Studies of an outbreak of Corynebacterium equi pneumonia in foals.
Abstract: Five out of 6 foals between 2 and 4 months old, on a ranch in northern California, developed pneumonia within a 3 week period in June and July 1978. Corynebacterium equi was recovered from each of the 5 foals by transtracheal aspiration. Clinical signs were variable but included increased respiratory rate, fever, cough, nasal discharge, harsh airway sounds over middle sized airways and wheezing over small airways. Cyanosis was present in the most severely affected foal. Radiographic findings included diffusely increased interstitial and peribronchial densities, areas of consolidation and, in 3 cases, dense focal areas indicating abscessation. Foals were treated with several different antimicrobial agents. Most were treated with penicillin and gentamicin. Four of the 5 affected foals recovered within 2 to 3 weeks but the first foal to be affected died 2 days after first receiving veterinary attention. At postmortem examination, pulmonary changes considered typical of C equi pneumonia were found, including wet, heavy dark red lungs which failed to collapse and numerous 1 to 7 cm thin-walled abscesses throughout the parenchyma, containing inspissated exudate. C equi was cultured from the exudate. Samples of soil and dust from 9 of 20 areas inhabited by infected foals yielded C equi of the same serological group as found in the foals. Eight paddocks in which foals had not been kept were negative for C equi. The organism was recovered from cobwebs in the stalls occupied by infected foals. Aerosol infection via dust was considered to be the route of infection. Pharyngeal, vaginal and faecal cultures from the dams of 3 affected foals were negative for C equi. Early diagnosis by transtracheal aspiration and appropriate therapy are considered to be extremely important in the successful treatment of C equi pneumonia. Preventive therapy should include control of environmental dust.
Publication Date: 1981-10-01 PubMed ID: 7318800DOI: 10.1111/j.2042-3306.1981.tb03500.xGoogle Scholar: Lookup
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Summary
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This study provides a detailed breakdown of an outbreak of Corynebacterium equi pneumonia in foals on a ranch in California, examining the symptoms, causes, and potential solutions for the disease, which recover after treatment with antibiotics.
Background
- The research details an outbreak of Corynebacterium equi pneumonia that affected five out of six foals between 2 to 4 months old, on a ranch in northern California, within a three-week period in June and July 1978. Corynebacterium equi was identified as the causative agent in each of the five ill foals through transtracheal aspiration, a diagnostic method in which a sample is obtained directly from the lung.
Clinical Signs and Radiographic Findings
- The clinical signs observed were not consistent among the foals but included increased respiratory rate, fever, cough, nasal discharge, and varying airway sounds. The worst affected foal also presented with cyanosis—a condition where the skin turns blue due to lack of oxygen.
- Examination through radiography revealed diffusely increased interstitial and peribronchial densities, areas of consolidation, and in some cases, dense focal areas indicating the presence of abscesses.
Treatment and Outcome
- Several different antimicrobial agents were used to treat the foals, with most administered penicillin and gentamicin. Four of the five affected foals recovered from the disease in 2 to 3 weeks, but the first foal to show symptoms died two days after receiving veterinary care.
- A postmortem examination on the deceased foal confirmed the typical features of Corynebacterium equi pneumonia, characterized by heavy dark red lungs that did not collapse and several small abscesses containing thickened exudate (fluid containing cells that are usually products of inflammation).
Source and Spread of Infection
- The organism behind the infection was sourced from soil and dust samples collected from nine out of twenty areas inhabited by the infected foals. The absence of the bacteria in eight paddocks where the foals were not kept supports the idea that the bacteria was acquired from the environment.
- The study identified cobwebs in affected foal stalls as carriers, leading to the hypothesis that dust inhalation was the main route of infection. This was further confirmed by the absence of the organism in the foals’ mothers, ruling out transmission via pharyngeal, vaginal, or fecal routes.
Preventive Measures
- The paper stresses the importance of early diagnosis through transtracheal aspiration and appropriate antibiotic therapy for successful treatment.
- Prevention strategies should involve control of environmental dust to reduce chances of infectious Corynebacterium equi particles.
Cite This Article
APA
Smith BP, Robinson RC.
(1981).
Studies of an outbreak of Corynebacterium equi pneumonia in foals.
Equine Vet J, 13(4), 223-228.
https://doi.org/10.1111/j.2042-3306.1981.tb03500.x Publication
Researcher Affiliations
MeSH Terms
- Animals
- Anti-Bacterial Agents / therapeutic use
- Corynebacterium / isolation & purification
- Corynebacterium Infections / drug therapy
- Corynebacterium Infections / epidemiology
- Corynebacterium Infections / microbiology
- Corynebacterium Infections / veterinary
- Disease Outbreaks / veterinary
- Female
- Horse Diseases / drug therapy
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horses
- Pneumonia / drug therapy
- Pneumonia / epidemiology
- Pneumonia / microbiology
- Pneumonia / veterinary
- Soil Microbiology
Citations
This article has been cited 9 times.- Hubelova D, Ulmann V, Mikuska P, Licbinsky R, Alexa L, Modra H, Gersl M, Babak V, Weston RT, Pavlik I. Nontuberculous Mycobacteria Prevalence in Aerosol and Spiders' Webs in Karst Caves: Low Risk for Speleotherapy. Microorganisms 2021 Dec 13;9(12).
- Shahani L. Rhodococcus equi pneumonia and sepsis in an allogeneic haematopoietic stem cell transplant recipient. BMJ Case Rep 2014 Jun 18;2014.
- Zink MC, Yager JA, Smart NL. Corynebacterium equi Infections in Horses, 1958-1984: A Review of 131 Cases. Can Vet J 1986 May;27(5):213-7.
- Smith KD, Butler DG. Fecal Isolation of Corynebacterium equi from a Foal with Chronic Diarrhea. Can Vet J 1984 Apr;25(4):180-2.
- Prescott JF, Travers M, Yager-Johnson JA. Epidemiological survey of Corynebacterium equi infections on five Ontario horse farms. Can J Comp Med 1984 Jan;48(1):10-3.
- Takai S, Iimori S, Tsubaki S. Quantitative fecal culture for early diagnosis of Corynebacterium (Rhodococcus) equi enteritis in foals. Can J Vet Res 1986 Oct;50(4):479-84.
- Zink MC, Yager JA. Experimental infection of piglets by aerosols of Rhodococcus equi. Can J Vet Res 1987 Jul;51(3):290-6.
- Prescott JF. Rhodococcus equi: an animal and human pathogen. Clin Microbiol Rev 1991 Jan;4(1):20-34.
- Ghielmetti G, Stevens MJA, Schmitt S, Kittl S, Cernela N, Biggel M, Schulthess B, Keller PM, Schrenzel J, Stephan R. Multi-host distribution of Rhodococcus equi (Prescottella equi) strains and their phylogenomic clustering. BMC Microbiol 2025 Jul 21;25(1):447.
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