Vitamin K synthesis impaired by antibiotic use

In all species bacterial flora in the intestine synthesize Vitamin K -  which is essential for normal blood clotting. All orally administered antibiotic agents are reported to reduce the numbers of  gut flora and so reduce the amount of Vitamin K produced. The following antibiotics in particular may depress blood concentrations of Vitamin K if they are given orally in high doses or for prolonged periods :

• Chloramphenicol
• Kanamycin
• Neomycin
• Penicillin
• Streptomycin
• Tetracyclines

As a result caution is needed if you are contemplating the concurrent use of anticoagulants with these antibiotics.

Antibiotic-related Vitamin K deficiency is rarely recognized in dogs and cats. If you have experienced clotting defects in a cat or dog that has been treated with one of these antibiotics Provet would like to hear from you at feedback@provet.co.uk 

Updated October 2013