Whether I have my "normal vet" hat on or my veterinary behaviour/ pain assessor hat on, pain in animals is something I deal with every single day.
Most animals are incredibly resilient- and when motivated to eat, drink, run and play, despite the fact they have underlying pain issues- they get on with it, regardless.
This doesn't mean the pain isn't there, it just means that it is at a manageable level rather than an overwhelming/ debilitating level, which stops other normal and necessary functions.
Unfortunately- pet owners are often shocked and surprised when they find out their pet is and probably, has been in pain for a long time- in some cases since puppy or kittenhood, if it is a hereditary or congenital defect they have been born with.
Equally- just because an animal allows a vet to manipulate their head/ neck/ back or limbs, doesn't mean it doesn't hurt. X-rays give us a good idea what is going on under the skin's surface, but they don't tell us about the nerves, muscles, ligaments or tendons which surround the bones we can see on the x-ray. A clean or "normal" looking x-ray does not mean the animal isn't experiencing pain. It just means we can't point our finger, or a little digital arrow, on the place we want to call the "source or root" of the problem.
"Animal pain is an aversive, sensory experience representing awareness by the animal of damage or threat to the integrity of its tissues; (note that there might not be any damage).
It changes the animal’s physiology and behaviour to reduce or avoid the damage, to reduce the likelihood of its recurrence and to promote recovery.
Non-functional (non-useful) pain occurs when the intensity or duration of the experience is not appropriate for damage sustained (especially if none exists) and when physiological and behavioural responses are unsuccessful in alleviating it."
Sometimes, reluctance to go for a walk, jump into the car or on/ off furniture or window ledges (if we're talking about cats), play rough and tumble games or tolerate snuggling up on the couch- might mean they don't feel up to it or they would prefer peace and quiet instead.
Animals cannot articulate that they feel uncomfortable or would prefer not to be touched or lifted, so instead they communicate in the only ways they can, that they want space and ideally distance from the situation they are worried about. Sometimes that looks like fear, sometimes it looks like aggression, but it is coming from the same place- "I'm in pain right now or I was painful there before and I don't want to be painful again, so leave me alone!"
There are some fantastic resources available to help pet owners recognise pain in their companion animals and to help explain why it can be: unpredictable, variable, exaggerated or "temporarily forgotten" if the motivation to have fun or do something nice is strong enough.
You may find the following links helpful:
Signs Of Pain - Cats Health and Advice | Cats Protection
How to Tell if a Dog Is in Pain | Signs & Symptoms Of Pain In Dogs (vets-now.com)
Pain recognition and its management in rabbits | Vet Times
Full article: Pain in birds: a review for veterinary nurses (tandfonline.com)
Pain Recognition and Management in Horses | News | Merck Equine (merck-animal-health-equine.com)
If you think, or if you've been told that your pet is in pain, do seek help from your veterinary surgeon right away- there are loads of things we can do to help. There are also qualified veterinary physiotherapists, hydrotherapists, rehabilitation practitioners and members of many other disciplines, relying on evidence- based medicine, licensed medications and recognised specialist techniques, to help support you and your pet to enjoy the best quality of life that we can give.