Help! Lump on Heifer

We recently gave our heifer a shot of LA 200 and she now has a large lump on the side of her neck she is in a show in 3 days and we need to get rid of it. Any ideas?

Best idea is never use liquamycin on show cattle.  They ought to be worth a $20 shot of draxxin.  Seems like shot knots can last for years.

The same thing happened to use a few years ago.  Luckily it was on the off-show side neck.  The vet made up a liniment/salve potion that we rubbed on her twice a day for a few weeks which reduced the size of the lumps.  It took probably 7 months or longer before the lumps stopped being noticeable. 

I sometimes give the shot behind the shoulder,  instead of the neck.  If it makes a knot it is less noticeable.  Also, the suggestion to use Draxxin instead of LA200 or LA300 by GoYWyo is a good one.  More expensive but better medicine.

That's really debatable and I would talk to a vet.  There are a lot of different antibiotics out there, and Draxxin is not only ridiculously expensive, but depending on what you are treating, it is not always the best option.

As far as the lump goes, cold compact on it, maybe some metacam, but the best thing for it is time.  I've had heifers have them never go away.