Generic Name
Trimethoprim/Sulfadiazine
Trimethoprim/Sulfamethoxazole

Brand Names
Tribrissen (veterinary-approved trimethoprim/sulfadiazine) also known as TMP-SDZ, SDZ-TMP, Co-trimazine

Septra, Bactrim (human-approved trimethoprim/sulfamethoxazole)

Type of Drug
Antibiotic and antiprotozoal

Form and Storage
Tablets, oral suspension, and injectable
Store at room temperature in a tight container.

Indications for Use
Treatment of susceptible gram positive and gram negative bacterial infections and coccidial infections.

General Information
FDA approved for use in dogs. Use of this medication in cats is a common and accepted practice. Available by prescription. Sulfonamides (sulfadiazine and sulfamethoxazole) are bacteriostatic and trimethoprim is bacteriocidal. In combination, they are bacteriocidal.

Usual Dose and Administration
Dogs and Cats: 13 mg/pound by mouth (tablets, oral suspension) every 24 hours. Dose may be divided and given every 12 hours. Doses vary by condition. Consult your veterinarian.

Side Effects
May see keratoconjunctivitis sicca. Monitor tear formation with the Schirmer tear test during and after long-term treatment. May also see lack of appetite, vomiting, diarrhea, fever, anemia, allergic reaction, liver damage, joint inflammation (arthritis), increased drinking and urination, facial swelling, or seizures.

Contraindications/Warnings
Not for use in patients hypersensitive (allergic) to it. Large dog breeds may be more likely to be allergic to it than smaller dog breeds.

Not for use in patients with liver disease, kidney disease, or blood disorders.

Not for use in pregnant or nursing animals.

May cause hypothyroidism with long term (6 weeks) use in dogs.

Shake the suspension well before each use. Does not need to be refrigerated.

Water should be available at all times and the animal should be encouraged to drink. The patient must not become dehydrated during treatment or sulfa crystals may form in the urine.

Drug or Food Interactions
May increase the effects of anticoagulants (blood thinners), methotrexate, phenylbutazone, thiazide diuretics, salicylates, probenecid, and phenytoin.

Antacids may decrease the sulfonamides absorption.

Trimethoprim may decrease the effect of cyclosporine and increase the risk of it causing kidney damage.

No known food interactions.

Overdose/Toxicity
May see lack of appetite, vomiting, diarrhea, depression, confusion, facial swelling, bone marrow suppression, or liver disease.