Robenacoxib is a non-steroidal anti-inflammatory drug (NSAID) developed for veterinary medicine to manage pain and inflammation in cats. Marketed under the trade name Onsior, this medication belongs to the coxib class of drugs. Veterinarians prescribe it to help felines recover from surgical procedures or to improve comfort and mobility associated with musculoskeletal conditions. Its specific formulation addresses the unique challenges of pain management in cats, which are highly sensitive to many standard human and canine NSAIDs.
How Robenacoxib Works in Cats
Robenacoxib functions by selectively inhibiting the cyclooxygenase-2 (COX-2) enzyme, which produces the inflammatory chemicals that cause pain and swelling. This selective action distinguishes it from older, non-selective NSAIDs, which block both COX-2 and the protective COX-1 enzyme. COX-1 is necessary for maintaining normal physiological functions, such as protecting the stomach lining and ensuring blood flow to the kidneys. By largely sparing the COX-1 pathway, robenacoxib minimizes the risk of gastrointestinal and renal side effects compared to non-selective alternatives.
The drug is FDA-approved for the control of postoperative pain and inflammation following common surgical procedures. These procedures include ovariohysterectomy (spay), castration (neuter), and various orthopedic surgeries. Robenacoxib is also frequently utilized in an extra-label or “off-label” manner for managing chronic musculoskeletal pain, such as that caused by feline osteoarthritis. While the approved duration for post-surgical use is short-term, its high COX-2 selectivity makes it a valuable tool for veterinarians managing longer-term pain, often with close monitoring.
The medication is absorbed quickly after oral administration and concentrates at the site of inflammation, enhancing its therapeutic action while reducing systemic exposure to healthy organs. This tissue-selective distribution contributes to its favorable safety profile in felines. The recommended oral dose generally ranges from 1 to 2.4 milligrams per kilogram of body weight.
Practical Administration Guidelines
Robenacoxib is most commonly prescribed in an oral tablet form for use at home, though an injectable form is often administered by the veterinary team before or immediately following surgery. The oral tablets are available in a specific 6-milligram strength for cats and are typically flavored to ease administration. The tablets are not scored and should never be split or broken, as this compromises accurate dosing.
The standard administration schedule for approved post-surgical use is once daily, not exceeding a maximum of three total doses. Owners must strictly adhere to the prescribed dosage and frequency, avoiding any temptation to increase the dose or administer it more often. Robenacoxib tablets may be given with or without food, but providing the dose alongside a meal is often recommended to mitigate potential mild stomach upset.
For labeled acute pain management, the duration of treatment is limited to three days. When the drug is prescribed off-label for chronic conditions like osteoarthritis, the veterinarian will establish a specific protocol, which may involve a lower dose or longer duration. This use necessitates regular check-ups and blood work to ensure the medication is tolerated well, especially when administered beyond the standard three-day period.
Recognizing Adverse Reactions
Robenacoxib remains an NSAID, and owners must be vigilant for potential adverse reactions affecting the gastrointestinal tract, kidneys, and liver. These organs are most susceptible to the effects of NSAID therapy. The most frequently reported signs of an adverse reaction are generally gastrointestinal, such as vomiting, soft stool, or diarrhea.
Owners should watch for changes in the cat’s general demeanor, including decreased appetite, lethargy, or reluctance to move. These behavioral changes can signal discomfort or a systemic issue, warranting immediate attention. Serious signs of toxicity include the presence of blood in the vomit or stool, which may appear dark or tarry, indicating gastrointestinal ulceration.
Changes in drinking and urination habits, such as increased thirst or frequency, can signal kidney compromise. Jaundice, a yellowing of the gums, skin, or whites of the eyes, suggests a serious problem with liver function. If any of these severe signs are observed, stop administering robenacoxib immediately and seek emergency veterinary attention.
Robenacoxib is contraindicated in dehydrated cats, as this condition significantly increases the risk of kidney damage. It must never be given concurrently with other NSAIDs or corticosteroids, since this combination elevates the risk of severe gastrointestinal and renal complications. Owners must provide the veterinarian with a complete list of all medications and supplements the cat is receiving to ensure safe use.