Side Effects of Smz-Tmp in Your Pet

Sulfa/trimethoprim, or SMZ-TMP, is an antibiotic approved for use with humans that veterinarians use off-label to treat dogs and cats, as well as other animals. The two drugs are more effective when combined. As a broad-spectrum antibiotic, it's used to treat bacterial and protozoal infections that affect the skin, respiratory and gastrointestinal systems and the urinary tract, among other illnesses. Like any medication, some patients may experience side effects, which tend to be species specific. The antibiotic should not be given to dogs that are pregnant or nursing.

  1. Side Effects in Cats

    • Side effects in cats that are given SMZ-TMP differ somewhat from dogs. Excessive drooling is a sign that cats are not tolerating the medicine. Other side effects include appetite loss, nausea, vomiting, diarrhea, low white blood cell counts, and anemia, which is evidenced by pale gums and exhaustion. These are serious reactions and require veterinary attention.

    Keratoconjunctivitis Sicca or Dry Eye in Dogs

    • Although rare, keratoconjunctivitis sicca, commonly referred to as dry eye, may be a result of long-term SMZ-TMP use. A dog suffering from dry eye may experience eye discharge, redness, squinting or any other eye problems. When this occurs, pet owners should stop the medication at once and contact a veterinarian.

    Joint Inflammation in Doberman Pinschers

    • Joint inflammation isn't a widely reported side effect in many breeds of dog, but doberman pinschers taking SMZ-TMP are particularly vulnerable. The drug should not be given to dobermans or doberman mixes. Any dog that suddenly experiences difficulty walking or getting up after ingesting SMZ-TMP should be taken to the vet.

    Immune Mediated Thrombocytopenia

    • Some dogs taking SMZ-TMP may develop immune mediated thrombocytopenia, which causes a decrease in the number of platelets in the blood. Platelets allow blood to clot, so low numbers may have serious repercussions for dogs. Signs of the condition include unusual bruises or bleeding. Taking the animal off the medication reverses the condition and allows platelets to recover.