Brand Name: EloxiOral, Loxicom, Melonex, Meloxidyl, Metacam, Mobic, Mobicox, Orocam, Ostilox 

Available in 7.5 & 15 mg tablets (human formulations) transmucosal spray & two strengths of oral suspension (veterinary formulations)

Background

Metacam is a member of the class of drugs known as NSAIDs (non-steroidal anti-inflammatory drugs), the same class as such common but not completely pet-safe over-the-counter remedies as Advil (ibuprofen), Aleve (naproxen), Orudis (ketoprofen), and aspirin as well as more controversial prescription drugs such as Celebrex (celecoxib) and Vioxx (rofecoxib). This class of drug is used for pain relief successfully in humans, but the development of safe NSAIDs for dogs has only been achieved relatively recently and continues to be problematic in cats. With the possible exception of aspirin, none of the human drugs listed above can be safely used in pets, and even aspirin has its issues.

While most humans are quite tolerant of NSAIDs, dogs and cats are more sensitive. The issues of concern that have prevented human NSAID use in pets are:

• Stomach ulceration - even perforation and rupture of the stomach can occur. This is not only painful but life-threatening.
• Platelet deactivation - platelets are the cells controlling the ability to clot blood, and, as a general rule, it is preferable not to promote bleeding. We would prefer platelets to remain active and able to function should we need them.
• Decreased blood supply to the kidney - this could tip a borderline patient into kidney failure.

A new plane of safety for pets was made possible by new biochemical knowledge. Inflammatory biochemicals responsible for the pain and inflammation we want to alleviate are produced by an enzyme called cyclo-oxygenase 2 or simply COX-2. The goal is to inhibit this enzyme without inhibiting its counterpart, cyclo-oxygenase 1. Cyclo-oxygenase 1, abbreviated COX-1, is what is called a constitutive enzyme. This means it is involved in producing regulatory biochemicals called prostaglandins that are important in maintaining the normal health and function of our bodies. We want to leave this enzyme alone. Cyclo-oxygenase 2, abbreviated COX-2, produces inflammation but is also important in regulating kidney blood flow and in some reproductive and central nervous system functions. We want to inhibit COX-2 in such a way that we do not disrupt its healthful functions.

In the past, NSAIDs could not distinguish the COX enzymes and inhibited them both. With the development of COX preferential and COX selective NSAIDs, we can inhibit COX-2 and leave COX-1 alone. The introduction of COX-2 preferential NSAIDs has reduced stomach and intestinal side effects by 50% in humans and has made FDA approval of certain NSAIDs possible for pets. Meloxicam was already available for human use, but human doses were way too high to be safe for most small animals. With an understanding of the COX system, oral liquids that can be precisely dosed for pets are now available.

How this Medication is Used

Meloxicam is generally given to control arthritis pain in dogs, although it can be given for many other painful conditions such as injuries, cancer, surgery, dental infections, and more. In dogs, it is typically given once a day as a pleasantly flavored liquid. The veterinary-approved product comes with a special dosing syringe marked to show how much to give for the pet's weight (rather than in milliliters as most syringes are marked).

Feline use of meloxicam is of some controversy. In Europe, Canada, Australia, and New Zealand, long-term use of the 0.5 mg/ml meloxicam formula in cats is registered, approved, and heavily marketed; however, this formula is not legally approved for cats in the United States. Further, the manufacturer has specifically discouraged feline use of meloxicam beyond its approved use in the U.S. (one dose for post-surgical pain relief). This paradox of marketing the product one way for most of the world and another way in the U.S. has been frustrating as there are substantially fewer oral pain relief options for cats available compared to what is available for dogs. Many veterinarians still use meloxicam for cats, but the advent of robenacoxib has provided a less controversial feline NSAID. Furthermore, there are other medications and supplements for feline pain relief that can be combined into a less controversial regimen.

If a dose is skipped, do not double up on the next dose. Give the dose when it is remembered and schedule the next dose accordingly. Store this product at room temperature.

Side Effects

Stomach upset: vomiting, diarrhea, and/or appetite loss are the important side effects to watch for, especially in the three weeks or so after beginning long-term meloxicam. These symptoms can have multiple meanings, so it is important to sort them out.

• Some pets are simply sensitive to NSAIDs despite the COX-preferential nature of meloxicam. These pets need nausea relief in the short term and a different pain management regimen after recovery.
  
  
• Some dogs have an unrecognized liver problem. Meloxicam is removed from the body by the liver, which means that a liver on meloxicam has extra work. This is not a problem for a normal liver, but a diseased liver could be tipped into failure from the extra load. This is why screening tests are so important prior to long-term use.
  
