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National Licensed Veterinarian (China) practice questions

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Question 1Companion-animal clinical reasoning and individual assessment

In the stated classical teaching sequence of inspection, palpation, percussion and auscultation, which listed order reproduces that convention rather than a mandatory physiological order for every veterinary examination?

  1. Auscultation, Palpation, Blood biochemistry, Endoscopy
  2. Percussion, Surgery, Inspection, Palpation
  3. Olfaction, Biopsy, Inspection, Auscultation
  4. Inspection (Visual exam), Palpation, Percussion, Auscultation (视诊、触诊、叩诊、听诊) Correct answer.

Explanation

The four fundamental non-invasive physical examination techniques in veterinary diagnostics are Inspection (视诊 / visual evaluation from a distance and up close), Palpation (触诊 / manual touch for temperature, pain, consistency), Percussion (叩诊 / tapping to elicit resonant/dull sounds), and Auscultation (听诊 / listening to heart, lung, and gastrointestinal sounds).

Question 2Companion-animal clinical reasoning and individual assessment

In feline and canine clinical diagnostics, what abnormal mucosal coloration is characteristically caused by elevated levels of circulating total bilirubin (> 2.0 mg/dL or > 34 micromol/L) due to pre-hepatic hemolysis, hepatic disease, or post-hepatic biliary obstruction?

  1. Cyanosis (发绀 / 紫绀)
  2. Jaundice / Icterus (黄疸) Correct answer.
  3. Pallor (苍白)
  4. Cherry-red hyperemia (樱桃红 / 充血)

Explanation

Jaundice (黄疸 / Icterus) is the yellow discoloration of mucous membranes, sclera, and non-pigmented skin caused by hyperbilirubinemia, resulting from hemolytic crisis (pre-hepatic), hepatocellular failure (hepatic), or bile duct obstruction (post-hepatic).

Question 3Companion-animal clinical reasoning and individual assessment

A 4-month-old unvaccinated puppy presents with acute onset of high fever (40°C), intractable vomiting, severe foul-smelling bloody diarrhea ('tomato soup' appearance), profound dehydration, and severe leukopenia (WBC 1.2 x 10^9/L). Rapid fecal ELISA is positive. What is the diagnosis and primary pathophysiology?

  1. Infectious Canine Hepatitis; primary endothelial necrosis in hepatic sinusoids
  2. Canine Coronavirus enteritis; superficial villus tip sloughing only without leukopenia
  3. Canine Parvovirus (CPV-2 / 犬细小病毒病); viral destruction of intestinal crypt epithelial cells and lymphoid bone marrow progenitor cells (病毒破坏肠隐窝上皮与骨髓造血干细胞) Correct answer.
  4. Salmonella enterica infection; chronic localized typhlitis without bone marrow involvement

Explanation

Canine Parvovirus Type 2 (CPV-2) targets rapidly dividing cells: the germinal cells of intestinal crypts (causing severe villous blunting, mucosal collapse, and foul-smelling hemorrhagic diarrhea) and hematopoietic progenitor cells in bone marrow and lymphoid tissues (causing severe panleukopenia).

Question 4Veterinary imaging, biomechanics and surgical planning

In diagnostic radiography of small animals, which contrast medium is strictly contraindicated for gastrointestinal imaging if perforation of the esophagus, stomach, or bowel is suspected?

  1. Non-ionic iodinated contrast (e.g., Iohexol / 碘海醇)
  2. Barium sulfate suspension (硫酸钡混悬液) Correct answer.
  3. Room air / Carbon dioxide negative contrast
  4. Sterile physiological saline

Explanation

Barium sulfate is an insoluble, non-absorbable heavy metal suspension. If gastrointestinal perforation is present, barium leakage into the mediastinum or peritoneal cavity causes severe, irreversible, foreign-body granulomatous peritonitis/mediastinitis with high mortality. Water-soluble iodinated agents (iohexol) must be used instead.

