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Choosing the Right Antibiotic

By March 6, 2022March 3rd, 2023No Comments

This week’s blog post is going to be a doozy. What is the DEAL with antibiotics?! You just pick one and it works, right? WRONG! I have recently had several clients give antibiotics to their animals before bringing them to a vet for help. I understand that trying to fix a problem on your own without the vet’s help is appealing. It saves you time and money, not to mention it saves you the stress of having to bring your animal to the vet. However, I want to talk about some of the reasons why this is not a good idea.

1. Choosing the right antibiotic (how do you know?)

How do you know which antibiotic to choose? There are only a few options available over-the-counter to consumers, and that is by design. Choosing the wrong antibiotic has some unwanted side-effects, which I will cover later. However, choosing the wrong antibiotic also means that it just won’t work.

Let’s cover some basics.

Antibiotics are medications that kill or slow down the growth of bacteria. Antibiotics DO NOT affect viruses. This is why it is important to visit a veterinarian to determine whether a virus or bacterial infection is the culprit of your pet’s illness.

Antibiotics work by a variety of different methods depending on the class of drug. Some inhibit cell wall synthesis of bacteria. Some inhibit protein synthesis of the bacteria. Some alter bacterial cell membranes. Some inhibit the synthesis of nucleic acid. This means that different kinds of bacteria are susceptible to different antibiotics.

Also, antibiotics penetrate tissues differently. For example, some antibiotics are primarily excreted by the liver. Therefore, these antibiotics will not build up very high levels in the bladder. This antibiotic would be a very poor choice for a urinary tract infection.

To choose the correct antibiotic for your animal’s illness requires knowledge of the type of organism causing the illness, the mechanism of action of the antibiotic and the location where the antibiotic works best.

2. Making the problem worse or unwanted side effects

Antibiotics are not necessarily a benign medication. They have side effects. Some of the more common side effects of antibiotics include vomiting and diarrhea. However, some antibiotics can cause damage to the kidneys. Some antibiotics, if they get into a vein, can even cause death of the animal. Antibiotics have a variety of administration methods and giving one incorrectly can be bad!

If you give your animal medication that is not intended for animals (like the rest of your prescription) you can cause them to become ill or even die.

3. Resistant bacteria

Resistant bacteria are a common theme in today’s news. In fact, governmental agencies are cracking down on antibiotic use in order to curb the threat of bacterial strains that are resistant to multiple antibiotics. These types of bacteria pose a threat to human and animal health, in that there are few drugs to treat them. Treating your animals without veterinary oversight is a leading cause of resistant bacteria. Improper dosing (wrong dose, wrong drug, wrong weight etc) can lead to resistant bacteria that might infect you, the owner, too!

4. Dosing

Choosing the proper dose of antibiotic for your pet is not a simple process. Many medications have multiple doses. Each dose may have an individual disease that it is effective for.

Dosing requires having an accurate weight on your patient. What about large animal patients?! Veterinarians are trained to be able to estimate weights as well as use tools such as weight tapes to get a more accurate idea of patient weight.

Finally, the dose on the bottle is not always the correct one. For example, the dose on a bottle of penicillin is 1 mL per 100 pounds. This dose is not helpful for treating most diseases, it is way too low!

You may ask why an incorrect dose is listed on the label of a medication. This is because companies spend a lot of money to label drugs. Penicillin was labelled a very long time ago. We now know that the proper dose of penicillin is much higher than that on the label. However, drug companies are not interested in doing the research (ie; spend millions of dollars) to generate the necessary data to determine efficacy at this dose. Particularly since the drug is already available and used regularly. Your veterinarian knows the proper dose of penicillin and can use it to treat your animals appropriately, if needed.

5. Increase cost to you

The final reason that treating your animals before having to visit a vet is that there is often a higher cost associated with doing this. If you treat your animal for 5 days with antibiotics that you got over the counter and it didn’t work, now you have to visit the vet anyway. Not only does this add to the cost of treating your pet, often, the infection or disease has progressed further than it would have if the appropriate antibiotic had been used in the first place. This means that your animal will need more medications to get the infection under control. Additionally, if your animal’s infection has become resistant to the medication you were giving, now the veterinarian must choose a different, probably more expensive medication to treat the disease.

The main point of this long blog post is that your veterinarian has the education and training to be able to pick the correct antibiotic for the disease presented. Your veterinarian knows the correct doses to treat your animal, for the correct route of administration and for the correct amount of time. It is a lot of information! Why do you think veterinarians have 8 years of post-graduate schooling!

As always, if you have a question about a specific condition your animal is experiencing, contact your regular veterinarian.

Emily Dutton