Symptom: Lethargy – Why is my pet so tired?
Recognising the Signs of Excessive Tiredness and Low Energy in Pets
Excessive lethargy in pets can manifest in various ways:
Decreased activity
Excessive sleeping
Slowed movements or reluctance to move
Physical signs of fatigue, such as trembling, unusual gaits, or weight shifting.
Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published October 2025 | Review date October 2028 | This advice is for UK pets only and is not a replacement for seeing a vet
Frequently asked questions
What are the common reasons for excessive tiredness or lack of energy in my pet?
There could be a variety of causes, ranging from simple lifestyle factors to serious underlying medical conditions:
- Excessive activity
- Obesity and weight gain
- Infections, usually due to effects of fever, infectious diseases like parvovirus, distemper or leptospirosis
More reading Canine Parvovirus, Feline Parvovirus, Distemper, and Leptospirosis
- Pain
- Heart or liver diseases, or diabetes
More reading Diabetes in Cats, Diabetes in Dogs
- Anaemia or underactive thyroid
- Renal disease
DO’s – What can I do at home if my pet has a lack of energy?
- Provide a quiet and comfortable rest area
- Ensure access to fresh water
- Appealing food
- Be aware of potential medical issues
- Avoid excessive exercise
DON'Ts – What I shouldn't do at home if my pet has a lack of energy?
- Don't tease or bother a sleeping pet, and avoid taking away food or toys
- Don't force activity
- Don't delay seeking veterinary advice if your pet's tiredness is persistent
When do I contact my vet if my pet has lack of energy?
- Prolonged lethargy lasting for more than 24-48 hours, especially in young pets.
- Age-related lethargy.
- Lack of energy with other symptoms such as vomiting or diarrhoea.
- Sudden onset of lack of energy, especially with other concerning symptoms like pale gums, collapse, or difficulty breathing.
- Severe lethargy unresponsive, or having difficulty getting up.