All of our hens are 1 yr old BO gals. We started with 4- Healthy as horses. A couple months ago one of our hens died without symptom. Down to 3. In response to this death I wormed first with Wazine, then 2 weeks later with 1% injectible Ivermectin (under the brand name Endo-Mectin) mixed 6 cc to 1 gallon of water in their only waterer for 2 days. This was now three weeks ago. I use food grade DE in the coop bedding, which is pine shavings. I have ALWAYS done this. It has been HOT here and all my gals have been panting, wings slightly splayed. I have a large box fan blowing through their run and have been adding ice to their waterer to keep the water cool. Yesterday I added a under-the bed rubbermaid stoarge container filled with water- it is big enough that they could play in it, but not drown- if they were at all inclined... Two days ago I noticed one of my girls (Charlotte) gaping every few minutes. I picked her up- Her crop felt empty. I couldn't feel any blockage. She did not gape while I held her. She is NOT gurgling. No vomitus. Her comb and waddles are bright and plump. She eats well when allowed to range and has been enjoying cold yogurt, strawberries, lettuce, corn on the cob, fresh peaches, and bell peppers as treats. There is free choice oyster shell in the coop. She runs to me to get treats and eats them from my hands. All of my girls have a little bit of messy feathers visible under their vent. Charlotte laid an egg with such a thin shell that it cracked when I collected it 3 days ago. She usually lays very thick shelled, chalky, bumpy eggs. I figured that the change to the thin shell was due to all the heat/panting. She has laid one normal egg since, but no egg yesterday. I have noticed an occassional sneeze from each of the girls and one hen (Lucy) has slightly off-colored, purplish comb. These gals used to look like they'd been to the spa, but now we have slightly messy bottoms and despite molting recently (it was a slow molt, perhaps yet not done??), their feathers look a bit worn and broken on the top of their back down by their tails. So my question- Was my worming method insufficient? Do I have gapeworm here? If so, can I use a few drops of the Ivermectin straight into their mouths? I know this stuff is meant for pigs and cattle, so I don't want to poison them, but I don't have the oil based kind to be used externally and I don't know that putting it in the waterer worked. Is there something else I should be doing? One gaping, all occassionally sneezing, another with purplish comb? What am I missing here? Thanks all, for all of your help and expertise!