Ok, this is long but since this seems to be a common question for those with sick ones (I'm sick at home myself so I've been on here all day)
I've dealt with a ton of rescues, syringe feeding of wormers, antibiotics, everything! Vet trips are a priority but Leos never forget how to hunt. I've had leos that had to be force-fed for months and are now happy, healthy hunters on their own. Their appetites just needed to be stimulated. This takes patience and commitment.
Pediasure is fantastic for rehydrating if the leo isn't drinking. If you want a cheaper alternative to the rescue solutions sold commercially these are what works awesome for me:
These slurries can be refrigerated for several days in airtight tupperware or frozen into "single serving" ice cubes. This is very cool because you then just defrost one ice cube per feeding. Try to syringe feed several times a day for tiny tummies.
#1: The Baby Food Mixture
o 1 mini tupperware container
o 1 jar veggie baby food (peas, carrots, mixed, etc)
o 1 jar meat baby food (turkey, beef, chicken)
o Reptical or similar Leo vitamin supplement
o Mini-syringes without needles from local vet
o tons of patience & love
Adding powdered supplement (calcium especially) to the slurry works great. The veggie baby food has more water content so when mixed with the meat baby food, its easier to suck up into the syringe and squeeze out into the mouth once the lil guy opens up. The worst thing is if the leo opens up and you can't get the slurry out of the syringe!
#2: If you have a strong stomach and a borrowed blender (hee hee!)...
o Meal worms, crickets, or other prey in blender
o Add vanilla ensure
o If needed add more vita-cal/other powder leo supplement
o Add and blend away -- mmm, mushed mealies... 
This can be frozen as ice cubes for later defrosting too.
I had one baby that I had to force syringe feed for 2 months and went on 3 courses of antibiotics (baytril suspension). Pico's now my calmest rescue do to all the handling. Just sits in your hand and only runs when put down. Here's a link. Click on "Pico" folder:
Link
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Too many Leos
1.0 feline "Spot"
0.1 canine "Tika"
