A“Antibiotic” literally means “against life”. That’s great if the life in question is a nasty bacterium. It’s not so good if the life is that of your animal companion. Properly used, antibiotics are usually safe and can help overcome serious, even lifethreatening infections. All too often, though, these drugs are used incorrectly, resulting in extra expense and potential harm to the animal (by destroying helpful bacteria). They can also cause side effects such as vomiting, diarrhea and allergic reactions. The most common side effects I see from the long-term use of antibiotics are a lack of improvement in the animal, as well as secondary yeast infections. I frequently see animals, usually with chronic skin diseases, that have been on antibiotics for months to years, even though many of them do not even have a diagnosed disease!

Worst of all, the overuse of antibiotics can encourage the development of antibiotic-resistant bacteria. A study1 done at the Cold River Veterinary Center in North Clarendon, Vermont showed that out of six ear swabs taken from patients, all had bacteria resistant to one or more antibiotics. Meanwhile, 78 percent of urine cultures also had antibiotic-resistant bacteria.

Why antibiotics don’t always work
There are several reasons why animals may not get better while
taking antibiotics:

Incorrect diagnosis: Only bacterial infections respond to antibiotics, so it’s important to determine that the disease is actually caused by bacteria before using them. For example, most doctors use antibiotics to treat cats with lower urinary tract disease, even thought most cats do not have bacterial infections of the bladder. The cats improve, leading everyone to believe the antibiotic cured them, when that is not the case.

Underlying medical problems: Animals with allergies and thyroid disease often have chronic bacterial skin infections. Until the underlying problem is diagnosed and treated, the skin will continue to get infected and the animal will require ever-longer doses of antibiotics.

Wrong antibiotic: No antibiotic works all the time. If the prescribed antibiotic does not work, the diagnosis needs to be reassessed, or a different antibiotic may be needed.

Wrong dose: Even the right antibiotic won’t work if it is not dosed correctly.

Wrong length of treatment: Antibiotic therapy can’t be stopped just because the animal seems better. Doing so will often caused a relapse from bacteria that weren’t killed but just dormant. I often see this in animals being treated for skin infections. Antibiotics for skin infections require a minimum treatment time of three to four weeks. However, many doctors reduce this to two weeks in an attempt to reduce costs (antibiotics for a large dog could easily run $50 to $100 or more for three to four weeks of treatment). Unfortunately, the dog relapses after temporarily improving and requires a second round of antibiotics, which ultimately costs more than if the dog had been treated properly in the first place.

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