What this means
A change in behaviour is very often the first sign that a dog is in pain or ill, not disobedience or stubbornness. A dog may become restless, timid, irritable or clingy, lose interest in play, withdraw, start hiding or react to things that never bothered it before. Sometimes a young dog learns with difficulty, does not remember what it already knew or seems unable to find its way around.
Many causes can lie behind such changes: pain, general illness, poorer sight or hearing, problems with the liver or other organs, changes in the brain or nervous system, and in older dogs age-related changes. Some brain and metabolic disorders are inherited and show in youth, while for others the cause becomes clear later. The cause cannot be worked out from behaviour alone, and it is best not to guess.
A short written note will help your vet: when the change began, whether it has changed since, whether your dog is also eating less, sleeping differently, walking in circles, bumping into things, falling or limping. Also write down what has always been normal for your dog so the difference shows. If you can, film the unusual behaviour.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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Pain or general illness
A dog in pain can become irritable, withdrawn or hide away. It is one of the most common reasons behaviour suddenly changes.
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A disorder of the brain or nervous system
Some inherited or later-appearing changes in the brain show as restlessness, disorientation, slow learning or different behaviour.
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A metabolic or storage disease
In some disorders substances build up in the body and slowly affect the brain. A change in behaviour can be the first sign.
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Liver or other organ disease
Poor liver function can also affect behaviour, so the dog may look confused or dull.
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Poorer sight or hearing
A dog that sees or hears less well can be timid, startle easily or seem disobedient when it simply does not notice what is around it.
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Age-related changes
Older dogs may become confused, change their sleep pattern or stop recognising surroundings. This too has to be assessed by a vet.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- When the change began and how quickly it grew
- How your dog's behaviour differs from its usual self
- Whether it is also eating, drinking or sleeping differently
- Whether it walks in circles, bumps into things or seems lost
- Whether it limps, falls or sometimes trembles
- Whether a young dog seems to be developing more slowly than others of its age
When to book a routine visit
If your dog's behaviour has clearly changed and the change does not pass in a few days or is growing, show it to a vet. A change in behaviour can be a sign of pain or illness.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- GM2 gangliosidosis Hormones and metabolism This is an inherited storage disease in which the body lacks an enzyme that breaks down certain fatty substances in nerve cells. These substances build up in the brain and spinal cord and gradually disrupt how the nervous system works. The disease appears in young dogs and progresses over time.
- Hydrocephalus Nerves and muscles Hydrocephalus is a condition in which too much cerebrospinal fluid builds up in and around the brain and presses on the brain tissue. It can be present from birth and show up in puppies, or develop later when inflammation, an injury or a tumour blocks the fluid from draining. The pressure on the brain can affect a dog's behaviour, movement, sight and ability to learn.
- L-2-hydroxyglutaric aciduria Hormones and metabolism This is an inherited metabolic disease in which the body cannot break down an acid formed during normal metabolism, so it builds up and gradually damages the brain. Because it is inherited, it comes down to the dog's genes, and a genetic test exists for it. Whether changes in a dog's behaviour and movement come from it is for a vet to determine.
- Neuronal ceroid lipofuscinosis Nerves and muscles This is a group of inherited diseases in which cells cannot break down certain waste substances, so these build up in the nerve cells of the brain and eyes and gradually damage them. The disease is progressive, so over time changes in the dog's behaviour, sight and movement become more marked. Genetic tests exist for some of its forms.
- Neuronal degeneration Nerves and muscles This is a condition in which nerve cells in the brain or spinal cord gradually die off and stop doing their job. Because neurons control movement, balance and behaviour, their loss gradually changes how a dog moves and responds to its surroundings. Signs can appear in a young dog and become more pronounced over time.
- Storage disease (lysosomal storage disease) Hormones and metabolism This is a group of inherited diseases in which cells lack an enzyme needed to break down certain substances, so these build up inside the cells and gradually damage them. Depending on which substance builds up and in which organs, the signs vary widely: the disease can affect the brain, nerves, eyes, liver or bones. Because there are many forms, which one is affecting a dog is for a vet to establish.
- Rabies Infections Rabies is a viral disease of the nervous system that a dog catches when it is bitten by an infected animal. It is dangerous to animals and to people alike. If your dog has been bitten by a wild or unknown animal, or its behaviour has changed so suddenly that you suspect rabies, phone a vet immediately.
Body systems: Hormones and metabolism Nerves and muscles Infections