Rimadyl is a brand of nonsteroidal anti-inflammatory drug that contains the active ingredient Carprofen. It is one of the FDA-approved pain relievers intended primarily for use on dogs with osteoarthritis and other inflammatory conditions where swelling and pain are the principal manifestations. Rimadyl exerts its effects by inhibiting the action of two isoenzymes in the dog’s body that mediate inflammatory reactions. Since it is approved by the FDA for use on dogs, it can only be obtained with a written prescription from a licensed veterinarian.
Rimadyl for dogs is currently indicated in the management of the following conditions:
- Canine osteoarthritis
Osteoarthritis is typified by the presence of inflammation in the joints as a result of the loss of bone tissue mass at the ends of each bone. Since this part of the bone is becoming more porous, sending fragments into the joint capsule, it causes irritation and inflammation in the said capsule. Rimadyl helps by modifying the prostaglandins that are present in such inflammatory processes.
- Canine inflammatory conditions
Any inflammatory condition can benefit from the use of Rimadyl. For instance, if there is toothache, Rimadyl can also be given since it works to negate the effects of prostaglandins as well as other substances of inflammation. It can also be used on other forms of canine arthritis as well as hip dysplasia, which is very common in certain breeds of dogs.
- Postoperative pain and inflammation
Surgical procedures, although described as highly controlled tissue injuries, will always produce inflammation as a result of such injuries to the tissues. Carprofen can help lessen the severity of pain and inflammation by acting on the different substances that mediate such processes.
An integral element of any inflammation is a rise in temperature, be it localized or the entire organism. Since the mechanism of action of carprofen is in the inhibition of both COX-1 and COX-2 isoenzymes, it should be able to reduce body temperatures in dogs with fever.
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Benefits of Rimadyl
The following are the benefits of Rimadyl for dogs.
- Reduces swelling as well as other manifestations of inflammation.
- Decreases pain sensation as a result of inflammatory processes.
- Improves overall mobility and level of physical activity.
- Assists in the faster resolution of tissue injuries and surgical wounds.
- Reduces fever associated with inflammatory conditions.
How Rimadyl Works
The anti-inflammatory and analgesic properties of Rimadyl are closely associated with its principal ingredient, Carprofen. This type of analgesic belongs to the group called nonsteroidal anti-inflammatory drugs that work to inhibit the effects of the enzymes cyclooxygenases 1 and 2 (COX-1 and COX-2) although its specificity to target COX-2 enzyme is species-dependent.
Nonsteroidal anti-inflammatory drugs or NSAIDs are divided into 2 major groups, depending on whether they exhibit specificity to COX-2 enzymes or not. Carprofen falls under the non-selective type of NSAIDs and thus can be clustered together with naproxen and ibuprofen. Selective NSAIDs are denoted by the presence of ‘coxib’ in their suffix such as ‘celecoxib’, the main ingredient of another anti-inflammatory analgesic for dogs, Celebrex.
To understand the mode of action of Rimadyl, it is important to understand what cyclooxygenases do in the first place. These enzymes are responsible for hastening the rate of formation of the pro-inflammatory substances prostaglandins and thromboxanes. Prostaglandins are major players in the initiation of inflammatory processes while thromboxanes are important in the formation of blood clots. Blood clotting is needed in tissue injuries to help prevent massive blood losses, putting a plug at the site of the tissue injury. Additionally, prostaglandins are powerful inhibitors of platelet aggregation or clumping. Technically, they’re the opposite of thromboxanes.
Carprofen works by preventing the conversion of arachidonic acid into prostaglandins and thromboxanes by acting on the isoenzymes that help facilitate such processes to occur. It is wise to understand that the process will still push through, however at a much slower rate. Enzymes are catalysts. They only speed up chemical processes so you don’t have to wait millennia (pun intended) for the process to be completed.
That said, acting on cyclooxygenases 1 and 2 will only slow down the process of inflammation. Technically, this slowed-down process should be enough to allow other immune system cells to manage the inflammation.
Potential Side Effects
Because of the effects of carprofen on both prostaglandins and thromboxanes, one can expect a myriad of potential effects other than its anti-inflammatory and analgesic benefits. It is generally safe, however, except for some potential issues in the gastrointestinal tract, kidneys, and liver. The following are just some of the better-known side effects of Rimadyl for dogs.
