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How NSAIDs Work in Dogs


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Non-steroidal anti-inflammatory medications (NSAIDs) are the most frequently prescribed drugs to treat pain and inflammation in dogs. They can be used in the short term, for instance postoperatively or after a traumatic injury, or over longer periods of time from chronic conditions like osteoarthritis.

Veterinary NSAIDs are very safe, but owners and doctors must carefully weigh their potential benefits and risks in before deciding whether to use one and picking the best drug based on an individual patient’s circumstances. Understanding how NSAIDs work helps owners be informed partners in decision-making.

The Role of Inflammation

NSAID Medications Infographic

Inflammation is central to how the body heals from injury and illness. It plays a role in the destruction of invading microorganisms and the removal of damaged or abnormal cells. Problems arise, however, when inflammation is too intense, develops in response to an inappropriate trigger, and/or continues on long after its useful time period. Inflammation is also not always selective and can damage nearby, healthy tissues.

The symptoms of inflammation in dogs are redness, warmth, swelling, and most importantly, pain. Non-steroidal anti-inflammatories are analgesics in part because they reduce the inflammation that triggers the sensation of pain.

"Inflammation is central to how the body heals from injury and illness, but it's not always selective and can damage nearby, healthy tissues."

When cells in the body are damaged, either because of disease or injury, they release chemical signals known as prostaglandins via the cyclooxygenase (COX-2) pathway. Prostaglandins make the nerves that transmit signals to the brain more sensitive to painful stimuli. Therefore, medications that limit the activity of the COX-2 pathway reduce the production of prostaglandins, relieve pain, and even help prevent some of the tissue damage that can result from rampant inflammation.

NSAIDs can also make patients less painful through their direct action on the spinal cord via inhibition of a process known as wind-up.

Other Roles for Prostaglandins in the Body

Prostaglandins are not just associated with inflammation. Another cyclooxygenase pathway (COX-1) makes prostaglandins that are important to the normal functioning of a dog’s body, including the production of mucus that protects the inner lining of the stomach, regulation of gastric acid secretion, and the kidney’s ability to excrete water.

Older non-steroidal anti-inflammatory medications (e.g., aspirin) reduce the production of prostaglandins through both the COX-1 and COX-2 pathways. As a result, they are more likely to be associated with side-effects like gastrointestinal ulcers caused by increased gastric acid production than medications that more selectively block the COX-2 pathway. In fact, dogs have to receive a low dose of aspirin to reduce the chances of an adverse event that the drug has questionable efficacy as a canine pain reliever.

The Benefits of “New” Dog Pain Relievers

Modern NSAID medications more selectively block the COX-2 versus the COX-1 pathway of prostaglandin production or have other changes to their molecular structure that reduce the incidence of side-effects associated with their use. As a result, veterinarians can prescribe doses that are high enough to provide good pain relief while not putting a dog’s health at undue risk. Examples of NSAIDs developed specifically for dogs include:

NSAIDs can be used on either an as-needed basis or daily for the treatment of more severe, chronic pain. Owners can modify their dogs’ NSAID dose on a day-to-day basis in response to the patient’s comfort level, but it is vital that dogs never receive more of an NSAID than has been prescribed by their veterinarian.

Reducing the Chance of Side Effects

The most common side effects related to the use of NSAIDs in dogs are associated with their effect on the gastrointestinal tract and include vomiting, diarrhea, poor appetite, and lethargy.

If a dog ever develops these symptoms while being treated with an NSAID, owners should stop giving the medication and call a veterinarian immediately. In the vast majority of cases, dogs that experience adverse effects as a result of NSAID use recover rapidly once they receive appropriate treatment. However, more serious gastrointestinal damage (e.g., perforating ulcers) and kidney or liver disease is infrequently reported with NSAID use in dogs, so veterinary attention should not be delayed.

While no NSAID is without the risk of side effects, wise decision-making greatly reduces the already small chance that a dog will develop health problems associated with their use. For example,

  • A veterinarian should perform a history, physical examination, and screening lab work before prescribing an NSAID to determine whether the medication is an appropriate choice for that individual patient. NSAIDs must be used with caution in patients with preexisting liver, kidney, or gastrointestinal disease. Lab work should be repeated on a regular basis (often once or twice a year) throughout the duration of treatment.
  • NSAIDs should be used judiciously. The goal is to find the lowest dose given as infrequently as possible for the shortest period of time while not compromising the dog’s comfort level. Often, NSAID doses can be reduced by using them in combination with other pain relievers (e.g., tramadol), nutritional supplements (e.g., Dasuquin, Glyco-Flex, and vitamin E), weight loss, physical therapy, and acupuncture.
  • Never use more than one type of NSAID at the same time or an NSAID in combination with a corticosteroid (e.g., prednisone). Treating a pet with more than one of these medications at a time greatly increases the risk of an adverse reaction.
  • When switching between NSAIDs, a five to seven day washout period during which time a dog receives no similar medications helps to reduce potentially deleterious drug interactions. To keep patients comfortable during this time an alternative class of pain-reliever (e.g., tramadol) can be used.

The development of newer, canine-specific non-steroidal anti-inflammatories has revolutionized the treatment of pain in dogs. Inexpensive, generic versions of these medications (e.g., carprofen) are readily available, so there is little reason to resort to the older drugs like aspirin that are associated with a high incidence of side effects in dogs.


Sources

Veterinary Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). U.S. Food and Drug Administration. Product Safety Information. Accessed 12/14/12.

Cyclooxygenase and NSAIDs. State University of New York at Albany. Accessed 12/14/12.

NSAIDS: Striking a balance. American Animal Hospital Association. Accessed 12/14/12.

The above is provided for information purposes only and should not be used for the diagnosis or treatment of any condition. This information does not cover all possible variables, conditions, reactions, or risks relating to any topic, medication, or product and should not be considered complete. Certain products or medications may have risks and you should always consult your local veterinarian concerning the treatment of your pet. Any trademarks are the property of their respective owners.