Could Carprodyl Kill your Dog?

The headline in today’s Daily Mail is typically attention-grabbing: “Could the drug that cost this beloved pet its life
kill YOUR dog too?” The article tells the sad story of a thirteen year old Labrador who died after taking pain-relieving
medication prescribed by her vet. There’s no doubt that many owners of elderly, arthritis-ridden dogs will be rushing to
their vets this week to find out if their own pets are at risk of the same fate.
So what is this drug? Why do vets prescribe medicine which may risk such a severe reaction? And when they do use it,
why don’t they tell owners about the potential dangers?
First, the medication was Carprodyl, a generic form of a chemical called carprofen, which is part of a group of drugs
known as non-steroidal anti-inflammatory drugs (NSAIDS). Carprofen has become perhaps the most widely used pain
relieving medication used in veterinary medicine since it was launched as “Rimadyl” by Pfizer, around fifteen years
ago. The patent on the chemical has now lapsed, so a wide range of cheaper generic alternatives have become available.
Most vet clinics in the UK are likely to sell some version of the product.
Second, why do vets prescribe it? Simply put, because it’s the most effective way of treating arthritis in dogs. Many
millions of older animals have been given extra, pain-free life thanks to this type of medication. Three years ago, a
major review was published in the Vet Record, comparing the wide range of treatments available to help dogs with
the common, painful, debilitating problem of arthritis. The review gathered together the results of research papers
published between 1985 and 2007, attempting to derive the best science-based opinion of the best treatment method.
The conclusion? There was strong evidence that carprofen and two other commonly used drugs from the same group
were “effective in moderating the clinical signs of osteoarthritis”. There was only weak or moderate evidence that other
treatments were effective. The conclusion for any vet reading this paper was clear: carprofen and other similar drugs are
the most effective way of helping animals with arthritis.
Obviously, an effective drug needs to be safe, so what about those risks? While it’s true that all drugs in this group can
have undesirable and potentially life threatening consequences, the incidence is very low. The most common side effect
is gastric irritation: affected dogs suffer from gastroenteritis which usually resolves when the medication is stopped.
Much more rarely, there’s a very low risk of kidney failure associated with non-steroidal anti-inflammatory drugs. The
cause of this is complicated: it’s more common in geriatric patients suffering from underlying heart, kidney or liver
disease, but it can seem to happen in a random fashion. To minimise this risk, vets may suggest blood or urine tests
before starting a dog onto anti-arthritis medication. Such tests don’t completely remove the small risk, and they add
significantly to the cost of treatment for a pet, so they aren’t always done.
So finally, why don’t vets always tell owners about the potential dangers of such medication? There’s a lot of variation
in what happens here: some vets do take the time to tell owners about every possible side effect of every drug that’s
used. The problem with this approach is that it’s time consuming, leading to longer (and more expensive) consultations
for owners. Most owners don’t particularly want to hear a long list of potential side effects that are unlikely to happen,
and they’re happy to trust that the vet, on balance, feels that the medication is most appropriate having taken all the risks
and benefits into account.
Vets may also feel that detailed listings of potential adverse reactions may lead to unnecessary worrying for an owner,
so they just mention the most common side effects (“stop the tablets and let me know if she gets an upset stomach”).
Sometimes a compromise may be to hand out the package insert with the tablets: the owner can then read the full list of
possible complications if they so wish (and if they have a magnifying glass).
I feel very sorry for the owners of any animal that suffers the consequences of a serious adverse reaction to medication.
There’s no easy answer here, but there’s a simple message: if you want to know about potential side effects of any drug,
ask your vet. We’re happy to tell you if you’re happy to listen. It’s likely that the same treatment decision will still
be made, but at least, in the rare instance of a severe reaction, you won’t have that awful sense of unfairness that you
weren’t told about the risk.

The headline in today’s Daily Mail is typically attention-grabbing: “Could the drug that cost this beloved pet its life kill YOUR dog too?” The article tells the sad story of a thirteen year old Labrador who died after taking pain-relieving medication prescribed by her vet. There’s no doubt that many owners of elderly, arthritis-ridden dogs will be rushing to their vets this week to find out if their own pets are at risk of the same fate.

So what is this drug? Why do vets prescribe medicine which may risk such a severe reaction? And when they do use it, why don’t they tell owners about the potential dangers?

First, the medication was Carprodyl, a generic form of a chemical called carprofen, which is part of a group of drugs known as non-steroidal anti-inflammatory drugs (NSAIDS). Carprofen has become perhaps the most widely used pain relieving medication used in veterinary medicine since it was launched as “Rimadyl” by Pfizer, around fifteen years ago. The patent on the chemical has now lapsed, so a wide range of cheaper generic alternatives have become available. Most vet clinics in the UK are likely to sell some version of the product.

Second, why do vets prescribe it? Simply put, because it’s the most effective way of treating arthritis in dogs. Many millions of older animals have been given extra, pain-free life thanks to this type of medication. Three years ago, a major review was published in the Vet Record, comparing the wide range of treatments available to help dogs with the common, painful, debilitating problem of arthritis. The review gathered together the results of research papers published between 1985 and 2007, attempting to derive the best science-based opinion of the best treatment method. The conclusion? There was strong evidence that carprofen and two other commonly used drugs from the same group were “effective in moderating the clinical signs of osteoarthritis”. There was only weak or moderate evidence that other treatments were effective. The conclusion for any vet reading this paper was clear: carprofen and other similar drugs are the most effective way of helping animals with arthritis.

Obviously, an effective drug needs to be safe, so what about those risks? While it’s true that all drugs in this group can have undesirable and potentially life threatening consequences, the incidence is very low. The most common side effect is gastric irritation: affected dogs suffer from gastroenteritis which usually resolves when the medication is stopped. Much more rarely, there’s a very low risk of kidney failure associated with non-steroidal anti-inflammatory drugs. The cause of this is complicated: it’s more common in geriatric patients suffering from underlying heart, kidney or liver disease, but it can seem to happen in a random fashion. To minimise this risk, vets may suggest blood or urine tests before starting a dog onto anti-arthritis medication. Such tests don’t completely remove the small risk, and they add significantly to the cost of treatment for a pet, so they aren’t always done.

So finally, why don’t vets always tell owners about the potential dangers of such medication? There’s a lot of variation in what happens here: some vets do take the time to tell owners about every possible side effect of every drug that’s used. The problem with this approach is that it’s time consuming, leading to longer (and more expensive) consultations for owners. Most owners don’t particularly want to hear a long list of potential side effects that are unlikely to happen, and they’re happy to trust that the vet, on balance, feels that the medication is most appropriate having taken all the risks and benefits into account.

Vets may also feel that detailed listings of potential adverse reactions may lead to unnecessary worrying for an owner, so they just mention the most common side effects (“stop the tablets and let me know if she gets an upset stomach”).

Sometimes a compromise may be to hand out the package insert with the tablets: the owner can then read the full list of possible complications if they so wish (and if they have a magnifying glass).

I  feel very sorry for the owners of any animal that suffers the consequences of a serious adverse reaction to medication. There’s no easy answer here, but there’s a simple message: if you want to know about potential side effects of any drug, ask your vet.  We’re happy to tell you if you’re happy to listen. It’s likely that the same treatment decision will still be made, but at least, in the rare instance of a severe reaction, you won’t have that awful sense of unfairness that you weren’t told about the risk.

If you are concerned that your dog is ill or sick please use our interactive dog symptom guide to find out what you should do

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