Cephalexin (Keflex)
A first-generation bactericidal cephalosporin antibiotic that inhibits bacterial cell wall synthesis, premier for canine bacterial pyoderma.
💬 In Plain English
Cephalexin (known commonly by the human brand Keflex) is one of the most widely prescribed antibiotics in veterinary medicine, particularly for dogs with bacterial skin infections (superficial pyoderma, "hot spots," or allergic skin sores). It belongs to the first-generation cephalosporin antibiotic family and kills bacteria by preventing them from building their protective cell walls. Because common canine skin bacteria (Staphylococcus pseudintermedius) produce penicillin-destroying enzymes, cephalexin’s resistance to these enzymes makes it the premier, dependable workhorse for dog skin.
🔬 Clinical & Technical Depth
For Vets & TechniciansFormal Clinical Definition
First-generation semi-synthetic beta-lactam cephalosporin antibiotic that binds penicillin-binding proteins (PBPs), disrupting peptidoglycan cell wall transpeptidation in dividing bacteria.
Why Veterinarians Use It
Veterinarians use cephalexin as empirical first-line oral antibiotic therapy for canine superficial bacterial folliculitis and uncomplicated skin and soft tissue wounds.
Clinical Context Encountered
Prescribed as oral capsules, tablets, or flavored suspensions given twice daily with food.
Clinical Reference Guide (Veterinary Medication)
What Owners Must Know
- Administer with food to reduce nausea and vomiting
- Continue treatment for at least 7 to 14 days past clinical resolution of all skin lesions
- Do not skip doses.
Potential Side Effects
- Vomiting and diarrhea (most common)
- Decreased appetite
- Allergic hypersensitivity rash (rare)
- •Always finish the entire course of cephalexin even if your pet’s skin looks completely healed: stopping early breeds resistant Staph strains (MRSP).
❓ Questions to Ask Your Veterinarian
Take these actionable questions with you to your next clinic visit or appointment:
- 1Should I give cephalexin with a meal or treat to prevent mild stomach upset?
- 2Why is it necessary to continue giving pills for 7 to 14 days past the complete visual disappearance of skin sores?
- 3Was a skin cytology performed to confirm bacteria rather than yeast (Malassezia)?
Academic & Clinical References
- World Association for Veterinary Dermatology: Guidelines for the Diagnosis and Antimicrobial Therapy of Canine Superficial Bacterial FolliculitisOrganization: World Association for Veterinary Dermatology (WAVD) • Accessed: 2026-01-10https://www.wavd.org