What this means
Lethargy is easiest to spot by comparing with how your dog normally is. A dog who always met you at the door and now only lifts their head, or one who used to carry the lead and now lies still, is a stronger signal than a general sense of being calmer than other dogs. The change is the measure, not the dog's temperament.
Lethargy is rarely the only sign. It helps to note whether your dog also eats or drinks less, breathes faster, has a different gum colour, vomits, or urinates differently from usual. Long-term illnesses often begin very quietly: the dog simply walks a little less far, sleeps more and plays less, so an owner can put it down to age.
Pain can look just like lethargy too, because a dog in pain moves less and hides. For that reason a vet usually first checks for pain, a raised temperature or another sudden cause, and only then looks for long-term conditions. Write down when you first noticed the change and how it has developed.
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 infection
Pain and inflammation make a dog move less and look for quiet. Lethargy may be the first sign, and sometimes the only one.
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A shortage of adrenal hormones
With this disorder a dog is weak and may eat less, vomit or have loose stools. The signs can come and go, which is why the condition can go unnoticed for a long time.
About the condition: Addison's disease -
An underactive thyroid
A shortage of thyroid hormone slows the metabolism. The dog becomes sleepy, gains weight more easily, may feel the cold and may lose coat.
About the condition: Hypothyroidism -
Kidney disease
Weakened kidneys no longer clear the body's waste products, so the dog feels unwell. Increased thirst, a smaller appetite and nausea are often seen with it.
About the condition: Kidney disease -
Heart disease
A heart that pumps poorly causes tiredness and fast breathing. The dog tires sooner on a walk and stops to rest more often.
About the condition: Heart disease -
Tumours and other long-term illness
Illness that lasts a long time wears the body down and lowers energy. Weight loss or a poor appetite often goes with the lethargy.
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 whether it is getting stronger
- Whether your dog eats and drinks as usual
- Whether breathing is faster, or your dog tires sooner on a walk
- Whether the gum colour has changed
- Whether there is vomiting, loose stools or different urination
- Whether your dog avoids being touched, or hides
When to book a routine visit
Book a visit if your dog has been lethargic for more than a day, eats or drinks less, or the change builds slowly and does not pass. If your dog stops responding, collapses or struggles to breathe, go straight away.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Addison's disease Hormones and metabolism Addison's disease is a condition in which the adrenal glands make too little of certain hormones that help the body cope with stress and keep its balance of salts and water. Its signs are vague and can come and go, so it is easy to miss. The condition can, however, suddenly worsen and become life-threatening, and then the dog needs a vet immediately.
- Hypothyroidism Hormones and metabolism Hypothyroidism is a condition in which the thyroid gland produces too little of the hormones that regulate metabolism. Because these hormones affect almost the whole body, a shortage gradually slows many of its processes. The changes come on slowly, so they are easy to mistake for ageing or simple laziness.
- Kidney disease Kidneys and bladder The kidneys filter the blood, remove waste from the body and help keep the balance of fluids and salts. When they are damaged suddenly, for example by poisoning or infection, or weaken gradually over a longer time, substances they should remove start to build up in the body. Long-term kidney changes can go unnoticed for a long time, because the healthy part of the kidneys takes over the work for a while.
- Heart disease Heart This is an umbrella term for various conditions in which the heart muscle, the valves or the heart rhythm stop working as well, making it harder for the heart to pump blood around the body. Some are present from birth, others develop with age, and they can go a long time without any noticeable signs. During a check-up the vet listens to the heart and decides whether further tests are needed.
- Cancer Cancer Cancer is not one disease but a whole group of different malignant tumours that can appear in almost any organ or tissue. They can grow slowly or quickly and spread to other parts of the body, so the earlier a change is noticed, the more options a vet has. Only a vet can tell whether a lump or other change is malignant.
- Parvovirus Infections Parvovirus is a highly contagious viral disease of dogs that damages the lining of the gut and the blood cells that defend the body against infection. Puppies and unvaccinated dogs are at greatest risk. The illness moves fast and the dog loses a great deal of fluid, so it needs a vet immediately.
- Leptospirosis Infections Leptospirosis is a bacterial infection that a dog catches from water, damp ground or objects contaminated with the urine of infected animals, especially rodents. The bacteria damage the kidneys and liver, and the illness can quickly become life-threatening, so the dog needs a vet immediately. Leptospirosis also passes to people.
- Babesiosis Parasites Babesiosis is a tick-borne disease caused by microscopic parasites that settle in the red blood cells and destroy them. In Lithuania it is spread by the ornate dog tick, so it is worth every dog owner knowing about. It can become life-threatening within days, so the dog needs a vet immediately.
- Lyme disease Infections Lyme disease is a bacterial infection passed to a dog by an attached tick. In Lithuania its bacteria are spread by the castor bean tick, which lives in woods, parks and long grass. Some infected dogs show no signs at all, while others develop painful joints weeks or months later; whether this disease is behind a dog's illness is for a vet to establish.
- Anaplasmosis Infections Anaplasmosis is a tick-borne bacterial infection whose bacteria settle inside white blood cells. In Lithuania it is spread, like Lyme disease, by the castor bean tick. Some infected dogs show no signs, while others develop a fever and a limp within a few weeks of the tick bite; what caused the illness is for a vet to establish.
- Pyometra General health Pyometra is a pus-filled infection of the womb that can develop in an unspayed bitch in the weeks after a season. Pus collects in the womb, and substances released by the bacteria harm the whole body. The condition can quickly become life-threatening, so the bitch needs a vet immediately.
- Gastroenteritis Digestion and liver Gastroenteritis is a sudden inflammation of the lining of the stomach and intestines, showing as vomiting and diarrhoea. It can be caused by food picked up or gone off, a sudden change of food, viruses, bacteria, parasites or toxic substances. A mild bout can pass in a day or two, while what caused it, and whether it is a more serious illness, is for a vet to work out.
Body systems: Hormones and metabolism Kidneys and bladder Heart Cancer Infections Parasites General health Digestion and liver