Understanding Antibiotic Use in Companion Animals: A Literature Review Identifying Avenues for Future Efforts

A qualitative analysis of the unwritten rules influencing antibiotic prescribing practices among French poultry veterinarians

Background

It is now recognized that a better understanding of prescriber behaviour is needed to improve antimicrobial stewardship programmes. Most studies conducted in the livestock sector have focused on farmers' perspectives, while the prescribing habits of veterinarians have remained overlooked.

Objective

Our study explored the psychosocial determinants associated with antibiotic prescribing practices in the French poultry sector by analysing the informal norms and unwritten rules that influence veterinarians' prescribing decisions.

Methods

A qualitative study was conducted in four French regions in February 2021. Using the biographical narrative interpretive method, semi-structured interviews were conducted with 16 poultry veterinarians with varying professional experience. Three main themes were retained for data analysis: (i) compliance with and deviations from prescribing recommendations, (ii) the influence of fellow veterinarians on antibiotic decisions and (iii) the key role of veterinary corporate groups.

Results

When prescribing antibiotics, junior veterinarians were strongly influenced by senior veterinarians who acted as role models driving clinical practices. Prescribing habits were shared through peer networks in which veterinarians participated throughout their careers. Finally, veterinary corporate groups helped to shape veterinarians' prescribing habits by promoting existing guidelines and even producing in-house recommendations.

Conclusions

We show that, in parallel with official guidelines, prescribing habits circulate among veterinarians and are shared in professional circles. Therefore, antimicrobial stewardship interventions should focus not only on official guidelines and communication channels, but also unwritten professional rules and organizations influencing veterinarians' prescribing practices.

Development of a new antibiotic-induced dysbiosis model of the canine colonic microbiota

As in humans, antibiotics are widely used in dogs to treat gastrointestinal infections, contributing to the global burden of antimicrobial resistance on both human and animal health. Close contact between pets and their owners can lead to horizontal transfer of gut microbes, including transmission of antibiotic resistance. Nevertheless, until now, the impact of antibiotics on the canine gut microbiota has been poorly described. The aim of this study was to adapt the canine mucosal artificial colon (CANIM-ARCOL) model, reproducing the main nutritional, physicochemical and microbial parameters found in the large intestine of the dog to simulate an antibiotic-induced perturbation. Following initial investigation of five antibiotic cocktails at in-field doses, a 5-day regimen of metronidazole/enrofloxacin (ME) was selected for further model development. Two CANIM-ARCOL bioreactors were inoculated with a faecal sample (n=2 donors) and run in parallel for 26 days under control or antibiotic conditions. ME reduced microbial diversity and induced major shifts in bacterial populations, leading to a state of dysbiosis characterized by an increase in the relative abundance of Streptococcaceae, Lactobacillaceae and Enterobacteriaceae, and a decrease in the relative abundance of Bacteroidaceae, Fusobacteriota and Clostridiaceae. Overall, mucus-associated microbiota were less impacted by antibiotics than luminal microbes. Microbial alterations were associated with drastic decreases in gas production and short-chain fatty acid concentrations. Finally, the model was well validated through in-vitro-in-vivo comparisons in a study in dogs. The CANIM-ARCOL model provides a relevant platform as an alternative to in-vivo assays for an in-depth understanding of antibiotic-microbiota interactions and further testing of restoration strategies at individual level.

Accessing the behavior and awareness of veterinary professionals towards antimicrobials use and antimicrobial resistance in Indian district

Introduction

Antimicrobial resistance (AMR) poses a significant public health threat, and understanding the awareness and practices of healthcare professionals is crucial for its mitigation. Since the animal sector plays a key role in India's economy, we decided to explore the understanding of Antimicrobial Use (AMU) and AMR among veterinary professionals.

Methods

The study aimed to evaluate the awareness and behavior of veterinarians and para-veterinarians working in the Jhunjhunu district, Rajasthan, India, concerning AMU and AMR. Questionnaire surveys were administered to them with closed-ended questions. The data was collected and subjected to statistical analysis to derive meaningful insights. The key findings highlight notable differences in certain behavioral aspects of antibiotic prescription among the two groups.

