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Trimethoprim-Sulfa in Veterinary Medicine-Facts and Information

Trimethoprim-Sulfa

Updated on September 10, 2024

Potentiated sulfonamide antimicrobial agent used to treat many infections common in small animals.

Trimethoprim-Sulfa

Summary

Used For: Bacterial and protozoal infections

Brands: Tribrissen, Bactrim, Septra

Species:

Dogs, cats and other small animals

Other names: TMP-SMX, TMP-SDZ, Trimethoprim-sulfadiazine, trimethoprim-sulfamethoxazole

Drug type: Antibiotic

Prescription required: Yes

Pregnancy and lactation: Use with caution, safety has not been clearly established in pregnant or lactating animals.

Side effects: Dry eye, hypothyroidism, anaphylaxis, liver disease, blood effects

General description

Trimethoprim-sulfa is a potentiated sulfonamide antimicrobial used to treat certain bacterial and protozoal infections in veterinary medicine.

Uses

Bacterial urinary tract infections, skin infections, and other soft tissue infections; also used for protozoal infections.

How it works

The combination of trimethoprim with a sulfonamide gives this medication a broader spectrum of activity against susceptible microorganisms with less antibiotic resistance than either component alone. Potentiated sulfa drugs kill microorganisms by inhibiting enzymes, causing the bacteria to die.

Dosage

Dosages vary greatly based on species and infection being treated. Follow prescribing directions from your veterinarian. Medications should only be administered to pets under the direct guidance of a veterinarian.

Forms

25, 100, 400 or 800 milligrams sulfadiazine in combination with 5, 20, 80 or 160 milligrams trimethoprim tablets for oral use.

Storage information & handling

Trimethoprim-sulfa should be stored at room temperature.

What results can I expect?

Assuming the infection is susceptible to trimethoprim-sulfa, resolution of the infection should occur during the treatment period.

Missed Dosage

If a dose is missed, continue with the next dosage at the scheduled time.

Overdose / acute toxicity

Signs of an overdose include nausea, vomiting, diarrhea, depression, confusion and facial swelling. Call your veterinarian immediately if you suspect your pet has received an overdose of trimethoprim-sulfa.

Side effects

May include: * Dry eye (KCS, Keratoconjunctivitis sicca) * Acute neutrophilic hepatitis (liver disease) with jaundice, vomiting, diarrhea, fever, decreased appetite, facial swelling, increased thirst and urination, hives and polyarthritis * Hypothyroidism (dogs) * Anaphylaxis * Blood effects (anemia, decreased production of certain white blood cells) * Cats: decreased or absent appetite, blood effects (anemia, decreased white blood cells)

Contraindications

Do not use in pets with: * Hypersensitivity to sulfas, thiazides or sulfonylurea agents * Severe kidney disease * Severe liver disease

Drug interactions

Trimethoprim-sulfa may interact with: * Amantadine * Antacids * Cyclosporine * Digoxin * Thiazide diuretics * Oral hypoglycemic agents * Methotrexate * Phenytoin * Tricyclic antidepressants * Warfarin

Precaution

Trimethoprim-sulfa should be used with caution in patients with: * Decreased kidney function * Decreased liver function * Urinary obstructions or urolithiasis (stones in the urinary tract)

Sources

*Plumb’s Veterinary Drug Handbook*

Related Questions

Hi! My cat was recently diagnosed with diabetes. He’s taking insulin and taking antibiotics for a Uti. It’s been 4 weeks and he wobles when he’s walking. He can’t jump up on the bed like he used to.He’s blood sugar is 250 it’s better than it used to. I don’t understand why he’s so wobbly.

Cats can develop what's called diabetic neuropathy, where their hindlegs become progressively weak. The best thing to do is try to get his diabetes under control as quickly as possible. Here is a link describing the conditon: http://www.diabeticcatcare.com/DCCCOK/Neuropathy.htm

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Is there a reason you want to stop the prednisone? I would recommend not stopping it and if you feel it is better to stop the prednisone then I would recommend weaning off of the prednisone. I would discuss how to wean the prednisone with your veterinarian. Thank you for using Boop by Petco.

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In severe outbreaks, 2 weeks between different drugs is ok. You will also need to use a household flea treatment in order to break the cycle, only 5% of the flea population are adults and actually present on pets, tge remaining 95% are eggs/large and will continue to hatch, develop and reinvest your pets. All in contact animals should be treated together and also given a tapeworm treatment because tapeworms are also transmitted by fleas

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My 8yo Golden had a falsepregnancy w milk. Cabergoline has resolved it now. I hear conflicting opinions about spaying. She has never mated. Some say not spaying would cause pseudopregnancy recurrence+dangerous conditions like Mammary T. But UCDavis studies say spaying increases other aggressive cancer risks among GoldenRs. Also, vet thinks that her anemia that keeps coming back after prednisolone trtmnts *might* be due to Ovary cysts, suggests spaying. What's the right approach for her health?

Thank you for contacting Boop by Petco with your question about Lav. I've heard many owners quote the UC Davis study, and there are a number of things wrong with the study. Check out this article on it: https://humanepro.org/magazine/articles/deconstructing-spayneuter-debate Not spaying her can cause a pseudopregnancy reoccurrence, but it doesn't increase her risk of mammary tumors. That's already going to be 25% because she's had more than two heats. Keep in mind, 50% of mammary tumors in dogs are malignant. She is eight years old, so she is already at a higher risk of developing cancer simply because she is an older dog. She is also at risk of a pyometra, which is an infection of the uterus that is fatal without treatment. The treatment for a pyometra is spaying the dog, which is an emergency during a pyometra and can cost many thousands of dollars. In all honesty, it's best to spay her. It will keep her from developing a pyometra as well as a pseudopregnancy, and it will keep her from getting pregnant if she accidentally mates. Dogs over the age of six should never have puppies. In my opinion, it's best for her to health to get spayed asap. I hope this helps!

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My cat was prescribed antibiotics for diarrhea and today was his second day of taking them. He’s required to take 0.5 mL of the antibiotic and another one after 12 hours (twice a day). Today, he lost his appetite (only ate a few treats) and threw up clear liquid twice and clear yellow liquid 3 times. He is also lethargic.

Hello, thank you for using Boop by Petco. I'm sorry to hear that Leo is having this problem. Many antibiotics cause gastrointestinal issues in cats so you will need to call your vet and let them know what is going on. Most likely they will have you stop one or both of the antibiotics and prescribe something different. I would also suggest that you put him on a pre/probiotic while he is taking antibiotics and then continue for at least one week after the antibiotics have been stopped. Hope this helps. Best wishes.

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I was advised by my daughter's dog trainer to contact a vet about my Yorkie's anxiety. She is 7 yo and 12 lbs. She started off scared of some fireworks in the neighborhood. Now it has progressed to even heavy rain. She keeps us up during storms because s she's so afraid and we can't console her. The trainer said a vet could try her on some trazadone. How can I get help with this?

Thank you for contacting Boop by Petco with your question about Ellie. I'm sorry she's having trouble with anxiety! Yes medications can help with anxiety, but she would need to see a vet in person to get the medication. We cannot provide a prescription for it from the site without seeing her in person; it's illegal, and against the user terms of the site. I recommend contacting her vet to make her an appointment to discuss the use of medication. A thundershirt may also help in conjunction with medication. You can buy them online, I also recommend looking at one of those. A tip to keep in mind when she is afraid is not to console her. It's natural to want to do that, but it actually reinforces the behavior. By consoling her, you are telling her it's ok to act this way. I hope this helps!

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Disclaimer

The information contained on this page is for educational purposes only. This medication should only be given under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.