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My dog has bloody diarrhea, vomiting on Prednisone/Doxy. Meds causing it?

Updated on September 23rd, 2025

Pet's info: Dog | Pomeranian | Male | unneutered | 3 years old | 3.3 lbs

Diagnosed with anemia on Saturday (Onion poisoning or AutoImmune,still not confirmed).After blood transfusion,vet put him on prednisone &Doxy. Monday gave him double dose Doxy by mistake (35 mg).Tuesday he had mild vomiting &diarreha with mucus &blood in stools.Wednesday started maalox (2ml twice/day) in addition to his meds. Today he has no appetite &his stools are watery with some blood drops by the end. Is it from maalox or doxy overdose?Should i stop it? Should I continue with pred &doxy?

1 Answer

Most Helpful Answer

Laura Johnson VMD

Answered By Laura Johnson VMD

Veterinarian

Published on December 21st, 2017

Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Poor Chlyo, this has been a tough week for him

I recommend calling your Vet. Maalox is not my first choice to fix diarrhea and vomiting. Doxycycline is an antibiotic notorious for causing tummy upset, regardless if you accidentally gave too much. High doses of steroids can cause tummy upset. Prednisone can not be abruptly stopped and needs to be weaned and in Chlyo's case is likely needed to save his life if he has immune mediated hemolytic anemia. There are other antibiotic choices to rule out tick borne disease causing his immune disease.

My recommendations is to call your Vet and have Chlyo seen again today. If he was my patient I would use cerenia, metronidazole and have him on prilosec or famotidine (pepcid). I would not stop or wean the prednisone unless his red blood cell count was normal. I would temporarily stop the doxycycline until he is eating and the stool is better and consider amoxicillin instead.

We can not tell you want to do on Petco Pet Education Center, formerly Petcoach because the laws in the US require a valid Veterinary Clinet Patient Relationship which means we have to actually touch and examine your dog. We can provide advice but your Vet needs to be the one to tell you what to do with the medications. In my opinion, and I have answered a lot of questions from you regarding Chlyo, is that he is a sick dog and he has been dealing with this diarrhea for 1-2 days and is now getting worse. It is in his best interest to be rechecked and examined by your Vet.

I hope this helps and I wish you and Chlyo the very best!
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