Excede, a new drug from Pfizer Animal Health, contains ceftiofur in the crystalline-free acid form. Approval was specific for respiratory-tract infections with Streptococcus equi, zooepidemicus variant, if the organism is sensitive to this particular drug.
This new drug form only requires two injections, spaced four days apart. This makes it much easier on owners doing their own injections and drastically cuts down on required farm visits for those having their horses treated by their veterinarian. With the original ceftiofur sodium form, treatment required up to 10 daily injections.
The drug itself has been around for a while, previously approved for other farm-animal species. A related drug, ceftiofur sodium, was already approved for equine use, for the same type of infection, but it required daily intramuscular injection. Excede should also only be used for the approved infection. it's available only through your veterinarian and by prescription.
The speed with which information can be spread on the Internet can be a good thing, however, it can also result in incorrect information and half-truths that cause panic.
There is an e-mail being circulated that claims Excede caused severe diarrhea, acid reflux and death of a horse. The horse was recovering from an injury and had been on oral trimethoprim sulfa before being switched to the Excede. The e-mail also claimed unidentified sources at Washington State University confirmed the drug caused diarrhea and acid reflux.
it's not clear what was meant by acid reflux here, since the esophagus of horses has a one-way valve that does not allow stomach contents to reflux.
No matter why, this owner?s experience was tragic, but that doesn't mean it's typical. When the safety question was raised by our veterinary editor on a large equine-veterinarian Internet group (based at Washington State), no problems were reported, although there is not much experience with the drug yet.
Every New Animal Drug Application (NADA) submitted to the FDA includes safety data. In one part of the NADA, 278 horses were treated with Excede for upper respiratory bacterial infections.
At least one episode of diarrhea was reported in 9% of the treated horses but also in 7% of a 95-horse untreated control group. All of the cases resolved spontaneously with either no treatment (30 horses) or a single dose of an anti-diarrhea drug (two cases)
There were 10 deaths in that portion of the NADA, five in the 278 Excede-treated horses, and five in the 95-horse untreated control group. Most of the horses died of worsening of the lung disease. One Excede-treated horse, which had ?clinical signs of gastrointestinal disease? at the start of the study, was found to have colitis with a Clostridial infection (noted on postmortem exam).
In a separate safety study, four groups of 12 horses each received either standard dose of Naxcel (the daily dose form of ceftiofur) or half-strength, regular-strength or double-strength dosing with Excede.
Two doses of Excede were given, 96 hours apart. One of the horses in the regular-dose group had loose manure for two days. One horse in the double-dose group had colic on one day only and recovered without any treatment.
This preliminary data may change with more field experience but so far Excede does not seem to pose any more risk of colitis developing than Naxcel (approved six years ago, with 27 adverse events related to colitis reported to FDA as of June 2009) or any other antibiotic. However, there was a worrisome incidence of laminitis noted during this study.
In a second safety study, four groups of eight horses received either saline only or injections of regular dose, double-dose or triple-dose Excede, six injections made, 96 hours apart. One horse in the regular-dose group had one episode of diarrhea, as did two horses in the triple dose group. No laminitis was noted in any of the horses. Mild-to-moderate injection site reactions were common in this study.
If your horse has a serious infection resistant to other antibiotics, we believe the benefits of Excede outweigh any potential risks. However, caution is advisable with use in a horse with a history of gastrointestinal upset. Time will tell if this new drug has any higher, or lower, risk of intestinal complications under field conditions, but we find the preliminary safety data reassuring.
However, the laminitis observed in one of the safety studies is a concern for us. Until more experience is gained with this drug in horses with laminitis, it may be wise to use with caution in a laminitic horse.