Carprofen for Dogs
Overview of Carprofen Use for Pets
Carprofen is an anti-inflammatory and analgesic drug for dogs. Better known as Rimadyl®, Novox®, Vetrprofen®, or Quellin®, this medication is used to treat pain and inflammation. Carprofen is a propionic acid that falls in the category of drugs called nonsteroidal anti-inflammatories (NSAIDs). It is not FDA approved for cats in the US, but is used frequently in dogs. This is a prescription medication and needs to be prescribed by a veterinarian, since it is not available over the counter.
NSAIDs inhibit the production of prostaglandins from arachidonic acid by the enzyme cyclooxygenase (COX). Prostaglandins are lipid compounds in the body that help maintain normal organ function and mediate physiological responses like inflammation. They are important in maintaining the normal health of the GI tract and are involved in the healing process of gastric ulcers. Prostaglandins also help in normal kidney function and act as a protective measure when the kidney is experiencing hypovolemia (volume depletion).
NSAIDS can also inhibit the production of thromboxane, which can hinder platelet aggregation.
There are two forms of cyclooxygenase enzymes: COX-1 and COX-2:
- COX-1 is associated with the normal production of prostaglandins that protect the gastric mucosa and help with normal platelet production.
- COX-2 is associated with the normal production of prostaglandins that help with brain function. More importantly, it gets induced during inflammation and helps with recovery and pain signaling.
NSAID medications can be COX nonspecific, meaning that they equally inhibit both non-selective COX-1 and COX-2, or they can be COX-2 selective. Carprofen is a non-selective COX inhibitor. This means it has action on COX-1 and COX-2. Other non-veterinary specific drugs that follow in this same category include: aspirin, ibuprofen, and naproxen. NSAIDs work by reducing pain, inflammation and fever. Unfortunately, they also have the risk of causing gastric ulcers, liver injury, and kidney injury.
Dogs and cats are overly sensitive to NSAID medications, therefore human NSAID medications are not recommended for use in these pets. Carprofen was designed with consideration for these species and, therefore, is uniquely created for them. There are other veterinary-approved NSAID medications that use these same considerations, some of which are non-selective COX inhibitors or veterinary-approved COX-2 selective.
Uses of Carprofen for Dogs
Carprofen is used in dogs for treatment of pain, inflammation, and in chronic conditions like arthritis. This medication is used in the post-operative period after orthopedic surgery. It is not commonly used for dogs that are having gastrointestinal distress (vomiting, diarrhea, loss of appetite) or in dogs that have underlying liver or kidney disease. Due to carprofen’s mechanism of action on both COX-1 and COX-2, this medication can cause gastrointestinal upset and kidney injury. Pet parents should be cautious administering any NSAID to dogs that have underlying kidney disease, since these dogs should not receive a non-selective COX inhibitor.
This drug is extremely useful in treating young, healthy, active dogs that have sustained soft-tissue injuries or are recovering from orthopedic surgery. This medication is used commonly in dogs recovering from Cranial Cruciate Ligament injuries.
Carprofen is also used for long-term management of arthritis. Chronic pain from osteoarthritis is noted in 20% of the dog population, and carprofen helps manage pain, improve mobility, and minimize inflammation. Using NSAIDs in addition to supplements and lifestyle modifications can greatly improve the quality of life in dogs with arthritis.
Carprofen can be also used as an adjunctive treatment of certain cancers in dogs to mitigate any pain or inflammation.
A veterinary visit is required before administering carprofen. During this visit, your vet will perform a physical exam to help localize the source of pain and inflammation and determine if NSAID medication is warranted. Prior to starting any NSAID, a blood work panel that checks liver and kidney values will be performed. This is an important step, since it helps to identify any underlying abnormalities and avoid the prescription of carprofen to a dog with underlying lab elevations.
Side Effects of Carprofen
Gastrointestinal issues are the most common side effects seen with carprofen. Injuries can be mild, such as irritation to gastric ulcerations, or as severe as perforation of the gastrointestinal tract.
Clinical signs to watch for include:
- Black/tarry stool
- Decreased/reduced or absent appetite
STOP carprofen use if any gastrointestinal side effects are noted and contact your veterinarian.
Underlying liver disease can be unmasked when taking carprofen, as well as idiosyncratic hepatopathy. An idiosyncratic hepatopathy is the development of a liver condition secondary to carprofen that is not predictable and not due to the dosage of the medication. These reactions are frustrating, since they are unpredictable and can go undetected on blood work before starting medication. This condition is often reversible with supportive care and ending carprofen use. If this condition develops, hospitalization is often required.
