Toxoplasmosis is an infectious disease caused by a single-celled parasite called Toxoplasma gondii. Toxoplasmosis can occur in both cats and dogs. Cats are generally asymptomatic carriers of this infectious disease but can be affected under certain circumstances. This disease is zoonotic, which means it is transmissible to humans, and pregnant women especially must be careful when handling their cat's litter boxes.

Kittens are more susceptible to toxoplasmosis infection than adult cats and have more severe signs of disease when infected. Also, cats that are outdoors and hunt wildlife are at higher risk than cats confined to an indoor environment. Animals that are fed raw or incompletely cooked meat are at higher risk, as well as animals that are immunosuppressed.

Cats usually contract the disease by the following means:

Transplacental transmission. The organism is ingested by a pregnant animal, multiplies in the placenta and then infects the developing fetus.

Ingestion of the organism when they feed on the tissues of infected birds and rodents.

Ingestion of food or water contaminated with infected feces.

Transfusion of infected blood (rare).

What to Watch For

The signs of toxoplasmosis in pets are nonspecific, and most cats show no signs of infection. These signs may include fever, loss of appetite and depression. Further signs may occur, but that depends on where the infection occurs; toxoplasmosis can affect any organ system but primarily affects the lungs, the central nervous system (brain) and the eyes.

Central nervous system signs may include depression, a head tilt, partial or total blindness, seizures and death.

Respiratory signs may include fever, cough, and increased respiratory rate and effort.

Uveitis (inflammation of the interior of the eye) may cause excessive blinking (blepharospasm), squinting, and sensitivity to light (photophobia).

Other signs that may be observed are ascites (accumulation of fluid in the abdomen), jaundice, hepatomegaly (liver enlargement), muscle pain, loss of appetite, and weight loss.

Diagnosis

The best method to diagnose toxoplasmosis is measurement of antibodies to the organism. Your veterinarian may also do other diagnostic tests, such as:

Complete blood count (CBC)

Biochemistry profile

Fecal examination

Ocular (eye) examination

IgG and IgM antibody testing (titers)

ELISA test (antigen test)

Chest x-rays

Cerebrospinal fluid analysis (CSF analysis)

Analysis of pleural (chest) or peritoneal (abdominal) fluid

Transtracheal aspirate

Treatment

Antibiotics such as clindamycin, trimethoprim-sulfonamide, or sulfonamides combined with pyrimethamine.

Anticonvulsants for seizures.

Intravenous (IV) fluids for debilitated animals.

Home Care

At home care consists of administering any medications prescribed by your veterinarian.

Preventative Care

Pet cats should be fed only dry, canned or cooked food. Cats should not be fed uncooked meat, entrails or bones as these tissues may contain toxoplasma cysts. Take measures to prevent cats from successfully hunting wildlife (keep indoors, attach bells to collars).

Secure trash containers to prevent garbage scavenging by cats. Remove carcasses of rodents or birds before cats can consume them.

Preventing human exposure from cats

Pregnant women and immunocompromised individuals should not clean cat litter boxes and they should avoid contact with cat feces and soil where cats may have defecated. If another family member cannot clean the cat litter box, the box should be emptied daily, and cleaned with scalding water once weekly.