Infectious

Question 1

Viral Arteritis agent

Answer 1

Arterivirus

Small enveloped single-stranded RNA virus

Question 2

Equine piroplasmosis causative agent and epidemiology

Answer 2

Theileria equi - reservoir is persistently infected horses

Babesia caballi - ticks and infected horses are the vector and reservoir

Ticks of the Ixodid species are vectors and transmit disease:
*Dermacentor [Anocenter] sp., Hyalomma sp., and 2 Rhiphicephalus sp. for B. caballi

*Dermacentor sp., Hyalomma sp., Rhiphicephalus (Boophilus) sp., and Amblyomma cajennense for T. equi

Dermacentor variabilis ticks are also capable of transmission

Question 3

Causative agent of EPM

Answer 3

Sarcocystis neurona and rarely Neospora hughesi

Question 4

Diagnostic tests for EPM

Answer 4

Western Blot (semi-quantitative test). For CSF but sensitive to blood contamination (false positives more likely)

Modified WB. Includes bovine sets with high titers of Sarcocystis cruzi to eliminate cross reactivity and increase Se and Sp.

ELISA. In serum to detect titers

IFA. Paired serum and CSF

Question 5

Infection with Listeria monocytogenes typically results in microabscess formation in the_________.

a. Cerebrum
b. Spinal cord
c. Brainstem/Cerebellum
d. Peripheral nerves

Answer 5

c. Brainstem/Cerebellum

Question 6

The primary agent of footrot in sheep is:

a. Dichelobacter nodosus
b. Fusobacterium necrophorum
c. Staphylococcus aureus
d. Actinomyces pyogenes

Answer 6

a. Dichelobacter nodosus

Question 7

A six-year old Angus cow presents with bilateral blepharospasm, excessive lacrimation, anterior uveitis, conjunctivitis and perilimbal corneal opacity. Nasal and oral mucosa appear reddened and inflamed. Which of these is the most likely differential?

a. Infectious bovine keratoconjunctivitis
b. Bovine mycoplasmal conjunctivitis
c. Malignant catarrhal fever
d. Bluetongue

Answer 7

c. Malignant catarrhal fever

Primarily of ruminants, caused by gammaherpesviruses belonging to the genus Macavirus.

Multisystemic clinical syndrome, the head and eye form being most commonly seen.

Question 8

Which of the following conditions is associated with the bovine leukemia virus?

a. Juvenile lymphosarcoma
b. Adult lymphosarcoma
c. Thymic lymphosarcoma
d. Cutaneous lymphosarcoma

Answer 8

b. Adult lymphosarcoma

Adult LSA is only form currently associated with BLV.

Question 9

Which one of the following statements pertaining to Equine herpesvirus 1 (EHV-1) myeloencephalopathy is TRUE?

A. CSF analysis typically reveals xanthochromia, increased protein concentration and markedly increased nucleated cell count.
B. Foals usually do not show neurological manifestations during outbreaks characterized by severe neurologic disease in adults.
C. Myeloencephalopathy occurs secondary to viral replication within spinal cord motor neurons.
D. Neurologic signs develop gradually and progress over a period of 5 to 10 days.

Answer 9

B. Foals usually do not show neurological manifestations during outbreaks characterized by severe neurologic disease in adults.

Question 10

Which of the following statements regarding Neosporosis in cattle is CORRECT?

A. Congenital infectious often result in the birth of clinically normal calves.
B. Neospora-associated abortions in cattle occur only sporadically and not as epizootics.
C. Removing cats from the feed storage areas will decrease the incidence of disease.
D. The prevalence in beef cattle is higher than in dairy cattle.

Answer 10

A. Congenital infectious often result in the birth of clinically normal calves.

Question 11

Which of the following pairs of organisms can cause equine protozoal myeloencephalitis?

a) Neospora hughesii and Sarcocytis neurona
b) Neospora caninum and Sarcocystis hughesii
c) Neorickettsia risticii and Sarcocystis falcatula
d) Neorickettsia hughesii and Sarcocystis neurona

Answer 11

a) Neospora hughesii and Sarcocytis neurona

Question 12

Which of the following is CORRECT regarding Mycoplasma bovis mastitis infections in dairy cattle?

a) Animals often have a history of mastitis unresponsive to antibiotics
b) Disease is most likely in first lactation heifers
c) Infection is usually limited to one teat, which is often swollen and painful
d) Subclinical infection is easily detected by increased somatic cell counts

Answer 12

a) Animals often have a history of mastitis unresponsive to antibiotics

Question 13

Which mutation is associated with the development of equine herpes myelitis?

a) Mutation in the viral GBE gene on chromosome 26
b) Phenylalanine-leucine substitution in the viral sodium channels
c) Point mutation on the GYS1 gene
d) Single nucleotide polymorphism (SNP) in the DNApo1 D752

