The Senior Dogs Project
"Blessed is the person who has earned the love of an old dog."
Important: If you believe your dog is experiencing an adverse reaction to Rimadyl, go directly to the Rimadyl Take Action Page.
The History of Rimadyl
Rimadyl (Carprofen), introduced by Pfizer Pharmaceuticals in January 1997, has proven to be a successful means of relieving arthritis symptoms in dogs. (In June, 2013, Pfizer's animal health division became "Zoetis.") Many users feel Rimadyl has vastly improved the quality of their dogs' lives and, in some cases, even extended their lives. Rimadyl is also often prescribed for post-operative pain. According to the Pfizer website, as of January 2012, more than 16 million dogs had used RIMADYL. However, over the years, a growing body of evidence has shown that the drug has serious side effects. Some dogs have died due to the unexpectedly rapid onset of side effects, and/or because the drug's side effects were not recognized by the attending veterinarian who did not take appropriate action. The Food and Drug Administration's Center for Veterinary Medicine maintains a list of thousands of Adverse Drug Events (ADE's)due to Rimadyl. The last time we reviewed these reports the date range was 01/01/1987 through 11/30/2011. Scroll to page 190 to see the types of ADE's and number shown for "Carprofen." You will find such events as 5,686 incidents of vomiting; 5,116 of anorexia; 3,941 of depression /lethargy; 2,052 deaths; 1,870 diarrhea; etc.)
Initially, it was not clear that Labradors were particularly susceptible to Rimadyl toxicity, since Labradors, more than other breeds, have joint problems and are given Rimadyl for relief. However, during the drug's initial post-approval phase Pfizer stated, ". . . approximately one fourth of all hepatic reports were in Labrador Retrievers." This appears to be an alarmingly high incidence and should guide your choice of using Rimadyl if your dog is a Labrador Retriever.
Many breeds, including Labrador Retrievers, are represented in the population that has experienced side effects or a fatal outcome from Rimadyl. Although the deaths and side effects reported on this site are only a representative sample, you will find many different breeds named in the reports.
Cautions about Administering Rimadyl
Please read the Food and Drug Administration's Center for Veterinary Medicine guidelines for non-steroidal anti-inflammatory drugs.
Veterinarians are advised to pre-screen a dog before prescribing Rimadyl and then to re-test and closely monitor the dog for possible toxic reactions at periodic intervals. The Senior Dogs Project has had repeated reports from people who have discussed Rimadyl with their vets and found that their vets were not aware that pre-screening and regular monitoring were suggested (but not required) by Pfizer. In many cases, the vets were not aware of the side-effects of the drug, or the period during which the side-effects might occur. (Note: Although originally this period was thought to be two to six weeks, adverse reactions have been reported after a matter of hours.)
Carprofen is not recommended for animals with known bleeding disorders and should not be used if a dog has pre-existing liver disease, inflammatory bowel disease, or a known tendency towards gastrointestinal ulceration.
Rimadyl should never be given along with any other non-steroidal anti-inflammatory drug (NSAID) such as aspirin, or along with any corticosteroids such as prednisone, prednisolone, or dexamethasone. The University of California at Davis recommends a two week "rest" period when changing from any NSAID to carprofen or from carprofen to another NSAID.
If Carprofen is used concurrently with phenobarbital, it is especially important that appropriate liver monitoring be performed. (Mar Vista Animal Hospital recommends bile acids testing every 6 months for dogs on phenobarbital.) ACE inhibitors such as enalapril or captopril may not be as effective in the presence of carprofen. (ACE inhibitors are used in the treatment of hypertension or heart failure.) It is also advised that the drug not be given to pregnant or nursing females because it has not been tested with them.
In cases where dogs have had toxic reactions and recovered, continued monitoring over an extended period (perhaps as long as a year) may be advisable because the long-term effects of liver or other organ damage are not yet known.
Deciding to Use Rimadyl
Carefully decide whether Rimadyl is appropriate for your dog by weighing the benefits against the risks. Keep in mind that it has been widely reported that many veterinarians are not fully informed about this drug. As Stephen Fried so eloquently summarizes in his book, Bitter Pills: "It's a question of whether the potential benefit is worth the risk and whether the patient understands that risk -- which depends on whether the doctor knows enough about the drug to really explain the risk."
If you decide your dog may benefit from Rimadyl and it is worth the risks involved, tell your vet that you want to determine the lowest possible dosage that can be used to obtain relief. Although the recommended dosage is 1mg/pound of weight twice per day, your dog may get relief at a lower dosage. A lower dosage could be instrumental in avoiding toxicity (although this is not guaranteed). In addition, your vet may recommend that Rimadyl be used for short periods (several weeks), or intermittently, as needed, with time off (several weeks) to give the dog's liver time to recover.
Insist on baseline tests and continued monitoring of the relevant functions during the entire time your dog takes the drug. Pfizer only recommends this and does not indicate that it is a requirement.
To avoid the gastric upset that occurs in some dogs, the drug should be given with food. Pepcid may also be used concurrently to control gastric upset.
As soon as your dog begins Rimadyl therapy and during the entire time he takes it, watch for the following symptoms, which are all signs of potential life-threatening reactions to the drug:
In the presence of any of these symptoms, IMMEDIATELY STOP the drug and take your dog to the vet. The earlier you catch the problem, the better the chances of complete recovery. For step-by-step instructions, go to the Rimadyl Take Action Page.
