NAVLE EXAM PREP QUESTIONS AND
VERIFIED ANSWERS 2025
A 2 week old Suffolk ram lamb has central corneal opacity of both eyes. Both lower
palpebrae appear inverted. No other animals are affected. Which of the following is the
most likely cause of this problem?
A) Branhamella spp infection
B) Dusty environmental conditions
C) Inheritance
D) Mycoplasma spp infection
E) Puncture by grass awns
- CORRECT ANSWER ✓ ✓: C) Inheritance
Explanation:
A 2-week-old Suffolk lamb with:
Bilateral central corneal opacity
Inverted lower eyelids (entropion)
No other animals affected
Very young age
...is most consistent with a congenital (inherited) entropion leading to secondary corneal
ulceration/opacification.
Key reasoning:
Entropion = inward rolling of the eyelid margin → eyelashes rub the cornea → irritation
→ opacity → ulceration.
,In lambs, especially Suffolk, Hampshire, and Dorset breeds, entropion is often hereditary
and appears within the first weeks of life.
Environmental or infectious causes (dust, Mycoplasma, Branhamella, grass awns)
typically cause unilateral, painful keratoconjunctivitis, not symmetrical bilateral opacities
in a neonate.
Option Why Incorrect
A) Branhamella spp (Moraxella ovis) Causes infectious keratoconjunctivitis (pinkeye),
often contagious and painful, not congenital or bilateral symmetrical in a single lamb.
B) Dusty conditions Environmental irritant → conjunctivitis in multiple animals, not
congenital entropion.
D) Mycoplasma spp Causes infectious keratoconjunctivitis in goats/sheep herds;
multiple affected animals expected.
E) Grass awns Cause focal traumatic ulcers, unilateral and painful, not congenital or
symmetric.
A 5-year-old crossbred cow who is being used as a recipient cow in an embryo transfer
operation is evaluated because of the acute onset of hematuria. The owner reports that
the cow strains to pass a small volume of urine. Palpation via the rectum discloses a
smooth left kidney. Laboratory studies show blood urea nitrogen (BUN) concentration is
65 mg/dL (N 10-30) (23.2 mmol/L [N 3.6-10.7]) and serum concentration is 8 mg/dL (N
1-2) (707.2umol/L [N 90-180]). Administration of a drug from which of the following
classes is the most appropriate treatment?
A) Anthelmintic
B) Antibiotic
C) Corticosteroid
D) Diuretic
E) Nonsteroidal anti-inflammatory drug
, CORRECT ANSWER ✓ ✓: A) Anthelmintic
Diagnosis:
Obstructive hematuria and renal azotemia caused by Dioctophyma renale (giant kidney
worm).
Key reasoning:
Finding I Interpretation
- Adult cow, acute hematuria & stranguria Suggests urinary tract irritation or obstruction
- Rectal exam: smooth left kidney The right kidney is affected (parasite lives in right
kidney; left kidney felt normal)
- Azotemia (↑ BUN 65, ↑ creatinine Post-renal/renal obstruction or damage
- Recipient cow (used for embryo transfer) Exposure to contaminated water sources
(parasite transmission)
- Etiology Dioctophyma renale (giant kidney worm), transmitted by ingestion of infected
annelid intermediate host (earthworm or raw fish/frog tissue)
Treatment:
Anthelmintic (A) — most appropriate initial therapy (Fenbendazole or ivermectin;
surgical removal may be needed if worm burden causes obstruction.)
Diuretics, corticosteroids, NSAIDs do not address the parasitic cause.
Antibiotics only indicated secondarily if concurrent pyelonephritis occurs.
Which of the following urinary complications may occur in dogs with heartworm
disease?
A) Chronic renal failure
B) Cystitis
C) Glomerulonephritis
D) Pyelonephritis
E) Renal cysts
, CORRECT ANSWER ✓ ✓ C) Glomerulonephritis
A 4-year-old female Holstein cow is diagnosed with lactic acidosis. If she survives the
acute disease, she is at greatest risk for which of the following conditions?
A) Cystitis
B) Mastitis
C) Metritis
D) Sole abscess
E) Uveitis
CORRECT ANSWER ✓ ✓ D) Sole abscess
Lactic acidosis (grain overload) in cattle leads to rumenitis — inflammation and damage
to the rumen wall. Once the rumen epithelium is compromised:
- Bacteria (e.g., Fusobacterium necrophorum, Arcanobacterium pyogenes) can enter the
portal circulation.
- They form hepatic abscesses.
- Bacterial toxins and emboli from these abscesses or rumenitis-associated endotoxemia
then affect laminar corium perfusion in the hooves.
- Result → Laminitis, which predisposes to sole ulcers/abscesses and other claw horn
lesions.
Which of the following is the most common clinical sign associated with guttural pouch
mycosis in the horse?
