Metronidazole: Side Effects in a Feline

Metronidazole is both an antibiotic and anti-protozoal drug used in cats with bacterial or parasitic infections. While this drug has not yet been approved for use in animals by the FDA, use in dogs and cats is commonly accepted veterinary practice. This drug can be used to treat IBS, digestive problems, periodontal disease, overgrowth of bacteria in the small intestine and many other disorders. Like all drugs, metronidazole may have side effects.

  1. Digestive

    • Cats treated with metronidazole may suffer from a loss of appetite, clinically called anorexia. They may also have nausea and vomiting, or have trouble with diarrhea. Owners should be prepared for litter box accidents. Some cats on metronidazole also have blood in the urine or feces, a sign that the vet should be consulted.

    Allergic Reactions

    • Some cats suffer from allergic reactions when taking this drug. If a cat shows signs of hives or swelling of the tongue, throat, lips or face, or if it seems to be having trouble breathing, an immune reaction is probably responsible. Owners should seek help immediately if they see any of these signs, as a serious reaction could be life threatening. An experienced vet can provide emergency care for cats suffering from these types of symptoms.

    Respiratory

    • Some cats suffer from minor respiratory problems when treated with metronidazole. These may include a runny nose and sneezing, a dry mouth, or a cough. If these side effects appear to be especially bothersome to the cat, discontinue use of the drug or consult a vet for additional information. Minor side effects are usually tolerable, however, and treatment may continue.

    Toxicity

    • In some rare cases, when metronidazole has been used for a very long time or administered in a high dose, cats will suffer from a toxic reaction. Signs of this type of side effect include staggering and disorientation, tremors, a head tilt, seizures and involuntary eye movement. Cats may also have a sudden drop in heart rate. These signs are very serious, and the drug should be discontinued immediately. The cat may take up to two weeks to recover, and should be monitored. In some cases, a cat suffering from an acute reaction to the drug may die.