The horse who drank coffee (or not)

Once upon a time there was a tiny laboratory at the Harness Track in Saratoga Springs, N.Y. where the Standardbred horses were blood tested before each race and the top three place horses had their urine tested after the race.  I was at first a technician and moved up the line to assistant director when the director and assistant left.  
We seldom found any major infraction in the use of drugs on the horses being raced.  The most common one was an oral medication given for lameness.  
One evening one of the techs found a specimen which showed an incriminating amount of codeine. This was in itself unusual, but it was a drug and we had to notify the judges.  A second blood sample was drawn from the horse and quickly run again.  It too proved positive.  So the horse was scratched from the race-meaning he was not allowed to race that night.  There was a sad tale behind it as we later found out that the horse in question was an older horse, the only one an elderly local couple had.  The man, himself, drove the horse and sulky in the races.  The horse was a great pet of the woman owner.  When they brought him to the track in their aging horse trailer pulled by their rusty, rattling Ford pick-up truck, the woman spent hours before each race brushing his bay coat, shining his hoofs,
and braiding ribbon into his black mane.  The night of their "shame"
the horse had been having a slight cough, so the woman, thinking only to ease the animal's discomfort, gave him a large dose of HER
cough medicine.  No intention of rule breaking.  She never thought about nor realized that the medicine contained a forbidden drug.
One afternoon as we tested the urine samples from the previous night, one of the winning horses tested positive for caffeine.  This was a first for us-certainly not a drug we ever expected to find. The horse in question had been blood tested pre-race and was found to be clean.  That; however, is the reason for testing the urine after the race.  There is sufficient time between drawing the blood and before the horse actually races to inject or otherwise give a medication.  There are guards in place around the stalls where the horses await their turn on the track, but even with lights, there are shadows and the possibility that a groom or trainer could quickly administer something without being detected.  But caffeine?  I have heard of horses that liked dill pickles and thought that was weird, but never have I seen a horse gulp down a cup of coffee.  Still the evidence was there.  So there were three tests done on that urine sample and all showed the high level of caffeine.  The case went to trial, as the owner totally denied having drugged his horse or any knowledge of anyone else doing it at his request.  It was eventually discovered that
the animal was a young mare, not yet trained to pee to the sound of a whistle after finishing her race.  The grooms all have a certain whistle that they use in training the racing horse to pee right away so they don't have to stand around for hours waiting for the required sample to be produced.  This night the mare did not pee right away.
She was offered water , walked about and still no pee.  The groom was disgusted.  He was missing a get-together at the local  bar.  He was getting tired and he drank several cups of black coffee to stay on his feet.  At last, exasperated with this whole thing, the young man led the mare into the stall, and standing in back of her, he, himself
peed into the plastic sample cup.  All that coffee he had consumed

enabled him to fill the rather sizeable cup to the required level.  He
snapped on the cap and handed the cup to the waiting guard who taped it shut and labeled it. Why hadn't the guard seen what occurred?  As I said, it was very late at night. The guard was tired too. There were shadowy areas in the stall.  The mare was large and the groom was small--and he stood in back of her.
So the mystery was solved.  We all know no horse would really drink enough coffee to show up so strongly on a drug test.