# Feline Leukemia FeLV and FIV Testing: Snap Tests vs PCR Differences


## Key Takeaways

- SNAP tests detect viral proteins (FeLV p27 antigen) or the host's immune response (FIV antibodies), offering rapid point-of-care results, whereas PCR tests detect the virus's genetic material (proviral DNA or RNA), providing a more direct confirmation of infection.
- A positive FeLV SNAP test in a healthy, low-prevalence cat population has a low positive predictive value and requires confirmatory PCR testing due to a high likelihood of false positives, a critical distinction before making diagnostic or treatment decisions.
- FIV antibody SNAP tests indicate exposure and immune response, not necessarily active infection, and can yield false positives due to vaccination or false negatives during the early window period (up to 2 months post-exposure) before antibody seroconversion.
- PCR testing is the recommended confirmatory method for positive FeLV SNAP tests and can differentiate between progressive, regressive, and abortive infections by detecting proviral DNA integrated into host cells.
- The interpretation of FeLV and FIV test results is significantly influenced by regional disease prevalence; higher prevalence areas increase the likelihood of a positive SNAP test being a true positive, while lower prevalence areas necessitate more rigorous confirmation.
- False negatives can occur with SNAP tests during very early infection stages before antigen/antibody levels are detectable, and with PCR if viral genetic material is present at extremely low levels or if novel viral subtypes evade detection.

---

When a [cat](/knowledge/veterinary-medicine/clinical-methods/cat) is tested for [feline leukemia virus](/knowledge/viruses/pet-viruses/feline-leukemia-virus) (FeLV) and [feline immunodeficiency virus](/knowledge/viruses/pet-viruses/feline-immunodeficiency-virus) (FIV), the results can be life-changing. The two most common testing methods are point-of-care (PoC) antigen/antibody tests, often known as SNAP tests, and polymerase chain reaction (PCR) tests. The essential difference is that SNAP tests detect viral proteins (antigens for FeLV) or the cat's immune response (antibodies for FIV), while PCR detects the genetic material (proviral DNA or viral RNA) of the virus itself. Because these methods measure different things, they can sometimes produce conflicting results. A positive SNAP test in a healthy cat may be a false positive, and a negative SNAP test does not always rule out infection. This article explains the science behind both tests, their limitations, and how veterinarians use them to make accurate diagnoses. This information is educational and is not a substitute for veterinary diagnosis or treatment.

## At a Glance: SNAP Tests vs PCR for FeLV and FIV

This table provides a quick comparison for pet owners. Always discuss specific results with your veterinarian.

| Feature | SNAP / PoC Tests | PCR Tests |
| :--- | :--- | :--- |
| **What it Detects** | **FeLV:** p27 Antigen (a viral protein). **FIV:** Antibodies produced by the cat's immune system. | **FeLV:** Proviral DNA (integrated into host cells). **FIV:** Proviral DNA. Some tests also detect viral RNA. |
| **Sample Type** | Whole blood, serum, or plasma. Whole blood is often preferred for FeLV. [<a href="#ref-1">1</a>] | Whole blood, serum, or plasma. Often requires a specialized laboratory. |
| **Turnaround Time** | 10 to 20 minutes in the veterinary clinic. | Days to weeks, as samples are sent to an external lab. |
| **What a Positive Result Means** | **FeLV:** The cat has the p27 antigen in its blood. This indicates active or recent infection but can be a false positive in low-risk healthy cats. [<a href="#ref-2">2</a>] **FIV:** The cat has antibodies, meaning it has been exposed to the virus. It does not confirm active infection. | **FeLV:** The virus's DNA is present in the cat's cells. This confirms infection (progressive or regressive). [<a href="#ref-3">3</a>] **FIV:** The virus's DNA is present, confirming infection. |
| **What a Negative Result Means** | **FeLV:** Generally reliable for ruling out progressive infection, but may miss very early or low-level infections. [<a href="#ref-1">1</a>] **FIV:** Generally reliable, but can be negative in the early stages (up to 2 months) after exposure before antibodies develop. | **FeLV:** Strongly suggests the cat is not infected, but a very early infection could be missed. [<a href="#ref-3">3</a>] **FIV:** Strongly suggests the cat is not infected. |
| **Primary Use** | Initial screening in shelters and clinics. | Confirmatory testing after a positive SNAP test. |
| **Key Limitation** | Low positive predictive value in healthy, low-prevalence populations. [<a href="#ref-2">2</a>] | More expensive and not always immediately available. |