Question 5Veterinary imaging, biomechanics and surgical planning

In veterinary gastrointestinal surgery, which of the following suture patterns is an Inverting Suture (内翻缝合法) commonly used to close hollow visceral organs (stomach, uterus, bladder) to create a serosa-to-serosa leak-proof seal?

  1. Ford interlocking suture pattern (福特氏连续锁边缝合)
  2. Lembert suture pattern (伦伯特氏缝合法) Correct answer.
  3. Simple interrupted suture pattern (单纯间断缝合)
  4. Cruciate mattress suture pattern (十字褥式缝合)

Explanation

The Lembert suture (and Cushing/Connell/Halsted patterns) is an inverting suture pattern that turns the cut edges inward, bringing serosal surfaces into direct contact (serosa-to-serosa). Serosal contact promotes rapid fibrin sealing and watertight healing in hollow viscera.

Question 6Veterinary imaging, biomechanics and surgical planning

In small animal soft tissue surgery, what are the three anatomical components that define a True External Hernia (真性疝)?

  1. Hernial ring (orifice), Hernial sac (peritoneal lining), and Hernial contents (viscera/omentum) (疝环、疝囊与疝内容物) Correct answer.
  2. Hernial fissure, Fistula tract, and Granulation tissue
  3. Incarceration groove, Suture knot, and Abscess pocket
  4. Mesenteric root, Omental bursa, and Parietal pleura

Explanation

A true anatomical hernia consists of three classic structures: (1) The Hernial Ring (疝环 - the defect in the muscular/fascial abdominal wall), (2) The Hernial Sac (疝囊 - outpouching of parietal peritoneum and skin), and (3) The Hernial Contents (疝内容物 - displaced abdominal viscera, fat, or omentum).

Question 7Ruminant metabolism, herd evidence and reproductive health

In the ruminant stomach anatomy, which compartment is lined with a glandular mucous membrane that secretes gastric juice, pepsinogen, and hydrochloric acid, functionally equivalent to the monogastric stomach?

  1. Rumen (瘤胃)
  2. Reticulum (网胃)
  3. Omasum (瓣胃)
  4. Abomasum (皱胃) Correct answer.

Explanation

The Abomasum (皱胃) is the true glandular stomach of ruminants (cattle, sheep, goats). Unlike the forestomachs (rumen, reticulum, omasum), which have stratified squamous aglandular epithelium for mechanical mixing and microbial fermentation, the abomasum possesses gastric glands that secrete hydrochloric acid, pepsinogen, and rennin for enzymatic digestion.

Question 8Ruminant metabolism, herd evidence and reproductive health

In ruminant digestive physiology, which volatile fatty acid (VFA / 挥发性脂肪酸) produced by microbial carbohydrate fermentation serves as the primary substrate for hepatic gluconeogenesis (糖异生)?

  1. Acetate (乙酸)
  2. Propionate (丙酸) Correct answer.
  3. Butyrate (丁酸)
  4. Valerate (戊酸)

Explanation

Propionate (丙酸) is the only major volatile fatty acid absorbed across the rumen wall that can be converted into oxaloacetate via methylmalonyl-CoA and succinyl-CoA, serving as the principal precursor for hepatic gluconeogenesis in ruminants to produce glucose.

Question 9Ruminant metabolism, herd evidence and reproductive health

During negative energy balance in high-producing dairy cows, massive lipolysis releases non-esterified fatty acids (NEFA). When hepatic beta-oxidation exceeds the capacity of the citric acid cycle due to oxaloacetate depletion, which key enzyme directs acetyl-CoA into ketogenesis (酮体生成)?

