NAVLE Bovine Herd Health 3

Question 1

A dairy herd manager asks about dry cow therapy. Which approach describes selective dry cow therapy (SDCT)?

Accepted Answer

Treating only cows with elevated SCC or positive culture at dry-off

Answer

Selective dry cow therapy targets only cows with evidence of intramammary infection, reducing antibiotic use compared to blanket dry cow therapy.

Question 2

Calf scours causing the highest mortality in calves under 5 days of age on a US beef operation is most commonly caused by which pathogen?

Accepted Answer

Escherichia coli (enterotoxigenic)

Answer

Enterotoxigenic E. coli (K99 fimbriae, F5 antigen) causes profuse watery diarrhea and rapid death in calves under 4 days old due to severe dehydration.

Question 3

A producer wants to reduce the risk of hardware disease (traumatic reticuloperitonitis) in his dairy herd. What is the most cost-effective preventive measure?

Accepted Answer

Administering rumen magnets to all cows

Answer

A permanent ceramic or bar magnet placed in the reticulum captures ingested ferrous metal objects, preventing them from penetrating the reticulum wall.

Question 4

Which internal parasite is responsible for 'ostertagiosis type II' (winter ostertagiosis) causing severe hypoproteinemia and diarrhea in yearling cattle?

Accepted Answer

Ostertagia ostertagi

Answer

Type II ostertagiosis occurs when inhibited L4 Ostertagia ostertagi larvae resume development in late winter/spring, massively emerging from gastric glands and causing profound hypoproteinemia.

Question 5

A beef operation loses 3 cows to sudden death with no premonitory signs. Necropsy reveals a 'paint-brush' hemorrhage pattern on the heart and rapid bloat. Which clostridial disease is most likely?

Accepted Answer

Blackleg (Clostridium chauvoei)

Answer

Blackleg (C. chauvoei) classically affects young cattle 6–24 months, causing myonecrosis with rapid death and characteristic crepitant swellings and myocardial hemorrhage.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Bovine Herd Health 3