5-month-old unvaccinated puppy with parvo, Giardia & worms - Day 5 of symptoms. What are the most critical days?

Hi everyone. I'm hoping to get some insight while we continue following our veterinarian's treatment plan.

My puppy is a 5-month-old female German Shepherd/Husky/Labrador mix. We adopted her about 3 months ago. She had been dewormed and received her rabies vaccine, but her previous owner hadn't completed her puppy vaccinations, and we were still in the process of getting her up to date when she became sick.

She has also always been a puppy who loves chewing on everything she finds. Our veterinarian suspects this may have contributed to her exposure to Giardia, amoeba, and intestinal worms, although we know it's impossible to know for certain.

Timeline:

Saturday: Vomited undigested food and stopped eating.

Sunday: Ate only two probiotic treats, drank water, then vomited large amounts of fluid multiple times that night. We took her to an emergency clinic.

The first clinic (attended by assistants, not a veterinarian) thought an X-ray showed a 10.2 mm wire and recommended surgery. We sought a second opinion instead.

Monday: Second clinic repeated X-rays, CBC, and parvo test.

• X-rays were clear (no foreign body).
• Tested positive for parvo.
• Fecal tests also showed Giardia/protozoa, intestinal worms, and amoeba.
• She was hospitalized.
• She was also force-fed.

CBC:

• WBC: 6.7 (ref 6–17)

• MCH: 19.5 (low)

• MCHC: 27.1 (low)

• Everything else was within the lab's reference range. A repeat CBC is planned but not yet done as of now (Wednesday).

Tuesday: She had bloody diarrhea and still refused food. The vet initially thought she seemed weaker, but when he opened her cage and gave her more space, she became much more alert and walked around sniffing the cage.

Wednesday (today):

• She chewed through her IV, so it had to be replaced, and she's now wearing an Elizabethan collar.

• She vomited three times despite antiemetics.

• She still refuses all food and water offered voluntarily.

• During our morning visit, when the cage was opened, she stood up, walked, and slightly jumped out of the cage, and immediately went to my family.

• During our afternoon visit, however, she seemed much groggier and less responsive. The staff told us she had received antibiotics, immune boosters, and another medication they described as being for her energy.

• The vet currently estimates her prognosis as 50/50 and says she'll remain critical until she starts eating on her own.

My questions:

1. Would today be considered Day 5 of symptoms, and is that how parvo is generally counted?

2. What are typically the most critical days for puppies hospitalized with parvo?

3. At what point do veterinarians usually become more optimistic about survival?

4. Besides eating voluntarily, what early signs suggest a puppy is beginning to recover?

5. Is it common for puppies with parvo to seem more alert at one point in the day and much weaker or groggier later? Could medications or exhaustion contribute to those fluctuations?

I know no one can predict her outcome, and I'm not asking for guarantees. I'm just trying to understand where she is in the course of this disease while continuing to follow my veterinarian's recommendations.

Thank you so much for your time. We love this little girl so much and are hoping and praying so hard she pulls through. ❤️