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Antibiotics in Dogs

Learn about antibiotic use in dogs.

Antibiotic use is necessary for treating some bacterial infections in dogs. There are things you should know about antibiotics, when they're used, and how you should use them.

What Are Antibiotics?

Antibiotics are medications used to stop bacterial infections. They do not work against viruses, fungi, or any other type of organism.

Each antibiotic only works against certain types of bacteria because of their mechanisms of action. Some are considered broad-spectrum because they kill many or even most types of bacteria. Others are more specialized.

How Are Antibiotics Chosen?

When a veterinarian prescribes an antibiotic to your dog, they generally choose a type known to work on most infections like the one they've diagnosed. Those antibiotics are often broad-spectrum, which means they work against a large majority of common bacteria.

However, the best way to choose an antibiotic is to do a culture and sensitivity test on the infection. A sample of debris produced by or tissue affected by the infection is grown in a Petri dish. The bacteria are identified under a microscope, and then the colony is treated with various antibiotics to see which ones kill it.

A bacterial culture and sensitivity test takes time, so depending on the severity of the infection, a broad-spectrum antibiotic may be started in the meantime. However, it's best if the sample is taken before the start of any antibiotics, which could interfere with the results.

Combatting Antibiotic Resistance

Over time, bacteria can develop resistance to certain antibiotics. That means the organisms evolve and adapt mechanisms of surviving through treatment with that medication. The result is that infections can continue and be difficult or impossible to treat. That can be life-threatening at times.

Here are some ways to combat antibiotic resistance, which is rapidly becoming a serious concern:

  • Non-bacterial infections should not be treated with antibiotics. Doing so allows some bacteria that may be in the dog's system but not causing an all-out infection to develop resistance.
  • When your dog is on antibiotics, the entire prescription should be given, even if the dog seems better before it's done. When antibiotics are stopped too soon, bacteria that have not yet been killed by the drug have the opportunity to survive and develop resistance to that medication. The infection can return (though the amount of time it takes may make it seem like a new infection) but be resistant and more difficult to cure.
  • If you think your dog is having a negative reaction to antibiotics, don't simply stop giving them. It's best to call the prescribing veterinarian, tell them what is going on, and follow their advice.

Side Effects of Antibiotics in Dogs

Most of the time, dogs do fine on antibiotics without experiencing side effects. However, some potential issues can occur.

The most common side effect of antibiotics in dogs is vomiting. Many times, giving the medication with food can combat that, but you should check with your vet if your dog vomits while on antibiotics.

A dog can have an antibiotic allergy, and that can cause anything from a mild reaction of vomiting or hives to a major one involving collapse and shock. Still, severe reactions to antibiotics are rare in dogs.

Some antibiotics have specific potential side effects, so check with your veterinarian about any you should be aware of for the medication your dog has been prescribed.

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