I have raised many baby chicks and, without fail, I have at least one or two each season who come down with a respiratory illness. I started working at our local wildlife shelter and have since learned how to medicate and force feed chicks (and sick adult chickens) who either need something a little more powerful than a water soluble antibiotic or won't eat or drink on their own.
The method I use is called gavage feeding or medicating.
You will need: 1. liquefied feed or oral suspension of antibiotics
2. Dosing Syringe (size dependent upon dosage)
3. Appropriately sized gavage tube, feeding syringe or urocatheter (gavage tube prefered).
4. You may need a small flashlight (I hold it in my mouth while I gavage chicks)
1. Figure out the appropriate dosage or serving size and draw it up into the feeding tube and syringe
2. Place chick or chicken on lap or tabletop in a well-lit area. Sometimes it helps to wrap larger birds in a towel or stick their heads through the arm of a toddler sized T-shirt to keep the flapping down.
3. Stretch the birds neck out or up while holding the mouth open.
4. Visualize the trachea (breathing tube) at the base of the tongue (you don't want to get the liquid in this orifice).
5. Visualize the esophagus at the very back, right-hand side of the birds mouth
6. Insert the tube into the esophagus, not the trachea. If you are not certain that you are in the esophagus, do not depress the plunger. If you are in the esophagus, you can usually see the tube, moving down the esophagus underneath the skin and feathers on the neck. Have some patience here, you may have to let them close the mouth and then re-open in several times and wait for them to move their trachea out of the way. Once you see the correct opening, you will know it. Take your time and don't rush, be absolutely sure.
7. Depress the plunger slowly and make sure that the liquid is not backing up into the mouth and down the trachea. As long as you have the neck and head stretched up completely and you have the tube IN the esophagus, AND you are not over-feeding/dosing the bird, this should not be a problem.
Here are some pictures and diagrams that you may find helpful:
The red arrow here is pointing to the trachea, where you do not want to get the liquid
This is the kind of gavage tube I use for chicks, except I cut the butterfly off of it and keep the tube at only about 4in long (for chicks). I use a bigger tube for bigger birds.
Another bird trachea. Notice how the tongue ends about half way into the mouth and the trachea is right behind it. The esophagus (where you want to put the tube) is in the way-back, right hand side of the mouth, what you would consider the throat in humans.