Toxoplasmosis and Neosporosis

Question 1

Which statement accurately describes dogs in the Toxoplasma gondii life cycle?
a) Dogs are definitive hosts that excrete oocysts.
b) Dogs are intermediate hosts that harbor tissue cysts.
c) Dogs can become infected but do not play a role in transmission.
d) Dogs are resistant to Toxoplasma gondii infection.

Answer 1

Dogs are intermediate hosts that harbor tissue cysts.

Question 2

What is considered as a major mode of Toxoplasma gondii transmission for dogs?

Answer 2

Ingestion of infected tissues.

Question 3

Dogs ingesting cat litter can serve as potential mechanical vectors for Toxoplasma gondii to people because _______________

Answer 3

They shed ingested sporulated oocysts in their stool.

Question 4

In dogs, which stage of Toxoplasma gondii is actively multiplying and can infect almost any cell of the body?

Answer 4

Tachyzoite

Question 5

Congenital transmission of Toxoplasma gondii in dogs is thought to be:
a) More common than in sheep and goats.
b) Less common than in sheep and goats.
c) The primary mode of transmission.
d) Impossible.

Answer 5

Less common than in sheep and goats.

Question 6

Postnatally acquired toxoplasmosis in dogs is generally:
a) More serious than prenatally acquired infection.
b) Associated with rapid progression to death.
c) Less serious than prenatally acquired infection.
d) Untreatable with available medications.

Answer 6

Less serious than prenatally acquired infection.

Question 7

Clinical toxoplasmosis in dogs is often associated with what concurrent conditions?

Answer 7

Canine distemper virus infection

Question 8

Generalized toxoplasmosis in dogs is seen mostly in?

Answer 8

Dogs younger than 1 year.

Question 9

What are the clinical signs are commonly observed in dogs with generalized toxoplasmosis?

Answer 9

Fever, tonsillitis, dyspnea, diarrhea, and vomiting

Question 10

Tissue cysts of Toxoplasma gondii containing bradyzoites are primarily formed in which organs of the dog?

Answer 10

Central nervous system (CNS), muscles, and visceral organs

Question 11

What is the main biological difference between bradyzoites and tachyzoites in terms of survival?

Answer 11

Bradyzoites can survive the digestive process in the stomach.

Question 12

How long can Toxoplasma gondii tissue cysts persist in the host?

Answer 12

Months or years, potentially for the life of the host

Question 13

What is the primary cause of cell necrosis during Toxoplasma gondii infection?

Answer 13

Intracellular growth of Toxoplasma.

Question 14

What is crucial for resistance to Toxoplasma encephalitis, as studied in experimentally infected rodents?

Answer 14

Interferon (IFN)-gamma-dependent cell-mediated immunity

Question 15

When do tachyzoites begin to disappear from visceral tissues and localize as tissue cysts (bradyzoites) in the host?

Answer 15

Approximately the third week after infection

Question 16

Clinical relapse of toxoplasmosis due to ruptured tissue cysts can occur during:
a) Periods of intense exercise.
b) Immunosuppression, such as with antitumor or glucocorticoid therapy.
c) A diet rich in protein.
d) Exposure to other parasites.

Answer 16

Immunosuppression, such as with antitumor or glucocorticoid therapy

Question 17

In dogs, clinical signs of toxoplasmosis may be localized to which systems?

Answer 17

Respiratory, neuromuscular, or gastrointestinal (GI) systems

Question 18

What is a possible outcome for dogs with severe toxoplasmosis involving the lungs and liver?

Answer 18

Death within a week.

Question 19

Icterus (jaundice) in dogs with toxoplasmosis usually results from?

Answer 19

Extensive hepatic necrosis.

Question 20

The most dramatic clinical signs of toxoplasmosis in older dogs have been associated with which systems?

Answer 20

Neural and muscular systems.

Question 21

Neurologic signs in dogs with toxoplasmosis depend on the site of lesion in which areas?

Answer 21

Cerebrum, cerebellum, or spinal cord

Question 22

Dogs with myositis due to toxoplasmosis may initially show ______ (3)

Answer 22

Abnormal gait, muscle wasting, or stiffness.

Question 23

Paraparesis and tetraparesis in canine toxoplasmosis may rapidly progress to _______

Answer 23

Lower motor neuron paralysis

Question 24

Historically, the prevalence of canine toxoplasmosis has decreased with the routine use of?

Answer 24

Canine distemper vaccines.