A) Corneal ulceration
B) Dysphagia
C) Epistaxis
D) Horner's syndrome
E) Paralysis of the facial (VII) nerve
VERIFIED ANSWERS 2025
A 2 week old Suffolk ram lamb has central corneal opacity of both eyes. Both lower
palpebrae appear inverted. No other animals are affected. Which of the following is the
most likely cause of this problem?
A) Branhamella spp infection
B) Dusty environmental conditions
C) Inheritance
D) Mycoplasma spp infection
E) Puncture by grass awns
- CORRECT ANSWER ✓ ✓: C) Inheritance
Explanation:
A 2-week-old Suffolk lamb with:
Bilateral central corneal opacity
Inverted lower eyelids (entropion)
No other animals affected
Very young age
...is most consistent with a congenital (inherited) entropion leading to secondary corneal
ulceration/opacification.
Key reasoning:
Entropion = inward rolling of the eyelid margin → eyelashes rub the cornea → irritation
→ opacity → ulceration.
,In lambs, especially Suffolk, Hampshire, and Dorset breeds, entropion is often hereditary
and appears within the first weeks of life.
Environmental or infectious causes (dust, Mycoplasma, Branhamella, grass awns)
typically cause unilateral, painful keratoconjunctivitis, not symmetrical bilateral opacities
in a neonate.
Option Why Incorrect
A) Branhamella spp (Moraxella ovis) Causes infectious keratoconjunctivitis (pinkeye),
often contagious and painful, not congenital or bilateral symmetrical in a single lamb.
B) Dusty conditions Environmental irritant → conjunctivitis in multiple animals, not
congenital entropion.
D) Mycoplasma spp Causes infectious keratoconjunctivitis in goats/sheep herds;
multiple affected animals expected.
E) Grass awns Cause focal traumatic ulcers, unilateral and painful, not congenital or
symmetric.
A 5-year-old crossbred cow who is being used as a recipient cow in an embryo transfer
operation is evaluated because of the acute onset of hematuria. The owner reports that
the cow strains to pass a small volume of urine. Palpation via the rectum discloses a
smooth left kidney. Laboratory studies show blood urea nitrogen (BUN) concentration is
65 mg/dL (N 10-30) (23.2 mmol/L [N 3.6-10.7]) and serum concentration is 8 mg/dL (N
1-2) (707.2umol/L [N 90-180]). Administration of a drug from which of the following
classes is the most appropriate treatment?
A) Anthelmintic
B) Antibiotic
C) Corticosteroid
D) Diuretic
E) Nonsteroidal anti-inflammatory drug
, CORRECT ANSWER ✓ ✓: A) Anthelmintic
Diagnosis:
Obstructive hematuria and renal azotemia caused by Dioctophyma renale (giant kidney
worm).
Key reasoning:
Finding I Interpretation
- Adult cow, acute hematuria & stranguria Suggests urinary tract irritation or obstruction
- Rectal exam: smooth left kidney The right kidney is affected (parasite lives in right
kidney; left kidney felt normal)
- Azotemia (↑ BUN 65, ↑ creatinine Post-renal/renal obstruction or damage
- Recipient cow (used for embryo transfer) Exposure to contaminated water sources
(parasite transmission)
- Etiology Dioctophyma renale (giant kidney worm), transmitted by ingestion of infected
annelid intermediate host (earthworm or raw fish/frog tissue)
Treatment:
Anthelmintic (A) — most appropriate initial therapy (Fenbendazole or ivermectin;
surgical removal may be needed if worm burden causes obstruction.)
Diuretics, corticosteroids, NSAIDs do not address the parasitic cause.
Antibiotics only indicated secondarily if concurrent pyelonephritis occurs.
Which of the following urinary complications may occur in dogs with heartworm
disease?
A) Chronic renal failure
B) Cystitis
C) Glomerulonephritis
D) Pyelonephritis
E) Renal cysts
, CORRECT ANSWER ✓ ✓ C) Glomerulonephritis
A 4-year-old female Holstein cow is diagnosed with lactic acidosis. If she survives the
acute disease, she is at greatest risk for which of the following conditions?
A) Cystitis
B) Mastitis
C) Metritis
D) Sole abscess
E) Uveitis
CORRECT ANSWER ✓ ✓ D) Sole abscess
Lactic acidosis (grain overload) in cattle leads to rumenitis — inflammation and damage
to the rumen wall. Once the rumen epithelium is compromised:
- Bacteria (e.g., Fusobacterium necrophorum, Arcanobacterium pyogenes) can enter the
portal circulation.
- They form hepatic abscesses.
- Bacterial toxins and emboli from these abscesses or rumenitis-associated endotoxemia
then affect laminar corium perfusion in the hooves.
- Result → Laminitis, which predisposes to sole ulcers/abscesses and other claw horn
lesions.
Which of the following is the most common clinical sign associated with guttural pouch
mycosis in the horse?
A) Corneal ulceration
B) Dysphagia
C) Epistaxis
D) Horner's syndrome
E) Paralysis of the facial (VII) nerve