## Understanding Feline Retroviruses: FeLV and FIV

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses that can cause serious, lifelong health problems in cats. While both can weaken the immune system, they are biologically distinct.

FeLV is a significant cause of morbidity and mortality in cats, leading to conditions such as acquired immunodeficiency, aplastic anaemia, and various neoplasias like lymphoma and leukaemia. [<a href="#ref-3">3</a>] The virus is transmitted primarily through saliva, such as during mutual grooming, sharing food bowls, and bite wounds. It can also be passed from a queen to her kittens. In a 4.5-year study at a Portuguese teaching hospital, the overall prevalence of FeLV was found to be 11.3%. [<a href="#ref-4">4</a>] The impact is severe; a UK sanctuary study found that FeLV-positive cats had a median life expectancy of only 41.5 months compared to 160.3 months for uninfected cats. [<a href="#ref-5">5</a>] This virus significantly shortens lifespan and increases the risk of lymphoma. [<a href="#ref-5">5</a>]

FIV is transmitted primarily through bite wounds, making outdoor, intact male cats the highest risk group. It is often compared to HIV in humans because it attacks the immune system, leaving cats vulnerable to secondary infections. [<a href="#ref-6">6</a>] The same UK sanctuary study found that FIV-positive cats had a median life expectancy of 149.1 months, a smaller reduction compared to FeLV, but still statistically significant. [<a href="#ref-5">5</a>] Oral disease is also significantly linked to FIV infection. [<a href="#ref-5">5</a>]

Both viruses are endemic in many parts of the world. A systematic review of cases in Brazil found that FeLV and FIV remain common, with FeLV-positive cats often developing lymphoma. [<a href="#ref-7">7</a>] In Portugal, a study noted that the country exhibited the highest prevalence of FeLV infection (8.8%) in a 2019 Pan-European study. [<a href="#ref-4">4</a>] Understanding the prevalence of these diseases in a given region is critical because it directly affects the predictive value of diagnostic tests.

## The Science of Testing: Antigens, Antibodies, and Nucleic Acids

To understand the difference between SNAP tests and PCR, you must first understand what they are looking for.

### SNAP Tests: Detecting Viral Proteins and Host Antibodies

SNAP tests, also known as point-of-care (PoC) lateral flow tests or ELISA (enzyme-linked immunosorbent assay) tests, are designed for rapid, in-clinic use.

- **For FeLV:** SNAP tests detect the p27 antigen, a core protein of the virus. If the virus is replicating in the cat's body, this antigen will be present in the blood. The test does not detect the virus itself, but a protein it produces.
- **For FIV:** SNAP tests detect antibodies. When a cat is infected with FIV, its immune system mounts a response and produces antibodies against the virus. The SNAP test detects these antibodies, not the virus itself. This is a crucial distinction: a positive FIV antibody test indicates that the cat has been exposed to the virus and has mounted an immune response, but it does not confirm that the virus is actively replicating or even that the cat is persistently infected.

### PCR Tests: Detecting Viral Genetic Material

PCR (polymerase chain reaction) is a molecular technique that amplifies specific sequences of DNA or RNA. In the context of FeLV and FIV testing, PCR is used to detect the proviral DNA of the virus.

- **For FeLV:** When FeLV infects a cat, it integrates a DNA copy of its RNA genome into the cat's own cells. This is called a provirus. PCR tests detect this proviral DNA. [<a href="#ref-3">3</a>] This is a more direct indicator of infection than the p27 antigen, as it confirms the virus's genetic material is present in the cat's cells.
- **For FIV:** Similarly, FIV integrates its genetic material into the host's cells. PCR tests can detect this proviral DNA, confirming that the virus has established infection. [<a href="#ref-8">8</a>] Some advanced PCR tests can also detect viral RNA, indicating active viral replication.