  1. Carnitine palmitoyltransferase-1 (肉碱掌勺酰基转移酶-1 / CPT-1)
  2. Acetyl-CoA carboxylase (乙酰辅酶A羧化酶)
  3. HMG-CoA synthase (HMG-CoA合成酶) Correct answer.
  4. Lipoprotein lipase (脂蛋白脂酶)

Explanation

Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMG-CoA synthase) is the rate-limiting enzyme in hepatic ketogenesis. When oxaloacetate is diverted to gluconeogenesis, excess acetyl-CoA condensation catalyzed by thiolase and HMG-CoA synthase yields acetoacetate and beta-hydroxybutyrate (ketone bodies).

Question 10Swine population medicine, infection and production systems

During post-mortem inspection of market hogs, multiple white, fibrous, starlike spots are observed beneath the liver capsule ('milk spot liver' / 乳斑肝). Which parasite's larval migration through the hepatic parenchyma causes this pathognomonic lesion?

  1. Ascaris suum (猪蛔虫幼虫移行) Correct answer.
  2. Metastrongylus apri (猪后圆线虫)
  3. Stephanurus dentatus (猪肾虫)
  4. Oesophagostomum dentatum (猪结节线虫)

Explanation

When infective eggs of Ascaris suum (pig roundworm) hatch in the gut, L3 larvae penetrate the intestinal wall and migrate via the portal vein to the liver. Their destructive migration and resulting eosinophilic inflammatory fibrosis produce hallmark chronic white interstitial hepatitis patches termed 'milk spots' (乳斑肝).

Question 11Swine population medicine, infection and production systems

In the gross necropsy of a pig that died of Classical Swine Fever (CSF / 猪瘟), what hallmark pathological lesions in the ileocecal valve/colon and kidneys are pathognomonic?

  1. Button-like necrotic ulcers (纽扣状溃疡) in the large intestinal mucosa and petechial hemorrhages on the renal cortex ('turkey-egg' kidney / 麻雀蛋样肾) Correct answer.
  2. Large fibrinous pleuropneumonia and pleural adhesions
  3. Diffuse pseudomembrane on the tongue and vesicular erosions on the snout
  4. Chalky white muscle streaks and hepatic necrosis

Explanation

Button-like intestinal ulcers and renal petechiae are classic pathological associations of classical swine fever in the relevant differential. They are not present in every animal or exclusive proof of that infection. Similar serious diseases require appropriate laboratory confirmation, biosafety and the actual competent-authority response rather than a diagnosis by appearance alone.

Question 12Swine population medicine, infection and production systems

A pig breeding farm experiences widespread reproductive failure in pregnant sows (late-term abortions, mummified fetuses, stillbirths) along with severe interstitial pneumonia, eyelid edema, and blue-purple discoloration of the ears in nursery piglets ('Blue-Ear Disease' / 蓝耳病). What pathogen is responsible?

  1. Porcine Parvovirus (PPV / 猪细小病毒)
  2. Swine Influenza Virus (SIV / 猪流感病毒)
  3. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV / 猪繁殖与呼吸综合征病毒 - Arteriviridae) Correct answer.
  4. Japanese Encephalitis Virus (JEV / 乙型脑炎病毒)

Explanation

The combined reproductive and respiratory herd pattern makes PRRS virus the most consistent listed cause in this teaching scenario. Clinical signs alone do not exclude other serious infections or coinfection. Representative testing and the relevant veterinary authority pathway are needed for a real herd event; no animal movement or vaccine programme is prescribed by this answer.

Question 13Equine clinical assessment, colic and locomotor problems

In equine biomechanics and anatomy, which specialized anatomical apparatus allows horses to stand for prolonged periods with minimal muscular exertion by locking the stifle and hock joints simultaneously?

  1. Reciprocal apparatus and patellar locking mechanism (互动装置与膝盖锁定机制) Correct answer.
  2. Suspensory apparatus of the navicular bone (舟骨悬吊装置)
  3. Brachiocephalic muscle kinetic chain (胸头肌动力链)
  4. Nuchal ligament funicular lamellar junction (项韧带索状部与层状部)

Explanation

The stay apparatus of the equine pelvic limb utilizes the patellar locking mechanism (hooking the medial patellar ligament over the medial trochlear ridge of the femur) combined with the reciprocal apparatus (peroneus tertius and superficial digital flexor muscles) to lock the stifle and hock in extension simultaneously, allowing prolonged standing with minimal energy expenditure.

