For the memory of Baxter.

All non-steroidal anti-inflammatory’s (NSAID’s) should be used with caution. Rimadyl (Carprofen) belongs to this class of drug, it is the main focus of this article. Much of the information here can equally be applied to other NSAID’s, particularly in regards to care and welfare of the animal in the case of an adverse reaction. However, as many of them have different modes of action, their side effects can vary. First and foremost, if you suspect your Newfie or pet is having an adverse reaction to any drug (not just NSAID’s), immediately discontinue its use and contact your vet, as swift intervention is critically important.

Rimadyl was introduced in 1997 and has become the drug of choice for treating arthritis, relieving pain and reducing inflammation. It is a selective cyclooxygenase-2 (COX-2) inhibitor, which is a major factor in the inflammatory pathway. In its first three years it was prescribed to more than 5 million dogs globally. Pfizer has published that in 1999, the adverse reaction rate was an extremely low 0.18%, so the chances of side effects occurring may be viewed as being rare. The US Food and Drug Administrations (FDA), Centre for Veterinary Medicine (CVM), received in Rimadyl’s first year of use 3626 adverse reaction reports which accounted for 39% of reports for all animal drugs. For any one of these reports, the actual cause of the illness may or may not have been directly attributable to Rimadyl.

Side effects of Rimadyl can cause vomiting, diarrhea, changes in appetite and drinking patterns, lethargy, behavioral changes, bloating of the abdomen, jaundice, changes in urination and constipation. Gastric problems are typically the first sign of a reaction. The adverse reactions (ADR’s) associated with this, as published by its manufacturer Pfizer include:

Gastrointestinal: Vomiting, diarrhea, inappetance, melena, hematemesis, gastrointestinal ulceration.
Behavioral: Sedation, lethargy, hyperactivity, restlessness, aggressiveness.
Hepatic: Inappetance, vomiting, jaundice, acute hepatic toxicity, hepatic enzyme elevation, abnormal liver function test(s), hyperbilirubinemia, hyperbilirubinuria, hypoalbuminemia. Approximately one-third of hepatic reports were in Labrador Retrievers.
Renal: Hematuria, polyuria, polydipsia, urinary incontinence, urinary tract infection, azotaemia, acute renal failure, tubular abnormalities including acute tubular necrosis, renal tubular acidosis, glucosuria.
Neurologic: Ataxia, paresis, paralysis, seizures, vestibular signs.
Hematologic: Immune-mediated hemolytic anemia, immune-mediated thrombocylopenia, blood loss anemia.
Dermatologic: Pruritis, increase shedding, alopecia, pyotraumatic moist dermatitis (hot spots), necrotizing panniculitis/vasculitis, ventral ecchymosis.
Immunologin or hypersensitivity: Facial swelling, hives, erythema.

While it has yet to be acknowledged by Pfizer and no cases have been recorded by the FDA, scientific literature does indicate that thrombotic and ischaemic (blood clotting) events could be caused by this type of drug (we are aware of one Newfie who may have been adversely effected in this manner).

Extreme cases can lead to death.

Many of these complications can be misdiagnosed by a vet as some other disease or ailment. This is in no fault of the vet, it is easy to suspect the symptoms are caused by other means, as an ADR is fairly uncommon and in some instances the vet may not have seen an ADR to this class of drug or be aware that they can occur. Pfizer initially published with this drug in its release that there were no known side effects. With years of use in millions of dogs a more accurate picture is becoming available and the data is being updated constantly.

It is often recommended that your dog have blood screening before taking the drug and to also have blood screening done during the course of treatment if the prescription is for a long course (eg. to treat arthritis). This is particularly helpful in spotting liver and kidney damage (although it can be cost prohibitive). There is no remedy to treat a reaction other than to treat the symptoms. In some instances it is advisable for the animal to be placed on an intravenous drip to ensure hydration. If in the instances of gastrointestinal problems, a change of diet is recommended until your animal is fully recovered.

With any drug prescribed by your vet, it is strongly urged that you request a package insert as this contains important information on the drug (this is applicable if the drug is repackaged from large stocks into small containers). Please read this pamphlet closely so that you are able to make an informed decision about whether or not to use the drug. Many pharmaceutical companies do not provide your veterinarian with enough of these pamphlets to be handed to each customer. Your vet should be able to obtain these via request to the company or you may be able to obtain them via the company’s own website. The implementation of any drug should be based on a risk/benefit assessment. Always ask yourself whether the benefits outweigh the risks. Searches of the web for information on side effects can be problematic as some reports may be unsubstantiated.

For arthritis, pain and inflammation, there are alternatives, some of which are natural, such as glucosamine (with or without chondroitin), acupuncture, homeopathy, chiropractic and holistic healing.

Note: This article is not meant to be alarmist in anyway. The aim of this article is to provide the reader with an understanding that while adverse reactions are rare, they can and do occur and can have life threatening consequences.

The information contained here is a brief outline. There is much more information on the subject than can be published here. If you have any questions please first consult your vet. You are also welcome to contact Damian Adams via email damian.adams@adelaide.edu.au if you would like more information or have concerns.