The key difference is that SNAP tests look for the "footprints" of the virus (its proteins or the host's immune response), while PCR looks for the virus's "blueprint" (its genetic code).

## SNAP Tests: Procedure, Advantages, and Critical Limitations

SNAP tests are the first line of defense in feline retroviral testing due to their speed and convenience.

### Procedure

A small blood sample is collected from the cat. Many experts recommend using anticoagulated whole blood for FeLV testing, as it has been shown to increase the detection of low-positive cats compared to plasma or serum. [<a href="#ref-1">1</a>] The sample is placed into the SNAP device, and results are typically available within 10 to 20 minutes.

### Advantages

- **Speed:** Results are available during the same veterinary visit, allowing for immediate clinical decisions.
- **Convenience:** They are easy to perform in a clinical setting and require minimal equipment.
- **Cost-Effective:** They are generally less expensive than PCR tests.

### Critical Limitations

The most significant limitation of SNAP tests is their positive predictive value (PPV), which is the probability that a positive test result is a true positive.

A 2026 study in *Frontiers in Veterinary Science* investigated the performance of FeLV lateral flow tests in shelter cats in Mississippi. [<a href="#ref-2">2</a>] The researchers used Bayesian latent class modeling to estimate the true prevalence of FeLV and the predictive values of the test. They found that in apparently healthy cats, the estimated true prevalence of FeLV was very low (0.8%). At this low prevalence, the estimated positive predictive value of a FeLV lateral flow test was only 40.1%. [<a href="#ref-2">2</a>] This means that in a population of healthy cats, more than half of the positive FeLV SNAP test results could be false positives. The study concluded that "the predictive value of a positive test is low for healthy cats" and that serial testing may not meaningfully improve this. [<a href="#ref-2">2</a>]

However, the same study found that the PPV was much better (99.0%) in sick cats, where the true prevalence of FeLV was higher (5.3%). [<a href="#ref-2">2</a>] This highlights a fundamental principle of diagnostic testing: the predictive value of a test depends heavily on the prevalence of the disease in the population being tested.

For FIV, the situation is different. A study evaluating two commercial FIV antibody detection PoC kits in Egypt found that sequential testing with two different rapid kits yielded a sensitivity of 98.7% when compared to a diagnostic panel. [<a href="#ref-9">9</a>] However, the study also noted that only 10 of the 76 FIV-infected cats (13.2%) were positive on PCR, highlighting the potential for antibody tests to detect exposure rather than active infection. [<a href="#ref-9">9</a>]

Because of the low PPV in healthy cats, experts advise that a positive FeLV PoC test result must be confirmed with a PCR test before a cat is diagnosed as infected. [<a href="#ref-3">3</a>] This is especially critical before making decisions about euthanasia, as some cats that test positive on a SNAP test may not actually be infected.

## PCR Tests: Procedure, Advantages, and Interpretation

PCR testing is a powerful confirmatory tool that offers a different perspective on infection status.

### Procedure

A blood sample is collected and sent to a specialized veterinary diagnostic laboratory. The lab extracts DNA from the sample and uses PCR to amplify specific FeLV or FIV gene sequences. The results are usually available within a few days.

### Advantages

- **Confirmation:** PCR is the recommended confirmatory test for a positive FeLV SNAP test. [<a href="#ref-3">3</a>]
- **Direct Detection:** It detects the virus's genetic material, providing a more definitive answer about whether the virus is present in the cat's cells.
- **Differentiation of Infection Status:** For FeLV, PCR can help differentiate between progressive, regressive, and abortive infections, which is crucial for prognosis.

### Interpretation and Limitations

Interpreting PCR results requires nuance. A positive PCR result for FeLV proviral DNA confirms that the virus has integrated into the cat's genome. [<a href="#ref-3">3</a>] This confirms infection, but it does not always mean the cat will develop clinical disease. Some cats with regressive infections may have proviral DNA but not be actively shedding the virus.

