NAVLE Small Animal Diagnostic Imaging 4 — Questions and Answers
Question 1: A 3-year-old German Shepherd Dog has progressive pelvic limb ataxia. MRI reveals an intramedullary T2-hyperintense lesion at L4 that does not contrast-enhance. The most likely diagnosis is:
- Intervertebral disc herniation
- Degenerative myelopathy
- Neoplasia (ependymoma)
- Fibrocartilaginous embolism (Correct answer)
Correct answer: Fibrocartilaginous embolism
Fibrocartilaginous embolism (FCE) typically appears as an intramedullary T2 hyperintensity without contrast enhancement, in young to middle-aged large breed dogs with acute onset.
Question 2: Which positional radiograph is recommended to evaluate for pneumothorax when only a small amount of free pleural air is suspected in a dog?
- Lateral recumbency with affected side down
- Dorsoventral with horizontal beam
- Standing lateral with horizontal beam (Correct answer)
- Ventrodorsal with horizontal beam
Correct answer: Standing lateral with horizontal beam
A standing lateral with a horizontal beam allows free pleural air to rise to the highest point (dorsal), making even small pneumothoraces visible between the lung and dorsal thoracic wall.
Question 3: In nuclear scintigraphy used in veterinary medicine, which radiopharmaceutical is most commonly used for bone scanning in dogs?
- Technetium-99m pertechnetate
- Technetium-99m methylene diphosphonate (MDP) (Correct answer)
- Gallium-67 citrate
- Iodine-131
Correct answer: Technetium-99m methylene diphosphonate (MDP)
Tc-99m MDP (methylene diphosphonate) accumulates in areas of active bone remodeling and is the standard radiopharmaceutical for skeletal scintigraphy in small animals.
Question 4: On thoracic radiographs, a cat with hypertrophic cardiomyopathy (HCM) most commonly shows which cardiac silhouette shape on the VD view?
- Globoid (round) silhouette
- Valentine heart shape (biatrial enlargement) (Correct answer)
- Right-sided enlargement with D-shape
- Normal silhouette despite severe disease
Correct answer: Valentine heart shape (biatrial enlargement)
HCM in cats classically produces a 'valentine heart' shape on VD radiographs due to bilateral atrial enlargement, though some cats have relatively normal-appearing hearts.
Question 5: Which ultrasound finding is most specific for portal hypertension in a dog?
- Decreased portal vein diameter
- Acquired portosystemic shunting vessels (Correct answer)
- Hepatic parenchymal hypoechogenicity
- Decreased hepatic artery Doppler flow
Correct answer: Acquired portosystemic shunting vessels
Acquired portosystemic collateral vessels (multiple tortuous vessels in the region of the left kidney or spleen) are the most specific ultrasound sign of portal hypertension.
Question 6: A dog presents with a suspected diaphragmatic hernia. Which radiographic finding would MOST suggest a peritoneopericardial diaphragmatic hernia (PPDH) rather than a traumatic diaphragmatic hernia?
- Acute onset following trauma
- Enlarged globoid cardiac silhouette without pleural effusion (Correct answer)
- Gas-filled bowel loops in the pleural space
- Discontinuity of the diaphragmatic line
Correct answer: Enlarged globoid cardiac silhouette without pleural effusion
PPDH is a congenital defect where abdominal organs herniate into the pericardial sac, causing an enlarged cardiac silhouette, unlike traumatic hernias where organs enter the pleural space.
Question 7: On dental radiographs of a dog, which finding indicates endodontic disease requiring root canal therapy or extraction?
- Lamina dura intact around all roots
- Periapical lucency (halo) at the root tip (Correct answer)
- Normal periodontal ligament space width
- Hyperdense root tip compared to surrounding bone
Correct answer: Periapical lucency (halo) at the root tip
A periapical lucency (radiolucent halo) at the root apex indicates periapical abscess or granuloma from pulp necrosis, confirming endodontic disease.
NAVLE Small Animal Diagnostic Imaging 4
A 3-year-old German Shepherd Dog has progressive pelvic limb ataxia.
MRI reveals an intramedullary T2-hyperintense lesion at L4 that does not contrast-enhance.
The most likely diagnosis is: