Download Rimadyl – Reproduced with permission of Canine Health Concern©

Rimadyl – Reproduced with permission of Canine Health Concern©
Rimadyl (Carprofen) was introduced by Pfizer Pharmaceuticals in 1997, has proven to be a
successful means of relieving arthritis symptoms in dogs. Many users feel it has vastly
improved the quality of their dogs’ lives and, in some cases, even extended their lives.
However, there is a growing body of evidence showing that the drug has serious side
effects. Some dogs have died due to the unexpected rapid onset of side effects, and/or
because the drugs side effects were not recognised by the attending veterinarian who did
not take the appropriate action.
It was not at first 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, Pfizer’s report on side effects that occurred during the drugs initial postapproval phase states, “.... 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 Lab.
Many breeds, including Labradors, are represented in the population that has experienced
side effects or fatal outcome from Rimadyl. Although the deaths and side effects reported
on their site are only a representative sample, you will find many different breeds named in
the reports.
Cautions about Administering Rimadyl
In the data sheet, Veterinarians are advised to pre-screen a dog before prescribing Rimadyl
and then to retest 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
side effects might occur. (Not: 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 alongside any other non-steroidal anti-inflammatory drug
(NSAID) such as aspirin, or along with any corticosteroids such as prednisone, prednisolone
or dexamethasone. The University at Davis California 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 the
appropriate liver monitoring be performed. (Mar Vista Animal Hospital recommends bile
acid testing every six 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 not to give to pregnant or
nursing females because it has not been tested on them.
In cases where dogs have a toxic reaction 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.
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
(http://www.srdogs.com/Pages/rimadylfr.html) has undertaken the task of posting reports
of both negative and positive experiences with Rimadyl. The negative reports far outweigh
the positive: However, that is not unexpected since people tend more often to report
problems than satisfaction.
Quite unexpected, however, and most disturbing 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, an number of dogs have died – in many instances due to
lack of knowledge about the drugs side effects. Some of those dogs could have been saved,
had kidney and liver functions been monitored, the symptoms recognised, the withdrawn in
time, and supportive therapy instituted. In other cases, the onset of liver, kidney or other
problems was 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. The Senior Dogs Project website 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 you 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?
Some Important Issues that have arisen from information received by the Senior Dogs
Project
1. Is Pfizer doing enough to inform and educate veterinarians and the public about the
administration and possible side effects of Rimadyl?
2. Should Rimadyl be recommended as a general pain reliever/anti-inflammatory, or
are the potential side effects too serious for any situations but those in which there
seems to be no safer alternative?
3. A new drug often produces side effects that were not evident in the clinical trials
that led to FDA approval. However, is the incidence of deaths and other severe
debilitation seemingly attributable to Rimadyl within acceptable FDA limits?
4. Is Pfizer consistent in recognising when Rimadyl is implicated and in reimbursing for
related medical expenses?
5. Is it appropriate for Pfizer to require “gag” orders (confidentiality Agreements) be
signed in exchange for payments of medical expenses to people whose dogs have
taken Rimadyl and had adverse drug experiences?