In all species, NSAIDs can impair renal blood flow and may complicate renal compromise, worsen congestive heart failure because
of their antidiuretic effects, and increase the nephrotoxicity of other drugs. Most of the veterinary literature, including
that on cats, has examined the analgesic efficacy of various NSAIDs in healthy patients. Thus, when treating a geriatric patient
with potentially limited renal reserve, use NSAIDs with caution. Cats with known renal disease should probably not receive
NSAIDs at all. Although COX-2 selective NSAIDs have a safer profile with respect to gastrointestinal ulceration, these drugs
still have the potential to cause gastrointestinal ulcers, particularly in patients that are stressed, inappetent, or critically
ill. Finally, NSAIDs are highly protein-bound and may displace other protein-bound drugs, resulting in a more profound effect
of the displaced drug. For example, in people given aspirin who then received the highly protein-bound drug midazolam, there
was an enhanced sedative effect from the benzodiazepine.21
In studies evaluating the analgesic efficacy of the various NSAIDs, typically for surgical procedures for which postoperative
pain is expected to subside within 24 to 36 hours (e.g. ovariohysterectomy, castration), the modern NSAIDs ketoprofen, carprofen, and meloxicam performed well. In one study comparing
the use of carprofen, ketoprofen, and meloxicam (all given once only), there was no difference among treatments in pain scores
of cats after ovariohysterectomy; overall pain scores were generally low, albeit higher than baseline values.17 In another study comparing butorphanol with carprofen, the researchers found no difference in analgesia between the two drugs,
although cats given either drug had significantly higher pain scores than their baseline scores through 12 hours postoperatively.22
The use of NSAIDs for analgesia in cats should be reserved for healthy cats undergoing only moderately painful procedures
(e.g. teeth cleaning, castration, treatment of simple abscesses) if the NSAID is used as the sole analgesic agent. Combine NSAIDs
with opioid analgesics for major visceral or orthopedic procedures, such as ovariohysterectomy and fracture repair. In cats
receiving glucocorticoids, avoid administering NSAIDs because of the combined risk for gastrointestinal ulceration. Do not
use NSAIDs in cats with renal compromise, congestive heart failure, preexisting gastrointestinal ulceration, or severe systemic
disease. Use them only with caution in geriatric cats. Finally, administer intravenous fluids to cats undergoing general anesthesia
expected to last longer than 20 to 30 minutes that have received an NSAID perioperatively. Intravenous fluid administration
helps preserve renal blood flow in the face of the NSAID's potentially adverse effect on renal perfusion by blocking prostaglandin-mediated
renal vasodilation that occurs in response to the reduced renal blood flow from the effects of general anesthesia (e.g. decreased cardiac output and blood pressure).
Q How effective is meloxicam as an analgesic in cats? What dosages are recommended for various situations and conditions?
Meloxicam is not more effective against pain in cats than any of the other modern NSAIDs described in the last section, but
its oral syrup formulation seems to be more palatable to cats and, thus, owner compliance is better.
The recommended initial dose for meloxicam is 0.1 to 0.2 mg/kg given subcutaneously (injectable formulation), intravenously
(injectable formulation), or orally (syrup formulation), followed by 0.1 mg/kg given orally once a day for no more than three
days, followed by 0.1 mg/cat or 0.025 mg/kg (based on lean body weight) either twice weekly or every other day.14 Meloxicam is FDA-approved in cats in only the injectable formulation for a one-time-only dose of 0.3 mg/kg subcutaneously.
Thus, long-term use of meloxicam, or the use of the syrup, is extralabel in cats. The syringe that comes with meloxicam is
too large to be useful in cats, so take time to instruct owners on proper administration when dispensing meloxicam.