Results and Discussion

It appears that 53.8% of veterinarians as compared to 25.8% para-veterinarians do not surely inform farmers about the importance of adhering to antibiotic withdrawal periods, thereby failing to raise awareness about proper antibiotic use. Moreover, para-veterinarians (46.6%) tend to engage less in evidence-based antibiotic prescription than veterinarians (81%). Furthermore, both groups exhibit a lower frequency of advice on Antimicrobial Susceptibility Testing (ABST), essential for informed prescribing decisions. Most significantly, both groups show a tendency to prefer critically important antibiotics for prescription, raising concerns about the escalating threat of AMR. This study thus emphasizes the areas that need targeted interventions to enhance responsible antimicrobial usage and curb the growth of AMR in the region.

Characterization of the semen microbiota of healthy stud dogs using 16S RNA sequencing

The reproductive microbiota of male dogs has never been investigated using culture-independent sequencing techniques. The purpose of the present study was to get seminal knowledge on the microbiota of the ejaculate. Specifically, factors as the fraction of the ejaculate, the sperm quality (normospermia, teratozoospermia), and the living environment were evaluated. The sperm-rich and the prostatic fractions of the ejaculate were collected from healthy stud dogs. Following the sperm analysis, samples from twenty animals (normospermic n = 10 and teratozoospermic n = 10) were stored at - 80 °C until further processing including DNA extraction and 16S rRNA sequencing. Alpha- (Shannon index) and beta- (Bray-Curtis, Unweighted UniFrac) diversities were assessed and compared (PERMANOVA) based on the group of samples (biological samples from the ejaculate and controls), the fraction of the ejaculate (sperm-rich and prostatic fractions), the animal group (normospermia and teratozoospermia), and the living environment of the animal (kennel or pet living in-house). The most abundant bacterial phyla in canine semen samples were Proteobacteria, Firmicutes, and Actinobacteria. Overall, the dominant bacterial family was that of Pasteurellaceae The genus Mycoplasma was never detected. No differences in terms of bacterial composition were found based on the fraction of the ejaculate and based on the animal group (P > 0.05). On the other hand, differences in alpha and beta diversities were highlighted based on the living environment (P = 0.001). Overall, the results of the present study provide preliminary insights on dog semen microbiota, opening a new chapter in the field of canine andrology. Our results suggest that the environment may play a role in influencing the reproductive microbiota of male dogs and that the prostatic fraction of the ejaculate can be used for further research as a representative of the semen microbiota.

Patient weight has diverse effects on the prescribing of different antibiotics to dogs

Introduction

Various factors including body weight-associated treatment cost may influence the probability of dispensing antibiotics to dogs in first-opinion practice, but their effect on specific drug choice remains unclear.

Methods

Multiple membership regression modeling was used to investigate the probability of dispensing 12 different antibiotics to dogs of different weights in the context of various disease presentations, using anonymized data obtained from electronic health records of 18 clinics between 2020 and 2022. Data from 14,259 dogs were analyzed.

Results

Treatment choice varied significantly with animal weight. Higher body weight was associated with an increased likelihood of dispensing lower cost antimicrobials such as amoxicillin and trimethoprim sulfonamide, while use of higher cost antimicrobials such as cefovecin was strongly biased to smaller animals. However, these effects were limited when restricted treatment options were available for the target condition.

Conclusion

This work demonstrates that anticipated financial costs may result in different treatment choices for canine patients depending on their body weight. Further work is needed to understand the impact of financial pressures on veterinarians' treatment choices, and the implications for the optimization of antimicrobial stewardship in first opinion practice.

Cross-sectional evaluation of a large-scale antimicrobial stewardship trial in Australian companion animal practices

BACKGROUND

Antimicrobial stewardship programmes (ASPs) are critically important for improving the appropriate use of antimicrobial agents in veterinary practice.

METHODS

One of three ASPs was implemented in 135 Australian general veterinary practices in 2018-2020. The ASP interventions and the perceived impact they had on antimicrobial prescribing were assessed by the veterinarians working in these veterinary practices. An online survey was distributed to all 520 veterinarians working in the trial practices and 267 responses were analysed.

RESULTS

Most veterinarians (174/267, 65%) thought they had an ASP at their clinic and most respondents who said that they were aware that they had an ASP at their clinic indicated that they had changed the way they prescribed antimicrobials because of the trial (125/170, 74%). Antimicrobial prescribing guidelines, the traffic light system for indicating antimicrobial importance, delayed prescribing and antimicrobial stewardship champions were reported to have had the biggest impact.

LIMITATIONS

All practices in the trial belong to a single corporate group, which may impact the external validity of these results when applied to general small animal practice.

