Abstract
Bronchointerstitial pneumonia was diagnosed postmortem in 19 foals in a 10 year retrospective study of submissions to a diagnostic center in Ontario. Mean age at death was 2.0 ± 0.05 (SEM) mo (range five days to four months). Fourteen of 19 were aged from 1.5 to 2.5 mo. Clinically, the disease was generally characterized by sudden onset of fever and increasingly severe dyspnea which developed into respiratory distress before death. Mean length of illness was 7.0 ± 0.33 days (range 1-21 days). The disease appeared to affect only individual foals on 19 different farms.
At postmortem, lungs were typically diffusely red, wet, firm, and failed to collapse. The major lesion recognized histologically was epithelial necrosis of alveoli and terminal bronchioles. Alveolar lumens contained large epithelioid cells, which were probably macrophages, and multinucleated syncytial cells were present in 16 of the 19 lungs. Inflammatory cells were sparse. Intraalveolar fibrin was prominent in all lungs. Bacteriological examination revealed no significant pathogen in 12 animals, but Rhodococcus equi was isolated from seven foals, associated in two animals with extensive abscesses. Viruses were not recovered from eight foals examined.
On the basis of the similarity and severity of lesions, the sporadic nature of the disease, and the similar age at onset which appears to coincide with declining maternally-derived immunoglobulins, we speculate that this disease may be the result of a viral infection.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Blakeslee J. R., Jr, Olsen R. G., McAllister E. S., Fassbender J., Dennis R. Evidence of respiratory tract infection induced by equine herpesvirus, type 2, in the horse. Can J Microbiol. 1975 Dec;21(12):1940–1946. doi: 10.1139/m75-281. [DOI] [PubMed] [Google Scholar]
- Buergelt C. D., Hines S. A., Cantor G., Stirk A., Wilson J. H. A retrospective study of proliferative interstitial lung disease of horses in Florida. Vet Pathol. 1986 Nov;23(6):750–756. doi: 10.1177/030098588602300614. [DOI] [PubMed] [Google Scholar]
- Fu Z. F., Robinson A. J., Horner G. W., Dickinson L. G., Grimmett J. B., Marshall R. B. Respiratory disease in foals and the epizootiology of equine herpesvirus type 2 infection. N Z Vet J. 1986 Sep;34(9):152–155. doi: 10.1080/00480169.1986.35331. [DOI] [PubMed] [Google Scholar]
- Griffiths P. D., Grundy J. E. The status of CMV as a human pathogen. Epidemiol Infect. 1988 Feb;100(1):1–15. doi: 10.1017/s095026880006550x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hietala S. K., Ardans A. A., Sansome A. Detection of Corynebacterium equi-specific antibody in horses by enzyme-linked immunosorbent assay. Am J Vet Res. 1985 Jan;46(1):13–15. [PubMed] [Google Scholar]
- Martens R. J., Martens J. G., Fiske R. A., Hietala S. K. Rhodococcus equi foal pneumonia: protective effects of immune plasma in experimentally infected foals. Equine Vet J. 1989 Jul;21(4):249–255. doi: 10.1111/j.2042-3306.1989.tb02161.x. [DOI] [PubMed] [Google Scholar]
- Studdert M. J. Comparative aspects of equine herpesviruses. Cornell Vet. 1974 Jan;64(1):94–122. [PubMed] [Google Scholar]
- Turk J. R., Brown C. M., Johnson G. C. Diffuse alveolar damage with fibrosing alveolitis in a horse. Vet Pathol. 1981 Jul;18(4):560–562. doi: 10.1177/030098588101800414. [DOI] [PubMed] [Google Scholar]
- Yager J. A. The pathogenesis of Rhodococcus equi pneumonia in foals. Vet Microbiol. 1987 Aug;14(3):225–232. doi: 10.1016/0378-1135(87)90109-x. [DOI] [PubMed] [Google Scholar]