Due to non-selective COX inhibition, some dogs will develop renal injury while on this medication. Serial blood work monitoring helps to identify any rise in kidney values.
Clinical signs that indicate renal injury are:
- Increased thirst
- Increased urination
- Change in urine color, smell, and/or frequency
- Straining to urinate
Carprofen should not be given concurrently with other NSAID medications. Using multiple COX inhibitors together multiplies the risk of gastrointestinal, liver, and kidney injuries. Those using an NSAID need a multiple day wash-out period before starting a different NSAID.
Carprofen should also not be used concurrently with steroidal anti-inflammatory (corticosteroids) medications such as prednisone, prednisolone, dexamethasone, temaril-P, depomedrol, and hydrocortisone. Using NSAID medications with corticosteroids can cause severe gastrointestinal injuries and increase the likelihood of intestinal perforation. Those on NSAIDs need a multiple day wash-out period before starting corticosteroids or vice versa.
Caution should be used if taking carprofen and phenobarbital concurrently. Phenobarbital is a barbiturate medication that is used to treat seizure disorders in dogs. These medications both require metabolism by the liver and could interfere with efficacy when used together. More frequent blood work monitoring may be needed if on these medications together for a long period of time.
Carprofen may also interfere with the efficacy of certain blood pressure medications. ACE inhibitor blood pressure medications, such as enalapril and benazepril, need dilation of vessels by the kidneys to be effective. Carprofen can interfere with the mechanism of these drugs. Monitoring of blood pressure should be done frequently and one or both medications may need to be altered.
How Carprofen Is Supplied
Carprofen comes in an injectable formulation for in-hospital use, in addition to oral pills for at-home use. Often, the pills are chewable, flavored tablets to ease administration of the medication. Caution should be taken to avoid leaving bottles of this medication on the counter or unattended, as they could inadvertently be ingested. Dogs can develop NSAID toxicities from ingesting an overdose of this medication.
The most common type of carprofen toxicity is due to ingestion of a large quantity of chewable tablets. This can be done by the dog that was prescribed the medication or by a housemate. Any overdose of carprofen needs to be addressed with a veterinarian and they will determine the appropriate course of treatment. The sooner treatment is initiated, the less likely injury will occur. Pet poison hotlines can also be used to discuss an overdose.
Treatment of carprofen toxicity includes inducing vomiting soon after ingestion, followed up by activated charcoal administration by a veterinarian to limit further medication absorption. Depending on the dose ingested and timeline, admission to the hospital for IV fluids and gastroprotectants, with serial blood work monitoring, may be recommended. A carprofen overdose should not be ignored as it can be life threatening.
Dosing Information for Dogs
Dosing is dependent on each individual dog and the underlying medical condition. This medication is generally given once to twice a day at home. The first dose will be given as an injection while in the hospital, followed by a transition to pills at home. The duration of administration depends on the specific condition, response to medication, and development of adverse effects.
Veterinary Follow Up
Long term use of carprofen requires regular blood work to monitor liver and kidney values. Based on each dog and their underlying medical condition, a plan will be established by your veterinarian for follow-up appointments, which should be performed every 6 months. A recheck should be made if side effects are noted or new clinical signs emerge.
Veterinary-prescribed carprofen should only be used for the patient it was prescribed for and should not be used for puppies under 6 weeks of age. This medication should not be used in human treatment and should be kept away from children.
Cats and Carprofen
Pain and inflammation can also occur in cats. Carprofen is not currently FDA approved for cats in the United States, despite being approved in the UK. Cats are particularly susceptible to NSAID injuries and tolerate selective COX-2 NSAID medications better than non-selective. There are two NSAID medications that are COX-2 selective that have been approved for cats, which are robenacoxib (Onsior®) and meloxicam (Metacam®). These medications should be preferentially used in cats over carprofen. Cats need blood work to evaluate liver and kidney function prior to starting these medications. Emergency medical care is needed if a cat consumes carprofen, since this could lead to severe side effects.
Alternate Treatment Measures
Alternatives to carprofen for treating pain and inflammation include:
- Other NSAID medications (both non-selective and selective).
- Corticosteroid medications. These tend to be more beneficial for inflammation and less for pain control.
- Opioid pain medications. These can be used concurrently with carprofen for moderate to severe conditions or used solely in NSAID sensitive/contraindicated dogs.
- Gabapentin. This medication helps more for nerve-derived pain and less for inflammation. This can be used concurrently or as a sole agent to treat pain.