On the contrary, you should always feed Nature's Farmacy DOGZYMES
Digestive Enhancer, Liquid Dispersible Digestive Enhancer or Canine
Paste to any dog taking antibiotics. Antibiotics do not discriminate
between harmful and beneficial bacteria and will often kill off all or
most of your dog's gut flora as it treats the ailment it was prescribed
for. Supplementing beneficial bacteria during antibiotic treatment can
often help to alleviate many digestive side effects.