Many years ago I worked for a vet and he said "never let anything die without using every weapon you've got!"
If she's going downhill and you've got no other meds, I'd try the La200. Here's what the Pfizer website says:
Uses:
Parental antibiotic treatment of a wide range of diseases caused by susceptible Gram-positive and Gram-negative bacteria.
LIQUAMYCIN LA-200 is approved for the treatment of pneumonia and shipping fever complex associated with Pasteurella spp. and Hemophilus spp.; infectious bovine keratoconjunctivitis (pinkeye) caused by Moraxella bovis; footrot and diphtheria caused by Fusobacterium necrophorum; bacterial enteritis (scours) caused by Escherichia coli; wooden tongue caused by Actinobacillus lignieresii; leptospirosis caused by Leptospira pomona; and wound infections and acute metritis caused by strains of staphylococci and streptococci organisms sensitive to oxytetracycline.
Key Features
Broad-spectrum oxytetracycline is effective against various bacterial diseases, including pinkeye, pneumonia, shipping fever, foot rot, diphtheria, bacterial scours, metritis, wound infections, leptospirosis (L. Pomona) and wooden tongue.
Contains Pfizer-quality oxytetracycline for proven dose-to-dose safety and consistency.
Ready to use. No mixing, refrigeration or special handing needed.
One dose delivers three days of sustained therapy. Fewer injections mean less labor and animal stress.
LA-200 has a long history of trusted, reliable performance as the pioneer antibiotic.
Beef Friendly subcutaneous (SC) option is available to minimize risk of carcass blemish.
Approved for use in lactating dairy cows.
Administered by SC or IV injection to beef and dairy cattle and calves, including pre-ruminating veal calves.