Trimethoprim/Sulfadiazine (Tribrissen®) for Dogs and Cats
Trimethoprim is an effective antibiotic that becomes even more effective when combined with a sulfonamide (sulfa drug), such as sulfadiazine and sulfamethoxazole. The combination, better known as Tribrissen®, exhibits a greater spectrum of activity against microorganisms that cause infectious disease for dogs and cats. The addition of trimethoprim to a sulfa drug forms a potentiated sulfa.
Trimethoprim-plus-sulfadiazine and trimethoprim-plus-sulfamethoxazole are the most often-used combinations in veterinary medicine. These are similar in antibiotic function and may be used interchangeably.
Trimethoprim-sulfa can kill a variety of bacteria. An additional effect of potentiated sulfa drugs is an ability to kill or suppress certain intracellular parasites, particularly Coccidia spp. and the microorganism responsible for the disease Toxoplasmosis. Trimethoprim/sulfadiazine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
Brand Names of Trimethoprim/Sulfadiazine
This drug is registered for use in humans and animals.
- Human formulations: Proloprim® (Glaxo Wellcome), Septra® (Glaxo Wellcome), Bactrim® (Roche) and various generic preparations
- Veterinary formulations: Tribrissen® (Schering) and various generic preparations
Uses of Trimethoprim/Sulfadiazine for Dogs and Cats
Trimethoprim/sulfadiazine is used in dogs and cats to treat infections likely to be susceptible to the drug. Trimethoprim/sulfadiazine has also been used to treat parasitic infections caused by the microorganisms toxoplasmosis and coccidia (an intestinal parasite).
Precautions and Side Effects
While generally safe and effective when prescribed by a veterinarian, trimethoprim/sulfadiazine can cause side effects in some animals:
- dry eye (keratoconjunctivitis sicca)
- liver inflammation
- lack of appetite
- facial swelling
- blood disorders such as hemolytic anemia or low platelet counts
With prolonged administration, potentiated sulfa drugs have been associated with abnormal thyroid tests and possibly with hypothyroidism in dogs
Trimethoprim/sulfadiazine should not be used in pregnant animals or animals with liver impairment, blood disorders, or known allergies to the drug. The drug may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with Trimethoprim/sulfadiazine.
How Trimethoprim/Sulfadiazine Is Supplied
Trimethoprim/sulfadiazine is available in the following forms:
- 30 milligram, 120 milligram, 480 milligram and 960 milligran tablets.
- 400 milligram oral paste
- Trimethoprim/sulfamethoxazole is also available in an injectable form.
Dosing Information of Trimethoprim/Sulfadiazine for Dogs and Cats
In dogs and cats, trimethoprim/sulfadiazine is typically dosed at 7 to 15 milligram/pound (15 to 30 milligram/kilogram) one to three times daily. Alternative dosing may be indicated in some dogs treated chronically with this drug.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your dog or cat feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance. Medication should never be administered without first consulting your veterinarian.