Foal susceptible to Lawsonia

Veulens krijgen antistoffen binnen via de biest van de moeder, maar na een maand of twee neemt de bescherming via de biest af (Foto: Digishots)

April 14, 2021
Foals ingest antibodies via the dam’s beestings (colostrum), but after one or two months the protection from the beestings decreases (Photo: Digishots)

At Animal Clinic Den Ham, Veterinarian Gerrit Kampman saw a Friesian mare come off the trailer with a foal that was a few months old. He says: ‘The foal was very skinny and listless and she turned out to have a fever. The owner said the foal had not yet been dewormed. Establishing the correct diagnosis when faced with this kind of rather common symptoms is pretty difficult.’

Low protein content

The first step towards a diagnosis was a blood test, by carrying out a quick-test at the clinic. This revealed the foal’s blood had a very low protein (albumin) content. The outcome pointed in the direction of the Lawsonia Intracellularis bacteria, which causes Equine Proliferative Enteropathy (EPE) in horses, an infection of the small intestine. By now this bacteria is widespread in the Netherlands and horses can be exposed to it to a greater or lesser extent, for example through the scat of infected rats and mice. But other species, like birds, foxes and sheep can also be infected.


A healthy horse with good resistance will experience little problems when contracting a mild infection with the Lawsonia bacteria and will develop antibodies. Research has shown that the older the horse the more antibodies against Lawsonia are found in the blood. Foals have not yet developed antibodies against this pathogen. They do however, ingest the antibodies via the dam’s beestings, but after a couple of months the protection from the beestings diminishes. When a foal happens to have a reduced resistance, for example as the result of a considerable worm infestation, and then gets in touch with the Lawsonia bacteria it can develop EPE and become very ill indeed. At his clinic, Kampman has noticed that the occurrence of EPE is more common in older, already weaned foals that have gone to a foal-raising yard.

Worm egg counts

‘To be positive that the Friesian filly foal had been affected by the Lawsonia bacteria we examined the droppings and did a worm egg count‘, Kampman explains. ‘The dropping samples confirmed the presence of the Lawsonia bacteria.’ The Friesian filly has ingested the bacteria via the mouth, suckling or drinking water. After ingestion, the bacteria travels to the small intestine where it enters the intestinal wall and cells. Triggered by the Lawsonia bacteria the intestinal cells start to multiply rapidly, which causes thickening of the intestinal wall. When taking an ultrasound scan of the abdomen of an EPE-affected foal this thickened intestinal wall shows up clearly. Kampman states: ‘Diagnosing a foal is affected by the Lawsonia bacteria is essential because the foal can rarely beat the infection all by itself. If EPE has been detected and anti-inflammatory treatment commences early then foals usually recover well.’

Read the full real-life story by veterinarian Gerrit Kampman in the May issue of Phryso





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