Why is my dog so lazy and sleepy after mating while in heat?

Lethargy is normal for dogs who are in heat, and is due to the hormonal and prostaglandin changes that occur with a heat. This lethargy will pass when her heat is over, and there's really nothing you can do for her since it is due to hormonal and prostaglandin changes. I would just let her rest, give her love and attention.

It's possible, if she is in heat and was outside, that a male dog came into contact with her. If she is now acting very ill or lethargic, it would be best to seek out veterinary care to make sure there isn't another underlying cause, injury, or illness causing her symptoms.

No, being very lethargic isn't normal for a dog in heat so I'd have Bailey checked out by a vet to be safe. Do not allow her outside alone, and do not take her into public places while she is in heat. She is technically fertile now if she is in heat, but the best time to breed a dog is between days 9-14 of their heat. A dog's heat will last three to four weeks. I would not breed her until at least her second heat. I hope this helps!

Dogs can feel lethargic and not want to eat during their heat cycle especially their first one. However, this shouldn't last long. Vomiting is a bit unusual for a heat cycle. She should get a physical examination by a veterinarian to make sure she doesn't have gastroenteritis or pancreatitis.

I'm sorry to hear that Daisy has not been feeling well. The loss of appetite, increased drinking, lethargy, and licking of her vulva following mating (presumably during her heat cycle/ estrus) could be due to a number of causes: a urinary tract infection, pyometra (uterine infection), or pregnancy (although this is less likely to cause some of the signs you've noted). At this point, your best bet is to take Daisy to her vet for an exam, blood work, urinalysis, and possibly abdominal x-rays to try to get to the bottom of this situation so that appropriate treatment can be started. If she has a urinary tract infection, she will need antibiotics, whereas if she has a pyometra, she will need to be spayed immediately because this condition is life-threatening if not addressed urgently. I hope this helps and that all goes well for Daisy!

Lethargy and diarrhea re not usually normal during a heat cycle. Most dogs will be actively looking to mate, alert, receptive and have swelling of the vulva along with some bleeding. If you are seeing discharge that is not bleeding, diarrhea and lethargy it is best to bring her into a vet as soon as possible.

Dogs have heat cycles and not menstrual cycles, however it is possible she is going into heat and hence the behavioral change, though she shouldn't refuse to eat, or be extremely lethargic during. If it persists for more than a day, doesn't improve, or her symptoms worsen, it is best to seek out veterinary care to rule out issues such as an infection or another illness that could be causing these symptoms as well.