Question 14Veterinary pathology, specimens and interpretation

In the cardiac conduction system of domestic mammals, which specialized myocardial cells are located in the subendocardium and conduct electrical action potentials at the highest velocity to coordinate rapid ventricular contraction?

  1. Sinoatrial node cells (窦房结细胞)
  2. Atrioventricular node cells (房室结细胞)
  3. Purkinje fibers (浦肯野纤维) Correct answer.
  4. Working ventricular myocytes (心室工作肌细胞)

Explanation

Purkinje fibers (浦肯野纤维) are modified cardiac muscle cells with large diameters, abundant glycogen, fewer myofibrils, and extensive gap junctions. They possess the highest conduction velocity (approx. 2–4 m/s) in the heart, ensuring synchronous depolarisation and contraction of both ventricles.

Question 15Veterinary pathology, specimens and interpretation

In mammalian renal physiology, what is the primary driving force that favors the filtration of plasma fluid across the glomerular capillary wall into Bowman's space?

  1. Bowman's capsule hydrostatic pressure (肾小囊流体静压)
  2. Plasma colloid osmotic pressure (血浆胶体渗透压)
  3. Glomerular capillary hydrostatic pressure (肾小球毛细血管流体静压) Correct answer.
  4. Renal medullary interstitial hyperosmolarity (肾髓质组织间隙高渗)

Explanation

Glomerular capillary hydrostatic pressure (PGC, approx. 45–60 mmHg in mammals) is the primary forward force promoting ultrafiltration. Bowman's capsule hydrostatic pressure and plasma colloid osmotic pressure oppose filtration.

Question 16Veterinary pathology, specimens and interpretation

According to the Frank-Starling Law of the Heart (心脏斯塔林定律), what intrinsic hemodynamic factor directly increases ventricular stroke volume during the subsequent cardiac cycle?

  1. Increased ventricular end-diastolic volume / preload (心室舒张末期容量 / 前负荷增加) Correct answer.
  2. Increased systemic arterial resistance / afterload (系统动脉阻力 / 后负荷增加)
  3. Decreased cardiac venous return (静脉回心血量减少)
  4. Selective stimulation of cardiac muscarinic M2 receptors (心肌M2受体选择性兴奋)

Explanation

The Frank-Starling mechanism states that greater ventricular filling during diastole (increased end-diastolic volume/preload) stretches myocardial sarcomeres toward their optimal length, thereby increasing the force of contraction and resulting stroke volume.

Question 17Veterinary epidemiology, zoonoses and food-chain protection

In veterinary epidemiology, what is the definition of Vertical Transmission (垂直传播) of an animal infectious disease?

  1. Transmission between animals of the same herd via aerosol droplets
  2. Mechanical transfer of pathogens between farms on truck tires
  3. Biological transmission through biting arthropod vectors
  4. Transmission of a pathogen directly from a maternal parent to its offspring via transovarial, transplacental, or colostral/perinatal pathways (病原体由母体经卵、胎盘或产道/初乳直接传给后代) Correct answer.

Explanation

Vertical transmission (垂直传播) refers to the direct transmission of infectious pathogens from parent (primarily female) to offspring during reproduction: via ovum (transovarial in poultry, e.g., Salmonella Pullorum), placenta (transplacental, e.g., PRRSV, BVDV), birth canal, or colostrum.

Question 18Veterinary epidemiology, zoonoses and food-chain protection

In veterinary parasitology and public health, which animal species serves as the ONLY definitive host (终末宿主) for Toxoplasma gondii (刚地弓形虫), capable of shedding environmentally resistant oocysts in feces?

