Question 1

What is Trimethoprim used for?

Accepted Answer

Trimethoprim is indicated for: Bacterial infections, Bacterial infections (TMP-sulfa), Respiratory/urinary infections, Susceptible infections (TMP-sulfa), Susceptible infections (with sulfonamide).

Question 2

What routes can Trimethoprim be administered by?

Accepted Answer

Available routes: PO, IV.

Question 3

Which species have cited Trimethoprim dosing data?

Accepted Answer

Trimethoprim dosing in the ExoticRx formulary covers 6 species: African Grey Parrot, Ball Python, Bearded Dragon, Cat (Domestic), Dog (Domestic), Rabbit (Domestic).

Question 4

Is Trimethoprim a controlled substance?

Accepted Answer

Trimethoprim is not federally scheduled as a controlled substance, but is veterinary prescription only in most jurisdictions.

Question 5

What are the warnings or contraindications for Trimethoprim?

Accepted Answer

Almost always used in combination with a sulfonamide. Folate supplementation recommended in cats and during pregnancy. KCS risk in dogs.

Question 6

What are the side effects of Trimethoprim?

Accepted Answer

Reported side effects, adverse reactions, and contraindications for Trimethoprim: Almost always used in combination with a sulfonamide. Folate supplementation recommended in cats and during pregnancy. KCS risk in dogs.

Question 7

How does Trimethoprim work?

Accepted Answer

Inhibits dihydrofolate reductase (DHFR) in folate synthesis pathway. Synergistic bactericidal activity when combined with sulfonamides.

Species	Route	Dose	Frequency	Evidence	Source
Dog (Domestic)	PO	15–30 mg/kg	q12h	Strong	Plumb's Veterinary Drug Handbook, 9th Ed
Cat (Domestic)	PO	15–30 mg/kg	q12h	Strong	Plumb's Veterinary Drug Handbook, 9th Ed

Trimethoprim

Drug Class

Routes

Indications

Mechanism of Action

Side effects & warnings

Species with Trimethoprim dosing data (6 dose rules)

Evidence levels across 6 dose rules

Backed by 2 published sources

Sample dosing (2 of 6 cited rules)

Upgrade for Full Details