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Lawsonia intracellularis: An emerging disease (Proceedings)
Emerging intestinal disease of the in the horse, referred to as Eequine proliferative enteropathy.
Lawsonia intracellularis
• Obligate intracellular curved, Gram Negative Bacterium
o Apical Cytoplasm of the intestinal enterocytes
o Crypt
Emerging intestinal disease of the in the horse
o Referred to as Equine Proliferative Enteropathy
• Disease primarily of pigs until the 1980s.
• Increased caseload in central Kentucky in the 2000s..
• Many Species : domestic and wildlife
o Pigs
o Hamsters
o Rabbits
o Fox
o Deer
o Ferrets
o Ostriches
o Non-Human Primates
• Horses : First Reported in 1982
• World Wide Distribution
o USA
o CANADA
o EUROPE (England, Belgium, Switzerland)
o SOUTH AMERICA
o AUSTRALIA
• Majority of cases are in Foals 2-8 month of age
o Few adult cases reported
Characteristics of Lawsonia
• Microaerophilic / anaerobic
• Genetically related to the sulfate-reducing bacteria, except...
o Obligately intracellular
o Causes proliferation of enterocytes
o Sulfate reduction not demonstrated
• Vibrio-shaped with a single polar flagellum
Clinical signs
• Ventral Edema
• Fever
• Colic
• Diarrhea
• Lethargy
• Weight loss
Seasonal omponent
Horses presented in the fall or early winter
Clinical pathology
• Hypoproteinemic
o Low Total Protein
o < 5.0 mg/dl
• Hypoalbuminemic
o < 2.0 mg/dl
Abdominal ultrasound
• May reveal segments of thickened small intestine
o Not very sensitive
Diagnostics (ante-mortem)
• Fecal Culture
• Not Practical
• Fecal PCR: Evaluated in Pigs
o Sensitivity : Variable (39-72%)
o Specificity : High (100%)
o HORSES?
• Early Clinical Cases
• Not good for Subclinical Cases
• Not good for Prolonged Cases
• SEROLOGICAL ASSAY
o IgG
o Employ LI cultured in Enterocytes
o OR
o Preparation of LI on slides as Antigens
• Staining of the bacteria either by flourescent (IFA) OR
• Peroxidase Labeled
• (Immunoperoxidase monolayer assay)
o POSITIVE > 1:60
Treatment
• Supportive Care
o Nutrition (TPN)
o Secondary Infections
o Fluids
o Colloids
• Hetstarch 10ml/kg IV
• Plasma 10-20 ml/kg IV
• ANTIBIOTICS
o Macrolides
• Erythromycin, Azithromycin (10mg/kg PO SID), Clarithromycin (7.5mg/kg PO BID)
o Tetracyclines
• Doxycycline 10mg/kg PO BID
• Oxytetracycline 6.6 mg/kg IV BID
o Chloramphenicol 50mg/kg PO TID to QID
