8 Month Old Losing Weight

I wouldn't worry too much if she is just dropping percentiles, but it sounds like she is also actually dropping weight. While this could just be that she is more active, I would still want to thoroughly look into it to be sure. One thing you could check are her Carnitine levels. My son dropped a pound between 6 and 9 mos checkups and it turned out his Carnitine levels were low. He needed to take an oral supplement for awhile and eventually outgrew it (which some do and some don't, but even if they don't it's just a matter of taking a supplement.) I know weight loss can be caused by a lot of things (and it sounds like you've got a good guess with intestinal parasites) and this may not help at all, but just one more thing to add to the list of things to check. (By the way it is a simple blood draw that checks this, so both the diagnosis and "cure" are relatively simple.) I would voice my concern to the dr. and if the the dr. thinks its okay to wait until 9 mos, then watch, but don't worry. Of course, if you are concerned, take her in. Better to be the overprotective mom who is in the dr.'s office unnecessarily than to have missed something crucial! Good luck!

The one thing that jumped out at me is that you mention hives, which are NEVER "normal". Your daughter is allergic to something, either the dog(s), something else in her environment, or food. If I were you, I would research that a little more. Keep a journal of her activities and food and see if you see a connection between anything and the hives.
A simple blood test can rule out food allergies. (My ND does a blood test that tests for 200+ food allergens.)

I would keep an eye on the weight loss for now, but wouldn't necessarily panic. I don't know anything about parasites, but perhaps testing her again would be wise, as would giving her medication for parasites regardless of the test results.

We are talking a very small weight loss so far. You never know, next month she could gain a few pounds! Babies can really be all over the map. One thing to consider is if you and her father are naturally skinny.

Good luck.

I don't have much experience in the weight loss division other than my breastfed son went from 95% at birth to 10% within the first 4 months and then stabilized.

But in terms of intestinal parasites, you are correct in that the tests for them are notoriously unreliable. If you suspect parasites, she probably has them. In Costa Rica, people just automatically treat for them every 6 months if they have any symptoms at all. One natural treatment is to grind up a few papaya seeds and mix them into soft food or a smoothie. They are used in many tropical areas to get rid of intestinal parasites. BTW you should treat the whole family. Giardia is extremely common and very easy to pass from person to person. I always was told you had to drink contaminated water but that is is not true.

Physical development can cause weight loss. There are a lot of things can can cause her to lose weight that are perfectly normal, so I wouldn't worry about it just yet. Also, most (if not all) ped offices do allow free weight checks at any time for infants.

J.,
I'm sorry you are so worried about this. You did the right thing by bringing her in and getting her tested for all that stuff.
In my experience, both my girls lost weight when they started crawling and walking. Has she recently started crawling?

Good luck
K.