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Metronidazole and Your DogPlease note: The information on our site is for everyone to read.
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Problems with Metronidazole long term
Metronidazole and possible liver damage
Metronidazole - flagyl
Metronidazole and cancer
also see Dog medication
also see Diarrhea
Problems with Metronidazole long term
Question: Could the frequent use of Metronidazol (for Giardia)
be as 'hazardous' as the use of Pred., for causing Cushing's-
like symptoms? There are numerous symptoms that
indicate the possibility of Cushing's -- how many of them
do you believe a dog should have, before it's reasonable to
test for it? I.e., if a breed (that is uncharactistic of having
Cushing's) does not eat, drink, or urinate excessively, but
is experiencing some hair loss and skin thinning (at a Sr. age),
would you test for Cushing's?
Answer: I have not seen Cushing's like syndromes using metronidazole. The only long term problem that I
know of with metronidazole use is that it is thought to be carcinogenic in some lab animals and
possibly in humans, with long term use. This has not been proven to occur in pets but it might be a
problem.I usually don't test for Cushing's disease unless clinical symptoms are occurring that have to be
corrected in order to make the patient comfortable or unless the client asks me to, prior to that time
when we include it in a list of possible differentials. I would probably test if there was bilateral hair
loss and other hormonal diseases, especially hypothyroidism, have been ruled out.Mike Richards, DVM
1/3/2001
Metronidazole and possible liver damage
Question: Have you ever heard of Flagyl affecting the liver enzyme levels?
Answer: Metronidazole (Flagyl Rx) is metabolized primarily by the liver. It
sometimes causes liver damage or makes existing liver damage worse. This is
thought to be a reversible effect which usually will resolve with
withdrawal of the medication.
Mike Richards, DVM
6/12/2000
Question: Hi Dr. Mike:
Have you anything to offer about Flagyl - pros/cons, dangers, etc? This is what I heard.." It is a type of antibiotic that is used commonly in dogs with gastric problems. I am very leery of it, as I had a very dear girlfriend die from
using this about 20 years ago. It is also called antiabuse, and used for alcoholics, as it makes them nauseated when they drink... it puts a big toll on the liver, and can cause liver shut down and failure."Thanks, Charlotte
Answer: Charlotte-
The first thing that is necessary is to clear up a misunderstanding in the
email responses what you heard. Antibuse (Rx) is disulfiram, not
metronidazole. However, metronidazole can cause vomiting when given with
alcohol, in a reaction that has been termed "disulfiram like" in the human
literature, so perhaps that is the reason for the confusion.Metronidazole has never been approved for use in dogs and cats but it is
used quite frequently to treat giardiasis and inflammatory bowel disorders.
It is also used to aid in the treatment of anerobic bacteria in the
respiratory tract.Metronidazole can cause neurologic signs if overdosed, including loss of
balance, visual problems, vomiting, rapid eye movements (nystagmus),
tremors and seizures. I have only seen this problem once or twice, when we
have tried to use metronidazole in young kittens to treat giardia and could
not get the dosage measured accurately using crushed pills. The kittens
didn't die, but they looked like they might. Now we use a compounding
pharmacy to make the medication into a dosage form we can give
accurately. Metronidazole is processed by the liver and may cause
increased toxicity if given to a patient with enough liver disease to
inhibit processing of the medication.If you need more specific information about any part of the above reply I
will try to find it for you. Our biggest problem with metronidazole has
been vomiting after administration, making it an unpleasant medication for
the pet and often ineffective when that occurs, too.Mike Richards, DVM
5/4/2000
2) The second question is do you know what the clinical trials indicate as far as the association of cancer and the use of metronidazole. Thank you for your help.
A: I am not aware of any studies linking metronidazole to cancer. It is known to be teratogenic (causes birth defects) when administered to lab animals who are pregnant but I don't know if this occurs in dogs and cats. I have no intention of giving it to a pregnant pet, though. It can also cause neurologic signs in some pets even at the recommended dosages. These go away when the medication is withdrawn (or at least they have in the few cases we have seen).
Mike Richards, DVM
Last edited 08/30/02
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