😿10 Symptoms of FeLV Every Cat Parent Should Know!
- CatDX.com
- Nov 6, 2025
- 4 min read
Updated: Nov 21, 2025
Feline Leukemia Virus (FeLV) is one of the most serious diseases a cat can catch. Think of it like a silent killer—it attacks your cat's defense system (the immune system), making them unable to fight off everyday germs and putting them at high risk for serious cancers.
Finding whether your cat has FeLV is tricky because its symptoms are often subtle and easy to miss until the disease has taken hold. Every cat owner needs to know these warning signs. Catching FeLV early can help manage the condition and, crucially, protect any other cats you live with!
Here are the top 10 things to watch out for in your cat that could signal the presence of FeLV.
1. 🍽️ Dropping Weight and Losing Their Appetite
Has your cat suddenly become a picky eater, or worse, started ignoring food entirely? If your usually enthusiastic eater is leaving kibble in the bowl, or if you notice they are looking thinner over a few weeks or months, pay close attention. Persistent weight loss without trying is a major warning sign for FeLV and many other serious cat illnesses.
2. 😴 Super Low Energy (Lethargy)
A cat that sleeps a lot isn't news, but if your playful kitty suddenly seems too tired to play, or if they just lie around much more than usual, something is wrong. This extreme tiredness or weakness is often linked to anemia (a low red blood cell count), which FeLV commonly causes. If your cat stops jumping on the counter or ignores their favorite toys, take notice.
3. 🧼 A Messy Coat
A healthy cat is a grooming machine—their coat should be clean, soft, and shiny. Cats with FeLV often stop grooming themselves because they feel too unwell, or the illness makes their coat greasy, dull, and matted. If your cat’s coat suddenly looks neglected, like they haven't touched it in days, it's a sign they aren't feeling well.
4. 👃 Sicknesses That Won't Go Away
Since FeLV weakens the immune system, your cat can't fight off germs well. This means they are constantly sick. Look for:
Never-ending sniffles: Frequent sneezing, runny eyes, or a snotty nose that keeps coming back, like a permanent head cold.
Chronic skin issues: Recurring patches of hair loss, scabs, or bumps on the skin.
If you are constantly at the vet getting medicine for the same recurring infection, FeLV could be the root cause.
5. ⚪ Pale Gums (Anemia)
This is one of the most important visual clues! Gently lift your cat's lip and look at their gums. Healthy gums are a vibrant, bubblegum pink. If your cat’s gums look very pale pink, almost white, or even bluish, they are likely severely anemic (low on red blood cells). FeLV often damages the bone marrow, where red blood cells are made, causing this potentially life-threatening symptom.
6. 👅 Severe Mouth and Gum Problems
Does your cat have terrible bad breath, drool a lot, or act like it hurts to eat? FeLV can cause severe, painful inflammation in the gums (gingivitis) and the entire mouth (stomatitis). This can lead to red, swollen gums and painful sores or ulcers on the tongue and cheeks, making mealtimes agony.
7. 🚽 Tummy Trouble
Digestive issues are common with FeLV. This can go one of two ways: either chronic, recurring diarrhea that's hard to treat, or severe, persistent constipation. Either way, major changes in your cat's bathroom habits or stool consistency are a sign that the body’s systems are breaking down.
8. 🍈 Swollen Lumps in the Neck or Body
Your cat has lymph nodes, which are small "security checkpoints" for the immune system. When the body is fighting a serious disease like FeLV, these nodes can swell up. You might feel them as small, firm bumps, particularly under your cat’s jaw, behind their knees, or around their shoulders. Swollen lymph nodes can mean a heavy infection or, sadly, the development of cancer (lymphoma), which FeLV strongly causes.
9. 🧠 Weird Behavior or Loss of Coordination
In some advanced cases, FeLV can affect the nervous system. This can show up as odd behaviors like sudden depression, irritability, or even physical problems like staggering, weakness, or trouble walking, especially in the back legs. While less common, these neurological signs are a serious emergency.
10. 🚫 Unexplained Fever
FeLV makes it hard for a cat to regulate its health, so they might have a fluctuating fever that comes and goes for no clear reason. Since you can't check a cat’s temperature by touch, you usually only notice the side effects: feeling warm, being very withdrawn, and not eating. If your cat feels "off" and the vet finds a high temperature, FeLV may be a possibility.
The Final Word: Get Tested the Easy Way!
The bottom line is simple: You can't diagnose FeLV just by looking at a symptom. Most of these signs can be caused by many other diseases.
If you are worried, there is now an easier, less stressful way to screen your cat. Instead of a potentially traumatic blood draw at the vet, consider CatDX.com.
The CatDX test uses a simple cheek swab to collect saliva and runs a highly accurate, lab-based PCR test to check for the virus.
Stress-Free: No blood draw or needles required.
Convenient: Collect the sample at home, on your cat's schedule.
Cost-Effective: Skip the mandatory vet exam fees for initial screening.
If your FeLV test comes back positive, it's essential to follow up with your veterinarian right away for a comprehensive exam and confirmatory blood testing. Proactive screening is the best way to ensure your beloved feline companions live long, healthy lives.
What makes CatDX.com different? We let you skip the vet and test for FeLV using saliva, not blood. Our tests are PCR-based is done in our laboratory. Read more below:
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