FIV (feline immunodeficiency virus) often looks like nothing at all for months or even years. Most cats infected with FIV appear completely healthy during a long silent phase, and the virus only becomes visible through secondary problems: chronic mouth inflammation, recurring infections, unexplained weight loss, and eye changes. There’s no single “look” to FIV. Instead, it slowly weakens a cat’s immune system until ordinary infections become harder to fight off, and those infections are what you actually see.
The Long Silent Phase
After initial infection, cats enter a brief acute phase that may include mild fever, lethargy, and temporarily swollen lymph nodes. Most owners never notice this stage because it’s subtle and resolves on its own. What follows is far more deceptive: an asymptomatic period lasting months to multiple years where the virus replicates very slowly inside immune cells. During this time, your cat will not show any outward signs of illness. They eat normally, play normally, and look perfectly healthy.
The only clues during this silent phase tend to show up on bloodwork, not on your cat’s body. Infected cats may have low white blood cell counts or elevated blood proteins, neither of which you can spot at home. This is why FIV is so often diagnosed through routine testing rather than because an owner noticed something wrong.
Weight Loss Is Usually the First Visible Sign
When FIV does start to show, weight loss is often the earliest change owners notice. It can be gradual enough to miss if you see your cat every day. You might realize their spine or hip bones feel more prominent when you pet them, or that they seem smaller when you pick them up. This weight loss happens because the immune system is now struggling, and the body is spending more energy fighting low-grade infections. It can also result from mouth pain that makes eating difficult, which brings us to the most recognizable sign of symptomatic FIV.
Severe Mouth Inflammation
Chronic, painful mouth disease is one of the hallmark problems in FIV-positive cats. The immune system’s inflammatory response becomes so abnormal that the body can’t handle routine oral bacteria. Small infections spiral into large ones, and the cycle feeds on itself.
What this looks like in practice: swollen, ulcerated, and bleeding gums. You may notice your cat drooling excessively, sometimes with blood-tinged saliva. Bad breath is common and often severe. Some cats seem eager to eat but physically can’t, approaching their food bowl and then backing away. Others paw at their mouths. A vet examining the inside of the mouth will typically find lesions under the tongue, on the lips, on the roof of the mouth, and around the back teeth.
Not every FIV-positive cat develops mouth disease, but when a cat has this kind of extreme oral inflammation, FIV is one of the first things a veterinarian will test for.
Eye Changes
FIV can cause uveitis, which is inflammation inside the eye. Signs include cloudiness in one or both eyes, visible redness, squinting, excessive tearing, and swelling around the eye. A cat with uveitis may become sensitive to light or keep one eye partially closed. These changes can come on gradually or appear fairly quickly, and they sometimes affect just one eye at first.
Eye inflammation in cats has several possible causes, but FIV is a well-known one. If your cat develops unexplained eye cloudiness or redness, especially alongside other signs on this list, FIV testing is a reasonable step.
Recurring Skin and Respiratory Infections
Because FIV compromises the immune system, infected cats become vulnerable to infections that healthy cats would easily fight off. What you’ll see depends on where those infections take hold:
- Skin: Wounds that heal slowly or not at all, recurring abscesses (especially in cats who go outdoors or have a history of fighting), patchy fur loss, and persistent skin infections that keep coming back after treatment.
- Upper respiratory: Chronic sneezing, nasal discharge, and congestion that lingers far longer than a typical cat cold. Some cats develop recurring bouts of respiratory infection several times a year.
- Ears and eyes: Stubborn ear infections and conjunctivitis that respond to treatment but return quickly.
The pattern matters more than any single episode. One ear infection isn’t cause for concern. But a cat who keeps getting the same types of infections, or whose infections don’t resolve normally with treatment, is showing the kind of immune weakness that FIV produces.
Coat and Lymph Node Changes
A healthy cat’s coat is sleek and smooth. As FIV progresses, the coat may become dull, rough, or unkempt. Some cats stop grooming themselves as thoroughly, which can look like matting or a greasy texture, particularly along the back. This sometimes reflects general malaise rather than a specific skin problem.
Swollen lymph nodes are another sign veterinarians check for during physical exams. You may be able to feel these yourself as small, firm lumps under the jaw, in front of the shoulders, or behind the knees. They’re not always obvious to the touch, but a vet knows exactly where to look and what size is abnormal.
Behavioral and Neurological Changes
In some cases, FIV affects the nervous system. This can look like subtle personality shifts: a previously social cat becoming withdrawn, confusion or disorientation, changes in litter box habits, or unusual aggression. Some cats develop unsteady movement or seem less coordinated than before. These signs are less common than the oral and skin problems but worth noting, especially if they appear alongside other symptoms.
How FIV Is Diagnosed
You can’t diagnose FIV by looking at a cat. The symptoms described above are clues, but they overlap with many other conditions. Diagnosis requires a blood test, typically a rapid screening test performed in a vet’s office. All positive results should be confirmed with a different, more specific test at a reference laboratory, because false positives do occur.
For kittens, timing matters. Kittens born to FIV-positive mothers carry their mother’s antibodies, which can trigger a positive test result even if the kitten isn’t actually infected. These maternal antibodies can take up to six months to clear, so kittens who test positive should be retested at 60-day intervals until they’re at least six months old before the result is considered reliable.
What to Expect After Diagnosis
An FIV diagnosis is not a death sentence. Many FIV-positive cats live for years after diagnosis, particularly with attentive care. The asymptomatic phase alone can last for years, and even when symptoms do appear, they’re often manageable. The key is catching secondary infections early and treating them promptly before they escalate.
Twice-yearly vet visits are generally recommended for FIV-positive cats, with close attention to the gums, eyes, skin, and lymph nodes at each exam. At home, monitoring means watching for the signs described above: unexplained weight loss, changes in appetite or eating behavior, mouth odor, eye cloudiness, slow-healing wounds, and recurring infections. Keeping an FIV-positive cat indoors protects both the cat (from exposure to other pathogens) and other cats in the neighborhood (since FIV spreads primarily through deep bite wounds during fights).
The most important thing to understand about FIV is that looking healthy doesn’t mean a cat is negative, and testing positive doesn’t mean a cat is sick. The virus operates on a long timeline, and many owners of FIV-positive cats report years of normal, happy life between diagnosis and the first sign of trouble.