  
• Another problem manifesting with upset stomach is an idiosyncratic hepatopathy (a liver condition that is not dose-dependent or predictable in any way). While this only occurs in 1 in 5,000 dogs, it is a more serious problem that likely would require hospitalization.
  
  
• Altered kidney function (especially in cats) is a concern with any NSAID and might also manifest as an upset stomach. This is another reason why pre-screening of kidney function before long-term use is especially important before beginning meloxicam

If a pet on meloxicam develops an upset stomach, discontinue the medication and report the problem to your veterinarian. It is prudent to check liver enzymes and kidney function (a blood test) to rule out the two liver side effect issues and kidney issues that could be seen with an upset stomach.

Other side effects typically require other pre-existing conditions that could be made worse by giving an NSAID (even a COX-preferential one). See the Concerns and Cautions section.

It is important to realize that COX-selectivity is not the sole factor in NSAID safety.

Interactions with Other Drugs

Drugs of the NSAID class should not be used concurrently as the potential for the aforementioned side effects increases. For similar reasons, NSAIDS should not be used in conjunction with corticosteroid hormones such as prednisone, dexamethasone, etc. A five to seven-day rest period is recommended when changing from one NSAID to another. Aspirin poses an exception due to its strong platelet inactivating abilities so 10 to 14 days is recommended when switching to another veterinary NSAID from aspirin. Allow at least one week between prednisone and meloxicam.

ACE inhibitors such as enalapril, or benazepril may not be as effective when taken with meloxicam. (ACE inhibitors are used to treat hypertension or heart failure.) This is because ACE inhibitors depend on the dilation of blood vessels in the kidneys, and such dilation can be interfered with by NSAIDs.

NSAIDs also are associated with a particular idiosyncratic reaction in the liver. This reaction seems to be a canine issue only and resolves with discontinuation of the NSAID, but it can be life-threatening if ignored. There is no way to predict which dogs will have this reaction.

Concerns and Cautions

Meloxicam works as well when given on an empty stomach as when given on a full stomach. If a patient has had some upset stomach issues with meloxicam these can often be minimized by administering the drug on a full stomach.

Maximum effect is seen approximately 8 hours after administration. When beginning a trial course of meloxicam, a response may take 3 or 4 days to show. If no response has been seen in 10 days, meloxicam has failed, and a different pain medication should be tried. If one NSAID fails, another may well work.

The veterinary formulations of meloxicam are oral liquids (either 1.5mg/ml or 0.5 mg/ml). The liquid formulation allows for accuracy in dosing. The human tablets are available in much higher strengths and will be inappropriate except possibly for very large dogs. It is important not to use human medications on pets unless your veterinarian has provided detailed dosing instructions.

Meloxicam should not be used in pregnancy or in lactation.

Meloxicam can be used in cats but with caution (see above regarding use in countries outside the U.S.). The original oral solution of meloxicam was commonly dosed in drops from the bottle. Since the wrong dose of meloxicam can be very dangerous for cats, it is important not to drop the drops directly into the cat's mouth from the bottle, as squeezing too strongly could easily deliver an overdose. The low dose (0.5 mg/ml) formula can be dosed with the provided syringe.  In the cat, this product is given either as a single one-time injection in association with surgery (its FDA-approved use) or long-term two to three times per week (its non-U.S. dose). Long-term use of this product in cats is "off-label" in the U.S.

As with all veterinary NSAIDs, periodic monitoring tests are important to check liver enzymes and kidney function and to generally screen the patient's health. Typically, an every six months schedule is recommended for dogs. There is no general consensus on what is appropriate for cats, but because of feline sensitivity toward NSAIDs, feline monitoring is especially important. If you are using this product for the cat, be sure you understand what monitoring schedule your veterinarian is recommending for your specific pet.

Patients being considered for long-term meloxicam use should be evaluated with a complete physical examination and initial screening blood test to identify any factors, such as liver or kidney disease, that might preclude the use of this or any other NSAID.

Meloxicam should be avoided, if possible, in patients with impaired function of the liver, kidney, or heart. It should also be avoided in dehydrated patients and patients with known GI ulcers.

If a patient has borderline kidney function, NSAIDs should be used with great caution or not at all, as they reduce blood flow through the kidneys. It is also important that NSAIDS not be given to dehydrated patients because of this potential side effect. This is particularly true in cats.

For More Information

The manufacturer of veterinary meloxicam, Boehringer Ingelheim, offers more information.

See information on veterinary non-steroidal anti-inflammatory drugs from the Food and Drug Administration (FDA).