Horse
Especially in older foals, Lawsonia intracellularis causes proliferative enteropathy, which is accompanied by significant hypoproteinaemia. The animals also show abdominal pain, reduced general condition and anorexia. Secondarily, oedema and a pear-shaped abdomen may occur.
Pig
Porcine proliferative enteropathy (PPE) is caused by an infection with the obligate intracellular, gram-negative bacterium Lawsonia intracellularis. It is widespread in pig herds, especially among weaners, store pigs and fattening pigs. Infected animals suffer from growth disorders and diarrhoea. Infection occurs via the oral route, the spread mainly through the purchase of infected animals. Often, the infection is subclinical.
PPE occurs in four clinically apparent forms: as acute and, if untreated, often fatal porcine haemorrhagic enteropathy (PHE) and as porcine intestinal adenomatosis (PIA), or less often as necrotic enteritis (NE) and as terminal regional ileitis (RI) with thickened and stiff ileum. While PHE mainly affects older fattening pigs and younger breeding pigs, the chronic forms PIA, NE and RI mainly occur in weaners and store pigs.
Small mammals
Infection with Lawsonia intracellularis presents with different clinical courses in small mammals. Ileitis is the typical manifestation. Haemorrhagic diarrhoea is a sign of acute disease, in the subacute form, there are reduced growth and diarrhoea as well. There may be no clinical signs in chronic Lawsonia infection. Young animals are often affected and contract the disease from their subclinically infected parents. A high population density, changes in food and other stress factors facilitate infections or worsen the clinical picture. L. intracellularis infections have primarily been described in hamsters, rabbits, ferrets and rats. It is important to be aware of the zoonotic potential.