A negative PCR result is generally strong evidence that the cat is not infected. However, it is possible to get a false negative if the infection is very early, before the virus has integrated into a sufficient number of cells to be detected.

## The Problem of False Positives and False Negatives

Understanding the reasons behind false results is essential for any cat owner.

### False Positives

- **FeLV SNAP Tests:** As discussed, false positives are a significant concern, particularly in healthy cats. [<a href="#ref-2">2</a>] The low prevalence of FeLV in healthy populations means that even a test with high specificity will produce a certain number of false positives. This is why confirmatory testing is so important. [<a href="#ref-3">3</a>]
- **FIV Antibody Tests:** A positive FIV antibody test can be a false positive if the cat has been vaccinated against FIV, as the vaccine stimulates the production of antibodies that are indistinguishable from those produced during natural infection. This is a major limitation of antibody testing.

### False Negatives

- **FeLV SNAP Tests:** False negatives can occur during the early stages of infection before the p27 antigen reaches detectable levels. A 2025 study found that testing whole blood on SNAP identified more low-positive cats than testing plasma or serum. [<a href="#ref-1">1</a>] This suggests that sample type can influence the sensitivity of the test.
- **FIV Antibody Tests:** False negatives can occur during the window period between exposure and seroconversion (the development of detectable antibodies), which can be up to 2 months. [<a href="#ref-6">6</a>]
- **PCR Tests:** False negatives can occur if the virus is present at very low levels or if the specific genetic sequence targeted by the PCR test has mutated. A study on FIV in Iran found significant amino acid substitutions in the V3-V5 env gene sequences, which could potentially affect the accuracy of some PCR tests. [<a href="#ref-6">6</a>] Similarly, a novel FIV subtype "X-EGY" was identified in Egypt, which may not be detected by all PCR assays. [<a href="#ref-9">9</a>]

## When to Test and How to Interpret Results

The decision to test and the interpretation of results should be guided by a veterinarian, but understanding the logic is helpful.

### Testing Recommendations

- **New Kittens or Cats:** All new cats entering a household should be tested for both FeLV and FIV.
- **Sick Cats:** Any cat showing signs of illness, such as fever, weight loss, oral disease, or recurrent infections, should be tested. [<a href="#ref-2">2</a>]
- **High-Risk Cats:** Cats with a history of fighting, outdoor access, or those from high-prevalence areas should be tested. [<a href="#ref-4">4</a>]
- **Before Vaccination:** Testing before FeLV vaccination is recommended to ensure the cat is not already infected.
- **Blood Donors:** Cats used as blood donors must be tested to prevent iatrogenic transmission.

### Interpretation of Results

The following is a general guide. Your veterinarian will provide specific advice.

| Scenario | FeLV SNAP (Antigen) | FeLV PCR (Proviral DNA) | Interpretation & Action |
| :--- | :--- | :--- | :--- |
| **Healthy Cat, Positive SNAP** | Positive | **Positive** | **Progressive or regressive infection.** Confirm with PCR. [<a href="#ref-3">3</a>] |
| **Healthy Cat, Positive SNAP** | Positive | **Negative** | **Likely a false positive SNAP result.** The cat is likely not infected. [<a href="#ref-2">2</a>] |
| **Sick Cat, Positive SNAP** | Positive | **Positive** | **Progressive infection.** The cat is likely infected and the virus is contributing to illness. [<a href="#ref-2">2</a>] |
| **Any Cat, Negative SNAP** | Negative | **Positive** | **Early or regressive infection.** The SNAP test may have missed a low-level infection. [<a href="#ref-1">1</a>] |
| **Any Cat, Negative SNAP** | Negative | **Negative** | **Not infected.** The cat is likely free of FeLV. |

