The liver is a very large and resilient organ. It can weigh anywhere from 10-20 pounds and it can often have as much as 2/3 of the organ diseased before a horse will exhibit obvious signs of illness. In the horse, there are many factors that can attack the liver. These range from toxic insults, parasites, bacterial/viral infections, various forms of cancer, and autoimmune (body attacking itself) mediated diseases.
One form of acute liver disease comes by the way of a syndrome called “serum sickness” or Theiler’s Disease. Theiler’s Disease is usually fatal in horses. Although the exact cause of this disease is unknown, it is thought to be attributed to a horse receiving some sort of equine biological agent during the previous 4-12 weeks. A common equine biological agent purchased and used by many people today is tetanus antitoxin.
Antitoxin is derived from the blood of healthy horses that have been hyperimmunized with repeated large doses of Clostridium tetani toxin. Tetanus antitoxin is only recommended for horses that have never been immunized for tetanus and have had a known exposure to Clostridium tetani. Tetanus antitoxin and tetanus toxoid are not the same products! Tetanus antitoxin has more side effects and poses a greater risk than tetanus toxoid. Tetanus antitoxin is widely sold in feed and tack stores valley wide and is often purchased by the lay person in an effort to “treat” their horse through home remedies.
The majority of vaccines given every spring contain the safer product tetanus toxoid. If your horse sustains a deep penetrating wound, puncture, or laceration and has been properly vaccinated in the last year, there is no need for tetanus antitoxin to be given. We strongly caution horse owners not to purchase and administer tetanus antitoxin without veterinarian consultation! In our practice, we have never used tetanus antitoxin. Please call our office if your horse sustains a wound or laceration. In the process of caring for your horse, we will administer all necessary vaccines (if needed) during that visit.