  1. Dogs and wild Canidae species
  2. Domestic cats and other Felidae family members (家猫及其他猫科动物) Correct answer.
  3. Swine and domestic boars
  4. Sheep, goats, and cattle

Explanation

Members of the cat family (Felidae) are the sole definitive hosts of Toxoplasma gondii. Only in feline intestinal enterocytes does the sexual cycle (gametogony and oocyst formation) take place, shedding millions of unsporulated oocysts in cat feces.

Question 19Veterinary epidemiology, zoonoses and food-chain protection

What is the mandatory obligate intermediate host (中间宿主) in the lifecycle of the common liver fluke, Fasciola hepatica (肝片吸虫), that infects cattle, sheep, and humans?

  1. Oribatid pasture mites (地螨)
  2. Biting midges (Culicoides spp. / 库蠓)
  3. Freshwater mud snails (Lymnaeidae family, e.g., Galba pervia / 椎实螺 / 截口土蜗) Correct answer.
  4. Coprophagous dung beetles (蜣螂)

Explanation

Fasciola hepatica requires freshwater snails of the family Lymnaeidae (notably Galba pervia / Lymnaea truncatula) as intermediate hosts. Miracidia penetrate snails, developing through sporocyst, redia, and cercaria stages before encysting as metacercariae on pasture vegetation.

Question 20Species-aware pharmacology, anesthesia and welfare

What is the primary antimicrobial mechanism of action of beta-lactam antibiotics (beta-内酰胺类抗生素), such as penicillins and cephalosporins, against susceptible bacteria?

  1. Inhibition of penicillin-binding proteins (PBPs) interfering with bacterial peptidoglycan cell wall cross-linking (抑制青霉素结合蛋白，阻碍细胞壁肽聚糖交联) Correct answer.
  2. Binding to the 30S ribosomal subunit to cause mRNA misreading
  3. Inhibition of DNA topoisomerase II (DNA gyrase) preventing DNA replication
  4. Disruption of cytoplasmic membrane phospholipids causing ion leakage

Explanation

Beta-lactam antibiotics (penicillins, ampicillin, cephalosporins) are bactericidal drugs that bind to and inhibit penicillin-binding proteins (PBPs/transpeptidases), preventing the cross-linking of peptidoglycan polymers in the bacterial cell wall, leading to cell lysis under osmotic pressure.

Question 21Species-aware pharmacology, anesthesia and welfare

Which of the following adverse effect profiles is most characteristically associated with aminoglycoside antibiotics (氨基糖苷类抗生素, e.g., gentamicin, kanamycin, amikacin) in domestic animals?

  1. Aplastic anemia and bone marrow suppression
  2. Articular cartilage erosion in immature growing animals
  3. Nephrotoxicity and ototoxicity / vestibulocochlear damage (肾毒性与耳毒性) Correct answer.
  4. Esophageal stricture in feline patients

Explanation

Aminoglycosides (gentamicin, amikacin, streptomycin) accumulate in renal proximal tubular cells and endolymph/perilymph of the inner ear, causing acute tubular necrosis (nephrotoxicity) and irreversible auditory/vestibular hair cell damage (ototoxicity).

Question 22Species-aware pharmacology, anesthesia and welfare

Ivermectin (伊维菌素) exhibits high safety in most livestock but can cause severe neurotoxicity (ataxia, tremors, coma) in Collies and related breeds. What is the underlying pharmacological and genetic mechanism of this toxicity?

  1. Deficiency of renal glucose-6-phosphatase enzyme
  2. A deletion mutation in the ABCB1 (MDR1) gene resulting in deficient P-glycoprotein efflux pump expression at the blood-brain barrier (ABCB1/MDR1基因突变导致血脑屏障P-糖蛋白缺失) Correct answer.
  3. Overexpression of hepatic cytochrome P450 3A4 enzymes
  4. Inhibition of acetylcholinesterase at the neuromuscular junction

Explanation

In Collies and Australian Shepherds, a 4-bp deletion mutation in the ABCB1 (MDR1) gene results in non-functional P-glycoprotein. Without P-glycoprotein to pump ivermectin out of the brain, the drug crosses the blood-brain barrier in high concentrations and binds to neuronal GABA receptors, causing CNS depression, tremors, and coma.

