Pain management is essential for the health of pets and strengthening relationships between veterinarians, pets, and their owners. The communication barrier between veterinarians and animals, and the subjectiveness of pain can cause challenges in practice. Pain scoring puts a number or scale on the pain experienced and dictates the need for management. There are multiple approaches to managing pain, and both traditional and new research should be considered.
In a clinical setting, pain measurement is based on self-evaluation, otherwise, there is no way for clinicians to know how both it feels and makes you feel. Animals however are unable to communicate with us their level of pain, so clearly, this is not an option. It is also believed they do not understand why it occurs or can anticipate relief.
Although many signs can be observed, it can still be difficult to locate the pain and determine how it is making them feel. Yet the need to quantify pain is incredibly important in treating and managing pain in animals. Not only is it essential in decreasing morbidity, but also for the welfare of the animal.
Although pain is complex it can be categorised as either acute or chronic.
When the pain is evoked by a specific disease or injury and has a biological purpose during healing it is considered acute. Examples of this include cuts or wounds, elective surgical procedures, and acute onset of disease.
When the pain persists beyond the expected course of the acute disease process and has no biological purpose it is called chronic. Chronic pain is thought to have a significant impact on the psychology of the patient.
Pain should be managed according to the time it persists for. Treatment for acute pain focuses on the underlying cause and interrupting nervous system signals. Whereas with chronic pain a multidisciplinary and holistic approach is necessary for the patient’s quality of life.
So how can you put a number on the pain that your patient is in?
Firstly, we should consider the baseline of typical behaviour and the factors which may be affecting pain. Take some time to become familiar with your patient and their history.
Conduct a thorough examination of the patient’s behaviour, mobility, and site of pain. Also consider the patient’s species, environment, site of pain, temperament, and history.
Observing physical and behavioural cues such as the patient's facial expression, body movements, crying, and behavioural states are considered gold standards for measuring pain.
Physiological indicators and biological markers can also provide additional information but must consider underlying conditions.
During physical exams use your fingers and hands to feel the patient and assess for abnormalities in an organ or body part.
Imagery can increase comprehension of the level of pain, this can include graphing trends, and using visual scales and diagrams.
Pain management requires anticipation, early intervention, and regular evaluation of patient response.
Scales attempt to place pain on a range for how minor to severe it is. Still, this is not the be-all-end-all solution for determining pain in animals.
The observer's expectations for how the animal should be feeling in response to stimuli can result in a bias. This could mean that if an analgesic has been administered, it may be assumed that they will feel a lower amount of pain than they actually are.
Let’s compare some of the tools available for pain measurement.
Simple descriptive scales (SDS) are based on observers choosing a grade from 3-5 that best fits the patient's pain.
| PROS | Easy to use, require little training and there is a possibility for owners to use it at home. |
| CONS |
High variability, oversimplified, lacks standardisation, and a limited amount of response options. |
In visual analogue scales (VAS) pain is measured based on observations from an absence of pain at 0 mm to maximal pain at 100 mm.
| PROS | More sensitive than SDS. |
| CONS |
Still significant variability, observer visual/motor coordination can reduce accurate mark allocation, and there is no guidance built into the scoring system, so it requires more training than SDS and VRS. |
Numerical rating scales have descriptors associated with each number but are otherwise like VAS
| PROS | More sensitive than SDS and more reliable than VAS. |
| CONS | Still significant variability. |
Essentially a modified version of VAS, dynamic and interactive visual analogue scales but patients are observed when resting, being handled and moving.
| PROS | More accurate than SDS |
| CONS |
Time-consuming. |
The Glasgow Composite Measure Pain Scale (CMPS) is a multidimensional tool that uses a psychometric approach. It is applied to patients suffering acute pain and is highly effective in clinical trials. Although it has an elevated level of precision it is difficult to use and tedious.
CMP-SF is the short form and constitutes six behavioural categories. It is more practical than the CMP and easier to carry out, score and interpret.
Once the severity of the pain is identified, it should be managed effectively.
