The use of antibiotics with most sport horses is not very common/excessive. At least with mine. I've had horses for 4 decades (most of that was as a one horse owner) and I remember using antibiotics maybe a half a dozen times if that many. What I've used the most of would be NASIDs (non-steroidal anti-inflammatory drug), mostly phenylbutazone (bute) or banamine. A typical dosage for a 1000lb horse would be 1-4 grams a day prescribed for inflammation. These are not terribly different from ibuprofen for humans. The other drug/supplement that is commonly used are glucosemine products, at most 5cc a week for a loading dose then 5cc once a month. But again we are talking about a gram or two a day in 50lbs of matter to be composted. Parasites. Even with regular worming most horses carry a small amount of intestinal parasites. However, according to veterinarians most equine parasites won't survive a in a clump of manure on a day hotter than about 85 degrees. They are more resistant to cold weather. I don't really know how to answer the herbicide in hay question. Most horse owners won't have any idea what was used for broad leaf weed control for their hay. I can say this: 2 4-D is the most commonly used broad leaf weed killer for agricultural in the world and I'm pretty sure it is not of the class that might be an issue. It is the herbicide I use when needed on my own pastures used for grazing and is the herbicide most people I personally know who grow hay use--including the source for my own hay. I've never run across anyone in my horse circle who has used their own composted manure/stall leavings and been anything other than thrilled with the results. So I would guess that the problem is on the untypical side of things and seeing my own results, worth the risk.

AVG completed, and after some digging I found: 1) 1 threat found 2) 1 file healed 3) 1 file deleted This seems to say the Trojan was found and "killed".

I do not know if what you are seeing is the real shield or if you have one of the fake AV infections which produces a fake shield it sounds like you do have one of the infections. Run malwarebytes asap and post the scan results here please. Please download Malwarebytes' Anti-Malware to your desktop. * Double-click mbam-setup.exe and follow the prompts to install the program. * At the end, be sure a checkmark is placed next to Update Malwarebytes' Anti-Malware and Launch Malwarebytes' Anti-Malware, then click Finish. * If an update is found, it will download and install the latest version. * Once the program has loaded, select Perform full scan, then click Scan. * When the scan is complete, click OK, then Show Results to view the results. * Be sure that everything is checked, and click Remove Selected. * When completed, a log will open in Notepad. Please save it to a convenient location. The log can also be found here: C:\Documents and Settings\Username\Application Data\Malwarebytes\Malwarebytes' Anti-Malware\Logs\log-date.txt

very very rarely do we get them fully clean using the mentioned programs, they do an excellent job to get it removed enough to be able to work with it and finish the job. Just follow my link and do post at LzD the team there will assist you, I can start a thread there for you if you prefer just let me know. It is likely you will need to use combofix with guidance and specific to your machine. I think many would be very surprised to find just how much remnant remains even when it seems to be back to normal. Which is why when one of the bad ones hits it is imperative to go to the security help forums and let the pros help. Looking at logs and in depth examination is essential. Unfortunately it is not something everyone is willing to do, it is time consuming and very detailed. The most important thing though is once you do get help from a forum like LzD it is imperative to stick with that forum and that team till they tell you it is all done. Following different suggestions on various places confuses the issue and is not fair to the helpers.