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How Health Issues Influence Behaviour
Animals, much like humans, communicate discomfort, pain or illness through changes in their behaviour. We often forget that the brain is an organ in the body. When behaviour was first studied, the brain was considered separate from the rest of the body. We now understand that behaviour must be considered holistically, as part of how the animal communicates how the rest of their body feels.
From this understanding, many studies, such as those by researchers such as Mills, have shown that certain behaviour patterns are irrefutably linked to pain or discomfort. When dogs experience pain or sickness, their instincts lead them to behave in ways that help them avoid further discomfort and stay safe.
Common ways medical problems influence dog behaviour include:
Reduced Activity Levels: dogs that are feeling unwell often show decreased activity. They might play less, sleep more, and interact less frequently with family members or other dogs. For example, a dog who previously got excited going for a walk may now avoid having their lead or harness put on. They might perform avoidance behaviours such as running away, hiding, or even growling when touched.
Increased Irritability: Ongoing pain, what is called chronic pain, from an old injury or arthritis, can lead to dogs becoming unexpectedly aggressive or defensive. Many issues affect dogs’ muscles and bones from hip dysplasia to a luxated patella and can often be missed during routine vet exams, where behaviour may be the only indication that something is amiss.
Changes in Appetite or Thirst: Health issues like diabetes, kidney disease, or thyroid disorders can significantly change your dog’s appetite or thirst, leading to unusual behaviours related to hunger or discomfort. Either drinking too much, ’not being motivated by food’, not eating, destruction of household items, or eating random things (called Pica) are all red flags that something is not right.
Altered Motivation: Why Your dog Acts the Way It Does
Pain alters motivation in favour of avoidance and defensive behaviours. Pain, discomfort, and chronic pain dictate a large amount of dog behaviour. An example of an avoidance behaviour is, how a dog moves during certain behaviours and provides us with information about what is going on in their body. A dog with hip issues will often ‘fail to maintain a squat’ while defecating. The normal behaviour when a dog needs to poop is to sniff, circle, and then hold a squat in one place to defecate. If the dog circles many times, appears like they need to ‘go’ but keeps circling, and then, when they do squat, they ‘waddle’ forward, this is a failure to maintain a squat. By understanding the normal biological movement of a dog and recognising that behaviour, including locomotion, is behaviour we can also see when it is not normal, which indicates an issue.
In addition, an example of defensive behaviours is when a dog cannot escape the discomfort or avoid the unpleasant feeling in their body. As such, they must protect themselves using the only option available at the time. For example, if we again take the dog with hip issues who is uncomfortable jumping in and out of the car but is made to, the dog may react defensively when pressured to jump up or down, as they feel they have no other choice to protect themselves from the pain or discomfort.
By understanding the normal biological movement of a dog and recognising that behaviour, including locomotion, is behaviour we can also see when it is not normal, which indicates an issue.
Every behaviour your dog exhibits has a biological reason behind it. Behaviour usually related to survival, safety, or meeting basic needs will be highly motivated. When our dogs are unwell, their motivations shift.
For example, if your dog feels constantly hungry or thirsty due to an illness, it might become protective or even aggressive around food or water, even towards trusted family members. Water and food suddenly become vital for survival, and guarding them becomes more motivating. Dogs with gastrointestinal issues, such as ulcers or intolerances, may start resource guarding unusual items and act defensively when you try to remove them. We also see dogs with hormonal issues, such as hypothyroidism, unable to hold their bladder and urinating in the house. These behaviours are often mistaken for training problems. While we may expect a dog to willingly give up an item or toilet outside, when a medical issue is present, it’s not a training problem but it is still behaviour.
Pain also causes subtle or small changes in normal behaviours, such as gait abnormalities in arthritic dogs. The lameness these dogs display is often masked by compensatory movement patterns adaptations that allow them to continue moving while reducing discomfort. These compensations can persist long after the pain has subsided, meaning the behaviour itself becomes part of the adaptation.
Vets often do not observe these gait issues in clinic settings, as the environment doesn’t allow for natural movement patterns to be seen. Behaviourists, however, are trained to spot these subtle deviations. Owners, too, may miss these changes because they see their dogs every day it’s a bit like the frog in boiling water; the changes are gradual and easily overlooked unless you know what to look for.
Several medical conditions are known to cause noticeable behavioural changes. We now have many papers and research studies that clearly detail the links between behaviour and pain. Behaviour is medicine, and it is also a diagnostic tool often the very first diagnostic we see, and the least invasive.
Understanding this shift can help identify health problems early and help us understand that training may not be the correct solution.
Recognising Signs of Pain in dogs
The great thing about behaviour being so recognisable as the first diagnostic in pain or discomfort is that YOU can evaluate your own dog’s behaviour. What follows in this blog is a set of questions you can answer based on the research to see if the behaviour you’re observing may be linked to pain or discomfort.
When answering the following questions, a trend to mostly RIGHT suggests a consistent behavioural pattern, whereas a trend to LEFT indicates less consistency and a greater probability that there is an underlying medical condition.
Evaluate Your Own Dog - Part One
Does the problem behaviour occur in response to an external event? ALWAYS THE SAME / RANDOM (For example: Does your dog only growl when you reach to pick up their toy same toy every time, or does it happen at random times with random objects and they change their mind?)
Does the problem behaviour occur in response to the same range of stimuli? ALWAYS THE SAME / RANDOM THINGS (For example: Does your dog always bark at other dogs they see, or only sometimes it seems random?)
Does the problem behaviour occur in a well defined set of contexts? ALWAYS THE SAME / RANDOM PLACES (For example: Does your dog only act out at the park, or does it also happen at home or on walks in the neighbourhood?)
