NAVLE Bovine Herd Health Management 2 — Questions and Answers
Question 1: A dairy herd is experiencing an elevated somatic cell count (SCC) averaging 400,000 cells/mL. Which organism is most commonly associated with contagious mastitis causing elevated bulk tank SCC?
- Streptococcus uberis
- Staphylococcus aureus (Correct answer)
- Klebsiella pneumoniae
- Escherichia coli
Correct answer: Staphylococcus aureus
Staphylococcus aureus is the classic contagious mastitis pathogen spread cow-to-cow during milking, and is the leading cause of elevated bulk tank SCC in dairy herds.
Question 2: A beef cow-calf operation has a 15% calf mortality rate in the first 30 days of life. Which intervention has the greatest impact on reducing neonatal calf mortality?
- Prophylactic antibiotic treatment at birth
- Ensuring adequate colostrum intake within 6 hours of birth (Correct answer)
- Vaccination of calves at birth against BRD pathogens
- Providing supplemental selenium at birth
Correct answer: Ensuring adequate colostrum intake within 6 hours of birth
Adequate colostrum intake (at least 10% of body weight within 6 hours) provides passive immunity and is the single most impactful intervention for reducing neonatal calf mortality.
Question 3: Which internal parasite of cattle causes 'bottle jaw' (submandibular edema) due to hypoproteinemia?
- Ostertagia ostertagi
- Haemonchus placei (Correct answer)
- Cooperia oncophora
- Trichostrongylus axei
Correct answer: Haemonchus placei
Haemonchus placei is a blood-sucking abomasal parasite that causes significant protein loss, leading to hypoproteinemia and the classic sign of submandibular edema (bottle jaw).
Question 4: A producer wants to implement a PRRSV (Porcine Reproductive and Respiratory Syndrome Virus) control program. Wait—this is a bovine herd. Which respiratory virus causes 'shipping fever' complex and is commonly controlled with modified-live virus vaccines in beef cattle?
- Bovine coronavirus (BCoV)
- Infectious bovine rhinotracheitis virus (IBRV/BHV-1) (Correct answer)
- Bovine respiratory syncytial virus (BRSV)
- Parainfluenza-3 virus (PI3)
Correct answer: Infectious bovine rhinotracheitis virus (IBRV/BHV-1)
IBRV (BHV-1) is a primary viral pathogen in the bovine respiratory disease complex, and modified-live IBR vaccines are a cornerstone of BRD prevention programs in beef cattle.
Question 5: In a feedlot, the recommended withdrawal time before slaughter must be observed when using which antibiotic for treatment of bovine respiratory disease?
- Flunixin meglumine
- Tulathromycin (Correct answer)
- Vitamin A injection
- Balanced electrolyte solution
Correct answer: Tulathromycin
Tulathromycin (Draxxin) has a meat withdrawal time of 18 days in the US, and compliance is required to ensure drug residue-free beef at slaughter.
Question 6: Which vaccination protocol is most appropriate for preventing clostridial diseases (blackleg, malignant edema) in beef calves?
- Single dose at weaning only
- Two doses 3-4 weeks apart starting at 2-3 months of age with annual boosters (Correct answer)
- Monthly intranasal vaccine starting at birth
- Passive transfer via colostrum is sufficient without active vaccination
Correct answer: Two doses 3-4 weeks apart starting at 2-3 months of age with annual boosters
Clostridial vaccines require a primary series of two doses 3-4 weeks apart to achieve protective immunity, with annual boosters to maintain protection.
Question 7: A veterinarian recommends a Selective Dry Cow Therapy (SDCT) program instead of blanket dry cow therapy. What is the PRIMARY advantage of SDCT?
- It eliminates the need for teat sealants at dry-off
- It reduces antibiotic use by treating only cows with existing infections or high SCC (Correct answer)
- It increases milk production in the subsequent lactation
- It prevents new environmental mastitis infections during the dry period
Correct answer: It reduces antibiotic use by treating only cows with existing infections or high SCC
SDCT reduces antimicrobial use by reserving intramammary antibiotic tubes for cows with evidence of infection, supporting antibiotic stewardship while maintaining udder health outcomes in low-SCC cows.
NAVLE Bovine Herd Health Management 2
A dairy herd is experiencing an elevated somatic cell count (SCC) averaging 400,000 cells/mL.
Which organism is most commonly associated with contagious mastitis causing elevated bulk tank SCC?