What Causes Bladder Infections in Dogs?

by Dr. Greg Magnusson, DVM

This question comes up pretty much EVERY time a dog comes in with a bladder infection, and I totally understand why. Humans like to know cause-and-effect for things. Like, I ate a yucky dinner, so now I have a tummy ache.

I think this need to know primarily stems from an owner’s desire to take good care of their animals. Which means, then, that the corollary to the question is “am I a good dog mommy?"

"Did I do something to cause this?"

So first, let me answer the question you DIDN’T ask – no, you did nothing to cause your dog’s bladder infection. You’re a fine dog mommy. Thank you for bringing her in so we could treat the infection!

That aside, if we shall delve into this further… let me now warn you that the answer to this question may get a bit yucky. 

Maybe even a lot yucky. Like, you probably don’t really want to know and should consider not reading further. If part “A” above was all you really needed to hear, you’re fine. You don’t have to be an expert in everything dog, that’s what we’re here for.

On the other hand, if you’re brave and bold and curious, let’s move on…

Female dogs get bladder infections because of a particular design quirk, that of a short urethra positioned right downward of the anus.

First, a lesson about poop. 

Poop is primarily made up of bacteria, solid undigestible components of food, and metabolic waste products from bile. But mostly poop is made of bacteria.

Imagine, if you will, poop falling out of your dog's butt. 

That’s like one big solid ball of E. coli falling, and guess where it passes by before it hits the ground? The urethra.

Yes, it’s true, she “wipes” afterward with her tongue, but do you REALLY think that’s clean? This is the same tongue that licks her feet after she walks outside, and she doesn’t brush her teeth between butt wipings, so expect that her mouth is full of bacteria too.

Remember, I warned you not to read this.

Compound this problem if she has diarrhea. Not only is it harder for her to clean up, but some might get on the tail, which then falls in front of the urethra…

So essentially, by attempting to clean herself free of poop, she wipes E. coli from the poop and Staph from her skin all over herself. It’s really no wonder some of that bacteria gets into the urethra once in a while...

…causing a bladder infection.

Oh wait, you have a MALE dog? Yes, they get bladder infections too, but MUCH less often because the prepuce is nowhere near the anus, and because the urethra is WAY longer from the tip of the prepuce all the way up into the bladder, making it harder for bacteria to “climb” into the bladder.

Now you know!

SPECIAL NOTE: Remember how I said bladder infections are primarily caused either by E. coli or Staph? That’s a GROSS oversimplification, there are TONS of different kinds of bacteria in poop and on the skin. Each bacteria responds best to a different antibiotic. This is why your friendly neighborhood veterinarian needs to obtain a urine sample using a STERILE NEEDLE AND SYRINGE and send some of that pee to the lab so they can culture it and identify which nasty bacteria we’re dealing with. Yes, it’s expensive for you  – lab fees are pricey!! But, you know… valuable, and essentially the most efficient way to get the CORRECT answer and FASTEST treatment possible, rather than me just guessing what kind of bacteria it is and choosing an antibiotic off the shelf.

Reprinted with permission from Leo's Pet Care, 10598 N College Ave # 200, Indianapolis, IN 46280 | www.leospetcare.com | indianapolisvet@gmail.com

Articles by Dr. Magnusson:
What's In The Blood? Blood Testing And Interpretation  
Everything You Never Wanted To Know About Anal Glands

Related articles:
The Always-At-Hand Diagnostic Tool: Whoa, Girl Dogs Have Anal Glands Too! 
Symptoms To Watch For In Your Dog: Bad Odor