Does the animal easily respond to environmental cues while performing the problem behaviour? (Is the behaviour easily interrupted by the opportunity to engage in other activities?) ALWAYS COMES BACK / TOTAL IGNORES ME (For example: If your dog is barking at the window, will they stop and come when you call them, or do they ignore you completely?)
Does the behaviour stop spontaneously? ALWAYS STOPS / DOG CAN’T STOP (For example: If your dog starts growling, do they calm down on their own after a short while, or does it keep escalating until you intervene?)
If you get more RANDOM, TOTAL IGNORES ME or DOG CAN’T STOP then it strongly suggests there is a medical condition at play.
This should be taken only as a guide, but a strong bias to the right should prompt an increased depth of medical investigation even in the relative absence of conventional physical indicators of disease.
Evaluate Your Own Dog - Part Two
Is this individual’s behaviour typical of that which would be expected for its age and developmental circumstances? YES NORMAL FOR THEM/ NO, NOT NORMAL FOR THEM (For example: Is your young puppy chewing everything like most puppies do, or is your older dog suddenly starting to chew in a way that doesn’t fit their age?)
Is the current behaviour characteristic of the individual’s previous adult pattern of behaviour? YES NORMAL FOR THEM/ NO, NOT NORMAL FOR THEM (For example: Has your usually calm adult dog suddenly started pacing or showing restlessness in a way that’s very different from their normal behaviour?)
Can the change in behaviour be linked to an identifiable change in the environment or a significant experience? YES NORMAL FOR THEM/ NO, NOT NORMAL FOR THEM (For example: Did your dog’s behaviour change right after you moved house, a new baby arrived, or after a frightening incident?)
Is this a normal but unwanted behavioural response (for example, food-guarding behaviour)? YES NORMAL FOR THEM / NO, NOT NORMAL FOR THEM (For example: Is your dog growling over their food bowl in a way that is typical food-guarding, or is it new and unusual for them?)
If you get more NO, NOT NORMAL FOR THEM then it strongly suggests there is a medical condition at play.
This should be taken only as a guide, but a strong bias to the right should prompt an increased depth of medical investigation even in the relative absence of conventional physical indicators of disease.
Additional Behavioural Signs to Monitor
The above quiz is only a strong indication that something might be medical, if you still are not sure here are a few more additional signs you can keep an eye on. Pay close attention to your dog and if you notice these potential signs of underlying health problems:
- Decreased playfulness, activity, or interaction, where normal they were active. ‘They are just slowly up’ is often something else.
- Increased anxiety, fearfulness, or nervousness, particularly to sound.
- Sudden aggressive or defensive behaviour, appears random or out of the blue. With no warning.
- Changes in grooming habits, such as excessive licking or scratching, licking paws or one site on the dogs body.
- Tail chasing, or the ‘zoomies’. It might seem cute of playful but often an indication something is not right.
- New or unusual eating and drinking behaviours, i.e. wont eat from their normal bowl, only drinks water in strange places.
- Reluctance or avoidance of normal activities, like walks or playing.
How Behaviour Helps Diagnose Medical Conditions
If your dog shows behavioural changes, the first step should always be a thorough veterinary check-up. However, I say this as someone who has worked in this field for a long time: while as a CAB and a member of the APBC/ABTC we are required to only work on veterinary referral, the reality is that vets are often overworked and understaffed in Ireland.
They may not have the time to do the same level of observation that a behaviourist can. Consultation times with vets are typically 15 minutes (if you’re lucky) they are excepted to turn it around so quickly (which is a lot of pressure placed on them), whereas a behaviourist will (or can) spend 2 hours with you and your dog.
Veterinary consultations also take place in clinics, which can be stressful or frightening environments for dogs. Fear and stress are fantastic at masking pain and making it hard to see them move, if there is pain or even if they are behaving normally. A behaviourist, however, comes to your home, where the dog is more relaxed, and we can observe their typical behaviour.
So while a veterinary check-up is essential and behaviourists should always work with vets and alongside them, I often find that starting with a behavioural assessment and providing the vet with detailed findings leads to better and faster diagnostics. It also reduces the burden on vets, who are already overstretched. If we can share the load and help them by contributing detailed behavioural observations, we can support both the veterinary team and achieve better care for the dog.
Why Early Intervention Matters
Identifying medical causes of behavioural issues early can significantly improve treatment outcomes. Early medical care reduces pain and discomfort, resolves behavioural problems more effectively, and prevents potential complications. Delaying veterinary attention might allow problems to worsen, making treatment harder and less effective.
‘‘What Should I Do Next? My dogs behaviour is unpredictable or random and graded high on the quiz’
If your dog is exhibiting concerning behavioural changes, or graded high on the above quiz, schedule a veterinary evaluation right away, and ask for a referal to a behaviourist. A good behaviourist will also want to ensure that your dog has seen a vet recently to make sure they are assessed. I will always recommend comprehensive medical assessments alongside behavioural evaluations, as this is in the dogs best interest. Identifying the root cause of your dog’s behaviour helps us develop personalised treatment plans and is critical for maintaining good ethical/welfare standards.
I believe in a holistic, compassionate approach to dog care. I combine medical knowledge with behavioural expertise, taking into account emotional, physical, and environmental factors affecting your dog. In complex cases where there maybe a medical issue at play, a team approach is critical.
If you’re worried about your dog’s behaviour and are unsure if this requires veterinary support, you can also reach out to me to discuss your case. I will always put your dog’s best interest first and foremost and guide you to the most appropriate professional.