CONCLUSION

Antimicrobial stewardship has a positive impact on antimicrobial prescribing in veterinary medicine and future interventions should focus on the implementation of the effective interventions identified in this study.

Drug prescription pattern in exotic pet and wildlife animal practice: a retrospective study in a Spanish veterinary teaching hospital from 2018 to 2022

Exotic companion animals have had an important role in our society since ancient times. Preserving animal health is necessary to do a responsible use of veterinary medicines. This study aimed to describe the prescription patterns of drugs in exotic pets and wildlife animals attending the Veterinary Teaching Hospital of the University of León (HVULE). A retrospective study was carried out between 2018 and 2022. Birds were the largest group of exotic animals attending the HVULE. Visits were related to emergency reasons and for musculoskeletal disorders. One-third of the animals were eventually euthanised. Regarding pharmacological treatments, the most frequently active ingredients used were pentobarbital, isoflurane, meloxicam, and within antibiotics, marbofloxacin (category B in the classification of European Medicines Agency).

Multidrug-Resistant Escherichia coli Strains to Last Resort Human Antibiotics Isolated from Healthy Companion Animals in Valencia Region

Failure in antibiotic therapies due to the increase in antimicrobial-resistant (AMR) bacteria is one of the main threats to public and animal health. In recent decades, the perception of companion animals has changed, from being considered as a work tool to a household member, creating a family bond and sharing spaces in their daily routine. Hence, the aim of this study is to assess the current epidemiological situation regarding the presence of AMR and multidrug resistance (MDR) in companion animals in the Valencia Region, using the indicator bacteria Escherichia coli as a sentinel. For this purpose, 244 samples of dogs and cats were collected from veterinary centres to assess antimicrobial susceptibility against a panel of 22 antibiotics with public health relevance. A total of 197 E. coli strains were isolated from asymptomatic dogs and cats. The results showed AMR against all the 22 antibiotics studied, including those critically important to human medicine. Moreover, almost 50% of the strains presented MDR. The present study revealed the importance of monitoring AMR and MDR trends in companion animals, as they could pose a risk due to the spread of AMR and its resistance genes to humans, other animals and the environment they cohabit.

Livestock grazing is associated with the gut microbiota and antibiotic resistance genes in sympatric plateau pika (Ochotona curzoniae)

With the overuse of antibiotics in health care and animal husbandry, antibiotic resistance becomes a serious threat to public health. Antibiotic residues from veterinary medicine have increased the dissemination of antibiotic resistance genes (ARGs) by horizontal gene transfer globally, leading to the enrichment of ARGs in wildlife. Plateau pika (Ochotona curzoniae) is a small herbivore endemic to the Qinghai-Tibetan Plateau. Previous studies reveal that pika evolves a coprophagy behavior toward cohabitated yak, which makes the pika population a potential reservoir of ARGs. Yet, little is known about the resistome of pika under different grazing intensities. Here, we sampled the cecum content of pika from three different grazing intensity areas in the Qinghai-Tibetan Plateau to evaluate the effect of grazing on its gut microbiota and resistome. By using the 16S full-length amplicon and metagenomic sequencing, our study revealed that livestock grazing significantly altered the gut microbial community of plateau pika as compared to prohibited grazing areas. We found bacterial lineage Prevotellaceae, Lachnospirales, and RF39 increased in grazing areas. Analysis of the resistome revealed that pika from continuous grazing areas enriched a higher abundance of colistin (MCR) and streptogramin (vat) resistance genes. Moreover, we observed significant correlations between the gut microbial community, ARGs, and mobile genetic element profiles, hinting that pika gut microbiota was an important shaping force of the resistome. In future studies, the continuous monitoring of wildlife gut resistome and environmental antibiotic residues is imperative for a better understanding and for tackling the horizontal gene transfer of ARGs across the wildlife-livestock interface.

Perceptions of antimicrobial stewardship: identifying drivers and barriers across various professions in Canada utilizing a one health approach

Introduction

As antimicrobial resistance (AMR) represents a substantial threat to the efficacy of available antimicrobial options, it is important to understand how to implement effective and practical mitigation efforts, including antimicrobial stewardship (AMS), across human, animal, and environmental sectors.