| Scenario | FIV SNAP (Antibody) | FIV PCR (Proviral DNA) | Interpretation & Action |
| :--- | :--- | :--- | :--- |
| **Any Cat, Positive SNAP** | Positive | **Positive** | **Confirmed infection.** The cat is infected with FIV. |
| **Any Cat, Positive SNAP** | Positive | **Negative** | **Exposure or false positive.** The cat may have been exposed and cleared the virus, or the result could be due to vaccination. PCR can help clarify. |
| **Any Cat, Negative SNAP** | Negative | **Positive** | **Early infection.** The cat may be in the window period before antibodies develop. |
| **Any Cat, Negative SNAP** | Negative | **Negative** | **Not infected.** The cat is likely free of FIV. |

## The Impact of False Positives: A Real-World Example

The consequences of a false-positive FeLV test can be severe. In a 2026 case report, two young cats in Brazil were euthanized due to clinical suspicion of lymphoma, a cancer strongly associated with FeLV. [<a href="#ref-10">10</a>] Both cats had tested positive for FeLV on a SNAP test. However, at autopsy, the diagnosis was disseminated histiocytic sarcoma, not lymphoma. [<a href="#ref-10">10</a>] While the FeLV-positive SNAP result was noted, the study highlights how a positive retroviral test can influence clinical decisions and potentially lead to a misdiagnosis or premature euthanasia. This underscores the absolute necessity of confirmatory PCR testing before making irreversible decisions based on a single SNAP test result. [<a href="#ref-3">3</a>]

## The Evolving Landscape of FIV Testing

FIV testing is complicated by the high genetic diversity of the virus. A 2025 study in Egypt identified a novel and dominant FIV subtype, "X-EGY," in a population with a high prevalence (31.7%). [<a href="#ref-9">9</a>] The study found that while two different rapid antibody kits had a high sensitivity (98.7%) when used sequentially, only 13.2% of those infected cats were positive on the PCR test used in the study. [<a href="#ref-9">9</a>] This discrepancy suggests that the PCR test may not have been optimized to detect this novel subtype, or that the antibody test was detecting cross-reacting antibodies from a past exposure.

This example illustrates a critical point: no single test is perfect. Antibody tests can over-diagnose infection (by detecting past exposure), while PCR tests can under-diagnose infection (if they miss novel viral strains). This is why a combination of tests, interpreted in the context of the cat's health and risk factors, is often the best approach.

## Regional Prevalence and Its Effect on Testing

The prevalence of FeLV and FIV varies significantly by region, which directly impacts the interpretation of test results.

- **North America:** FeLV prevalence has declined in recent decades, but it remains a concern, especially in shelters. The low prevalence in healthy cats makes false positives a significant issue. [<a href="#ref-2">2</a>]
- **Europe:** Portugal had the highest FeLV prevalence (8.8%) in a 2019 Pan-European study. [<a href="#ref-4">4</a>] A later study in the Lisbon area found an overall FeLV prevalence of 11.3%, with a peak of 14.1% in 2020. [<a href="#ref-4">4</a>] In such high-prevalence areas, a positive SNAP test is more likely to be a true positive.
- **South America:** FeLV and FIV remain endemic in countries like Brazil, with a high incidence of FeLV-associated lymphoma. [<a href="#ref-7">7</a>]
- **Australia and New Zealand:** There is a perception of a decline in progressive FeLV infection, but it remains an important health threat. [<a href="#ref-3">3</a>]

This regional variability means that a veterinarian's interpretation of a SNAP test result will differ depending on where the practice is located. In a low-prevalence area, a positive result is more likely to be a false positive and will almost certainly be followed by a PCR test. [<a href="#ref-3">3</a>]

## Limitations and When to Contact a Veterinarian

This article provides a detailed overview, but it cannot predict the outcome for any individual cat. Breed, age, lifestyle, and overall health all play a role in how a cat responds to a retroviral infection. For example, a study on ocular microbiota found that co-infection with FIV and FeLV significantly altered the conjunctival microbiome, promoting the growth of specific opportunistic pathogens. [<a href="#ref-11">11</a>] This is just one example of how these viruses can have complex and unpredictable effects.

