Non-steroid anti-inflammatories (NSAIDs) are the fastest growing category of veterinary medicines. At the London Vet Clinic we use them to manage acute or chronic pain, to reduce inflammation and to lower high fevers. (Rather surprisingly, we also use them to slow the growth of certain forms of cancer such as bladder cancer.)
NSAIDs are divided into three ‘generations’. Broadly speaking, aspirin is first generation, carprofen (Rimadyl) and meloxicam (Metacam) are second generation and firocoxib (Previcox), mavacoxib (Trocoxil) and robenacoxib (Onsior) are third generation.
NSAIDs can produce unwanted side-effects, specifically stomach irritation, even ulceration. The second and third generation NSAIDs were developed to reduce gastric toxicity in humans. They did so but were also associated with fatal heart complications in people, due to atherosclerosis. This condition is virtually unknown in dogs and cats so it is not a major problem.
An alternative that we are presently trialing is robenacoxib (Onsior). Its mechanism of action suggests that it may have a longer duration of action and fewer side effects than second generation NSAIDs. Its high safety index applies to cats as well as dogs. Meloxicam (Metacam) and robenacoxib are the only NSAIDs licenced for use in cats.
Mavacoxib (Trocoxil) is unique in that it has an extremely long half-life. This means that a tablet need only be given once a month. We worried that if a dog had a toxic reaction to mavacoxib, that reaction would be prolonged because of the drug’s very long half life but that has not proven to be the case. In reality, if vomiting, for example, occurs it occurs for no longer than it does for other NSAIDs.
SAFE USE OF NSAIDS
We select NSAIDs for their safety , efficacy, ease of giving and cost. The most common side effects are gastrointestinal although kidney and liver problems are also possible. Unwanted side effects are most commonly associated with:
Too great a dose for the dog or cat’s body weight
Used together with another NSAID
Used together with corticosteroids
Accumulation of the drug in the body because or dehydration, kidney or liver dysfunction or other health issues.
HOW WE USE NSAIDs
We routinely use NSAIDs both during and after surgery to reduce pain. This is one reason we always give intravenous fluids to any surgical individual who may become dehydrated.
We routinely use NSAIDs (together with weight management, joint nutrients and controlled exercise) for dogs and cats with osteoarthritis. We are happy to provide repeat prescriptions but need to see your dog or cat at least once every six months, often for a blood test for liver and kidney function and signs of dehydration, before providing further medication.
WHAT ABOUT THE SLOW RESPONDER?
Each NSAID has its own mechanism of action. It’s frustrating but if one NSAID does not reduce your dog or cat’s osteoarthritic pain, the best course is through trial and error to try another. We usually like an internal of three to five days between finishing one NSAID and starting another. If we are stopping an NSAID because your pet has experienced an unwanted side effect we stop until we are satisfied that any pathological changes have resolved. We provide an alternative method of pain control during this internal.
CATS AND NSAIDs
Kidney disease is much more common in cats than in dogs. Osteoarthritis, on the other hand, is equally common in both species. This means that very accurate dosing is vital as is routine monitoring of kidney function. Because it is in liquid form we prefer meloxicam (Metacam) as it is easiest both to dose accurately and to give to cats.
OTHER DRUGS WE USE FOR OSTEOARTHRITIS
For long term management of osteoarthritic pain in dogs we use a ‘multi-mode’ approach. In addition to weight control, nutritional supplements and controlled exercise we initially use NSAIDs. If however this combination is not as effective as we want we frequently add pain killers (analgesics) licenced for use in humans that are also used extensively in dogs.
We use tramadol when pain affects your dog’s mood or behaviour. Lameness may not diminish but your dog seems happier even though it still limps. The most common side effect from tramadol is mild sedation.
We use gabapentin if we suspect neurological pain. Because it is metabolized by the liver and eliminated by the kidneys we usually run a routine blood sample before starting a course. As with tramadol, the most common side effect is mild sedation. NSAIDs, tramadol and gabapentin appear safe to use alongside each other.
Paracetemol is generally safe for dogs BUT HIGHLY TOXIC TO CATS. On its own it is not a very potent analgesic but when combined with an NSAID or tramadol it can be an effective pain killer. Paracetemol should be avoided in any dog with liver problems.
At the London Vet Clinic we may recommend nutritional supplements in combination with other strategies such as weight control, exercise modification, physiotherapy/hydrotherapy and environmental management in addition to drug therapy to manage chronic osteoarthritic pain in dogs.