It will be helpful to Pfizer and may help to save your or another dog's life if you report any negative reactions your dog has or had when taking Rimadyl. You need only have a suspicion that Rimadyl is implicated. You may call Pfizer at 1-800-366-5288 and the FDA at: 1-888-332-8387 (or 1-888-FDA-VETS).
A Review of the Controversy about Rimadyl
Is Rimadyl a "miracle drug" that can help your dog? Or are the potential side effects too dangerous? There is a line-up on both sides of the issue. This website has undertaken the task of posting reports of both negative and positive experiences with Rimadyl. The negative reports far outnumber the positive; however, that is not unexpected, since people tend more often to report problems than satisfaction.
Quite unexpected, however, and most distressing are these factors that are emerging: (1) the lack of adequate warning about the potential side effects of the drug; (2) the number of veterinarians who seem unaware that Rimadyl has any side effects at all; (3) the severity and at times sudden onset of the side effects, which include death.
The bottom line: Many dogs seem to benefit from taking Rimadyl. Some who might have been euthanized due to mobility problems have been returned to excellent function and quality of life. On the other hand, a number of dogs have died -- in many instances due to lack of knowledge about the drug's side effects. Some of these dogs could have been saved, had kidney and liver functions been monitored, the symptoms been recognized, the drug withdrawn in time, and supportive therapy instituted. In other cases, the onset of liver, kidney or other problems was so sudden and severe, there was no possibility of reversing the effects. The Pfizer literature states that Rimadyl sometimes "uncovers" an existing condition. It is not always possible to prove that the drug was responsible for causing the condition.
Recommendations: Be fully informed about Rimadyl's potential side effects. Be sure your veterinarian is fully informed, as well. This site provides or has links to all the currently available information about drug administration, side effects, and symptoms. Read the material carefully and thoroughly. Share it with your vet. With this information and in consultation with your vet, decide whether the risks are worth the potential benefits of the drug for your dog. Should you decide to use Rimadyl, observe your dog closely for signs of side effects, and have your vet do baseline screening and regular monitoring as suggested by Pfizer.
Over the years since the introduction of Rimadyl, a large network of concerned consumers has formed to be supportive to guardians of dogs that appear to be suffering adverse side effects of Rimadyl. The need for this network grew out of the realization that many vets (in some cases fearful of litigation for malpractice) refused to admit that a drug they had prescribed could be the cause of a dog's illness or death. If you need the support of this network, you may access it by writing to the following E-mail address: email@example.com
Information Provided in a Technical Bulletin from Pfizer Animal Health -- Excerpts
The Technical Bulletin issued by Pfizer Animal Health in May 1998 is entitled, "First-Year Clinical Experience with Rimadyl (carprofen): Assessment of Product Safety." Here are some of the main points Pfizer makes in the bulletin:
One million dogs in approximately 22,000 veterinary practices were treated with Rimadyl during 1997. The vast majority of dogs have benefited from pain relief provided by Rimadyl, and experienced an improved quality of life.
Approximately 70% of possible adverse drug event reports received by Pfizer Animal Health have been in dogs 8 years of age or older. In a recent study [McPhail CM, Jappin MR, Meyer D, et al: Hepatocellular toxicity associated with carprofen administration in 21 dogs. JVIM 12 (3:214 May-June 1998, Abstract)], 21 dogs developed liver toxicity while on Rimadyl therapy. Of these, 17 recovered when the drug was discontinued and they received supportive care. Three dogs died and one dog was euthanized.
Pfizer states that, "Fortunately, reported adverse events associated with Rimadyl are small in number (approximately 0.2%, or 2/10ths of 1% of all dogs treated in 1997) and generally resolve with discontinuance."
NSAID therapy, according to Pfizer, "could potentially unmask occult disease, which has previously been undiagnosed. . . . " and further, Pfizer states, ". . . animals may have 'silent' ulcer disease characterized by a lack of clinical signs." Regarding kidneys, Pfizer notes, "Pre-existing occult renal disease, common in geriatric dogs, may be exacerbated by the administration of any NSAID, including Rimadyl."
Specifically for geriatric patients, Pfizer recommends the following as being "prudent": 1. Complete history and physical exam before dispensing NSAID. 2. Definitive diagnosis for NSAID therapy so therapeutic response can be monitored. 3. Baseline and repeat laboratory data should be considered on a case-by-case basis. 4. Follow-up communication with owners. 5. Inform owners of clinical signs of drug intolerance. 6. Repeat laboratory tests before refilling prescriptions, especially in patients with history of gastrointestinal signs, renal and hepatic disease. 7. Recheck evaluations after 3-4 weeks, then 3-6 months thereafter in patients requiring chronic NSAID therapy.
Pfizer announces in this bulletin that, " . . . Pfizer provides financial support for reasonable and appropriate diagnostic evaluations" in order to "define causality when possible."
The signs of possible drug intolerance listed in a table in the report are: decreased appetite, lethargy, vomiting, diarrhea, abnormal urination, abnormal water consumption, behavioral changes. "In all cases of suspected adverse reactions, the drug should be discontinued and supportive care shold be given, based on evaluation of history, clinical signs and physical examination." The type of supportive care mentioned in the bulletin is "intravenous fluid therapy."
|To our world-wide visitors: Please note that, in your country, "Rimadyl" may be known as "Carprofen" or "Zenecarp" or "Norocarp" (the UK generic version of Rimadyl). All are the same drug. Thus, if your vet prescribes it by any of these names, the same cautions apply.|