Written by Anna Hollisey
Antibiotics are prescribed for bacterial infections in dogs, including skin infections, ear infections, and urinary tract infections (UTIs).
You may have heard that the power of antibiotics is waning. That’s true for dogs as well as humans*. Bacteria have evolved to resist our antibiotics, so veterinarians are prescribing with caution.
Antibiotics work by killing or preventing the growth of bacteria, although they don’t all do it in exactly the same way; for example, penicillin attacks bacterial cell walls. The first dose will affect the weakest bacteria, but many will survive until the final dose – which is why each course of treatment is carefully measured.
If you don’t complete the course of antibiotics, the strongest bacteria remain inside your dog’s body, which increases resistance to the medication, so the bacteria can be harder to eliminate next time. This is why your dog (and you) must always finish the prescribed course even if you’ve seen an improvement in the original symptoms.
Although some of these antibiotics are also used by humans, dogs shouldn’t be given human antibiotics. They are typically at a different dosage and can also contain unwanted ingredients – some of which, like xylitol, are toxic to dogs. Misuse of antibiotics has also contributed to the surge in antibiotic resistance.
So always use an antibiotic which is licensed for domestic animals and supplied by your vet.
These are the most common antibiotics prescribed for dogs:
Antibiotics are suitable for a wide range of bacterial infections, including:
They may also be given after surgery to prevent infection of a wound.
The most common side effects of antibiotics are vomiting and diarrhea. This is because antibiotics affect the balance inside your dog’s gut. This disruption can cause irritation, which might make your dog need to defecate more often, with loose stools. Sometimes they appear to be constipated or lose their appetites. On the other hand, some dogs get extra-hungry while they’re on antibiotics! These side effects typically last for around 24 hours after the first treatment.
If your dog is suffering from diarrhea after taking antibiotics, offer them some bland food which is gentle on their digestive system. Plain cooked chicken and rice is a popular option. You could also make them some homemade broth. Supporting their gut with a probiotic supplement is also a great idea.
Dogs can, in rare cases, be allergic to antibiotics (especially Amoxycillin or Penicillin). These allergic reactions might include hives or facial swelling, labored breathing, and seizures – seek urgent veterinary help if your dog develops any symptoms.
Most antibiotics are only available with a veterinary prescription. However, you can buy topical antibiotics at a pharmacy counter – the kinds which are used to treat skin infections or wounds.
One of the most commonly prescribed antibiotics for dogs is one that you’re probably familiar with – Amoxycillin. It’s readily available, it’s affordable, and it’s broad-spectrum, which means it is suitable for a wide range of different infections.
If your dog has a urinary tract infection (with symptoms such as drinking more water than usual, urinating in the house or more often than usual, discomfort, or blood in their urine), you should consult your vet for testing. They will recommend the best antibiotic for your dog; common options for UTIs are Amoxycillin or a fluoroquinolone such as Marboflaxacin (see the list above).
*Did you know? In one study in 2022, the authors noted (with surprise) that their tests showed that antibiotic resistance is not transmitted from humans to dogs or vice versa. Learn why some dogs suffer from recurrent ear infections. You can also find out more about periodontal disease, kennel cough, or Lyme’s Disease.