Methods

A mixed-methods questionnaire was distributed virtually to attendees of the virtual One Health Antimicrobial Stewardship Conference (March 10-12, 2021) and their professional networks. Respondents (n = 81) were largely from the veterinary (75%) or human (19%) health sectors. Qualitative data were analyzed in NVivo using template analysis whereas quantitative data were analyzed in STATA using Kruskall-Wallis tests. The questionnaire asked respondents about their perceptions of AMS, as well as the perceived barriers and drivers of AMS efforts.

Results

Perceptions of what AMS meant to the respondents personally and their profession as a whole were grouped into 3 main themes: 1) AMS strategies or considerations in antimicrobial prescribing and use; 2) responsibility to maintain health and preserve antimicrobial effectiveness; and 3) reducing antimicrobial use (AMU) as a goal of AMS efforts. Identified AMS barriers had 3 main themes: 1) lack of various prescribing and AMU support mechanisms; 2) shift in prescriber attitudes to drive change; and 3) stronger economic considerations to support shifting prescribing practices. Drivers of AMS had the following themes: 1) leadership to guide change; 2) education to support optimizing AMU; and 3) research to identify best practices and opportunities for action. Across all questions, 2 cross-cutting themes emerged: 1) a One Health understanding of AMS; and 2) blame placed on others for a lack of AMS success.

Conclusion

Overall, sector-specific, but particularly cross-sectoral AMS drivers and barriers were identified, highlighting the importance of a One Health approach in AMR research and mitigation.

Exploring antibiotic resistance with chemical tools

Antibiotic resistance is an enormous problem that is accountable for over a million deaths annually, with numbers expected to significantly increase over the coming decades. Although some of the underlying causes leading up to antibiotic resistance are well understood, many of the molecular processes involved remain elusive. To better appreciate at a molecular level how resistance emerges, customized chemical biology tools can offer a solution. This Feature Article attempts to provide an overview of the wide variety of tools that have been developed over the last decade, by highlighting some of the more illustrative examples. These include the use of fluorescent, photoaffinity and activatable antibiotics and bacterial components to start to unravel the molecular mechanisms involved in resistance. The antibiotic crisis is an eminent global threat and requires the continuous development of creative chemical tools to dissect and ultimately counteract resistance.

Occurrence of Multidrug-Resistant Bacteria Resulting from the Selective Pressure of Antibiotics: A Comprehensive Analysis of ESBL K. pneumoniae and MRSP Isolated in a Dog with Rhinorrhea

Because of public health concerns, much greater scrutiny is now placed on antibiotic use in pets, especially for antimicrobial agents that have human analogs. Therefore, this study aimed to characterize the phenotypic and genotypic profiles of multidrug-resistant bacteria isolated from nasal swabs samples taken from a one-year-old male Serra da Estrela dog with rhinorrhea that was treated with amikacin. An extended-spectrum β-lactamases (ESBL) Klebsiella pneumoniae was isolated in the first sample taken from the left nasal cavity of the dog. Seven days later, methicillin-resistant (MRSP) Staphylococcus pseudintermedius was also isolated. Nevertheless, no alterations to the therapeutic protocol were performed. Once the inhibitory action of the antibiotic disappeared, the competitive advantage of the amikacin-resistant MRSP was lost, and only commensal flora was observed on both nasal cavities. The genotypic profile of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae revealed the same characteristics and close relation to other strains, mainly from Estonia, Slovakia and Romania. Regarding MRSP isolates, although resistance to aminoglycosides was present in the first MRSP, the second isolate carried aac(6')-aph(2″), which enhanced its resistance to amikacin. However, the veterinary action was focused on the treatment of the primary agent (ESBL K. pneumoniae), and the antibiotic applied was according to its phenotypic profile, which may have led to the resolution of the infectious process. Therefore, this study highlights the importance of targeted therapy, proper clinical practice and laboratory-hospital communication to safeguard animal, human and environmental health.

Outbreak management of multidrug-resistant Bordetella bronchiseptica in 16 shelter-housed cats

CASE SERIES SUMMARY

This case series describes an outbreak of multidrug-resistant (MDR) Bordetella bronchiseptica in 16 shelter-housed cats with infectious respiratory disease. Four cats presented with acute dyspnea on the same day, each with a history of previous upper respiratory disease that had resolved with treatment. Early diagnostic testing and culture and sensitivity allowed for targeted antimicrobial therapy and environmental interventions. A case definition based on exposure and clinical signs identified 12 additional presumptive cases, including the likely index case. Comprehensive outbreak management included diagnostic testing, risk assessment, vaccination, use of isolation and quarantine, increased surveillance and review of biosecurity practices. The outbreak resolved in 26 days.