**You should contact your veterinarian immediately if:**
- Your cat has tested positive on a SNAP test and you have not yet discussed confirmatory PCR testing.
- Your cat is showing any signs of illness, such as lethargy, loss of appetite, weight loss, fever, pale gums, or difficulty breathing.
- Your cat has been in a fight with a cat of unknown health status.
- You are considering adopting a new cat and want to understand the testing options.

Do not make decisions about euthanasia or long-term prognosis based solely on a single test result. Always seek professional veterinary guidance.

## Frequently Asked Questions

### 1. What is the main difference between a SNAP test and a PCR test for FeLV and FIV?
The main difference is what they detect: SNAP tests detect viral proteins (FeLV antigen) or host antibodies (FIV), while PCR tests detect the virus's genetic material (proviral DNA). [<a href="#ref-3">3</a>]

### 2. My cat tested positive on a FeLV SNAP test but is acting healthy. Should I be worried?
Yes, but a positive result in a healthy cat has a high chance of being a false positive, especially in areas with low FeLV prevalence. A confirmatory PCR test is essential before confirming the diagnosis. [<a href="#ref-2">2</a>][<a href="#ref-3">3</a>]

### 3. Can a SNAP test for FIV be wrong?
Yes. A positive FIV antibody test can be a false positive if the cat has been vaccinated, and it can also detect past exposure rather than active infection. A negative test can be a false negative during the early window period after exposure. [<a href="#ref-9">9</a>]

### 4. Is a PCR test always the best option for initial screening?
No. SNAP tests are the recommended initial screening tool because they are fast and cost-effective. PCR is generally used as a confirmatory test after a positive SNAP result. [<a href="#ref-3">3</a>]

### 5. My cat tested negative on a SNAP test but positive on PCR. How is this possible?
This can happen during the early stages of infection when the antigen or antibody levels are too low for the SNAP test to detect, but the virus's DNA is already present in the cells. [<a href="#ref-1">1</a>]

### 6. What is a "regressive" FeLV infection?
A regressive FeLV infection occurs when a cat is infected with the virus, but the immune system suppresses viral replication. The cat may test positive on PCR (proviral DNA) but negative on a SNAP antigen test, and it may not develop clinical disease. [<a href="#ref-3">3</a>]

### 7. If my cat tests positive for FIV on a SNAP test, does that mean it will get sick?
Not necessarily. A positive FIV antibody test indicates exposure to the virus. Some cats can live long, healthy lives with FIV, though they are at increased risk for secondary infections and oral disease. [<a href="#ref-5">5</a>]

### 8. Are there any home testing kits for FeLV and FIV that I can use?
Yes, there are at-home test kits available, but they are not recommended as a substitute for veterinary testing. Professional veterinary clinics use validated tests and can properly interpret results in the context of your cat's health and local disease prevalence. A positive result from an at-home kit must be confirmed by a veterinarian.

## Sources

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<a id="ref-2"></a>[<a href="#ref-2">2</a>] [Feline leukemia virus point-of-care lateral flow tests have low positive predictive value in apparently healthy shelter cats.](https://pubmed.ncbi.nlm.nih.gov/41868399/)

<a id="ref-3"></a>[<a href="#ref-3">3</a>] [Feline leukaemia virus (FeLV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management.](https://pubmed.ncbi.nlm.nih.gov/40716042/)

<a id="ref-4"></a>[<a href="#ref-4">4</a>] [Prevalence of feline leukemia virus infection and associated diseases in a Portuguese domestic cat population: A 4.5-year cross-sectional study.](https://pubmed.ncbi.nlm.nih.gov/41505408/)

<a id="ref-5"></a>[<a href="#ref-5">5</a>] [Twenty-year lifetime histories of FIV- and FeLV-infected cats in a sanctuary in the UK indicate an effect of retroviral infection on longevity.](https://pubmed.ncbi.nlm.nih.gov/42216781/)

