My poodle's nipple is red & swollen after first heat. Is it normal?

This looks like a mild skin infection/inflammation. I suggest you use these medicated pads on it. If after about a week to 10 days of use, the lesion is not better or looks worse then your vet should examine him. ( https://www.allivet.com/p-5393-douxo-chlorhexidine-3-ps-pads-for-dogs-and-cats-30.aspx )

Congratulations on your puppy! It is difficult to tell for certain from a photo, but it looks as though Mollie could have a pustule located adjacent to her nipple and that is what you are seeing. this is a little spot of infection under the skin (like a whitehead pimple in people). This isn't uncommon in puppies (we call it puppy pyoderma) and we often treat with a medicated shampoo or topical antibiotic in mild cases. I would wash the area with a mild soap and apply a triple antibiotic ointment for now and schedule an appointment with the vet to have it looked at to be on the safe side, as I said it is impossible to say for certain from a photo if this is exactly what is going on.

Nigeria's teat looks very inflamed! This can be due to trauma or infection. You can try applying a cool (not cold) compress to the area for about 5 minutes twice daily and make sure she is not licking or causing further trauma. If it does not resume a normal appearance within 24 hours, I recommend to take her to the vet. Watch for any lethargy, discharge, further swelling or pain as this likely indicates and infection and should be seen. I hope it this helps and feel free to post any further questions.

If you are concerned then you should get a second opinion. It is not normal for a nipple to be red and swollen. It could be infected and she may need an antibiotic to treat. Call another vet and schedule an examination.

a higher hormone activity level such as during heat can indeed make the mammary complexes get more blood supply in preparation for a possible pregnancy. This should go away a little while after coming out of estrus (estrus = heat, and your dog is in heat for about three weeks after she stops bleeding. If the redness does not subside, or if the skin starts to look diseased, you should have your vet give Fufu a skin exam.

That could be a normal reaction of the mammary glands after the season, and it is likely to resolve spontaneously one or two weeks after the season. if signs persist more than that and discharge comes out from nipples a check up would ideal as false pregnancy or mammary gland inflammation/infection may be present.

It doesn't look too serious to me. The nipple is mildly inflammed, which could be due to the surgery she had (for example it was irritated while the skin was scrubbed for the surgery). Please, monitor the nipple for the next few days. If you notice that it is getting more red, swollen or is painful for Ell, please, take her to your local vet for a check.