19 Mar
Sarah Heath details some of the behavioural signs and advice for educating caregivers on what to look for.
Image © Anton Maltsev / Adobe Stock
The importance of OA as a physical health condition in feline patients is well documented and has been recognised for a number of years (Hardie et al, 2002; Godfrey, 2005; Clarke and Bennett, 2006).
Prevalence is reported to be high in cats and various studies have highlighted the fact that, while its incidence is higher in older cats, it is not exclusively a disease of old age.
In a study of cats older than 6 years of age, 61% had OA in at least one joint and 48% had more than one joint affected. When cats older than 14 years were selected from the study population, 82% had OA in at least one joint (Slingerland et al, 2011).
Agreement exists across a range of studies that the majority of feline OA cases are classified as primary (Lascelles et al, 2010; Clarke et al, 2005; Godfrey, 2005), with a minority of cases being attributable to other existing joint pathology or to trauma (Clarke et al, 2005; Godfrey, 2005).
However, reporting of trauma by feline caregivers may be limited by their awareness of incidents – especially when cats have an indoor/outdoor lifestyle.
Authors have also suggested that repetitive low-grade joint trauma over a period of time may be significant in the aetiology of feline OA and this could be very difficult for caregivers to identify (Bennett et al, 2012).
The diagnosis of OA through imaging (Lascelles et al, 2012; Bennett et al, 2012) is well documented, as is the use of arthrocentesis for confirmation of diagnosis in the case of inflammatory arthritis (Lemetayer and Taylor, 2014).
In a canine context, a traditional expectation also exists of recognisable behavioural changes associated with OA, such as decreased interest in exercise, vocal manifestation of pain, objection to handling and overt lameness, and information about these changes is used in the diagnosis process.
This limited view of potential presentations of OA in dogs is now being challenged and more subtle behavioural changes are increasingly recognised as important indicators of the disease in a canine context (bit.ly/3TwMsyc).
In cats, information about the lack of correlation between lameness and the presence of OA has been available for many years.
Twenty years ago, authors were reporting a significant differential between cats with radiographic evidence of disease (90%) and those exhibiting lameness (4%; Hardie et al, 2002), and it was suggested that lameness is not a major clinical sign of painful arthritic disease in the feline patient (Clarke and Bennett, 2006).
Information about the specificity and sensitivity of recognised components of an orthopaedic examination in cats with OA has led to questioning of the ability to rely on clinical evidence in the consulting room as an accurate predictor of the presence or absence of OA in a feline patient (Lascelles et al, 2012).
Increasing understanding of the emotional impact of the veterinary visit experience on feline patients has further increased appreciation of the various limitations of a clinical examination in a veterinary consultation room and this has the potential to impact on the diagnosis of OA in feline patients (Rodan et al, 2022; Taylor et al, 2022; Dowgray and Comerford, 2020).
Reporting of behavioural change in cats with OA was identified as a useful tool in the monitoring of response to analgesia in a paper by Clarke and Bennett (2006), with caregivers reporting reduced ability to jump and reduced activity levels in their cats, which improved following the administration of pain relieving medication.
Monitoring of response to treatment is an important part of chronic pain management and in the context of canine OA a range of validated scoring systems are available.
In the context of feline OA, the use of patient-specific outcome measures is recognised as an appropriate way to monitor patients and behavioural indicators have an important role in this process (Monteiro and Steagall, 2019).
The use of behavioural indicators in assessment of treatment success in cases of feline OA has been reported in the literature for many years (Lascelles et al, 2007; Bennett and Morton, 2009).
The most commonly discussed behavioural changes in a feline OA patient are those that are directly related to compromised mobility and the physical sensation of pain (Klinck et al, 2012). Decreased ability to jump and groom are commonly listed, and decreased activity levels are also cited.
One of the main difficulties for caregivers is that these changes can occur gradually and when the cat is senior in years they are often regarded as a normal part of the ageing process.
Differences in social interactions between caregivers of dogs and cats can also influence the detection rate of altered mobility.
Dog caregivers will often notice a decreased interest in play or going for a walk, but for cat caregivers, their direct involvement in their cat’s movement may be limited.
In addition to the behavioural change that occurs as a result of the physical dimension of pain, limited range of movement, physical discomfort and so on, it is also important to remember that pain has an emotional and cognitive component. This leads to a need to consider other less obvious behavioural indicators of pain in feline patients (Mills et al, 2020; Monteiro, 2020).
Chronic pain from OA will contribute to the emotional load of the individual and make it more vulnerable to other emotional pressure.
