Findings:
- The cardiac silhouette is generally enlarged and rounded. The craniocaudal dimensions of the cardiac silhouette measures 6.7 times the length of a mid thoracic vertebral body (normal 5.6-6.3).
- Reference: Lamb CR, O’Callaghan MW, Paradis MR. Thoracic radiography in the neonatal foal: a preliminary report. Veterinary radiology. 1990 Jan;31(1):11-6.
- The pulmonary vasculature and parenchyma are within normal limits.
- A small amount of gas is present within the thoracic esophagus.
- The stomach is distended, with a large gas cap within the non-dependent aspect of the stomach. This gas cap has a well-defined interface with a moderate amount of homogeneous soft tissue opaque material within the gravity dependent aspect of the stomach.
Conclusions:
- Generalized cardiomegaly without evidence of left-sided congestive heart failure. In light of the reported Rhodococcus equi infection, consider endocarditis and/or pericardial effusion (r/o pericarditis) associated with septicemia as a possible etiology. Congenital heart diseases, such as a ventricular septal defect, may also be a consideration.
- Gastric atony or gastric outflow obstruction.
Follow-up:
- The foal had no prior history of heart murmur and was growing and acting normally before being diagnosed with Rhodococcus.
- An echocardiogram showed severe volume overload of the left ventricle with severe thickening of the aortic valve (involving all 3 cups), supporting a diagnosis of aortic valve endocarditis
- NECROPSY:
- Bacterial vegetatitive valvular endocarditis, aortic valve, severe, chronic, with left marked fibrosing and destructive suppurative myocarditis and mineralization, heart.
- Stricture, pyloric, locally extensive, severe, chronic, with proximal duodenal dilation, stomach.
- Pseudomembranous suppurative to eosinophilic typhlocolitis, severe, acute to subacute, with marked submucosal edema of right dorsal colon, dorsal large colon.
- Pneumonia, multifocal, mild, subacute, with edema and pleural effusion, lung.
- Fibrinous arthritis and synovitis (nonerosive), multijoint, moderate, acute to subacute, right and
left carpal and hock joints, legs.
A little bit more…
- Vegetative bacterial endocarditis is rare in foals (Collatos et al.).
- Lesions most commonly affect the aortic and mitral valve leaflets. Although not reported in foals, mural lesions have been documented in adult horses (Collatos et al.).
- Rhodococcus equi bronchopneumonia is a well-recognized cause of morbidity and death in foals 3 weeks to 6 months of age and may occur with a variety of extrapulmonary disorders (Reuss et al.).
- A study looking at extrapulmonary manifestations of R equi infection in foal documented pericarditis as being a more prevalent complication than endocarditis (Reuss et al.).
- A diagnosis of pericarditis in foals with R. equi is associated with a poor chance of survival (Reuss et al.).
References:
- Reuss SM, Chaffin MK, Cohen ND. Extrapulmonary disorders associated with Rhodococcus equi infection in foals: 150 cases (1987–2007). Journal of the American Veterinary Medical Association. 2009 Oct 1;235(7):855-63.
- Collatos C, Clark ES, Reef VB, Morris DD. Septicemia, atrial fibrillation, cardiomegaly, left atrial mass, and Rhodococcus equi septic osteoarthritis in a foal. Journal of the American Veterinary Medical Association. 1990 Oct 15;197(8):1039-42.
