Help with reduced appetite in puppy with prolonged heat

[guitar4721]

My 8.5 month old toy fox terrier puppy who weighs 6.7 pounds has had reduced appetite for over a week. We took her to the vet yesterday because she has been in heat since February 6 and continues to bleed, and because of her reduced appetite. The workup (x-rays, CBC, ultrasound) was negative for an infection, but she continues to have reduced appetite. She barely touched the prescription food that the vet prescribed (Purina Pro Plan Veterinary Diets EN Gastroenteric). We also tried boiled chicken and rice earlier this week, which she ate well, but which causes a lot of constipation. She doesn't touch various two different kinds of kibble (including the one she's always eaten, which she used to love up until about 1.5 weeks ago). Notably, we also reintroduced training treats around 2 weeks ago; before that we had basically only been giving her kibble - so I'm wondering if part of this is that she's just lost interest in kibble and healthy foods after tasting the good stuff.

I'm at a loss for what to do about her diet. How do we get her to eat a balanced meal? We've tried to add appetite stimulants like peanut butter, parmesan, and yogurt to her kibble. She eats the stimulants well, and also takes treats, but doesn't touch the nutritious food she really needs. I'm worried that she's already lost some weight - and she's tiny so has a very small margin.

 

[sheba92766]

@guitar4721 Mix fresh foods in. Kibble is boring and shouldn’t be fed alone.
Add wet, freeze dried raw, broths, pumpkin, plain Greek yogurt, etc.

 

[girlplea]

@guitar4721 Have you tried actual appetite stimulants such as mirtazapine or capromorelin?

Prolonged estrus in puppies isn't that uncommon. But I am confused why your vet has not suggested hormone replacement therapy seeing that its lasted longer than a month...

 

[guitar4721]

@girlplea Thanks! No we haven't gone for pharmacological interventions yet. The vet earlier today recommended returning to boiled chicken and rice for now, which she has continued eating - and says we'll manage any constipation that might emerge from this diet with laxatives.

Regarding her prolonged estrus, the plan is to spay her in 2 weeks if she continues to bleed. If she stops bleeding by then, we'll wait 4-6 weeks to spay her as would normally be indicated. There hasn't been discussion of hormonal treatments at this point, since we are planning to spay her anyway (she is going through her first heat because she had a tucked vuvla, which the heat definitely corrected).