RELEVANCE AND NOVEL INFORMATION

Management of an MDR B bronchiseptica outbreak in shelter-housed cats has not been previously described. Along with standard population and environmental measures, early and appropriate use of necropsy, PCR and bacterial culture allowed rapid and appropriate use of effective, second-line antibiotics. Shelters are resource-challenged population centers. Veterinarians working in animal shelters can play an important role in helping to develop cost-efficient and effective antimicrobial stewardship practices for companion animal settings. Outbreak management expertise and funding for diagnostic testing, as well as application of the principles of antimicrobial stewardship, are essential components of shelter medicine practice.

Canine Saliva as a Possible Source of Antimicrobial Resistance Genes

While the One Health issues of intensive animal farming are commonly discussed, keeping companion animals is less associated with the interspecies headway of antimicrobial resistance. With the constant advance in veterinary standards, antibiotics are regularly applied in companion animal medicine. Due to the close coexistence of dogs and humans, dog bites and other casual encounters with dog saliva (e.g., licking the owner) are common. According to our metagenome study, based on 26 new generation sequencing canine saliva datasets from 2020 and 2021 reposited in NCBI SRA by The 10,000 Dog Genome Consortium and the Broad Institute within Darwin’s Ark project, canine saliva is rich in bacteria with predictably transferable antimicrobial resistance genes (ARGs). In the genome of potentially pathogenic Bacteroides, Capnocytophaga, Corynebacterium, Fusobacterium, Pasteurella, Porphyromonas, Staphylococcus and Streptococcus species, which are some of the most relevant bacteria in dog bite infections, ARGs against aminoglycosides, carbapenems, cephalosporins, glycylcyclines, lincosamides, macrolides, oxazolidinone, penams, phenicols, pleuromutilins, streptogramins, sulfonamides and tetracyclines could be identified. Several ARGs, including ones against amoxicillin–clavulanate, the most commonly applied antimicrobial agent for dog bites, were predicted to be potentially transferable based on their association with mobile genetic elements (e.g., plasmids, prophages and integrated mobile genetic elements). According to our findings, canine saliva may be a source of transfer for ARG-rich bacteria that can either colonize the human body or transport ARGs to the host bacteriota, and thus can be considered as a risk in the spread of antimicrobial resistance.

Fijian Veterinarian and Para-Veterinarians' Behavior, Attitude and Knowledge Toward Antimicrobial Use and Antimicrobial Resistance: A Qualitative Study

Antimicrobial resistance (AMR) is a global health issue affecting humans and livestock. Reduction in antimicrobial use (AMU) and appropriate use of antimicrobials in livestock production systems have been encouraged. Lack of access to qualified veterinarians, policies regulating AMU and knowledge of AMU and AMR have been identified as drivers of inappropriate AMU behavior in developing countries. Hence, para-veterinarians take a lead role in providing veterinary services to livestock farmers in developing countries. Our previous work found Fijian farmers lack knowledge and understanding of AMU and AMR. However, the attitude, knowledge, and behavior of Fijian veterinary professionals toward AMU and AMR is currently unknown. Therefore, this qualitative study used face-to-face, semi-structured interviews to explore and understand Fijian veterinarian and para-veterinarians' attitude, knowledge, and behavior toward AMU and AMR. A sample of at least ten participants was targeted and recruited from the Central and Western divisions of Viti Levu, Fiji. The Theory of Planned Behavior (TPB) informed the development of the semi-structured interview guide. The interviews were audio-recorded and analyzed using reflexive thematic analysis and deductively using the TPB framework. Our analysis generated three key themes: 1) Antimicrobials prescribed and used based on availability and cost rather than clinical need, 2) Para-veterinarians awareness and knowledge of AMR influence treatment decisions, and 3) Limited resources impede effective consultation and veterinary service delivery. This study demonstrated para-veterinarians (not veterinarians) lacked knowledge and understanding of AMU and AMR. The availability and cost of antimicrobials rather than clinical justification drove antimicrobial prescribing amongst the para-veterinarians. Veterinarians did not visit farms to provide veterinary services; therefore, para-veterinarians provided the veterinary services to the livestock farmers. Lack of human resources, antimicrobials, and physical resources incapacitated veterinary service delivery, where services to farmers' were delayed or not provided at all. Terms of reference for veterinary service delivery and para-veterinarian training framework targeting prescribing, dispensing, use of antimicrobials and risks associated with inappropriate AMU are recommended as part of antimicrobial stewardship (AMS) programmes. Allocation of physical and human resources to Fijian veterinary services should be considered part of AMS programmes to improve veterinary service delivery to livestock farmers and optimize the AMU at the country level.

