There are a number of troublesome and stubborn bacterial organisms that have plagued both human and veterinary medicine for years. In horses, some of these give rise to common but debilitating infections that, until fairly recently, were difficult to treat. One particular bacterial species among these is Pseudomonas aeruginosa. This bacteria was able to change its antibiotic susceptibility with each antibiotic exposure, and become resistant to multiple drugs in response to every medication used against it.1 Eventually, the aminoglycoside class of antibiotics was developed and there was finally a way to kill Pseudomonas. Unfortunately, this medication was available in injectable form only, often necessitating hospitalization for the patient, and carrying risks of potential kidney damage with prolonged use.2

A major breakthrough against Pseudomonas came with the development of the fluoroquinolone class of antibiotics. These medications are active against many bacterial types including  Pseudomonas. They are available in oral form and are not associated with the serious side effects that plagued the aminoglycoside group.1 Fluoroquinolones act by deactivating bacterial enzymes necessary for the transcription of DNA.

Related Bacterial Infections in the Horse

Myasthenia gravis a bacterially-mediated condition that is characterized by failure of neuromuscular conduction due to reduction in the number of acetylcholine receptors at the neuromuscular junction.3 It is caused by the development of circulating antibodies directed against the acetylcholine receptors at the neuromuscular junction. It is fairly common in mature dogs, uncommon in cats and sometimes occurs in horses, resulting in a condition known as Shivers. The condition is characterized by exercise-induced stiffness, tremors, and weakness that usually resolves with rest. Focal myasthenia gravis presents as facial, pharyngeal, or esophageal weakness without generalized weakness.2

Urinary tract infections (UTIs) are another troublesome condition affecting horses. Healthy adult horses seem to have a natural resistance to disorders of the urinary tract, but when problems in the renal system do occur, they are serious and must be dealt with promptly. UTIs are more likely to affect mares and foals. Mares are generally more susceptible to lower urinary tract infections, because their urethras are shorter than those of male horses and so can more easily transport bacteria to the bladder, resulting in bacterial cystitis. Foals, especially newborns, are also susceptible to UTIs.

Ciprofloxacin for Equines

Ciprofloxacin has demonstrated a significant postantibiotic effect in both gram-negative and gram-positive bacteria and is active in both the stationary and growth phases of bacterial replication. 

Enrofloxacin and ciprofloxacin have similar spectrums of activity. Both have good activity against many gram-negative bacilli and cocci, including most species and strains of Pseudomonas aeruginosa, Klebsiella spp, Escherichia coli, Enterobacter spp, Campylobacter spp, Shigella spp, Salmonella spp, Aeromonas spp, Haemophilus spp, Proteus spp, Yersinia spp, Serratia spp, and Vibrio spp.4 Other organisms that are generally susceptible include Brucella spp, Chlamydia trachomatis, staphylococci, Mycoplasma spp, and Mycobacterium spp (except for M. avium [paratuberculosis]). Ciprofloxacin has weaker activity against streptococci and enterococci and is not recommended in the treatment of these infections, and it is ineffective against anaerobes.3

Development of resistance to ciprofloxacin is a concern with many bacteria, particularly E. coli, staphylococci, and P. aeruginosa. Being effective against Staphylococci, ciprofloxacin is commonly used for skin infections.3 

Ciprofloxacin carries numerous potential drug interactions. Please consult your veterinarian prior to beginning any treatment regimen.

Where to buy Ciprofloxacin 

Ciprofloxacin is available in the U.S. through several pharmaceutical manufacturers and through veterinary custom compounding companies. 

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

1Dowling PM, Wilson RC, Tyler JW, Duran SH. Pharmacokinetics of ciprofloxacin in ponies. J Vet Pharmacol Ther. 1995 Feb;18(1):7-12. 

2Yamarik, T. A., Wilson, W. D., Wiebe, V. J., Pusterla, N., Edman, J., Papich, M. G. Pharmacokinetics and toxicity of ciprofloxacin in adult horses. J. vet. Pharmacol. Therap. 33, 587–594.

3Merck Veterinary Manual.