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Cher, Feline Specialist
Category: Cat
Satisfied Customers: 21416
Experience:  Feline Healthcare & Behavior Specialist 40+ years Experience
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Light blood in urine. responded well on amoxicillin, but it

Customer Question

light blood in urine. responded well on amoxicillin, but it came back when the 14 day dosage was complete.
JA: I'm sorry to hear that. What is the cat's name?
Customer: Maggie
JA: Is there anything else important you think the Veterinarian should know about Maggie?
Customer: 6 years old female about 8 pounds
Submitted: 4 months ago.
Category: Cat
Expert:  Cher replied 4 months ago.

Hi, I'm Cher. Welcome to JustAnswer.

I'm reviewing your question now and will post back with your reply, shortly.

Customer: replied 4 months ago.
Also have access to Bactrim DS just not sure of dosage
Expert:  Cher replied 4 months ago.

Hello again,

I'm sorry Maggie is experiencing this problem with a small amount of blood in her urine.

Is she spayed?

Is she exhibiting any discomfort or straining when she urinates?

Is she visiting the litterbox more often than usual, to urinate?

Is she urinating elsewhere in the house, besides the box?

Does she spend any time outdoors?

Thank you for all your additional information and after you reply, please allow me a short while to compose and send your detailed answer.

Kind regards,


Customer: replied 4 months ago.
She is spayed, total indoor cat, does not appear in pain or discomfort but is urinating outside of box
Expert:  Cher replied 4 months ago.

Hi again, and thanks for your very helpful reply.

Did the vet do a urinalysis and urine culture, when Maggie was seen and prescribed the 14 day round of Amoxicillin? If not, this should be done, now, (especially the urine culture) as it is important to know what kind of bacteria we're up against, in order to use the appropriate antibiotic. Obviously, the Amoxicillin was effective, but only for the two weeks she was on it.

Another antibiotic should be tried at this time, to knock out any urinary infection completely. I would not recommend giving Bactrim DS, unless it was prescribed by the vet. Can you tell me the strength (mgs.) of the Bactrim? Because it's a combination of two drugs, it would have something like 800/160 to indicate the amount of each drug in a tablet. Also, can you tell me what numbers are on one side or both sides of the Bactrim DS you have?

Clindamycin is another broad spectrum antibiotic that is used in urinary tract infections.

She's urinating outside the box because she's associating the box with any discomfort she may feel (even though she's not showing discomfort) upon urinating; this is very common in cats with urinary infections. She thinks if she feels a different surface under her paws, the discomfort will disappear.

Can you answer my questions about the strength of the Bactrim DS and the number(s) written on the tablet?



Customer: replied 4 months ago.
800/160 is the mg
Expert:  Cher replied 4 months ago.

Thank you for that information. That would be an 800mg. tablet

Because Maggie is only 8 lbs., I don't think you could cut the tablet into a small enough piece, to administer. The dosage is 13 mg. per lb. by mouth, every 24 hours, or 6.5 mg per lb by mouth every 12 hours. The tablet is bitter and causes foaming at the mouth, which is not dangerous, but uncomfortable for the cat.

I would not take a chance and give her a medication that was not prescribed for her, but either bring her back to the vet for the tests I mentioned previously (urinalysis/culture) or if she's had these tests, just request another medication and get her started on another class of antibiotic that will resolve her infection, if she does, indeed have a bacterial, urinary, kidney or bladder infection. She could have a fungal or viral infection, as well.

It might also be a good idea to have a routine blood test performed, to see if all her values, including liver and kidneys are within normal limits. This will also allow her vet to prescribe the most appropriate medication for her condition.

I hope all will be well with Maggie and please let me know how she's doing and what medication your vet decided to begin her on, since the Amoxicillin helped, but did not eradicate the infection. Thank you!

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Warm regards,

Expert:  Cher replied 4 months ago.

Oh, I wanted to include this webpage, about Bactrim DS, which explains the dosage and it's uses:

Expert:  Cher replied 4 months ago.
I'm just following up on our conversation about your pet. How is everything going?
Expert:  Cher replied 3 months ago.

Hi again,

I just thought I'd check in to see how things are going with you and Maggie. My primary goal is to always provide the best answer possible. Did you find my answer helpful? Please let me know.

I look forward to your reply.

Warm regards,