FeLV detection in cat analyses from veterinary centers in Quito (2021–2024)
Animals : an open access journal from MDPI · 2025
In plain language
A study reviewed 850 cat analyses from veterinary centers in Quito and reported 28.59% positive results for FeLV. That figure describes the included analyses, not all cats in the city. Cats aged 1–5 years accounted for 54.32% of positive cases, but the authors found no statistically significant differences between age groups. The study cannot tell us how many cats with FeLV developed or will develop cancer.
Scientific detail
The retrospective study, published in Animals in 2025 (doi: 10.3390/ani15101469), evaluated 850 eligible cat analyses from veterinary centers in Quito during 2021–2024. Records included sex, date of birth, test result, and sample type. The Results section reports 876 analyses before exclusions. Whether repeat analyses from individual cats were excluded is not reported, so the 850 analyses cannot be confirmed to represent distinct animals. No clinical comparison group is described; laboratory assay controls do not make this a controlled clinical study.
The authors reported FeLV-positive RT-qPCR results in 243 patients (28.59%) and negative results in 607 (71.41%). This positivity frequency applies to the selected dataset and does not establish infection prevalence among all cats in Quito. Confidence intervals for the positivity estimate are not reported. Cats aged 1–5 years accounted for 54.32% of positive cases, with no statistically significant differences between age groups according to the authors. The proportions of positive cases within demographic categories describe the composition of those cases, not category-specific infection risks or cancer risks. The predominance of one age category does not establish greater susceptibility associated with that age. The claims about sampling, positivity, and age distribution are classified as level C evidence in the knowledge object.
The authors do not explicitly present study-specific limitations in the Discussion. Limitations identified during information extraction include the use of veterinary-center laboratory submissions without a reported population-based sampling design, and the absence of a clinical comparison group and longitudinal cancer follow-up. In addition, the overall sex labels conflict between the Results prose and Table 1.
The study provides direct feline epidemiological evidence about FeLV detection and exposure-frequency context for lymphoma, leukemia, and oncogenesis research. It reports no cancer diagnoses, tumor characterization, or longitudinal oncological outcomes; neoplasia is discussed as background rather than measured as an outcome. The detection frequencies therefore cannot establish the incidence of FeLV-associated lymphoma or leukemia, progression from infection to cancer, or oncogenic mechanisms. This conclusion is an inference about the scope of the data, not evidence that positive cats lacked malignancies.
What we know
Within the 850 eligible analyses, the authors reported 243 patients positive for FeLV by RT-qPCR (28.59%) and 607 negative (71.41%). Cats aged 1–5 years accounted for 54.32% of positive cases, with no statistically significant differences between age groups according to the authors. These findings, classified as level C evidence, describe the selected laboratory dataset and do not establish age-specific infection risks or prevalence among all cats in Quito.
What we don't know
Whether repeat analyses from individual cats were excluded and confidence intervals for positivity are not reported. The overall sex labels conflict between the Results prose and Table 1. Without a reported population-based sampling design, a clinical comparison group, or longitudinal cancer follow-up, these data do not establish population prevalence, the incidence of FeLV-associated malignancies, the proportion of infected cats that will develop cancer, or mechanisms of oncogenesis. The absence of oncological outcomes does not demonstrate an absence of malignancies in positive cats.
Evidence
EvidenceLevel C — Preliminary evidenceConfidence 100/100
Cats aged 1–5 years accounted for 54.32% of FeLV-positive cases, but the authors reported no statistically significant differences among age groups.
Excerpt verified in the source — verbatim, in the source's own language“Regarding the ages of FeLV-positive animals, 54.32% (132/243) were cats between 1 and 5 years old, 22.22% (54/243) were between 1 month and 11 months, 18.52% (45/243) between 5 and 10 years, and 4.94% (12/243) between 10 and 19 years ( Table 2 ), with no statistically significant differences among age groups ( p = 0.22).”
These percentages describe the age composition of positive cases, not age-specific infection probabilities or cancer risks. The predominance of one age category does not establish an age-related susceptibility effect.
EvidenceLevel C — Preliminary evidenceConfidence 100/100
RT-qPCR identified FeLV positivity in 243 patients (28.59%) and negativity in 607 patients (71.41%) in the included dataset.
Excerpt verified in the source — verbatim, in the source's own language“Regarding the presence of the virus in the samples, RT-qPCR determined that 243 patients (28.59%) tested positive for the virus, while 607 patients (71.41%) tested negative for the feline leukemia virus ( Table 1 ).”
This is the observed laboratory positivity frequency in the selected dataset. It does not establish the infection prevalence of all cats in Quito, a malignancy frequency, or the proportion of infected cats that will develop cancer.
EvidenceLevel C — Preliminary evidenceConfidence 100/100
The study retrospectively evaluated 850 eligible cat analyses from veterinary centers in Quito, using records that contained sex, date of birth, test result, and sample type.
Excerpt verified in the source — verbatim, in the source's own language“This is an observational, retrospective study based on laboratory analyses conducted between September 2021 and December 2024, on animals treated at veterinary centers in Quito, Ecuador. Inclusion criteria were laboratory reports that included the patient’s sex, date of birth, test result, and sample type. Records that did not contain all this information were eliminated. A total of 850 cat analyses met the inclusion criteria and were evaluated, which included information on sex, date of birth of the patient, test results, and the type of sample obtained.”
This establishes the retrospective sampling frame and eligible analysis count. It does not establish population-representative sampling or confirm that all analyses corresponded to distinct cats. Laboratory assay controls do not make this a controlled clinical study.
InferenceConfidence 99/100
The reported FeLV detection frequencies cannot establish the incidence or mechanisms of FeLV-associated lymphoma or leukemia in this cohort.
This is an inference about the scope of the reported data: the study measures viral positivity and demographic distributions, without reporting cancer diagnoses, tumor characterization, or longitudinal oncological outcomes. It does not imply that FeLV-positive cats lack malignancies.
Provenance
Source: Retrospective Analysis of Feline Leukemia Virus (FeLV) Frequency in Domestic Cats in Quito, Ecuador (2021-2024).
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