Side Effects of Cephalexin in Dogs

By Jane Meggitt

While cephalexin, marketed under the brand name Keflex, isn't approved for use in dogs by the U.S. Food and Drug Administration, veterinarians can prescribe it under the FDA's "off-label" provision. Your vet might use this antibiotic to treat a variety of bacterial infections, including those found in the skin, bladder and bone, along with pneumonia. While cephalexin usually is safe, side effects are always a possibility. Call your vet immediately if your dog exhibits any side effects while on cephalexin.

Side Effects and Contraindications

While most dogs tolerate cephalexin without incident, some experience side effects from the medication. Most of these side effects are gastrointestinal in nature, consisting of nausea, vomiting or diarrhea. Dogs also might exhibit hypersalivation, or excessive drooling, along with excitability. Pregnant or lactating dogs shouldn't receive this drug. Dogs diagnosed with kidney failure or epilepsy should not receive cephalexin, nor should dogs allergic to penicillin. If your dog suffers from diabetes, cephalexin can cause false positives when testing for urinary sugar levels.