My chihuahua in heat is licking and whimpering. Is this normal?

Hi, this is a behaviour that is normal in certain contexts. You need to keep an eye on everything else, if they are eating well, and drinking well and there are no abnormalities in the urine that you can see, I would not worry about it. Hope this helps !

It is normal during a heat cycle for the vulva to become very swollen. She is probably licking constantly to clean off and remove the bloody discharge that is coming out. She is just trying to keep herself clean. They can bleed pretty heavily for part of the heat cycle.

Chiquis likely is suffering from a bacterial dermatitis in this area or possibly a yeast infection. You will need to keep her from licking by placing a cone/e-collar on her. I suggest you make an appointment with your vet for an exam. The vet will likely take a swab and check the material under the microscope to verify that this is indeed a bacterial infection or a fungal (yeast) infection and them prescribe the relevant antibiotic or antifungal medication.

Biting at the paws or legs is more of an indication of something such as an allergy or irritation and may or may not be related to her heat cycle. If she is also licking or chewing at her vaginal area a lot or you are seeing strange discharge not related to her heat cycle from the vaginal area, then it could indicate irritation, inflammation or a possible infection that should be checked out by your vet. Some inflammation and discharge is normal during the heat cycle, however you are seeing any additional signs of illness or strange symptoms, a vet check is always best to rule out more serious conditions. If she is biting and chewing a lot, an Elizabethan (cone) collar may be useful to stop her from licking and chewing and worsening any irritation until you can get into your vet.

Sometimes dogs will feel uncomfortable during their first cycle. They may be lethargic, have a decreased appetite, and crave attention more than normal. All of this is completely normal. The itchy paws does not really fit with being in heat, and could be caused by fleas, mange, lice, infections (bacterial or yeast), ringworm, allergies, among others. You can try a medicated shampoo, like Dechra MalAcetic Ultra Shampoo along with a good flea preventative. If it continues after her heat cycle is over, you should see a vet for diagnosis.

Licking her vaginal area is a sign of heat, but without seeing in person, I can't say for sure she is in heat. I would recommend keeping her indoors most of the time, walking her on a lead to toilet, and keeping away from intact males so she does not become pregnant.

I would be concerned she may have an infection causing her pain and discomfort hence the licking and self trauma. It is very early for her to be back in a true heat (although not impossible) and I recommend a full vet check as soon as possible to determine exactly what is going on