Peer-reviewed veterinary case report
Mesenteric lymphangitis and sepsis due to RTX toxin-producing Actinobacillus spp in 2 foals with hypothyroidism-dysmaturity syndrome.
- Journal:
- Veterinary pathology
- Year:
- 2012
- Authors:
- Löhr, C V et al.
- Affiliation:
- Department of Biomedical Sciences · United States
- Species:
- horse
Plain-English summary
Two foals with a condition called congenital hypothyroidism-dysmaturity syndrome, which affects their growth and development, became seriously ill due to an infection from a type of bacteria known as Actinobacillus. Both foals showed signs of severe inflammation in their lymphatic system and had other physical issues, such as contracted tendons and one having an unusual jaw shape. Tests revealed that the bacteria were present in their tissues, but identifying the exact type was complicated. Genetic testing helped clarify that one foal had a specific strain of Actinobacillus, while the other had a different strain. Unfortunately, both foals had severe health issues, and the outcome was not successful.
Abstract
Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass spectrometric analysis of the two Actinobacillus isolates did not allow unequivocal identification. Comparative genetic analysis was done on these and similar isolates, including phylogeny based on 16S rRNA, rpoB and recN genes, as well as RTX (repeat in toxin) toxin typing of apxIA-apxIVA and aqxA genes. One isolate was identified as Actinobacillus suis sensu stricto, based on the presence of apxIA and apxIIA but not aqxA, whereas the other isolate had aqxA but neither apxIA nor apxIIA, consistent with A equuli ssp haemolyticus. Based on genotypic analysis of the isolates included for comparison, 3 of 3 equine ASLOs and 2 of 5 A equuli isolates were reclassified as A equuli subsp haemolyticus, emphasizing the importance of toxin genotyping in accurate classification of actinobacilli.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/21460119/