While antibiotics are essential medicines for treating bacterial infections, it is important to remember that their use leads to selection of resistant strains of bacteria. Resistance may be intrinsic (chromosomal DNA changes) or acquired (by plasmid transfer).

It is important that the veterinary profession uses antibiotics responsibly in order to:

• Minimize the selection of resistant veterinary pathogens (and therefore safeguard animal health)
• Minimize possible resistance transfer to human pathogens
• Retain the right to prescribe certain antibiotics.

Following these guidelines will help to maximize therapeutic success of antibacterial agents while at the same time minimizing the development of antibiotic resistance, thereby safeguarding antimicrobials for future veterinary and human use. These guidelines should be read in conjunction with the individual drug monographs, updated BSAVA Guide to the Use of Veterinary Medicines and the PROTECT ME guidance. 

Following the PROTECT ME guidance can help reduce resistance:

Prescribe only when necessary

Consider non-bacterial disease (e.g. viral infection), nutritional imbalance or metabolic disorders where antibiotic therapy would be redundant. Remember also that some bacterial disease will self-resolve without antibiotics. Offer a non-prescription form to support a decision not to prescribe antibiotic therapy.

Reduce prophylaxis

Antibiotics are not a substitute for surgical asepsis and the need for prophylactic antibiotics in surgery should be carefully considered. Prophylactic antibiotics are only appropriate in a few medical cases (e.g. immunocompromised patients).

Offer other options

Consider therapeutic alternatives (e.g. lavage and debridement of infected material, analgesia, cough suppressants, fluid therapy or nutritional modification). Use topical preparations as these reduce the selection pressure on resident intestinal flora (the microbiome). Use effective hygiene techniques and antiseptics to prevent infections.

Treat effectively

Before prescribing antibiotics, consider which bacteria are likely to be involved and how effectively the chosen drug will penetrate the target site. Use the shortest effective course and avoid underdosing. Ensure compliance with appropriate formulation and clear instructions.

Employ narrow spectrum

Unnecessarily broad-spectrum antibiotics could promote antibiotic resistance; selecting narrow-spectrum antibiotics limits the effects on commensal bacteria. Use culture results to support de-escalation (switching to a narrower spectrum antibiotic) whenever possible.

Culture appropriately

A sample for culture should be collected before starting antibiotic therapy. Culture is essential when prolonged (>1 week) treatment courses are anticipated, when resistance is likely (e.g. hospital-acquired infections) and with life-threatening infections. If first-line treatment fails, do not use another antibiotic without culture and susceptibility results (avoid cycling antibiotics).

Tailor practice policy to patients

A customized practice policy can guide antibiotic selection to address the bacterial infections and resistance patterns that you encounter, minimizing inappropriate use. 

Monitor culture results

Track and record culture profiles and update your practice policy accordingly. Monitor for preventable infections (e.g. postoperative) and alter practices if needed. Audit your own antibiotic use, particularly of critically important antibiotics (e.g. fluoroquinolones and cefovecin).

Educate others

Share this important message to reduce the threat from multi-resistant strains of bacteria and improve the health of pets and people.

European Medicines Agency categorization of antibiotics

In 2019, the EMA launched a public consultation on its updated scientific advice on the categorization of antibiotics. The scientific advice ranks antibiotics by considering both the risk that their use in animals causes to public health through the possible development of antimicrobial resistance and the need to use them in veterinary medicine. It now addresses all classes of antibiotics, including those classified as critically important antimicrobials for human health by the World Health Organization (see Appendix of Useful Websites).  Readers are encouraged to check and consider the EMA’s updated scientific advice on the categorization of antibiotics when prescribing these medicines for animals in their care. The categorization can also be used as a tool for the preparation of treatment guidelines (Appendix of Useful Websites). The classification comprises four categories:

• Category A (Avoid) includes antibiotics that are currently not authorized in veterinary medicine in the European Union (EU). These medicines may not be used in food-producing animals and may be given to individual companion animals only under exceptional circumstances
• Category B (Restrict) refers to quinolones, 3rd- and 4th-generation cephalosporins and polymyxins. Antibiotics in this category are critically important in human medicine and their use in animals should be restricted to mitigate the risk to public health
• Category C (Caution) covers antibiotics for which alternatives in human medicine generally exist in the EU, but only few alternatives are available in certain veterinary indications. These antibiotics should only be used when there are no antibiotic substances in Category D that would be clinically effective
• Category D (Prudence) includes antibiotics that should be used as first line treatments, whenever possible. These antibiotics can be used in animals in a prudent manner. This means that unnecessary use and long treatment periods should be avoided, and group treatment should be restricted to situations where individual treatment is not feasible.

Antibiotics in small mammals

Antibiotic therapy in several small mammal species poses a greater risk when compared with other species due to the suppression of normal bacterial flora, resulting in overgrowth of other species, notably Clostridium, resulting in enterotoxaemia and death. Mice, rats, ferrets and usually gerbils are fairly resistant, whereas hamsters, guinea pigs, chinchillas, degus and rabbits are more susceptible. The risk of enterotoxaemia is related to several factors, including the drug selected, the dose, the route of administration and the animal’s nutritional status  and general health. Antibiotics that have been associated with this problem when given orally include penicillins, lincosamides, cephalosporins and erythromycin. Some species appear more sensitive to certain drugs than others, while some medications appear welltolerated by alternative routes (e.g., injectable benzylpenicillin in rabbits). See individual monographs for more details.

References

Allerton F and Nuttall T (2021) Antimicrobial use: importance of bacterial culture and susceptibility testing. In Practice43, 500–510

Sykes J and Greene J (2011) Infectious Diseases of the Dog and Cat, 4th edn. Saunders, Philadelphia