Many dog behaviour problems have underlying medical causes that must be excluded before behavioural treatment, with pain being a particularly common driver of apparent aggression and anxiety.
The intersection of medicine and behaviour in dogs is underappreciated by both owners and many trainers. A dog displaying sudden aggression may be in pain; a dog with anxiety may have a thyroid disorder; a dog with elimination problems may have urinary disease. Treating the behaviour without addressing the medical cause is ineffective and potentially cruel — the animal continues to suffer while receiving behavioural interventions that cannot address the root cause. Veterinary assessment before behaviour modification is not merely good practice but an ethical requirement of welfare-centred behaviour work.