STORY AT-A-GLANCE
- Dogs and cats naturally sleep several hours a day, so it can sometimes be difficult to tell if your pet is lethargic
- It’s important to observe your pet for signs of lethargy because it’s a symptom of many health and behavioral conditions that affect companion animals
- Some common underlying causes for lethargy in dogs and cats include an underlying illness, toxin ingestion, veterinary drugs, recent rehoming and grief over the loss of another pet in the family
- Dogs and (especially) cats who are anxious or frightened can appear lethargic, so if you just brought your pet home, he’ll need some time to adjust to his new environment and family
- Give your pet lots of positive TLC and avoid overstimulation in his first few weeks with you
Editor's Note: This article is a reprint. It was originally published September 16, 2017.
Dogs and cats (especially cats) are wired to sleep somewhere in the neighborhood of 10 to 12 hours a day, and require even more shut-eye as they age. This is why it may seem as though every time you lay eyes on your furry companion, he’s sawing logs.
Given his need for lots of sleep, it can be difficult to tell when your pet is actually lethargic and not just drowsy-as-usual. That’s why it’s so important to have a good understanding of what constitutes “normal” for your pet — normal behavior, normal eating patterns, normal sleeping patterns, normal poop, normal pee and so on.
When you know your dog’s or cat’s “normal” like the back of your hand, you’ll recognize immediately when something is off, such as when he’s more sluggish than usual. Lethargy is a symptom of many disorders that affect pets, including behavioral problems. Some of the most common causes are explained below.
5 Common Reasons for Lethargy in Dogs and Cats
- Your pet has an underlying illness — A decrease in your pet’s activity level can indicate an underlying health problem that needs investigation. This is especially true if there’s also a change in her appetite, elimination habits and/or interaction with family members or other pets in the household. A dog or cat who is sick will often be unusually quiet and sluggish, so if your pet is lethargic for 24 hours or so, it’s time to give your veterinarian’s office a call. Depending on your pet’s symptoms, you may be asked to bring her in right away.
For example, lethargy accompanied by persistent vomiting or bloody vomit, stool or urine is cause for immediate concern. A pet’s refusal to eat is another red flag. The sooner you get your pet diagnosed and begin treatment the better her chances for a full recovery.
- Your pet has ingested a poison — This frightening scenario can occur both outdoors, especially during the warmer months of the year, and indoors if your pet happens to eat the wrong people food (e.g., chocolate or anything sweetened with xylitol), gets into a bottle of NSAIDs or samples a toxic houseplant.
If your dog or cat suddenly grows lethargic or has other symptoms of toxicity (e.g., vomiting) and you know or suspect he’s eaten something poisonous, get him to your veterinarian or the nearest emergency animal hospital immediately. - Your pet is on a new medication — If your veterinarian has put your dog or cat on a new or different medication and she suddenly seems lethargic, the drug is probably the cause. All medications have short- and long-term side effects that can range from mild to life-threatening. If you see any change in your pet’s behavior after starting a new medication, report it to your veterinarian immediately.
Finding a holistic or integrative vet is also recommended, as they may be able to suggest safer, less toxic remedies, especially if your dog or cat is taking a particularly toxic drug (e.g., prednisone) or long-term medication for a chronic condition. - Your pet is newly adopted — Dogs and (especially) cats who are anxious or frightened can appear lethargic, so if you just brought your pet home, he’ll need some time to adjust to his new environment and family. He could be acting sluggish simply because he’s in unfamiliar territory and a bit overwhelmed.
Give your pet lots of positive TLC and avoid overstimulation in his first few weeks with you. If he’s otherwise healthy, his activity level will naturally increase as he learns to trust you and gets comfortable in his new surroundings.
- Your pet has lost a friend — When two pets are closely bonded and one of them dies, the surviving dog or cat may experience what experts refer to as a “distress reaction” that is similar in many ways to human grief.
In addition to lethargy, some of the signs include changes in sleep patterns; changes in eating habits; lack of interest in normal activities; reluctance to be in a room or home alone, or away from human family members; and wandering the house, searching for their lost friend.