- Loose, watery, or very frequent passage of stools
- Retching or vomiting
- Decreased appetite
- Increased thirst
- Frequent urination
- Dry mouth
- Unusual sleepiness or drowsiness
- Loss of coordinated movements
- Fatigue or inability to complete an activity
- Stumbling or staggering gait
These are still considered to be generally mild to moderate side effects of Rimadyl. Unfortunately, there have been reports of dogs dying all of a sudden after receiving Rimadyl. This prompted the FDA to request the manufacturer of Rimadyl, Pfizer, to advise pet parents that one of the potential side effects of Rimadyl is death.
Other potentially serious side effects of Rimadyl include the following.
- Partial or full paralysis
- Blood in the stool or urine
- Dark, tarry stools
The latter side effect is almost always a manifestation of an upper GI bleeding, most likely due to gastric or duodenal ulcerations. If there is blood in the stool, it usually is an indication of lower GI bleeding. The presence of blood in the urine is always indicative of massive damage to the kidneys. If any of the serious adverse reactions are preset, you should stop giving Rimadyl immediately and seek veterinary consultation.
It is also possible for certain dogs to present with allergic reactions. They may show swelling of the face, tongue, or lips as well as hives and difficulty breathing. If any of these develops over the course of Rimadyl therapy, you need to seek veterinary advice at once.
Things You Should Know about Rimadyl
Rimadyl for dogs is a duly-approved anti-inflammatory drug for use in canines with osteoarthritis and other conditions where the principal manifestation is inflammation, swelling, and pain. It requires a valid prescription from a duly-licensed veterinarian owing to some serious side effects associated with bleeding in the dog’s gastrointestinal tract.
What You Should Tell Your Vet before He Prescribes Rimadyl
It is important for your vet to know if your pet has any allergies to NSAIDs or even to aspirin. It is also critical that any history of stomach ulcers, active or latent kidney or liver disease, bleeding disorder, high blood pressure, history of fluid retention, or a diagnosis of congestive heart failure or any other heart disease be divulged to your vet. Lactating and pregnant dogs may also have to be given other treatments.
How to Give Rimadyl to Your Dog
The recommended dose of Rimadyl is 2 milligrams for every pound of a dog’s body weight. The computed dose can be given once a day or divided into two doses to be given 12 hours apart. Because of the potential of Rimadyl to cause gastrointestinal upset, it should always be administered with food. It is also important to give dogs plenty of water to aid in the more efficient elimination of the drug from the dog’s kidneys.
Rimadyl for dogs is available in 3 dose formulations containing 25, 75, and 100 milligrams in flavorful chewable tablet form. It is also available in a non-chewable formulation with the same dose formulation. Under no circumstances should Rimadyl be given to cats or any other pet or animal.
What to Do If You Miss a Dose
In the likelihood that a dose of Rimadyl is missed, the missed dose should be administered at once. However, if the time of administration is only a few hours away from the next scheduled administration of Rimadyl, then the missed dose should be considered as such – missed. Compensating for the missed dose should never be attempted. Just resume the normal dose scheduling as if the missed dose did not occur.
What to Do in Case of Rimadyl Overdose
One of the clearest signs that Rimadyl overdose has occurred is the sudden appearance of the adverse reactions we have outlined above. More specifically, if you notice any of the signs of gastric ulcerations such as vomiting with blood-streaked vomitus or defecating black and tarry stool, the dog should be brought to an emergency facility at once. Other manifestations you have to watch out for include stomachache, headache, blurred vision, excessive panting, drowsiness, scant or absent urine, and very slow breathing.
Some Drug Interactions
Aspirin and other NSAIDs have the potential to adversely interact with Rimadyl. Cough and cold remedies as well as drugs for allergy may also interact with carprofen. Other substances that Rimadyl may interact with include warfarin, prednisone, probenecid, insulin, and furosemide. If there are other drugs, supplements, or even nutraceuticals that you’re giving to your pet, you may have to inform your vet about these.
Rimadyl for dogs is an effective way to manage pain and inflammation in arthritis in dogs as well as other inflammatory conditions and pain syndromes. While it is effective, Rimadyl also poses several safety issues related to its action on cyclooxygenases.