Yes, kittens can get toxoplasmosis from their mother through two routes: across the placenta during pregnancy and through her milk while nursing. Both forms of transmission produce more severe disease than infection picked up later in life, and congenitally infected kittens frequently die of lung or liver disease within days of birth.
How Infection Passes From Mother to Kitten
When a pregnant cat becomes infected with Toxoplasma gondii for the first time, the parasite enters her bloodstream in its rapidly dividing form. That blood-borne stage can cross the placenta, causing inflammation in the placental tissue and spreading directly to developing fetuses. The timing matters: kittens infected at different stages of gestation develop different patterns and severity of disease. Many kittens born to mothers who were actively infected during pregnancy end up carrying the parasite, and some of those newborns begin shedding infectious eggs (called oocysts) in their feces shortly after birth.
The second route is through nursing. Researchers have detected the parasite in the milk of five out of six experimentally infected cats using lab techniques. Because kittens nurse immediately and continuously, this creates a window for infection even if they avoided exposure in the womb. In studies where kittens were allowed to suckle from infected mothers, researchers could not always determine which route caused the infection, since both were happening simultaneously.
Why Congenital Infection Is More Dangerous
Kittens infected before or shortly after birth face a much harder fight than adult cats. Their immune systems are immature, and the parasite can establish itself in multiple organs before any defense kicks in. The most common targets are the liver, lungs, and brain. Congenitally infected kittens frequently develop hepatitis, pneumonia, and brain inflammation. Visible signs include a swollen belly from fluid buildup (ascites), extreme lethargy, and labored breathing.
The disease can be rapidly fatal when the lungs or nervous system are heavily involved. In older studies using certain parasite strains, most kittens that were allowed to live after birth were clinically ill and either died or had to be euthanized within eight days. A few survived weeks or even months without obvious symptoms, but they were the exception. In one study tracking 24 kittens from infected mothers, three died or were euthanized early, including one that developed a progressive head tilt starting at five days old, a sign of central nervous system damage. The mother cat in that litter also died of generalized toxoplasmosis just days after giving birth.
The specific parasite strain plays a role in outcomes. Some strains appear to cause higher kitten mortality than others, which partly explains why results vary between studies.
Signs to Watch For in Newborn Kittens
The symptoms of congenital toxoplasmosis overlap with other serious neonatal infections, making it tricky to identify without testing. The hallmark signs are:
- Breathing difficulty: rapid, labored, or open-mouth breathing from lung inflammation
- Lethargy and weakness: kittens that don’t nurse, don’t move normally, or fade quickly
- Swollen abdomen: fluid accumulation from liver damage
- Neurological problems: head tilt, tremors, uncoordinated movement, or seizures from brain inflammation
- Eye inflammation: congenital infection can cause uveitis (swelling inside the eye), which may be visible as cloudiness or discharge
In some cases, kittens appear normal at birth but develop signs within the first week or two. Others are stillborn or too weak to survive their first day. If a mother cat was a stray, recently adopted, or known to hunt, and her kittens are failing to thrive, toxoplasmosis is one possibility a veterinarian would consider.
How Vets Diagnose It
Diagnosing toxoplasmosis in very young kittens is complicated. Blood antibody tests, the usual first step in older cats, are harder to interpret in neonates. The presence of one type of antibody (IgG) confirms exposure but says nothing about when infection happened. Another type (IgM) appears about a week after infection but can persist for months or even years, so a positive result alone doesn’t confirm an acute case. A shorter-lived antibody type (IgE) is a better marker of current infection because it fades faster.
The most reliable method for confirming congenital toxoplasmosis is PCR testing, which detects the parasite’s DNA directly. Real-time PCR targeting a specific gene sequence is considered the best-performing technique for diagnosing congenital infection. In practice, though, many cases in kittens are diagnosed after death through tissue examination, because the disease progresses so quickly that testing results may not return in time.
Treatment and Realistic Expectations
When toxoplasmosis is caught early enough, treatment centers on antiparasitic drugs given orally for three to four weeks. The standard choice for cats is clindamycin. A combination of sulfadiazine and pyrimethamine, which work together to block the parasite’s ability to reproduce, is another widely used option. Some newer drugs can also reduce oocyst shedding, which helps limit environmental contamination.
The challenge with congenitally infected kittens is that the disease is often advanced by the time symptoms appear. Treatment works best when started as soon as infection is suspected, but very young kittens with severe lung or brain involvement may not respond in time. Kittens that survive the acute phase can recover, though some may have lasting effects, particularly if the brain or eyes were damaged.
The Role of the Mother Cat’s Immune Status
A critical detail: transplacental transmission happens primarily when a cat is infected for the first time during pregnancy. Cats that were exposed to Toxoplasma before becoming pregnant typically have immune protection that prevents the parasite from reaching the bloodstream again in significant numbers. Their kittens are generally safe.
This means the highest-risk scenario is a previously unexposed cat who encounters the parasite while pregnant, usually by eating an infected rodent, bird, or undercooked meat. Indoor cats with no hunting access and no raw diet have a much lower chance of first infection during pregnancy. Stray or feral cats, especially young ones in their first pregnancy, carry the greatest risk because they’re more likely to be encountering the parasite for the first time while also reproducing.
After initial infection, cats typically shed oocysts for a window of about 4 to 13 days, producing 20 million or more during that period. If this shedding phase happens to coincide with late pregnancy or early nursing, the kittens face maximum exposure through multiple routes at once.