Answer 13

d) Single nucleotide polymorphism (SNP) in the DNApo1 D752

Question 14

In utero infection of a calf with BVDV during day 45-125 of gestation will most likely result in which of the following syndrome?

a) Abortion of the calf
b) Cerebellar hypoplasia
c) Mucosal disease
d) Persistent infection

Answer 14

d) Persistent infection

Question 15

The most important virulence factor for Mannheimia hemolytica is:

a) Lipoteichoic acid
b) Leukotoxin
c) Virulence associated protein A
d) Variable surface lipoprotein O

Answer 15

b) Leukotoxin

Question 16

What is the underlying pathophysiologic mechanism of equine leukoencephalomalacia?

a) Alterations in axonal transport of lipid
b) Alterations in sphingolipid metabolism
c) Chronic vitamin E deficiency
d) Meningitis secondary to infection with Fusarium verticillioides

Answer 16

b) Alterations in sphingolipid metabolism

Question 17

You are called to examine a group of first calf Holstein heifers for the complaint of skin lesions. The heifers reside in a 200-cow dairy in the Northeastern United States. Lesions are generally observed 2 to 3 weeks after calving. The observed problem affects approximately 50% of fresh heifers. No cows in their second or greater lactations have been affected.
The characteristic lesion is multiple thin-walled 1-2 cm diameter vesicles confined to the skin of the teats and ventral udder which progress to painful erosions.

Erosions generally resolve over a period of 2 weeks to 2 months. A small proportion of the heifers develop severe secondary mastitis and deep cellulitis.

There are no lesions on the hands of animal handlers.
What is the MOST likely cause of the teat leasion in this herd?

A. Bovine herpesvirus-2
B. Pseudo cowpox
C. Vesicular exanthema
D. Vesicular stomatitis

Answer 17

A. Bovine herpesvirus-2

Question 18

What serotype is the most common isolate from pneumonic lungs with Mannheimia haemolytica?

Answer 18

Serotype A1 is the most common in cattle lung, A6 is the next most common.
A2 is common in nasopharynx from normal cattle, but has been associated with disease in sheep and goats (as well as A7 and A9)

There are at least 12 serotypes, not all are pathogenic and some pathogenic one are not pathogenic for the same species.

Question 19

What is considered a prerequisite for the diagnosis of BLV and how can you test for it?

Answer 19

Presence of gp51 is considered necessary for a dx of BLV unless the cow is in the periparturient period.
Serologic testing to identify the antibody against the 51-kD envelope glycoprotein (51gp) can be used.

Question 20

Which enterotoxin is secreted by rotavirus in foals and is a noncompetitive inhibitor of the Na-glucose symporter, leading to enhance intestinal chloride secretion.

a. A1
b. LPS
c. D7 Rotavirus enterotoxin
d. NSP4

Answer 20

d. NSP4

Question 21

Which of the following causes fetal infection and neurologic signs in lambs:

a. Border disease
b. Maedi-visna
c. Jaagsiekte
d. Bluetongue virus

Answer 21

a. Border disease

Also known as hairy shaker disease (Australia and New Zealand) is a congenital disorder of lambs characterized by low birth weight and viability, poor conformation, tremor, and an excessively hairy birth coat in normally smooth-coated breeds. Goat kids may also be affected, and a similar condition occasionally occurs in calves. The disease has been recognized in most sheep-rearing areas of the world, including the western USA. There are currently seven recognized genotypes (BDV-1 to BDV-7) for the border disease virus.

Question 22

Which of the following agents causing mastitis in dairy cattle responds well to antibiotic treatment?

a. Streptococcus agalactiae
b. Streptococcus uberis
c. Staphylococcus aureus
d. Mycoplasma bovis

Answer 22

a. Streptococcus agalactiae

Question 23

Tyzzer disease, an acute hepatitis affecting foals from 7 to 42 days of age is cause by which of the following agents?

a. Clostridium perfringens
b. Clostridium difficile
c. Clostridium piliforme
d. Clostridium haemolyticum

Answer 23

c. Clostridium piliforme

Question 24

Which of the following test is considered the test of choice for diagnosis of equine protozoal myelitis in the horse?

a. Western blot on serum
b. IFAT on serum
c. SAG 1, 5, 6 ELISA on CSF
d. SAG 2, 4/3 ELISA serum:CSF ratio

Answer 24

d. SAG 2, 4/3 ELISA serum:CSF ratio

Question 25

What is the most common agent involved in otitis media in dairy calves?

Answer 25

Mycoplasma bovis.

M. arginini has also been reported in otitis media cases, other pathogens isolated include P. multocida and A. pyogenes.

Question 26

Causative agent of Malgnant Catarrahal Fever (MCF)

Answer 26

The 2 most important are OvHV-2 (ovine herpesvirus 2), which causes sheep-associated MCF, and AlHV-1 (alcelaphine herpesvirus 1), which causes the wildebeest-associated form of this disease.