Cardiac changes in twenty cats with feline infectious peritonitis
Journal of veterinary internal medicine · 2026
In plain language
This study examined the hearts of twenty cats with feline infectious peritonitis (FIP) and no history of heart disease; it was not a study of FeLV. Part of the heart wall was thickened in some cats, and the median level of a blood marker of heart muscle injury was elevated at the initial assessment. Fluid was also found around the lungs and heart in some cats, without an identified cardiac cause. The findings suggest possible heart muscle inflammation or injury, but do not definitively confirm it or support conclusions specific to FeLV.
Scientific detail
This descriptive clinical study prospectively assessed cardiac changes in twenty cats with naturally occurring FIP and no previous history of heart disease. The claims in the supplied object are classified as level C evidence. No control group is reported, so the findings do not demonstrate causation; the object's limitations field is marked as not reported. This population does not establish findings in cats with FeLV or pre-existing heart disease.
Echocardiographic thickening of the left ventricular posterior wall was observed in a subset of cats. At initial evaluation, median cTnI exceeded the upper limit of the reported reference interval. This elevation of a myocardial injury biomarker applies to the group median and does not, on its own, diagnose myocarditis or establish clinical prognosis.
Pleural and pericardial effusions were observed in some cats, but the study did not identify a cardiac cause for them. This does not establish their non-cardiac cause either. The authors conclude that cats with FIP can present with increased cTnI and ventricular wall thickening suggestive of myocarditis or myocardial injury; these findings do not demonstrate a definitive histopathologic diagnosis.
Feline leukemia virus antigen testing was performed as part of screening for concurrent infections associated with myocarditis. Direct relevance to FeLV is limited to this methodological aspect: the supplied source does not report the test results or any FeLV-specific cardiac findings. It also does not demonstrate that FeLV contributed to the observed changes or establish a mechanism related to this virus.
What we know
In this descriptive study of twenty cats with FIP and no history of heart disease, left ventricular posterior wall thickening was observed in some animals, and median initial cTnI exceeded the reported upper reference limit. Pleural and pericardial effusions occurred in some cats, without an identified cardiac cause. The authors consider the cTnI and ventricular wall changes suggestive of myocarditis or myocardial injury. The evidence is classified as level C and does not demonstrate causation. FeLV antigen testing was included in the assessment.
What we don't know
The supplied data do not establish a definitive histopathologic diagnosis of myocarditis, clinical prognosis from the cTnI elevation, or the non-cardiac cause of the effusions. FeLV test results and cardiac findings specific to this virus are not reported, and its contribution to the observed changes is not demonstrated. Findings in cats with pre-existing heart disease are not established either.
Evidence
EvidenceLevel C — Preliminary evidenceConfidence 99/100
Left ventricular posterior wall thickening was observed in a subset of cats with FIP.
Excerpt verified in the source — verbatim, in the source's own language“The left ventricular posterior wall from right parasternal long axis and short axis was thickened in 55% (11/20) and 25% (5/20) of cats, respectively.”
This supports the presence of echocardiographic ventricular wall thickening in some cats with FIP. Because the study is descriptive and no control group is reported, it does not prove causation.
EvidenceLevel C — Preliminary evidenceConfidence 98/100
The study prospectively assessed cardiac changes in twenty cats with naturally occurring FIP and no previous history of heart disease.
Excerpt verified in the source — verbatim, in the source's own language“ANIMALS: Twenty cats with naturally occurring FIP without previous history of heart disease.”
This establishes the feline study population described in the source. It does not establish findings in cats with FeLV or in cats with pre-existing heart disease.
EvidenceLevel C — Preliminary evidenceConfidence 99/100
Pleural and pericardial effusions were observed in some cats, but the study did not identify a cardiac cause for those effusions.
Excerpt verified in the source — verbatim, in the source's own language“Pleural effusion was present in 40% (8/20) of cats and pericardial effusion in 25% (5/20) of cats, but a cardiac cause was not identified for these effusions.”
This supports that effusions were present in the cohort and that the authors did not attribute them to a cardiac cause. It does not establish the non-cardiac cause of the effusions.
EvidenceLevel C — Preliminary evidenceConfidence 98/100
Median cTnI at initial evaluation was above the reported upper reference interval in cats with FIP.
Excerpt verified in the source — verbatim, in the source's own language“Median cTnI at initial evaluation was 0.37 ng/ml (interquartile range [IQR], 0.20-0.83; upper reference interval, 0.20 ng/ml).”
This indicates myocardial injury biomarker elevation at initial evaluation at the group median level. It does not by itself diagnose myocarditis or establish clinical prognosis.
EvidenceLevel C — Preliminary evidenceConfidence 99/100
The authors conclude that cats with FIP can present with increased cTnI and ventricular wall thickening suggestive of myocarditis or myocardial injury.
Excerpt verified in the source — verbatim, in the source's own language“Cats with FIP can present with increases in cTnI and ventricular wall thickening, findings suggestive of myocarditis or myocardial injury.”
This captures the authors' stated conclusion. It suggests possible myocarditis or myocardial injury but does not prove a definitive histopathologic diagnosis or FeLV-related mechanism.
EvidenceLevel C — Preliminary evidenceConfidence 98/100
Cats diagnosed with FIP were tested for feline leukemia virus antigen as part of screening for concurrent infections associated with myocarditis.
Excerpt verified in the source — verbatim, in the source's own language“Cats diagnosed with FIP were tested for common concurrent infections associated with myocarditis by testing serum for feline immunodeficiency virus (FIV) antibodies, feline leukemia virus antigen (FeLV), Dirofilaria immitis antigen, Bartonella spp. immunoglobulin G (IgG), and Toxoplasma gondii IgG and immunoglobulin M (IgM) as well as by testing blood for nucleic acids of Bartonella spp. and coronavirus (SARS-COV-2).”
This shows FeLV antigen testing was included in the workup. It does not report FeLV antigen results or show that FeLV contributed to the cardiac findings.
Provenance
Source: Descriptive assessment of cardiac changes in cats with feline infectious peritonitis.
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