If your Shih Tzu is not eating, drinking, and only sleeping, it's often due to a cold or fever. You can check their temperature to confirm. However, it might also be due to boredom. Try taking them out for a walk. If your dog also shows symptoms like vomiting or diarrhea, it could be gastroenteritis. If they have a fever, eye or nasal discharge, or diarrhea, be cautious of canine distemper or parvovirus.

Reasons and Solutions for a Shih Tzu Not Eating, Drinking, and Only Sleeping
1. Cold or Fever
A sudden loss of appetite, accompanied by lethargy, a dry nose, and abnormal body temperature could indicate a cold or fever. Take their temperature to be sure. For a cold, you can give them a reduced dose of children's cold medicine and ensure they stay warm. For a fever, anti-inflammatory medication is needed. You can also apply rubbing alcohol to their paw pads and belly to help lower their temperature. This can help with the discomfort and lethargy.
2. Poor Mood or Boredom
Excessive sleepiness and loss of appetite can also stem from boredom and lack of mental stimulation. Often, this occurs when owners don’t spend enough time playing with their dogs and neglect their needs. Increase outdoor walks and interactive playtime. A more engaging routine can help restore your dog's appetite and energy levels.
3. Gastroenteritis
If your Shih Tzu suddenly stops eating, becomes lethargic, and starts vomiting or having diarrhea, they could have gastroenteritis. If confirmed, withhold food and water for 24 hours initially. Then, administer anti-inflammatory medication, followed by probiotics after a couple of hours. If symptoms persist beyond three days, seek veterinary care.
4. Canine Distemper or Parvovirus
Loss of appetite and excessive sleepiness can also be symptoms of serious illnesses like canine distemper or parvovirus. These conditions usually include symptoms like eye or nasal discharge, recurring vomiting and diarrhea, and high temperatures. It's recommended to purchase test kits for distemper and parvovirus at a pet store for home testing. If your dog tests positive, seek immediate veterinary care. Time is crucial for these diseases.