Toxoplasmosis in Dogs
Dr. Anne Marie Manning
Toxoplasmosis is an infectious disease caused by a single-celled parasite called Toxoplasma gondii. Toxoplasmosis can occur in both cats and dogs. This disease is zoonotic, which means it is transmissible to humans, and pregnant women especially must be careful. Transplacental transmission – The organism is ingested by a pregnant animal, multiplies in the placenta and then infects the developing fetus.
Animals that are fed raw or incompletely cooked meat are at higher risk of developing toxoplasmosis, as well as animals that are immunosuppressed.
Dogs usually contract the disease by the following means:
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 dogs 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.
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)
Ocular (eye) examination
IgG and IgM antibody testing (titers)
ELISA test (antigen test)
Cerebrospinal fluid analysis (CSF analysis)
Analysis of pleural (chest) or peritoneal (abdominal) fluid
Antibiotics such as clindamycin, trimethoprim-sulfonamide, or sulfonamides combined with pyrimethamine
Anticonvulsants for seizures
Intravenous (IV) fluids for debilitated animals
Home Care and Prevention
At home care consists of administering any medications prescribed by your veterinarian.
Feed only dry, canned or cooked food. Do not feed uncooked meat, entrails or bones as these tissues may contain toxoplasma cysts. Secure trash containers to prevent garbage scavenging and remove carcasses of rodents or birds before they are consumed.