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Dr.Fiona, Dog Veterinarian
Category: Dog
Satisfied Customers: 6273
Experience:  16 years experience as a companion animal veterinarian in British Columbia, California and Ontario
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My dog has been on Flagyl for 2 days after a terrible 3 days

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My dog has been on Flagyl for 2 days after a terrible 3 days of barfing and diarrhea- (ste something gross I guess). His stool is well formed but still a little on the dark side- not tan like the home cooked chicken and rice he is eating- and also a little shiny/mucousy- is the flagyl making it that way??

Hi there Customer,

Welcome to Just Answer! I would like to help you and your dog with this question, but need a bit more information in order to better assist you.


What did the diarrhea look like before you started the Flagyl (metronidazole)?


Has he stopped vomiting?


Is he still having more frequent bowel movements?



Customer: replied 8 years ago.
Hi Fionna, thanks for the responce,
The diarrhea was urgent as was the vomit. It all started last sunday- last sun and mon his poops was just fluid and tan- then got worse with tarry dark and mucus (colon blood) then also had fresh blood and just clear liquid coming out. Wed he got a barium dose and xrayed- nothing blocking, pooped it out thursday morning and it looked like it draged sand and grras out. Thursday is when the fresh blood came out- after the barium.

He stopped vomiting tuesday night / was in vet getting hydration tuesday and wed for vomiting- he was vomiting like he wanted to get something up for sure.

Bowel movements are no longer frequent yesterday morning and this morning- still feeding home cooked chix and pasta about 1 cup on am and 1 cup @ 5.

Poor dog - and poor you having to clean up after him!


What age and breed of dog is he?


Is he eating enthusiastically?


Hi again,

What you are describing in your dog sounds like he may have colitis.

With colitis, dogs tend to have more frequent bowel movements, a sense of urgency, sometimes straining, and mucus and even blood on the stools. The stools often start out a bit soft, or pudding like and become gelatinous, shiny and mucoid as it progresses. The colon normally makes mucus to help the stool to pass along, so when it is inflamed it makes a lot of mucus, and also can have erosions that lead to bleeding.

Colitis could be caused by a large number of different things. Examples are stress, dietary indiscretion (eating something he shouldn't have), bacterial and viral infections, and parasites. In a sensitive dog, even a one-meal food change could trigger this.

If a dog with no history of stress were to come in to my hospital, and we didn't have to consider money (so I could do all the tests I would want to do!) I would start with a physical exam and then a number of tests:

- fecal analysis to rule out hookworms, whipworms and coccidia

- an ELISA test for Giardia. Giardia used to be hard to diagnose, but this test is fast and easy and accurate.

- a fecal smear to look for Campylobacter

- a fecal culture (sent out to a lab) to check for Clostridium or other unusual bacteria. This test takes 3-4 days.

Then, if the dog were my patient, I would see how the dog responded to treatment as follows:

- fibre trial - I would start the dog on metamucil. I usually suggest 1 tsp per 10 lbs body weight given 2 or 3 times a day, or 2 tablespoons twice daily per 10lbs body weight of Pumpkin. Do this for at least one week. Do this for at least one week.

- medication trial:

I would try metronidazole ( as a first line treatment but there are a number other drugs that can be helpful too:

Panacur (fenbendazole, ,

Tylosin ( )

and even steroids (prednisone )

Now, in terms of what people can do at home for dogs that I have seen and diagnosed with colitis, I suggest the following:

1. When he has an episode of blood and mucus on the stool, you should WITH-HOLD FOOD! Do not offer anything for 12- 24 hours. This gives the intestines a chance to rest and heal.

2. When he is fasting, he can have lots of clear fluids. So, water is fine, but also he can have pedialyte, Gatorade, apple juice diluted 50:50 with water, or chicken or beef broth diluted 50:50 with water. Give the fluids in small amounts frequently. For a dog that is about 20lbs that means about 1/4 cup an hour.

3. After 12-24 hours if the diarrhea has stopped, you can start your dog back on a bland diet. For patients that I see, I recommend a mixture of 75% cooked white rice, and 25% low fat protein. For the protein you could use extra lean ground beef, boiled with the fat scooped off, or chicken breast boiled with fat scooped off or even scrambled egg cooked without fat in the microwave. Feed small frequent meals. For a dog this size, I would suggest 2-3 tablespoons every 3 to 4 hours.

4. After 1-2 days on the rice mix, you would gradually change your dog back to the normal diet and food. So, on day 3, give the rice mixture, but bigger meals, spaced further apart. On day 4, mix a little tiny bit of the normal food in there, and decrease the frequency so it is down to 3 meals or so. And so on.

5. Keep your dog as quiet as possible - just out to relieve himself and back in.

6. Start 2 tablespoons twice daily per 10lbs body weight of canned Pumpkin. Be sure to use plain canned pumpkin and NOT pie filler!

I'll give you links to further information:

In terms of preventing this problem, it is very helpful to have dogs prone to this on a bit of OAT bran (very important it is OAT bran and not wheat bran) in their food daily. For a dog this size, I would suggest 2-4 teaspoons daily, divided between his meals.

Alternatively, you may just wish to keep him on the Metamucil or canned pumpkin.

Also, you may wish to consider a DAP (dog appeasing pheromone) diffuser to decrease stress if this has been a factor in the last few weeks. It contains a smell that calms dogs, but is not a drug and is perfectly safe. It has no odour to humans. Here is more about them:


If your boy begins vomiting again, or loses his appetite, then a trip to your vet would be in order. In the meantime, you may wish to start him on the canned pumpkin as it is very quickly effective in most dogs at helping to resolve the colitis more quickly, especially when used with the Flagyl.

The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.


Customer: replied 8 years ago.
PS remember he is already taking the Flagyl- won't that clear up any bacteria like salomonella??

So okay this is a lot of info-

Should I use oatmeal instead of noodles? or is rice the best-

We already had a test for Giardia- not that. and he is getting a regular de-worming with his heart worm tab each month. He had a fecal test in sept, his regular check-up, everything normal. He did test pos for lymes- not terribly high count C6 was 101- but he went on a doxy dose for 30 days. that was in july- I did not repeat the lyme vacc this year- seems redundant and useless.

He is a highly active dog, a NSDTR, a Toller, and pretty high energy- would he require a more protien and fatty diet for high performance dogs? He has been eating wellness brand and over the last month has converted from the puppy formula to the adult. Is it too rich? It was suggested we go to Eagle Pack Duck and oatmeal- what is your take on these brands?

I was also told young dogs rarely get colitis- he is only 15 months, and has kind of been thru a lot already. Could this be a one time occurance?

Hi again,

Good to hear that he was negative for Giardia and is regularly dewormed! Colitis can be caused by parasites, but can also be caused by dietary indiscretion, which is quite likely in a young dog like this.


Wellness is an excellent food, and the adult version is perfect. I would NOT switch to a high performance food unless you cannot keep weight on him with the adult food. The high peformance is harder to digest and not desirable except for working dogs, usually.


In terms of oatmeal... it is not really that he should be on Oatmeal, just that he needs a fibre source in what he is eating. So, you can do one of 3 things:

1. Oat bran added to his food

2. Metamucil added to his food

3. Canned pumpkin added to his food.


This could certainly be one time occurrence! If you could figure out what triggered it (getting into garbage, a sudden food change, something stressful like you being away, etc) that would help to figure out how to avoid it in future.


Hope that helps! :-)


The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.



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