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Medications & Supplements

Pyrimethamine

Pyrimethamine is an antiprotozoal tablet given by mouth and used off-label to treat certain parasitic infections. Common side effects include vomiting, low appetite, tiredness, and low blood cell counts. Cats are more likely to have more severe side effects. Pregnant women should handle this medication carefully.
Ranitidine

Ranitidine is given by mouth or injection and is used off-label to treat ulcers and erosions in the stomach and upper small intestine, reflux, or gastrointestinal motility issues. Give as directed. Side effects are uncommon but may include stomach upset. Do not use in pets with a history of allergies to this class of drugs. If a negative reaction occurs, call your veterinarian.
Rawhide-Based Oral Hygiene Chews

Rawhide-based oral hygiene chews are chews with an abrasive texture that can help prevent or delay the formation of dental plaque and calculus build-up on your pet’s teeth. C.E.T.® Enzymatic Oral Hygiene Chews is one common brand.
Remdesivir

Remdesivir is an injectable, antiviral medication used to treat feline infectious peritonitis (FIP) in cats. The injection may be painful or cause swelling or inflammation. Its use is still being evaluated and any concerns should be reported to your veterinarian immediately.
Rifampin

Rifampin is commonly used off label to treat infections in horses, and occasionally in dogs and cats. It is usually given by mouth in the form of a capsule or compounded liquid. The most common side effects are vomiting, diarrhea, or reduced appetite. Liver dysfunction is possible. A change in the color of urine, tears, and saliva to a red/orange color is expected but may stain fabrics. Use with caution in pets that have pre-existing liver disease, are pregnant, are elderly, or are lactating. If a negative reaction occurs, call your veterinary office.
Rivaroxaban

Rivaroxaban is an anticoagulant used to prevent or treat blood clots in cats and dogs. It is used off label (extra label) in veterinary medicine. Rivaroxaban comes in tablet form. Monitor for unusual bleeding, bruising, pale gums, extreme weakness, collapse, and/or difficulty breathing.
Robenacoxib

Robenacoxib (brand name: Onsior) is given by mouth in the form of a tablet to treat pain and inflammation associated with surgery or other musculoskeletal conditions in dogs and cats. Do not use this medication in pets that are allergic to it, or in pets concurrently using corticosteroids or other NSAIDs. If a negative reaction occurs, call your veterinary office.
Ronidazole

Ronidazole is an antiprotozoal, antiparasitic medication given by mouth and is used off label to treat Tritrichomonas infections in cats and pet birds, and to treat giardia in dogs and cats. Ronidazole is given by mouth in the form of a capsule or liquid.
Ropinirole Ophthalmic

Ropinirole ophthalmic (Clevor®) is the first FDA-approved drug for inducing vomiting in dogs. Your veterinarian may prescribe this drug off label to use for your dog at home. Ropinirole ophthalmic comes as a single-use dropper for use in the eye.
S-Adenosyl-Methionine (SAMe)

SAMe is given by mouth and is used on label and over the counter to treat liver disease and other conditions. Give as directed by your veterinarian. Side effects are uncommon but may include mild stomach upset. Antidepressants, dextromethorphan, meperidine, pentazocine, and tramadol should be used with caution when given with SAMe. Inform your veterinarian of all medications, vitamins, and supplements that your pet is taking. If a negative reaction occurs, please call your veterinary office.