In the month of new resolutions, I always think the best I can do for my painful patients is to understand how to look for pain! I’m currently reviewing some literature for another project and this paper by Bell et al (2014) is on the reading list.
It’s from 2014 (but I think very relevant to 2021) and examines the attitudes of vets to chronic pain. The authors are experienced pain researchers and ask pertinent questions.
The paper reports the results of a survey in which 300 respondents, a mixture of first opinion vets and worldwide specialists in anaesthesia and oncology, were asked to answer questions on their attitudes to chronic pain. The authors describe their intentions to;
· Determine the most commonly perceived causes of chronic pain in dogs in UK practice.
· Determine the classes of analgesic drugs commonly administered to dogs with chronic pain.
· Determine how painful different cancers are in the eyes of practitioners.
· Determine how often analgesia is administered to cancer pain patients.
· Analyse trends in the above according to demographics.
The top cause of chronic pain was osteoarthritis (OA), with the top five including dental, aural, spinal and neoplasia. This paper cites 20% of the canine population being affected with OA, with other experts (Lascelles, unpublished observation) rating this figure as high as 50%. The take home message here is that we all have a chronic pain caseload.
We are well-equipped to deal with chronic pain arising from mild to moderate OA with licensed classes of drugs (the NSAIDs and the piprants) and some promising options on the near horizon targeting nerve growth factor. Beyond these options we are limited with licensed options – but that doesn’t mean that those licensed options are ineffective or that we should instantly reach for off licence analgesics.
Classes of drugs reportedly used by vets in this survey for chronic pain included NSAIDs, corticosteroids, NMDA antagonists, gabapentin, amitriptyline and bisphosphonates. NSAIDs ranked highly in being drugs used frequently for the treatment of chronic pain. Opioids featured in these reports – assumed to be related to the availability of tramadol in general practice, although there are no studies to date documenting the efficacy of tramadol in OA in dogs – although the story in cats may be a little more promising.
The evidence in general for gabapentin in any type of chronic pain is limited, and we rely on anecdote or experience in lieu of evidence. This survey did not mention pregabalin as an option – a recent study documents pregabalin as an effective analgesic in dogs following spinal surgery. We plan to review the gabapentinoids in an upcoming webinar so watch this space.
The respondents of this survey rarely used NMDA antagonists such as amantadine and memantine. The evidence for amantadine supports it use as a second line agent in addition to NSAIDs in OA which we review here. Memantine is an option which has been explored in lieu of amantadine and you can find details here. With an understanding of the mechanisms of chronic pain and the 2008 Lascelles study you will see why amantadine is my second line for OA pain. In cancer pain we have central sensitisation, so I consider amantadine a logical option for such cases.
The bisphosphonates were rarely used by respondents of this survey – which is surprising given the high numbers of specialist oncologists responding to this work. Perhaps it is a reflection of my experience and oncologists I have worked with who consider pamidronate or zoledronic acid effective options in management of bone cancer pain. I will add this topic to the list for a pain update! I consider the pain of bone cancer to be very difficult to manage effectively with oral analgesics and often use a combination of oral medications, ketamine by infusion and targetted nerve blocks.
Acupuncture and physiotherapy were options that a number of respondents mentioned in this work as having a significant benefit on rehabilitation.
When asked about pain and provision of analgesia, there was a significant correlation between pain attributed to a condition and the tendency to provide analgesia. Primary bone tumour rated as a condition in which analgesia was always provided, followed by oral tumours whereas analgesia was rarely prescribed for skin, lung and mammary tumours. In any neoplastic condition, pain management and quality of life go hand in hand and the use of a health-related quality of life instrument such as Vetmetrica provides the means for owners to monitor their pet’s pain.
On the topic of neoplasia, 55.8% agree that pain associated with cancer was underdiagnosed. When asked about the statement ‘Pain associated with cancer is easy to treat’, 55.4% disagreed. Reasons for this were discussed and included;
Multiple mechanisms
Concurrent disease
Debility caused by the tumour
We will explore cancer pain in a separate pain update.
The major barriers to effective chronic pain management were documented as:
Difficulties with pain assessment
Despite a number of pain scales for assessment of chronic pain, it seems this is still a barrier. The authors highlight the importance of behavioural observations in this assessment and recommend using a pain scale which incorporates this. Other authors remind us of the importance of selecting the correct pain scale for the circumstance and understanding the limitations of what that scale can achieve.
Expense of drugs
With chronic pain, it is unlikely that one agent can achieve comfort. The multimodal approach will certainly increase cost. Bear in mind this is a vet’s interpretation of the situation and does not necessarily mean that owners will consider cost a barrier.
Owner compliance
Although considered a significant factor, the only compliance studies that exist in the veterinary literature relate to antibiotic administration. Whether findings regarding analgesics would be similar is another question. For us as pain practitioners we should aim to prescribe analgesics that the owner can administer easily to the pet at the frequency that is achievable.
Other barriers which were discussed are a lack of knowledge, side effects and licensing. Lack of knowledge need not be a barrier with our telemedicine service. The Zero Pain Philosophy team will provide case advice on any pain condition and provide recommendations to veterinary surgeons to help manage any painful case. Find out more here. With our knowledge and experience we can help you navigate any questions regarding side effects and licensing.
This paper raises a number of questions that need further exploration. Over the coming months we will expand on these topics in our pain updates, webinars and podcasts. Join our mailing list to receive notifications of when these updates happen. Our site members receive all of our content for a monthly subscription. Find out more here about our cost effective options for the whole practice.
You can only find pain if you look for it. If pain is hard to detect, consider an analgesic trial. If you need help with a case, please do not hesitate to consider contacting us for a telemedicine consultation. We are here to help and will use our knowledge and experience to give your patients the best.
References
Bell, A., Helm, J., & Reid, J. (2014). Veterinarians’ attitudes to chronic pain in dogs. Veterinary Record, 175(17), 428. https://doi.org/10.1136/vr.102352
This post was written by Matt Gurney.
Matt & Carl established Zero Pain Philosophy to provide educational resources & telemedicine to veterinary professionals enabling optimal management of pain.
Matt Gurney is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and is Head of Anaesthesia at Anderson Moores Veterinary Specialists. Matt is President of the European College of Veterinary Anaesthesia & Analgesia.
Carl Bradbrook is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and is President of the Association of Veterinary Anaesthetists. Carl works at Anderson Moores Veterinary Specialists.