Question 25

What is the approximate size range of Toxoplasma gondii tissue cysts?

Answer 25

15-60 µm

Question 26

What anatomical structure is formed by the thin elastic wall that separates Toxoplasma gondii tissue cysts from the host cell?

Answer 26

Cyst wall

Question 27

What hematologic findings is most commonly observed in dogs with acute systemic toxoplasmosis?

Answer 27

Nonregenerative anemia and neutrophilic leukocytosis.

Question 28

In dogs with acute hepatic necrosis due to toxoplasmosis, what biochemical abnormalities are generally observed?

Answer 28

Increased serum ALT and ALP activities.

Question 29

If a dog develops muscle necrosis due to toxoplasmosis, which serum enzyme activity would likely be increased?

Answer 29

Serum creatine kinase

Question 30

Why are Toxoplasma gondii oocysts rarely found in routine fecal examinations of cats (the definitive host), despite high seroprevalence?

Answer 30

Cats only shed oocysts for a short period (1-2 weeks) after first exposure.

Question 31

If 10 µm-sized oocysts are found in a dog's fecal examination, which of the following should be considered until proven otherwise, given the infectious nature of the organism?

Answer 31

Toxoplasma gondii

Question 32

Grossly, what is the predominant lesion observed in various organs (e.g., brain, lung, liver) of dogs with acute systemic toxoplasmosis?

Answer 32

Necrosis

Question 33

In dogs with pulmonic toxoplasmosis, what kind of lesions are often found in the subpleura and parenchyma of the lungs? a) Clear fluid accumulation. b) Gray white nodular foci up to 5 mm in diameter. c) Large cysts. d) Hemorrhage only.

Answer 33

Gray white nodular foci up to 5 mm in diameter.

Question 34

When myositis involves the muscles of the limbs in dogs with T. gondii infections, what gross changes are typically observed in the affected muscles?

Answer 34

Paleness, reduced mass, and replacement by connective tissue in severe cases.

Question 35

What diagnostic technique can definitively demonstrate Toxoplasma gondii in tissues and distinguish it from Neospora caninum?

Answer 35

Immunoperoxidase staining

Question 36

What is the drug of choice for treating clinical toxoplasmosis in dogs?

Answer 36

Clindamycin

Question 37

How quickly do clinical signs of systemic illness in dogs usually begin to resolve after initiating clindamycin therapy for toxoplasmosis?

Answer 37

Within 24 to 48 hours.

Question 38

What combination of drugs is synergistic in the therapy of systemic toxoplasmosis, although less suitable than clindamycin?

Answer 38

Pyrimethamine and rapid acting sulfonamides.

Question 39

What is a key measure in preventing toxoplasmosis in dogs, related to their diet?

Answer 39

Feeding only dry or canned, commercially processed dog food.

Question 40

Neospora caninum was previously confused with which other protozoan parasite?

Answer 40

Toxoplasma gondii

Question 41

What animals are the definitive host for Neospora caninum, shedding oocysts in its feces?

Answer 41

Domestic dog or coyote

Question 42

What is a key difference in oocyst shedding between Neospora caninum in dogs and Toxoplasma gondii in cats?

Answer 42

N. caninum-infected dogs may shed oocysts over an extended period of several months, unlike the transient shedding in cats.

Question 43

What is considered as the predominant route of transmission for Neospora caninum in naturally infected dogs?

Answer 43

Transplacental transmission.

Question 44

Tachyzoites of Neospora caninum are found within various cells of infected carnivores, including _____ (4)

Answer 44

Macrophages, polymorphonuclear cells, spinal fluid, and neural cells.

Question 45

Where are Neospora caninum nonseptate tissue cysts mainly found in chronically affected dogs?

Answer 45

Neural cells (brain, spinal cord, peripheral nerves, retina) and occasionally muscles.

Question 46

How long after ingesting tissue cysts do unsporulated N. caninum oocysts begin to be shed in dog feces?

Answer 46

5 days or later

Question 47

Sporulation of N. caninum oocysts, making them infective, occurs how long after shedding outside the body?

Answer 47

24 to 72 hours.

Question 48

Give 3 dog breeds has been noticeably prevalent in published case reports of neosporosis.

Answer 48

German shorthaired pointers, Labrador retrievers, and Boxers

Question 49

Seroprevalence of Neospora caninum in dogs is often higher in which population?

Answer 49

Dogs being fed raw meat.