In the Heath Model of Emotional Health, this is explained in terms of emotions being like water going into a sink, with engaging emotions represented by the cold tap and protective emotions by the hot tap. If the protective emotion of pain is constantly dripping into the sink, a resulting residue of emotion will result, which limits the amount of space in the sink for other emotional input.
The practical consequence of this is that the cat is more likely to exhibit significant behavioural change when it is emotionally challenged by another trigger, such as noises, another cat in the household or a person interacting with it.
It becomes less tolerant of environmental pressures and may show behavioural changes such as indoor toileting, inter-cat tension and confrontational responses to their caregivers, which are not in direct response to physical pain.
It is, therefore, important to ask caregivers about their cat’s overall demeanour and about any alterations in the way they react to a range of stimuli such as sounds and people or other cats, irrespective of whether there is any physical contact between them.
Another consideration is the potential for the physiological response to emotional challenge (“stress”) to alter an individual’s perception of the significance of pain. This can result in cats with protective emotional responses, such as fear-anxiety or frustration, to a range of different stimuli being more sensitive to the impact of chronic pain from OA than an individual that has an engaging emotional response to those stimuli.
For example, a cat that is in a state of fear-anxiety due to living with incompatible cats in a multi-cat household may perceive more significance in relation to their OA-associated pain – and, therefore, find it more debilitating than a cat living in a harmonious multi-cat environment.
The cognitive component of pain also needs to be considered and some behavioural responses can be seen in anticipation of the physical sensation of pain in a context where it has previously occurred.
This can lead to behavioural change in specific places, such as the veterinary practice or the cat carrier, or situations such as when caregivers attempt to handle their cat.
The anticipation may lead to a behavioural response before any direct physical contact occurs and this may make it less likely for pain to be considered as a cause. This highlights the need to take a chronological history of any behavioural change in the cat and map that against any physical health history.
Once OA has been diagnosed and treatment instituted, it is important to monitor the patient to assess their response to treatment. Behavioural changes related to the physical dimension of pain are commonly used as a tool in this process.
Two main scoring systems are available for cats, namely, the Feline Musculoskeletal Pain Index (Zamprogno et al, 2010; Benito et al, 2013) and more recently the MI-CAT (Klinck et al, 2015; 2018), which has two versions – one for caregivers (MI-CAT[C]) and one for veterinary personnel (MI-CAT[V]).
Both systems are based on caregivers identifying whether the cat can perform certain activities associated with mobility, including jumping, playing, grooming and using the litter tray, together with alterations in social behaviour toward other pets or people.
The complexity of the relationship between pain and behavioural change can make the monitoring of feline OA challenging and taking a more individualised approach to chronic pain monitoring can be beneficial. This involves the use of client or patient-specific outcome measures (Gruen et al, 2014; Monterio and Steagall, 2019).
These outcomes are selected based on the presenting signs in the specific patient and can include behavioural changes directly related to mobility and physical pain, such as jumping, but do not have to be limited to these.
No set outcomes exist and the ones selected will depend on the information gathered about the individual during the consultation. They can include outcomes related to alterations in the cat’s emotional state and responses to stimuli such as noises or visitors to the home.
Caregivers will then observe their cat over a period of time and score the presence/absence and frequency or intensity of the selected outcomes to give a personalised assessment of the impact of pain management interventions.
Behavioural change is one part of the jigsaw when working to identify OA in feline patients and for many caregivers it is the first sign that all is not well with their pet (Overall, 2003). Clinical experience in behavioural referral practice suggests that behavioural changes associated with the condition may be noticed well before other clinical signs and often in association with mild radiographic changes, which may have been considered to be insignificant.
The evidence that OA is a common condition in cats, and one that is not limited to old age, is overwhelming. The debilitating impact on patients from physical, emotional and cognitive perspectives is also well accepted. It is, therefore, important to increase awareness of the condition among feline caregivers and more proactive screening for the disease could be beneficial.
The aim is to improve treatment opportunities for these cats and encourage intervention earlier in the disease process.
Asking caregivers questions about the behaviour of their cat at routine veterinary appointments could help in this process.
In one study, a checklist of six questions related to behaviours such as jumping, climbing, chasing and running was proposed to act as a screening tool for use in veterinary consultations (Enomoto et al, 2020).
This can help to improve identification of behavioural changes related to the physical impact of OA and combining such tools with broader questions about the cat’s emotional health and their levels of protective emotions, such as fear-anxiety and frustration, in a variety of contexts may further improve detection of this common feline disease.
By introducing these questions to caregivers during routine booster appointments before any OA changes have occurred, their awareness of the significance of behavioural change will be increased – therefore enabling them to identify signs of the disease in the early stages.