<a id="ref-6"></a>[<a href="#ref-6">6</a>] [Molecular detection and genotyping of feline immunodeficiency virus (FIV) in domestic cats from Tehran, Iran.](https://pubmed.ncbi.nlm.nih.gov/41386113/)

<a id="ref-7"></a>[<a href="#ref-7">7</a>] [Feline lymphoma associated with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infections in Brazil- Systematic review.](https://pubmed.ncbi.nlm.nih.gov/41111634/)

<a id="ref-8"></a>[<a href="#ref-8">8</a>] [A newly developed multiplex RT-PCR enables detection of blood-associated viral nucleic acids in cats.](https://pubmed.ncbi.nlm.nih.gov/42329486/)

<a id="ref-9"></a>[<a href="#ref-9">9</a>] [Ancient and dominant: a novel feline immunodeficiency virus subtype "X-EGY" identified in Egyptian cats associated with high prevalence.](https://pubmed.ncbi.nlm.nih.gov/40877940/)

<a id="ref-10"></a>[<a href="#ref-10">10</a>] [Disseminated histiocytic sarcoma in 2 FeLV-positive cats in Brazil.](https://pubmed.ncbi.nlm.nih.gov/42310831/)

<a id="ref-11"></a>[<a href="#ref-11">11</a>] [A Comparative Study on the Impact of FIV and FeLV Infection on the Ocular Microbiota in Persian Cats: Insights From Co-Infection and Single Infections.](https://pubmed.ncbi.nlm.nih.gov/41497367/)

<a id="ref-12"></a>[<a href="#ref-12">12</a>] [Corrigendum to Feline lymphoma associated with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infections in Brazil- Systematic review [Veterinary and Animal Science volume 30 (December 2025) 100514].](https://pubmed.ncbi.nlm.nih.gov/41835954/)

<a id="ref-13"></a>[<a href="#ref-13">13</a>] [Cross-species transmission of host adaptation of feline leukemia virus between domestic cats and the wild felid Leopardus guigna.](https://pubmed.ncbi.nlm.nih.gov/42288833/)

<a id="ref-14"></a>[<a href="#ref-14">14</a>] [Descriptive assessment of cardiac changes in cats with feline infectious peritonitis.](https://pubmed.ncbi.nlm.nih.gov/42139320/)

<a id="ref-15"></a>[<a href="#ref-15">15</a>] [Feline leukemia virus-negative acute lymphoid B-cell aleukemic leukemia in a cat with prolonged survival.](https://pubmed.ncbi.nlm.nih.gov/41929732/)

<a id="ref-16"></a>[<a href="#ref-16">16</a>] [Pathological characterization of lymphomas with involvement of the alimentary tract in feline leukemia virus-infected cats.](https://pubmed.ncbi.nlm.nih.gov/41454673/)

<a id="ref-17"></a>[<a href="#ref-17">17</a>] [Pilot Studies Testing Novel Minimized Pan-Coronavirus (CoV) Vaccines in Feline Immunodeficiency Virus-Infected Cats With or Without Feline CoV Serotype-1 (FCoV1) Coinfection and in Specific-Pathogen-Free Cats Against Pathogenic FCoV2.](https://pubmed.ncbi.nlm.nih.gov/41295545/)

<a id="ref-18"></a>[<a href="#ref-18">18</a>] [Leishmania (Leishmania) infantum and Leishmania (Sauroleishmania) tarentolae in outdoor cats and report of infection in feline-derived peripheral blood mononuclear cells.](https://pubmed.ncbi.nlm.nih.gov/40859264/)

<a id="ref-19"></a>[<a href="#ref-19">19</a>] [Chronic Atypical Myelomonocytic Leukemia of Eosinophilic Lineage in a Cat With Feline Leukemia Virus: A First Case Report.](https://pubmed.ncbi.nlm.nih.gov/41768374/)

<a id="ref-20"></a>[<a href="#ref-20">20</a>] [Field evaluation of two commercial feline immunodeficiency virus antibody detection point-of-care kits in domestic cats.](https://pubmed.ncbi.nlm.nih.gov/41981624/)

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