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6. Improving antimicrobial use

companion09.jpgDon says, Since antimicrobial use is strongly associated with the occurrence of antimicrobial resistance that may pose a risk to human health, some individuals and groups argue that antimicrobial use in animals should be limited or discontinued.

Sue says, Antimicrobial use in animals is extremely important to animal health and welfare. These are life-saving drugs and as veterinarians, we need to advocate for the welfare of animals. However, we also need to be cognizant of our role in public health. Antimicrobial use needs to be appropriate and prudent.  Prudent use involves important factors such as when to use antimicrobials, length of therapy and antimicrobial selection. Several veterinary professional organizations have published guidelines on the prudent use of antimicrobials (15-19).

Recently, a study looked at antimicrobial use by veterinarians and observed some areas where antimicrobial use could be improved. These include eliminating the common use of antimicrobials in elective, uncomplicated sterilization surgeries (i.e. ovariohysterectomy, castration) and reducing antimicrobial use in other clean surgical procedures. Antimicrobial use could likely be reduced for diseases such as feline lower urinary tract disease, feline upper respiratory tract disease and canine infectious tracheobronchitis (2). In one population of cats, antimicrobial use could possibly be reduced by up to 25% if the common use of antimicrobials to treat feline upper respiratory tract disease and feline lower urinary tract disease was discontinued (2).

Using antimicrobials only when appropriate is important, as is antimicrobial selection and application. There is some evidence to suggest that fluoroquinolones and cefovecin may be over used, particularly in cats (2) (Table 1) - and veterinarians need to ensure that the dosing of antimicrobials is appropriate. Dosing antimicrobials below the recommended dose could lead to treatment failure, thereby possibly requiring the use of additional antimicrobials. This may provide additional selection pressure for the occurrence of antimicrobial resistance. As well, dosing antimicrobials above the recommended dose ranges could lead to adverse events like toxicity.

Appropriate use of antimicrobials requires knowledge of many factors. Veterinarians synthesize this information with other clinical and diagnostic data to make the best choice for a positive clinical outcome.




Table 5 The frequency of antimicrobial use in specific conditions.


Frequency of diagnosis in outpatients (if applicable)

Percentage of cases where antimicrobials are used

Percentage of overall non-topical (oral or parenteral) antimicrobial use in outpatients (if applicable)

Most frequently prescribed antimicrobials

Feline upper respiratory tract disease

 6% of all disease conditions diagnosed in cats



Amoxicillin-clavulanic acid, doxycycline and fluoroquinolones

Feline lower urinary tract disease

6% of all disease conditions diagnosed in cats



Amoxicillin-clavulanic acid and fluoroquinolones

Canine infectious tracheobronchitis

2% of all disease conditions in dogs



Amoxicillin, amoxicillin-clavulanic acid and chloramphenicol

Elective, uncomplicated sterilization surgeries




Procaine penicillin, benzathine penicillin

Other clean surgical procedures




Cephalosporins, ampicillin, procaine penicillin

Source: Murphy, 2010



Table 6 The dosing of antimicrobials by small animal veterinarians when compared to a readily available pocket-type formulary designed as a practical aid to veterinarians (20).


Percentage dosed below referenced range

Percentage dosed above reference range

Overall percentage dosed outside of referenced range












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