Multiple medications should be used that complement each other to target the multiple steps in pain perception and decrease side effects. There needs to be careful consideration of the pain level anticipated and the needs of the patient when choosing the right medications.
| Opioids |
Incredibly powerful in the management of chronic pain, they work well with a-2 adrenergic agonists. Combined they provide elevated levels of sedation and pain relief. |
| NSAIDs |
Used to treat fever, inflammation, and pain. Can be administered before surgery, or for the management of acute and chronic pain states. |
| Local anaesthesia | Beneficial in rendering complete pain relief, they are considered safe and should be used in all surgeries. |
| A-2 Adrenergic agonists |
Because of the adjacent receptors to opioids, they pair well together. They are reliable in being able to provide pain relief, and sedate and relax muscles in dogs and cats. |
| Ketamine |
When used preoperatively it can prevent hypersensitivities to pain. It is still being researched for its applications in pain relief but there are promising results that it can reduce pain and speed up recovery. |
At the same time pain management isn't all about drugs.
Compelling evidence supports that treatments other than medications are still fundamental in pain management.
Techniques that increase healing progression by restoration of strength and increasing muscle flexibility.
Therapeutic exercises like static weight-bearing aids can improve blood and lymph flow, and in humans have been shown to provide pain relief like NSAIDs.
Physical modalities include temperature therapy (hot and cold), laser therapy, electrical stimulation and more.
Manual techniques can increase circulation, reduce swelling, and restore joint function through hands-on treatment such as joint mobilisation and trigger point pressure.
Physical rehabilitation aims to restore strength, function, endurance, and senses to reduce pain in patients' bones and muscles.
Nutritional screening should be made a regular part of check up and is especially important for pain examinations. This is because nutritional imbalances can risk the development of orthopaedic diseases.
Maintenance or progression to a leaner body decreases the risk of disease including degenerative joint diseases. Weight loss is believed to reduce the feeling of pain in both dogs and cats.
Increased pain sensitivity can directly result from stress, anxiety, fear, and distress. Ensure gentle patient handling which avoids sites of pain. Provide soft cushioned surfaces for bedding and position patients so their injured limbs are elevated. Additionally, massage can soothe patients but should only be used when the patient is used to human contact.
The insertion of fine needles into the skin works by releasing endorphins and increasing serotonin levels. Although it requires additional training and is complex in terms of its placement, it has shown to be an effective pain management technique.
Apply gentle pressure to the patient's soft tissues with your hands. It can provide psychological relief of stress and anxiety and therefore alleviate pain. Also physiologically improves blood flow and mobilises lymphatic fluid to speed up recovery.
In severe cases or where pharmacological and adjunctive therapies fail, a surgical approach is required. This may include limb amputation, joint replacement, excision arthroplasty, arthrodesis, and denervation.
There are exciting advancements in the ways we can treat pain. Using cognitive strategies or antidepressants which are popular for humans, behavioural training, and hyperbaric oxygen therapy (HBO) are just some examples.
You should not underestimate the impact of the state of mind and pain perception. By taking simple measures to reduce anxiety, stress and fear associated with vet visits, your patients' pain can be directly alleviated.
Injuries or the prevention of recovery which are caused by behavioural issues need to be ironed out. Pet owners should be referred to an animal behavioralist for a care plan. An in-home or virtual visit may also be beneficial so that a professional can observe behaviours and implement training.
Technologies widely used for humans like HBO have shown promising results in pain management for animals too. HBO is providing the patient with pure oxygen in a pressurised environment. The University of Florida College of Veterinary Medicine Small Animal Hospital showed that it can reduce swelling and improve healing and infection control.
Unidimensional scales like the SDS, VAS and NRS are practical and easier to complete but limited in understanding the experience of pain. They only evaluate the sensory dimension of pain and are highly variable to the observer bias.
Multidimensional tools such as DIVAS and VRS can look at a wider pain experience. They are more accurate but are limited by the time they require to complete in comparison to unidimensional scales. CMP-SF is a useful indicator of pain it is valid and reliable and quicker then CMPS
Pain management needs to be multimodal in terms of the medication administered and include non-pharmacological approaches. There are exciting developments in techniques to reduce pain perception, like the fear-free technique, behavioural training, and HBO therapy.
Understanding pain in animals is complex and should be evaluated in a manner that observes all aspects. Effective treatment needs to be based on the measured pain level and focus on both medicinal and drug-free techniques.
Do you use any of these scoring tools or pain management techniques in your practice? Feel free to share your experiences in the comments.