which is comparable to the median steady-state plasma MTZ concentrations of 8.2 and 18.8 μg/mL found in our study. Cats from the previous study5 were dosed orally with metronidazole benzoate, so it is possible that in vivo genotoxicity was also due in part to benzoic acid, which is genotoxic.23

Plasma MTZ concentrations were quite variable in the dogs in our study, which could be due to differences in bioavailability or biotransformation, as well as owner or dog compliance. However, we found no correlation between plasma drug concentrations and in vivo DNA damage, which is similar to one study7 in people. This could be due to the small number of dogs enrolled or to inconsistent compliance with administration. It is also possible that an unmeasured reactive metabolite of MTZ is mediating genotoxicity and that this metabolite, or resulting free radical damage, is variably generated among individuals. However, MTZ is metabolized to a hydroxylated metabolite that has comparable genotoxicity to the parent MTZ, at least in human subjects.24

When we exposed canine PBMCs in vitro with MTZ, we did find a significant increase in genotoxicity at 100 μg/mL, a concentration that was higher than plasma concentrations detected in vivo in this study. This concentration of MTZ was also genotoxic in human and feline PBMCs in vitro using the comet assay5,8 and in the current study in feline PBMCs using the γ-H2AX assay. This suggests that the differences in in vivo genotoxicity between our study and the previous feline study were not due to inherent species differences in PBMC susceptibility to MTZ, although more comprehensive experiments, including TC50 determinations, would be needed to fully assess species differences.

The current study has several limitations. First, the sample population was small, and the individual dogs in each dosing group were not the same. A crossover design may have minimized interindividual differences in MTZ disposition or DNA damage susceptibilities and allowed us to detect more subtle increases in DNA damage in vivo. We also did not examine DNA damage in other tissues, such as the liver or bone marrow. We found unexpectedly large variability in plasma MTZ concentrations among dogs, especially in the higher-dose group, and we had inadequate power to correlate plasma drug concentrations with DNA damage in this small population. Finally, we did not evaluate concurrent cytotoxicity, and while the γ-H2AX is more sensitive than the comet assay for DNA lesions such as double- and single-stranded DNA breaks and DNA oxidation, the γ-H2AX, unlike the comet assay, does require viable cells to generate signals.22 Incorporation of multiple genotoxic endpoints, such as the comet assay and the micronucleus assay, could have provided a more comprehensive assessment of MTZ genotoxicity in dogs.

The in vitro genotoxicity shown in this study may support a more limited use of MTZ in dogs and cats, when possible, especially given the variability in plasma MTZ concentrations observed. In dogs, MTZ is commonly prescribed for acute gastroenteritis, chronic enteropathies, and hepatic encephalopathy.13 While some dogs given oral MTZ for acute, noninfectious diarrhea showed faster improvement of fecal consistency scores than control dogs,25 probiotics have been shown to be more effective.26 Additionally, healthy dogs administered oral MTZ show substantial fecal microbiome disruptions with reduced numbers of microbial populations, increased bacterial metabolic by-products, and increased fecal dysbiosis index, and these changes persist for more than 30 days after MTZ discontinuation.27

In summary, we found that MTZ causes genotoxicity in vitro in both canine and feline PBMC, but that plasma metronidazole concentrations did not reach genotoxic concentrations at 1 hour after dosing in the small number of healthy dogs treated with up to 21.2 mg/kg, q 12 h for 7 days in this study. Additional work is needed to assess the safety of MTZ in dogs that are clinically ill, who may have delayed MTZ biotransformation or impaired DNA damage pathways, or who required more prolonged treatment courses.

References

  • 1.

    Hall EJ. Antibiotic-responsive diarrhea in small animals. Vet Clin North Am Small Anim Pract. 2011;41(2):273286. doi:10.1016/j.cvsm.2010.12.004

  • 2.

    Lidbury JA, Cook AK, Steiner JM. Hepatic encephalopathy in dogs and cats. J Vet Emerg Crit Care. 2016;26(4):471487. doi:10.1111/vec.12473

    • Search Google Scholar
    • Export Citation
  • 3.

    Volkmann M, Steiner JM, Fosgate GT, Zentek J, Hartmann S, Kohn B. Chronic diarrhea in dogs–retrospective study in 136 cases. J Vet Intern Med. 2017;31(4):10431055. doi:10.1111/jvim.14739

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4.

    Bendesky A, Menéndez D, Ostrosky-Wegman P. Is metronidazole carcinogenic? Mutat Res. 2002;511(2):133144. doi:10.1016/s1383-5742(02)00007-8

  • 5.

    Sekis I, Ramstead K, Rishniw M, et al. Single-dose pharmacokinetics and genotoxicity of metronidazole in cats. J Feline Med Surg. 2009;11(2):6068. doi:10.1016/j.jfms.2008.06.011

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6.

    Palermo AM, Mudry MD. Metronidazole induced DNA damage in somatic cells of Drosophila melanogaster. Curr Drug Saf. 2013;8(3):195198. doi:10.2174/15748863113089990035

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7.

    Elizondo G, Gonsebatt ME, Salazar AM, et al. Genotoxic effects of metronidazole. Mutat Res. 1996;370(2):7580. doi:10.1016/0165-1218(96)00022-5

  • 8.

