Updated: Oct 14, 2020
A common question I am asked is should I go multimodal from day one in osteoarthritis with my analgesics?
Let's be clear - NSAIDs are always our first line, unless we can find a clear contra-indication. NSAIDs are the most effective drugs in this situation as well as being veterinary licensed. Before we consider options beyond NSAIDs, read this first.
To date there are no specific indications of superiority regarding safety or efficacy with NSAIDs. Factors influencing choice between drugs and preparations relate to compliance which is certainly the most important factor with long-term use.
It has been demonstrated that cyclo-oxygenase (COX) enzymes play a role in central sensitisation (Samad and others 2001, Veiga and others 2004) and that COX inhibitors can inhibit this process (Veiga and others 2004), hence the rationale for NSAID use on a long-term basis. OA is a progressive disease and our aim is excellent control of peripheral processes in order to prevent central sensitisation - preventive analgesia.
Central sensitisation (CS) can drive disease progression in joints via a downward modulatory effect whereby central changes stimulate further inflammation in the peripheral tissues. The hope here is that by controlling (or preventing) CS with NSAID use a peripheral benefit can be noted longer term (Sluka et al 1994). Ask yourself how painful the pet is and whether you think there could be central sensitisation - this will help decide if you should add other agents earlier on.
It helps to explain to all owners that OA is progressive and that at some stage we will need to add another drug to control the pain. Incorporating pain scoring can help judge this.
No studies have evaluated the comparative efficacy of everyday versus intermittent NSAID therapy in dogs with osteoarthritis and current recommendations are for daily use. The concept of dose reduction has been studied with meloxicam. The authors concluded that dose reduction is possible on a long term basis however if the dose is reduced to less than 60% labeled dose the risk of pain breakthrough increases (Wernham et al 2011). Rationale for reducing dose in the hope of a reduction in adverse effects is not supported by the literature.
Two studies examined by Innes et al (2010) support the concept that pain levels decrease over time and it is the author’s opinion that NSAID treatment should continue for at least 30 days before assessing response which is supported by the findings of Reymond et al (2012) who investigated the use of robenacoxib or carprofen in dogs suffering with osteoarthritis. For all efficacy endpoints (veterinarian and owner derived), mean scores decreased with both robenacoxib and carprofen progressively up to the last time point at day 84.
Analgesic prescribing will not deal with all of the factors associated with arthritis. Canine Arthritis Management is an excellent resource with information for vets and owner on managing arthritis in a true multimodal sense where everything matters.
So we should prescribe NSAIDs for 30 days and ensure that the owner can administer the drug effectively. At that point we should reassess progress and use pain scores. If we need a second option my preferred number 2 is amantadine and you can read here the rationale for that along with doses. If the NSAID fails to control the pain adequately then move to amantadine sooner.
Other options for OA management in dogs include paracetamol which is explored here. Of huge benefit to many of my patients, both dogs and cats is acupuncture - especially for pets with concurrent disease where some medications may be contra-indicated.
Management of osteoarthritis is multimodal and requires regular reassessment. There is a clear role here for team work with vets and nurses to ensure that all angles are met in delivering excellent care. Getting the analgesia right for the individual pet is key and will enable the patient to undertake the physical therapy aspects with improved comfort levels.