Implications of Veterinary Medicine in the comprehension and stewardship of antimicrobial resistance phenomenon. From the origin till nowadays

•

Antibiotic resistance is a well-known phenomenon with several implications

•

The contribution of Veterinary Medicine is underestimated.

•

It was believed that only livestock was responsible for antibiotic resistance.

•

Companion animals, wild animals and environment are more involved than estimated.

•

Educational tools for public and more veterinary specialists are needed.

Antimicrobial resistance (AMR) is defined by the entire scientific community as the major threat for human health and it is responsible for an increase in morbidity and mortality rates. The reasons behind this phenomenon are complex and the solution is achievable only considering the One Health approach, that encompasses the integration and implementation of human health, veterinary medicine and environmental status. Authors aimed to write this review to summarize to readers the three milestones of One-Health, underlying the most important topics in which veterinary medicine is mostly involved. Therefore, a short introduction about the history of AMR in veterinary medicine is provided, then more detailed aspects about the impact of AMR related to pets, food producing animals, wild animals and environment are discussed. Finally, some critical aspects about current and future issues are considered.

Comparison of Short- versus Long-Course Antimicrobial Therapy of Uncomplicated Bacterial Pneumonia in Dogs: A Double-Blinded, Placebo-Controlled Pilot Study

Simple Summary

Dogs diagnosed with bacterial pneumonia are often treated with long courses of antibiotics (3–6 weeks) and chest X-rays are used to help guide the duration of treatment. This is in stark contrast with humans with the same disease who are often treated for 5–10 days, and chest X-rays are not considered to be useful for monitoring response to treatment. The main goal of this study was to determine whether a shorter course of antibiotics (10 days) would be sufficient to treat dogs with bacterial pneumonia. Eight dogs with pneumonia were randomly assigned to receive 10 or 21 days of antibiotics. They were evaluated at 10, 30 and 60 days after diagnosis. At 10 days, 6/8 dogs had resolution of both clinical signs and evidence of inflammation on bloodwork and 5/8 dogs showed improvement in the chest X-rays. After 60 days, none of the dogs had clinical signs or evidence of inflammation on bloodwork regardless of antibiotic therapy duration. However, 3/8 dogs showed changes in the chest X-rays. This study suggests that a 10-day course of antibiotics may be sufficient to treat dogs with bacterial pneumonia, and chest X-rays may not be a reliable marker to monitor response to therapy.

Abstract

Current treatment for canine bacterial pneumonia relies on protracted courses of antimicrobials (3–6 weeks or more) with recommendations to continue for 1–2 weeks past resolution of all clinical and thoracic radiographic abnormalities. However, in humans, bacterial pneumonia is often treated with 5–10-day courses of antimicrobials, and thoracic radiographs are not considered useful to guide therapeutic duration. The primary study objective was to determine whether a short course of antimicrobials would be sufficient to treat canine bacterial pneumonia. Eight dogs with uncomplicated bacterial pneumonia were enrolled in this randomized, double-blinded, placebo-controlled study comparing clinical and radiographic resolution with differing durations of antimicrobial therapy. Dogs received a course of antimicrobials lasting 10 (A10) or 21 (A21) days. Dogs randomized to the A10 group received placebo for 11 days following antimicrobial therapy. Patients were evaluated at presentation and 10, 30 and 60 days after the initiation of antimicrobials. At 10 days, 6/8 dogs had resolution of both clinical signs and inflammatory leukogram, and 5/8 dogs had improved global radiographic scores. After 60 days, clinical and hematologic resolution of pneumonia was noted in all dogs regardless of antimicrobial therapy duration; however, 3/8 dogs had persistent radiographic lesions. Thoracic radiographs do not appear to be a reliable marker to guide antimicrobial therapy in canine bacterial pneumonia as radiographic lesions may lag or persist despite clinical cure. This pilot study suggests a 10-day course of antimicrobials may be sufficient to treat uncomplicated canine bacterial pneumonia.