    Rodriguez Ferreiro G, Cancino Badías L, Lopez-Nigro M, et al. DNA single strand breaks in peripheral blood lymphocytes induced by three nitroimidazole derivatives. Toxicol Lett. 2002;132(2):109115. doi:10.1016/s0378-4274(02)00039-5

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Menéndez D, Rojas E, Herrera LA, et al. DNA breakage due to metronidazole treatment. Mutat Res. 2001;478:153158. doi:10.1016/s0027-5107(01)00136-1

  • 10.

    Plumb’s. Metronidazole. Plumb’s Veterinary Drugs. Updated June 2022. Accessed June 25, 2022. https://app.plumbs.com/drug-monograph/qwJQIPmiviPROD.

  • 11.

    Stancil SL, van Haandel L, Abdel-Rahman S, Pearce RE. Development of a UPLC-MS/MS method for quantitation of metronidazole and 2-hydroxy metronidazole in human plasma and its application to a pharmacokinetic study. J Chromatogr B Analyt Technol Biomed Life Sci. 2018;1092:272278. doi:10.1016/j.jchromb.2018.06.024

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Marks SL, Kather EJ. Antimicrobial susceptibilities of canine Clostridium difficile and Clostridium perfringens isolates to commonly utilized antimicrobial drugs. Vet Microbiol. 2003;94(1):3945. doi:10.1016/s0378-1135(03)00061-0

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13.

    Neff-Davis CA, Davis LE, Gillette EL. Metronidazole: a method for its determination in biological fluids and its disposition kinetics in the dog. J Vet Pharmacol Ther. 1981;4(2):121127. doi:10.1111/j.1365-2885.1981.tb00720.x

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14.

    Lapytsko A, Kollarovic G, Ivanova L, Studencka M, Schaber J. FoCo: a simple and robust quantification algorithm of nuclear foci. BMC Bioinformatics. 2015;16:392. doi:10.1186/s12859-015-0816-5

    • Search Google Scholar
    • Export Citation
  • 15.

    Craun K, Ekena J, Sacco J, Jiang T, Motsinger-Reif A, Trepanier LA. Genetic and environmental risk for lymphoma in boxer dogs. J Vet Intern Med. 2020;34(5):20682077. doi:10.1111/jvim.15849

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16.

    Dobiás L, Cerná M, Rössner P, Srám R. Genotoxicity and carcinogenicity of metronidazole. Mutat Res. 1994;317(3):177194. doi:10.1016/0165-1110(94)90001-9

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    Lamp KC, Freeman CD, Klutman NE, Studencka M, Schaber J. Pharmacokinetics and pharmacodynamics of the nitroimidazole antimicrobials. Clin Pharmacokinet. 1999;36(5):353373. doi:10.2165/00003088-199936050-00004

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18.

    JL, De Méo MP, Laget M, et al. Evaluation of the genotoxic activity of metronidazole and dimetridazole in human lymphocytes by the comet assay. Mutat Res.1997;375(2):147155. doi:10.1016/s0027-5107(97)00010-9

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19.

    McArt DG, McKerr G, Howard CV, Saetzler K, Wasson GR. Modelling the comet assay. Biochem Soc Trans. 2009;37(4):914917. doi:10.1042/BST0370914

  • 20.

    Yu Y, Zhu W, Diao H, Zhou C, Chen FF, Yang J. A comparative study of using comet assay and gammaH2AX foci formation in the detection of N-methyl-N′-nitro-N-nitrosoguanidine-induced DNA damage. Toxicol In Vitro. 2006;20(6):959965. doi:10.1016/j.tiv.2006.01.004

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21.

    Nikolova T, Marini F, Kaina B. Genotoxicity testing: comparison of the γH2AX focus assay with the alkaline and neutral comet assays. Mutat Res Genet Toxicol Environ Mutagen. 2017;822:1018. doi:10.1016/j.mrgentox.2017.07.004

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22.

    Kopp B, Khoury L, Audebert M. Validation of the γH2AX biomarker for genotoxicity assessment: a review. Arch Toxicol. 2019;93(8):21032114. doi:10.1007/s00204-019-02511-9

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23.

    Yılmaz S, Ünal F, Yüzbaşıoğlu D. The in vitro genotoxicity of benzoic acid in human peripheral blood lymphocytes. Cytotechnology. 2009;60(1-3):55. doi:10.1007/s10616-009-9214-z

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24.

    Menéndez D, Bendesky A, Rojas E, Salamanca F, Ostrosky-Wegman P. Role of P53 functionality in the genotoxicity of metronidazole and its hydroxy metabolite. Mutat Res. 2002;501(1-2):5767. doi:10.1016/s0027-5107(02)00012-x

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25.

    Langlois DK, Koenigshof AM, Mani R. Metronidazole treatment of acute diarrhea in dogs: a randomized double blinded placebo-controlled clinical trial. J Vet Intern Med. 2020;34(1):98104. doi:10.1111/jvim.15664

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26.

    Shmalberg J, Montalbano C, Morelli G, Buckley GJ. A randomized double blinded placebo-controlled clinical trial of a probiotic or metronidazole for acute canine diarrhea. Front Vet Sci. 2019;6:163. doi:10.3389/fvets.2019.00163

    • Search Google Scholar
    • Export Citation
  • 27.

    Pilla R, Gaschen FP, Barr JW, et al. Effects of metronidazole on the fecal microbiome and metabolome in healthy dogs. J Vet Intern Med. 2020;34(5):18531866. doi:10.1111/jvim.15871

    • PubMed
    • Search Google Scholar
    • Export Citation
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