NAVLE Swine Medicine and Production

Question 1

A commercial sow farm reports a sudden increase in late-term abortions, stillbirths, and weak-born piglets across multiple farrowing rooms. Serology confirms Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). Which viral characteristic best explains the reproductive failure observed?

Accepted Answer

PRRSV infects porcine alveolar macrophages and spreads hematogenously to the fetoplacental unit during the last trimester

Answer

PRRSV targets porcine alveolar macrophages (PAMs) and monocyte-derived cells. During viremia — which is most consequential in the last trimester — virus crosses into the fetoplacental unit, causing fetal infection, death, and mummification. Early gestation infection rarely causes fetal loss; late gestation is the vulnerable window.

Question 2

A nursery pig presents with acute onset of polyarthritis, meningitis, and sudden death. Gram-positive cocci in pairs and short chains are isolated from CSF. What is the most likely causative organism?

Accepted Answer

Streptococcus suis serotype 2

Answer

Streptococcus suis serotype 2 is a leading cause of meningitis, polyarthritis, and septicemia in nursery and weanling pigs. It is a Gram-positive coccus in pairs/short chains. Erysipelothrix is Gram-positive but rod-shaped; Haemophilus parasuis (Glässer's disease) is Gram-negative; Mycoplasma lacks a cell wall.

Question 3

Postweaning multisystemic wasting syndrome (PMWS) associated with Porcine Circovirus type 2 (PCV2) is diagnosed in a 6-week-old pig. Which histologic lesion in lymph nodes is considered pathognomonic?

Accepted Answer

Lymphoid depletion with histiocytic replacement and intracytoplasmic basophilic inclusion bodies

Answer

PCV2-associated PMWS characteristically produces lymphoid depletion with replacement by histiocytes/macrophages that contain intracytoplasmic basophilic inclusion bodies (viral antigen). This combination is considered pathognomonic. Lymphoid hyperplasia is the opposite of what occurs.

Question 4

A gilt in a farrow-to-finish operation develops diamond-shaped, raised, red skin lesions over the trunk 2 days after moving to the breeding barn. The most appropriate treatment is:

Accepted Answer

Penicillin G IM, NSAIDs, and isolation

Answer

Diamond-shaped urticarial skin lesions (diamond skin disease) are classic for Erysipelothrix rhusiopathiae infection in pigs. Erysipelas responds well to penicillin G; NSAIDs reduce fever and inflammation. Corticosteroids are contraindicated in bacteremic animals; enrofloxacin has poor activity against Erysipelothrix.

Question 5

Which of the following is the recommended nutritional strategy to prevent osteochondrosis dissecans (OCD) in fast-growing market pigs?

Accepted Answer

Ensuring Ca:P ratio of approximately 1.2:1 with adequate vitamin D and controlled growth rate

Answer

OCD in pigs is a developmental orthopedic disease linked to rapid growth, genetic selection for leanness, and mineral imbalances. A Ca:P ratio near 1.2:1 with adequate vitamin D3 and avoiding excess growth rate are the primary preventive strategies. Extreme calcium restriction or excess both impair endochondral ossification.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Swine Medicine and Production