Why is my 8-day-old puppy lethargic, not gaining weight, and crying?

Excessive crying can be a sign of a health issue, so I would have him seen by a vet immediately (take along his mother and siblings as well). Newborn puppies are extremely fragile, and very susceptible to cold and low blood sugar, so any potential problems with them need to be check out by a vet right away to give them their best chance at survival. His crying could signify problems in feeding (not getting enough milk), cold, or low blood sugar. Please take him into an ER vet or find a vet on call to see him now.

Poor Mojo! He could be crying because he is hungry or cold, but without seeing him in person, I can't say for certain. I can say that newborn puppies are extremely fragile, and whenever there is problems with them, they have to see a vet immediately in order for them to have the best chance of survival. I would take Mojo into a vet right away for medical treatment.

If this pup is really two weeks old, and won't suck from the bottle or suck from mom, she may be very ill and needs to see a veterinarian right away. She may have some kind of infectious disease which requires testing and treatment for her to get better. She looks dehydrated in this picture, and that happens very quickly when puppies stop nursing. Please seek help as soon as possible.

Constant crying can be a sign of failure to thrive in a puppy. If this is the only puppy with diarrhea it could be a concern as well. I’d recommend having your vet examine the puppy to determine what might be going on. They might recommend medications or this pup may need to be supplemented with a bottle to make sure he is getting enough nutrition.

When puppies that young cry constantly like that, it's a sign that something is wrong with them, such as they are very cold or very hungry. Make sure the puppy is warm, and give it a teaspoon of honey or Karo syrup to prevent it from becoming hypoglycemic. Have the puppy, along with Lexi and his littermates, seen by a vet ASAP.

Considering the puppy is losing weight and failing to thrive, I would bring him into your local vet for an exam to check for any physical deformities that may be affecting his ability to nurse properly and eat, and for any potential illnesses or issues that could be causing him to not do as well. If he is able to eat with a bottle, I'd also recommend increasing his feedings if he still seems hungry, to try and keep weight on him and get him back up to speed.

Young puppies will whine or vocalize when cold, hungry, sick, injured or if left alone for long periods of time. You can make sure he is fed, warm and has company. To diagnose illness or injury, he would need to be physically examined by your veterinarian.