Possible Side Effects:
It is common to find sulfa crystals in the animal's urine during a urinalysis a test on the urine, which does not pose a problem in animals that remain well hydrated.
Less common, keratoconjunctivitis sicca KCS, dry eye may occur with long-term use of trimethoprim/sulfa. Stop giving the medication and consult your veterinarian if your pet experiences discharge from the eye, redness of the eye, squinting, or other signs related to the eye.
Other less common side effects in dogs include anemia resulting in pale gums and tiredness low platelets resulting in bleeding tendencies fever loss of appetite, vomiting diarrhea joint inflammation arthritis resulting in lameness kidney damage resulting in increased thirst and urination liver damage and skin rashes with possible sensitivity to sunlight. Stop giving the medication and consult your veterinarian if your pet experiences any of these signs.
Dogs can develop hypothyroidism with long-term use.
Cats will often drool excessively if allowed to taste the medication. Side effects in cats may include loss of appetite, low white blood cell counts and anemia resulting in pale gums and tiredness. Consult your veterinarian if your pet experiences any of these side effects.