Question 50

Why is there a strong statistical association between Neospora infections in dairy herds and the presence of dogs on farms?

Answer 50

Dogs are the definitive hosts and can contaminate feed or pastures with oocysts.

Question 51

What is a common way for dogs on farms to acquire Neospora caninum infection, as suggested by comparative analyses with uninfected dairy farms?

Answer 51

Consumption of vaginal discharges, aborted materials, or milk from cows.

Question 52

What is the main clinical manifestation of Neospora caninum infection in herbivores like cattle?

Answer 52

Abortion

Question 53

Which of the following is true regarding clinical findings of neosporosis in dogs compared to toxoplasmosis? a) Neosporosis mainly causes gastrointestinal signs. b) Neurologic deficits and muscular abnormalities predominate in neosporosis. c) Neosporosis only affects puppies. d) Toxoplasmosis is always more severe.

Answer 53

Neurologic deficits and muscular abnormalities predominate in neosporosis.

Question 54

What is the most severe and frequent clinical presentation of neosporosis in young dogs (under 6 months)?

Answer 54

Ascending paralysis of the limbs.

Question 55

At what age are clinical signs of neosporosis often first noticed in the youngest puppies?

Answer 55

3-9 weeks of age

Question 56

A key feature distinguishing neosporosis from other forms of paralysis in dogs

Answer 56

Gradual muscle atrophy and stiffness, usually as an ascending paralysis.

Question 57

What is arthrogryposis, a common development in puppies with neosporosis, a result of?

Answer 57

Scar formation in the muscles from lower motor neuron damage and myositis.

Question 58

What signs may develop in some pups with neosporosis due to the muscle and joint effects?

Answer 58

Joint deformation and genu recurvatum

Question 59

Despite severe paralysis, what characteristic attitude do dogs with neosporosis typically maintain? a) Comatose state. b) Depressed and lethargic. c) Alert attitudes. d) Aggressive and irritable.

Answer 59

Alert attitudes.

Question 60

Older dogs that become ill from Neospora caninum infection most likely develop disease from?

Answer 60

Reactivation of a chronic subclinical infection.

Question 61

Besides multifocal CNS involvement and polymyositis, less common manifestations of neosporosis in older dogs can include: (3)

Answer 61

Myocarditis, dermatitis, or pneumonia.

Question 62

Cutaneous neosporosis is most common in dogs that _________

Answer 62

Become immunosuppressed from concurrent illnesses or drug therapy.

Question 63

What type of hosts are deer and cattle in the Neospora caninum life cycle, as their carcasses may be preyed upon by dogs and coyotes?

Answer 63

Intermediate herbivore hosts.

Question 64

In canine feces, N. caninum oocysts are very similar in morphology to those of ________________

Answer 64

Hammondia heydorni

Question 65

What is a key structural difference between tissue cysts of N. caninum and T. gondii?

Answer 65

N. caninum tissue cysts have thicker walls than those of T. gondii.

Question 66

Grossly, what is a common lesion observed in dogs with neosporosis, particularly in striated muscles?

Answer 66

Multifocal streaks of necrosis, fibrosis, and mineralization.

Question 67

In pups with disseminated neosporosis, parasite-containing lesions can be found in which neural and muscular tissues?

Answer 67

Muscles, heart, brain, spinal cord, nerve roots, and retina.

Question 68

What are the predominant histologic findings in neural and muscular tissues of dogs with neosporosis?

Answer 68

Nonsuppurative encephalomyelitis, polyradiculoneuritis, ganglionitis, myositis, and myofibrosis.

Question 69

What is true about Neospora caninum's inflammatory response compared to Toxoplasma gondii? a) N. caninum induces less inflammation. b) N. caninum appears to induce more inflammation and causes severe phlebitis and dermatitis. c) Both induce identical inflammatory responses. d) N. caninum only causes inflammation in the brain.

Answer 69

N. caninum appears to induce more inflammation and causes severe phlebitis and dermatitis.

Question 70

Which age group of dogs generally responds better to treatment for neosporosis?

Answer 70

Older (over 16 weeks) puppies and adult dogs.

Question 71

For dogs with neurologic involvement due to neosporosis, which drug combination should be used because of better penetration of the CNS?

Answer 71

Trimethoprim-sulfonamide or pyrimethamine and sulfonamide

Question 72

What is the effect of clindamycin on Neospora caninum tachyzoites and bradyzoites?

Answer 72

Effective against tachyzoites but not encysted bradyzoites.