Mycobacterium avium subsp. hominissuis infection in horses with granulomatous enterocolitis – first report in Poland.
Abstract: Gastrointestinal mycobacteriosis in horses is difficult to diagnose because of the pathogen's intracellular nature and the non-specific clinical symptoms. Effective accurate diagnosis facilitates prognosis and treatment. Current diagnostic procedures and methods of collecting material do not permit definitive antemortem diagnosis. However, culturing, acid-fast bacilli staining, histopathology, PCR and immunological marker evaluation may prove useful. Unassigned: Three horses were admitted to a clinic for intensive care and a final diagnosis. Physical examination and additional tests were performed. Unfavourable prognoses and lack of treatment response prompted euthanasia decisions. Necropsy was performed, as were histological, microbiological and molecular investigations. Unassigned: The clinical condition of the animals deteriorated despite therapy. Two horses were euthanised when they did not respond to treatment and had poor prognoses. Intestinal mycobacteriosis caused by subsp. was diagnosed postmortem using laboratory investigations. One horse's diagnosis was established antemortem by cytological and microbiological examination of biopsy material from an abdominocentesis, and this animal was also euthanised because of its poor prognosis. Unassigned: Mycobacteriosis should be considered in the differential diagnosis of chronic debilitating equine diarrhoea in addition to rhodococcosis, lawsoniosis, salmonellosis, gastric ulcers and food intolerance. Peritoneal fluid obtained by abdominocentesis proved to be an effective diagnostic method for microbiological and molecular identification of subsp. in horses with suspected enteric mycobacteriosis and concomitant ascites.
© 2025 Beata Nowicka et al.
Publication Date: 2025-12-10 PubMed ID: 41497459PubMed Central: PMC12767164DOI: 10.2478/jvetres-2025-0067Google Scholar: Lookup
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- Journal Article
Summary
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Overview
- This study reports the first confirmed cases of Mycobacterium avium subsp. hominissuis infection causing granulomatous enterocolitis in horses in Poland.
- The research highlights challenges in diagnosing equine gastrointestinal mycobacteriosis and proposes effective diagnostic approaches including abdominocentesis for ante-mortem detection.
Background and Importance
- Gastrointestinal mycobacteriosis is a challenging disease to diagnose in horses due to the intracellular nature of the pathogen and vague clinical symptoms.
- The disease presents as chronic, debilitating diarrhea and granulomatous inflammation of the intestines, with other differential diagnoses such as rhodococcosis, lawsoniosis, salmonellosis, gastric ulcers, and food intolerance commonly considered.
- Mycobacterium avium subsp. hominissuis is a subspecies within the Mycobacterium avium complex, recognized in other species but newly reported in horses in this Polish study.
Clinical Presentation and Case Descriptions
- Three horses were admitted to a clinic for intensive care due to chronic gastrointestinal symptoms and deterioration despite treatment.
- All animals exhibited non-specific clinical signs, complicating initial diagnosis.
- Two horses were euthanized following worsening of symptoms and poor prognosis after ineffective therapy.
- One horse was diagnosed ante-mortem through cytological and microbiological analysis of biopsy samples from abdominal fluid collected via abdominocentesis but was also euthanized due to poor prognosis.
Diagnostic Methods and Challenges
- Traditional diagnostic methods such as culturing, acid-fast bacilli staining, histopathology, PCR, and immunological markers can aid diagnosis but often fail to provide definitive ante-mortem results due to the intracellular lifestyle of the bacteria.
- The study underscores the value of peritoneal fluid obtained from abdominocentesis as a sample source for cytological, microbiological, and molecular identification of the pathogen in live animals with suspected intestinal mycobacteriosis.
- This method proved effective in identifying Mycobacterium avium subsp. hominissuis in horses that presented with ascites and enteric signs, facilitating earlier detection compared to traditional approaches.
Postmortem Findings and Confirmation
- Necropsy of the euthanized horses revealed granulomatous lesions in the intestines confirming the diagnosis of mycobacteriosis.
- Laboratory investigations including histological examination, microbiological culture, and molecular assays validated the presence of Mycobacterium avium subsp. hominissuis as the causative agent.
Implications and Recommendations
- The study recommends including Mycobacterium avium subsp. hominissuis infection in differential diagnoses of chronic diarrheal diseases in horses to ensure accurate diagnosis and appropriate management.
- Given the severity and poor prognosis associated with this infection, early detection through innovative sampling methods like abdominocentesis is critical.
- The research provides an important reference as the first documented case series of this infection in Polish horses, contributing to global veterinary knowledge on equine mycobacteriosis.
Cite This Article
APA
Nowicka B, Łopuszyński W, Krajewska-Wędzina M, Biazik A, Sobuś M, Polkowska I, Szacawa E.
(2025).
Mycobacterium avium subsp. hominissuis infection in horses with granulomatous enterocolitis – first report in Poland.
J Vet Res, 69(4), 545-552.
https://doi.org/10.2478/jvetres-2025-0067 Publication
Researcher Affiliations
- Department of Animal Surgery, 20-950 Lublin, Poland.
- Department of Pathomorphology and Forensic Veterinary Medicine, 20-950 Lublin, Poland.
- Department of Food Hygiene of Animal Origin, University of Life Sciences in Lublin, 20-950 Lublin, Poland.
- Department of Veterinary Surgery, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland.
- Department of Diagnostics and Clinical Sciences, Institute of Veterinary Medicine, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland.
- Department of Animal Surgery, 20-950 Lublin, Poland.
- Department of Bacteriology and Bacterial Animal Diseases, National Veterinary Research Institute, 24-100 Puławy, Poland.
Conflict of Interest Statement
Conflict of Interests Statement: The authors declare that there is no conflict of interests regarding the publication of this article.
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