Controversies in Anaesthesia – When to Give NSAIDs

Last week’s webinar threw up statistics which were both reassuring and alarming. In 1999 only 50% of vets prescribed analgesia for patients undergoing routine surgery but reassuringly ,in 2013, 98% now give opiates and/or NSAIDs. However when you analyse this data further it showed that 75% of vets give NSAIDs to dogs undergoing surgery but alarmingly only 33.4% give NSAIDs to cats. These statistics were delivered by Matt Gurney BVSc CertVA DipECVAA MRCVS from NorthWest Surgeons who led last week’s veterinary webinar discussing ‘controversies in anaesthesia – when to give NSAIDs’ and strongly believes that any animal in pain should be given an NSAID unless there is a very good reason not to. 

Concurrent use of steroids and ACE inhibitors in patients include some of the reasons to avoid NSAIDs and their use in trauma patient is also controversial. Matt cited a retrospective study looking at 185 cats which had been referred onwards secondary to trauma. 35% of these cases were in shock at presentation and 52% of these shocked cats had been given a NSAID which in Matt’s opinion may be a little too hasty in the shocked patient. Matt advises always ensuring patients have normal blood pressure and are fully hydrated prior to giving an NSAID. Matt’s usual first line analgesic in trauma cases would be methadone at a dose of 0.3mg/kg IV/IM in cats which can always be titrated up in 0.1mg/kg increments. 

The use of NSAIDs alongside steroids is contra-indicated as it has been associated with significant gastric ulceration and the addition of antacids to try and counteract this effect is unlikely to be successful.   Matt advised paracetamol as an alternative drug to consider in dogs where NSAIDs are contraindicated , with a small retrospective study showing a reduction in the dose of methadone required in those patients given paracetamol.  However a larger prospective study is required to prove the benefits associated with the use of paracetamol in dogs. 

The use of concurrent ACE-inhibitors alongside NSAIDs can also be problematic as it is feared they may potentiate hypotension  during anaesthesia and it is also a highly protein bound drug which may compete with other protein bound compounds. It is recommended that ACE inhibitors be stopped 24 hours before and after surgery in order to minimize any associated side effects. 

Matt also stressed that ‘cats need NSAIDs too’. A study in 1998 showed pain control provided by NSAIDs was superior to that of pain control provided by opiates. However there is a reason why only 33.4% of vets provide NSAIDs to cats undergoing surgery and I suspect concern lays with the potential detrimental effects NSAIDs could have on renal function especially in cats suffering from renal disease. Matt cited a case of a cat requiring a dental which had mild azotaemia after pre-anaesthetic bloods were performed. Under these circumstances Matt advised optimising this cat’s circulating volume by providing fluid therapy prior to the anaesthetic and the presence of a full bladder after fluid therapy is always a good indicator of good hydration. Ideally Matt advises all patients should be provided with fluid therapy and have their BP monitored  throughout an anaesthetic. Occasionally some patients will go on to develop acute kidney injury following an anaesthetic but if BP has been monitored regularly and fluid therapy provided then it is unlikely that any further interventions would have made any difference to these idiosyncratic cases. 

In concluding this veterinary webinar Matt advised that NSAIDs are safe and efficacious drugs to use as long as we consider each case individually. The importance of a multimodal approach to pain control was also emphasized with the use of local anaesthetics playing an important role alongside opiates and NSAIDs.  Matt’s main objective in leading this webinar was to ensure vets would consider using NSAIDs as a significant part of the pain control strategy during surgery when deemed appropriate and for me this is exactly what he has achieved. 

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