When your dog is lethargic and not eating or drinking, it’s natural to worry. This behavior isn’t just about skipping a meal or being a little tired—it can be an indicator of a deeper health problem that requires attention.
If your dog suddenly lacks energy and refuses food and water, you may be witnessing the early signs of a serious illness or condition.
We outline the common reasons your dog is lethargic and not eating or drinking, how to identify associated symptoms, and what steps to take. Whether the issue is temporary or chronic, recognizing the signs early can make a significant difference in your dog’s recovery.
Dog Lethargic and Not Eating or Drinking: Why It Happens
This often indicates an underlying health issue affecting your dog’s energy, appetite, or hydration. It can be caused by gastrointestinal problems, infections, dehydration, pain, chronic illnesses, toxin exposure, stress, or medication side effects.
When a dog feels unwell, their body may respond by conserving energy, avoiding food, and rejecting water, especially if they’re nauseous or in discomfort.
Common Causes of Dog Lethargic and Not Eating Or Drinking
Gastrointestinal issues
Digestive problems such as gastritis, pancreatitis, intestinal blockage, or colitis are among the most common reasons a dog is lethargic and not eating or drinking.
These conditions often cause discomfort, nausea, or vomiting, making your dog avoid food and water.
Even a simple upset stomach from eating something they shouldn’t have can cause a temporary loss of appetite and energy.
However, if this persists for more than a day or two, it’s time to consult a vet.
Related: Dog diarrhea and not eating (Causes and what to do)
Infections
Bacterial, viral, or parasitic infections can cause dogs to become lethargic and stop eating or drinking.
Conditions such as parvovirus, kennel cough, or leptospirosis can result in fever, vomiting, diarrhea, and extreme fatigue.
Infections tax the immune system and often come with symptoms like nasal discharge, coughing, vomiting, diarrhea, or swelling.
These illnesses also dehydrate your dog, worsening their lethargy and reluctance to drink.
Dehydration
Dehydration is both a symptom and a cause of lethargy and appetite loss.
If your dog isn’t drinking enough water, their cells can’t function properly.
Dehydration causes fatigue, dry gums, sunken eyes, and a dry nose.
Dogs may avoid drinking due to nausea, mouth pain, or because they’re feeling unwell overall.
This lack of hydration leads to more fatigue, creating a vicious cycle.
Prompt rehydration—either orally or through veterinary-administered fluids—is critical.
Pain or injury
If your dog is lethargic and not eating or drinking, it may be due to physical pain or discomfort.
Sprains, fractures, abdominal pain, or internal injuries can reduce a dog’s desire to eat or move.
Dogs are known to hide pain, so even if they’re not yelping or limping, they could still be suffering.
Watch for subtle signs like trembling, whining, a hunched posture, or refusing to lie down in their usual spot.
Any combination of lethargy, lack of appetite, and pain requires urgent vet care.
Heatstroke
During hot weather, dogs are especially vulnerable to heatstroke.
Overexposure to heat can cause a dog to become lethargic, pant excessively, and stop eating or drinking.
Left untreated, heatstroke can damage internal organs and even become fatal.
If your dog is panting heavily, drooling, vomiting, or has a high body temperature alongside lethargy and appetite loss, seek veterinary help immediately.
Chronic illnesses
Chronic health conditions such as kidney disease, liver failure, heart disease, or diabetes often present with symptoms like fatigue, poor appetite, and lack of thirst or excessive thirst.
For example, a dog with kidney failure may feel nauseous and refuse to eat or drink.
Similarly, liver disease can cause vomiting, confusion, and depression.
These illnesses typically develop slowly, so catching them early through regular vet visits is essential.
Stress and anxiety
Dogs can become lethargic and not eat or drink due to emotional or psychological stress.
Triggers include moving to a new home, loud noises like fireworks, new people or pets in the household, or changes in routine.
Stress can reduce appetite, disturb sleep patterns, and drain a dog’s energy.
In such cases, dogs may also display behaviors like pacing, hiding, whining, or excessive licking.
Side effects of medication
Certain medications, such as antibiotics, pain relievers, or anti-inflammatory drugs, can cause lethargy and reduce appetite as side effects.
If your dog recently started a new medication and is now lethargic and not eating or drinking, consult your vet.
The dosage may need adjustment, or an alternative drug might be better tolerated.
Related: Dog Vomiting and Not Eating or Drinking (Explained)
Toxin ingestion or poisoning
Ingesting a toxic substance—such as human medication, chocolate, xylitol, rodenticide, or poisonous plants—can result in symptoms like vomiting, diarrhea, tremors, seizures, and extreme lethargy.
If your dog refuses food and water and also shows sudden changes in behavior or physical symptoms, poisoning is a real possibility.
Immediate emergency care is critical in these situations.
What to do if your dog is lethargic and not eating or drinking
If you notice your dog is lethargic and not eating or drinking, here are the immediate steps to take and how to determine if professional help is needed.
1. Monitor symptoms closely
Keep track of how long your dog has been lethargic and refusing food or water.
Note any other symptoms like vomiting, diarrhea, bloating, pain, or changes in urination.
This will be helpful information for your veterinarian.
2. Check for signs of dehydration
Lift the skin between your dog’s shoulders—if it doesn’t snap back quickly, they may be dehydrated.
Also look for dry gums, sunken eyes, and dry nose.
3. Encourage hydration
Offer fresh, clean water frequently.
If your dog refuses to drink, try adding low-sodium chicken broth or ice cubes to make it more appealing.
Avoid forcing water, as it may lead to choking.
4. Offer bland food
For dogs with minor stomach upset, offering a small portion of plain boiled chicken and rice might encourage them to eat.
However, if your dog continues to refuse food or vomits it up, stop offering food and call the vet.
5. Provide a calm environment
If stress is the suspected cause, ensure your dog has a quiet, safe space to relax.
Use calming aids like pheromone sprays, and avoid loud noises or abrupt changes in their routine.
6. Call the veterinarian
If your dog is lethargic and not eating or drinking for more than 24 hours—or sooner if other symptoms appear—call your veterinarian immediately.
Puppies, senior dogs, or dogs with preexisting conditions are particularly vulnerable.
7. Emergency care is necessary if:
Your dog has not eaten or drunk anything in over 24 hours
There is vomiting or diarrhea present
You suspect toxin ingestion
Your dog appears to be in pain
There are signs of dehydration or collapse
Key Takeaway
When your dog is lethargic and not eating or drinking, it’s not something to ignore.
While a temporary dip in appetite or energy may occur due to minor issues like stress or a mild upset stomach, persistent or worsening symptoms should always be taken seriously.
By paying close attention to your dog’s behavior, identifying other symptoms, and acting quickly, you can help ensure they get the care they need.
Don’t hesitate to contact your vet if you’re in doubt—early intervention can make a major difference in recovery and overall health.