An Introduction to Veterinary Antibiotics

Bacterial infections require veterinary antibiotics to kill the infection. It's important to know the side effects and contraindications of the different antibiotics.


Amforal is an oral medication while Kantrim is given in a shot. It is used most frequently to treat severe diarrhea. Side effects include pain at the injection site and darkened feces.


Amikacin are dog antibiotics that are only used when others fail to work. Because amikacin causes kidney damage, hearing loss or balance disorders, pet owners should only use this as a last resort.


Most veterinarians use aminopenicillin, commonly called amoxicillin, veterinary antibiotics. The most common side effects in dogs and cats include:

  • Diarrhea
  • Excessive drool
  • Loss of appetite


Animax kills yeast infections of the ear, skin, paws or anal glands. Common side effects of these veterinary drugs are excessive thirst and urination.


Azithromycin is used to treat a wide variety of bacterial infections. The veterinary antibiotics' side effects include diarrhea and vomiting. In some animals, liver damage occurs.


Dog antibiotics known as cephalosporins work effectively on many bacterial infections and have few side effects. Nausea is the only thing pet owners should watch for.


Quinolone animal antibiotics like ciprofloxacin or enrofloxacin should never be used on puppies. They impact the development of bones and joint tissue. Side effects in adult animals include lack of appetite, nausea and vomiting. Enrofloxacin can cause blindness in cats.


The veterinary drugs clindamycin treat oral infections like an abscessed tooth. They can affect the kidneys and liver.


Doxycycline is a tetracycline used to treat bacterial infections and tick-borne illnesses like Lyme disease. Pregnant dogs should not be given the medication because the animal antibiotics slow bone growth. Side effects include;

  • Diarrhea
  • Loss of appetite
  • Rashes
  • Vomiting


Used for intestinal, prostate and skin infections, erythromycin is used in dogs and cats. The three side effects to watch for are:

  • Diarrhea
  • Loss of appetite
  • Vomiting


Gentamicin is given through an injection and is generally only used in a veterinary hospital or clinic. It can cause kidney damage and hearing loss. For this reason, it's often best to avoid this medication unless absolutely necessary.


Novobiocin includes a steroid making it a popular choice for bacterial infections of the skin. Pregnant animals, diabetic animals and animals with ulcers should not use this animal antibiotic. Side effects include:

  • Blood disorders
  • Diarrhea
  • Fever
  • Lack of appetite
  • Rashes

Penicillin Family

Penicillin veterinary antibiotics treat a number of hard to kill bacterial infections. Many pets are allergic to penicillin, so use care when using these veterinary drugs. It is important to give penicillin antibiotics an hour before or two hours after a pet's meal. Watch for:

  • Diarrhea
  • Excessive salivation
  • Loss of appetite
  • Vomiting

Sulfa Drugs

Sulfa antibiotics treat coccidial bacterial infections. It's important that your pet drinks lots of water because sulfa drugs build up in the urine causing crystals.


One of the safest antibiotics because there are very few side effects, Tylosin is mixed into a pet's water. The only side effect pet owners notice is slight diarrhea after the first dose.