Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock.
QUESTION: A couple of years ago, I heard about research into a vaccine for Lawsonia. Does it work, and can I be comfortable it's safe for my horse?
DR. LAURIE METCALFE: For anyone unfamiliar with “Lawsonia”, Lawsonia Intracellularis is actually the organism causing this disease, technically Equine Proliferative Enteropathy (EPE); however this disease is often just referred to as Lawsonia. This is an intracellular bacteria found in the crypt cells of the small intestine, causing proliferation of the intestinal walls, most common in foals four to nine months old.
Thickening of the small intestine causes malabsorption and protein loss. This loss of protein, specifically albumin, results in peripheral edema (throatlatch, distal limb, abdomen). Many of these foals are febrile and depressed, and can even present as just colic or diarrhea. Many have poor appetites resulting in a profound weight loss.
Diagnosis can be confirmed by fecal PCR or blood titer. Treatment includes weeks of anti-microbials and foals can take months to return to adequate body condition. Plasma can be administered to replace protein and other factors as well as restoring oncotic pressure (cause of the edema). Treatment can get quite expensive.
Most can agree that it is usually better to prevent disease than have to treat disease. In 2012, a few studies were performed using a live avirulent vaccine labeled for pigs (the original species affected by this disease). Vaccine was given intrarectally, twice, 30 days apart. Studies confidently demonstrated safety, but one possibly lacked a significant environmental challenge.
Another included an experimental challenge with very promising results, however involved very small sample sizes. Several years ago, due to necessity on some endemic farms that had historically lost foals to Lawsonia every year, a few veterinarians, myself included, began using this vaccine off label for the prevention of EPE. We have now administered hundreds and hundreds of doses on endemic farms with minimal to no side effects, with profound success in preventing clinical disease. Vaccination is rarely 100 percent preventative, and vaccination failure is always possible, but if administered correctly with appropriate timing and handling of the product, this one comes very close.
I would not hesitate to recommend this vaccine with confidence to anyone interested in using it, especially on farms that see cases of EPE or Lawsonia year after year. It requires no more time and effort than other vaccinations, and for farms that use it, the benefits are well worth the cost. Results have far exceeded any expectations we had for the prevention of this devastating condition.
Dr. Laurie Metcalfe completed her Animal Science degree from the University of Wisconsin-Madison and decided to pursue veterinary medicine only after working as an ICU and surgery technician at Rood & Riddle for 3 years. Dr. Metcalfe returned to Wisconsin to attend veterinary school and became an ambulatory veterinarian at Rood and Riddle, where she is now a shareholder. She specializes in neonatal medicine, enjoying foals as well as herd health and general medicine.
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