Why is my Chihuahua puppy weak and disoriented? Low sugar or calcium?

The CBC that you posted does not show any significant abnormalities. Hypocalcemia (low blood calcium) is not terribly common in puppies, it is most common in pregnant or nursing dogs. Hypocalcemia can be caused by severe malnutrition. More commonly, small breed puppies, like chihuahuas, can easily become hypoglycemic (low blood sugar). Sometimes this is caused by not eating frequently enough. I recommend that Bread be fed a good quality puppy food every 6 hours to prevent hypoglycemia. If she is lethargic, you can rub honey or caro syrup on her gums to help. If she will lap it up, you can also offer her a small amount of sugar water (but don't leave it out longer than a few minutes as it can quickly go bad and grow bacteria). In the US, we have a supplement called Nutrical, but it is not a calcium supplement, it has some vitamins, fat, protein, and sugar to help prevent this from happening. Other causes of hypoglycemia in puppies are congenital defects like portosystemic shunt or hydrocephalus, and other issues like bacterial infection (less likely based on the CBC), intestinal parasites, stress, or diarrhea.

She could be hypoglycemic. Small breed dogs should eat more frequent, smaller meals throughout the day as to not let their blood sugar drop. I suggest you do this and if she is still not acting normally she should see a vet.

If she is remaining sleepy, has poor balance or vomiting I would be concerned about a possible head injury and recommend she be assessed by a vet as soon as possible. Otherwise continue to monitor for food and fluid intake and ensure no rough play for the next 48 hours

Since I am unable to examine Tia, I would have her examined by your veterinarian to ensure this is nothing serious. If she is acting strange, she could have had a seizure or may be about to have seizure. Certain systemic illnesses may also exhibit similar symptoms. I would definitely get her in for a full workup to be on the safe side. Please feel free to contact me with any other questions / concerns you may have. I am also available via consultation.

Sounds like Ori may have low blood sugar (hypoglycemia) but that is not common in this size or age of puppy. I suggest you give a bit of Karo syrup or honey by mouth (just a teaspoon or two). If no improvement within 15 minutes of giving him that then he needs to see a vet ASAP.

So, potential serious concerns would be 1. poisoning (ie antifreeze, pot, chemicals, rotten carcasses, etc.) 2. seizures (dogs get epilepsy and it commonly presents in puppies 3. metabolic issue like a liver shunt can cause neurologic symptoms 4. trauma to the brain like being hit by a car. Any neurologic symptoms are very serious and I would take him to an emergency veterinarian for a full workup.

If the sugar water is not working anymore then the cause for the vomiting and walking like a drunk is not hypoglycemia. This is very concerning and actually an emergency. You need to take Luna to a Pet ER for an exam and blood tests and respective treatment. Please take her there now.