Lawsonia Intracellularis

Last Updated on March 24, 2022 by Allison Price


Lawsonia Intracellularis causes Equine Proliferative Enteropathy. Horses are often called “Lawsonia.” is an obligate intracellular bacterium found in the proliferating cells of the intestinal crypt epithelial. Hyperplasia is a thickening or thickening the intestinal walls that leads to protein loss and malabsorption. Although the method of transmission to horses is not known, it is most likely that it is transmitted via the fecal or oral route.


Lawsonia is most common among young horses aged between 2-8 months and 8-12 months. However, it can also occur in adult horses. Late fall and early winter are the most common times horses experience lawsonia (August through January). Ventral edema is the most common clinical sign in affected horses. It can be seen in the jaw, abdomen, or stomach. However, horses may also experience lethargy and diarrhea. Low total protein and low levels of albumin are the most frequent findings on blood tests. The average albumin level in affected horses is below 3.0 mg/dL (reference range 3.4-4.1 mg/dL). Transabdominal ultrasound can often visualize thickened and edematous intestinal walls.

Lawsonia Intracellularis


Lawsonia can be diagnosed using typical clinical signs and a positive fecal DNA PCR, as well as a serum IPMA titre greater than or equal 1:60. A fecal sample and a blood sample taken in a red-top tube should both be submitted to the laboratory for analysis. A silver stain or postmortem PCR of a section from the intestinal wall is the best way to diagnose. However, it is not possible to obtain a tissue sample via surgery. Only three laboratories in the United States can perform Lawsonia titers.


The antimicrobial agent should have good intracellular penetration and be administered to affected animals. There are many options for treating affected animals, including doxycycline (LA200), clarithromycin, chloramphenicol, oxytetracycline (LA200), and doxycycline. Metronidazole can also be used with any of these antimicrobials. You may need to give antimicrobials for several weeks, or until your albumin levels show a trend toward the reference range.

Horses suffering from severe edema (intestinal and subcutaneous), or with low protein levels, should be administered Hetastarch and/or plasma. To correct electrolyte and dehydration, horses with severe edema may require intravenous fluid therapy.


Horses with the disease are usually able to survive if they are treated quickly. These horses can take several months to recover from the infection. Horses with severe illness may not be able to survive.


It is difficult to take preventative measures until we understand how and where the organism lives. Be familiar with the signs and symptoms of the disease to help diagnose infected horses quickly and get them on the right path. During treatment, sick animals should be kept separate from the rest. Hagyard Equine Medical Institute veterinarians have conducted clinical research and found positive results with an intra-rectal vaccination. Ask your veterinarian for information about this vaccine as a preventive measure against this disease.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!