Question 23Companion-animal clinical reasoning and individual assessment

A 6-month-old stray dog is rescued with a history of biphasic fever (双相热), purulent oculonasal discharge, severe coughing, hyperkeratosis of the footpads and nasal planum ('hard pad disease' / 硬足垫病), followed 3 weeks later by localized chorea (myoclonus muscle twitching) and seizures. What is the pathogen?

  1. Rabies Virus (狂犬病毒 - Lyssavirus)
  2. Canine Adenovirus Type 2 (犬腺病毒2型)
  3. Bordetella bronchiseptica (支气管败血鲍特氏菌)
  4. Canine Distemper Virus (CDV / 犬瘟热病毒 - Morbillivirus) Correct answer.

Explanation

Canine Distemper Virus (CDV, genus Morbillivirus) produces multi-systemic pathology: respiratory catarrh, gastrointestinal enteritis, hyperkeratosis of digital footpads and nose planum (hard pad disease), and secondary central nervous system demyelinating encephalitis causing characteristic rhythmic myoclonus (chorea) and seizures.

Question 24Companion-animal clinical reasoning and individual assessment

A 5-month-old kitten presents with sudden high fever, profound lethargy, persistent vomiting, severe dehydration, and sitting with its head hung over the water bowl without drinking. Complete blood count reveals WBC count of 0.4 x 10^9/L (extreme panleukopenia). What is the causative virus?

  1. Feline Panleukopenia Virus (FPV / 猫泛白细胞减少症病毒 / 猫瘟病毒 - Parvovirus) Correct answer.
  2. Feline Herpesvirus-1 (FHV-1 / 猫疱疹病毒1型)
  3. Feline Calicivirus (FCV / 猫杯状病毒)
  4. Feline Leukemia Virus (FeLV / 猫白血病病毒)

Explanation

Feline Panleukopenia Virus (FPV / feline distemper) is a feline protoparvovirus that destroys active mitotic cells in the bone marrow (causing profound panleukopenia affecting all leukocyte cell lines) and the intestinal crypt epithelium (causing intractable vomiting and severe hemorrhagic enteritis).

Question 25Companion-animal clinical reasoning and individual assessment

A 1-year-old cat presents with progressive abdominal distension, fluctuating fever unresponsive to antibiotics, and weight loss. Abdominocentesis yields viscous, straw-yellow, sticky fluid with high total protein (> 35 g/L), low albumin/globulin ratio (A:G < 0.4), and a positive Rivalta test (李凡他试验阳性). What disease does this effusion profile strongly indicate?

  1. Bacterial septic peritonitis caused by gastrointestinal perforation
  2. Congestive right-sided heart failure pure transudate
  3. Effusive 'Wet' Feline Infectious Peritonitis (渗出型猫传染性腹膜炎 / 湿性传腹 - FIP / Feline Coronavirus mutation) Correct answer.
  4. Hepatic cirrhosis pure hypoalbuminemic transudate

Explanation

Effusive (Wet) FIP is caused by mutated Feline Coronavirus (FCoV) replicating in monocytes and inducing systemic pyogranulomatous vasculitis. The resulting peritoneal effusion is characteristically straw-yellow, viscous, non-septic, high in protein (> 3.5 g/dL) and globulins (A:G < 0.4–0.6), and strongly positive on the Rivalta test.

Question 26Ruminant metabolism, herd evidence and reproductive health

A dairy cow consumes a large quantity of finely ground corn grain. Within 12 hours, she develops anorexia, severe depression, dehydration, cold extremities, and sloshing rumen sounds. Rumen fluid analysis reveals a pH of 4.5 and absence of live protozoa. What is the primary diagnosis?

  1. Simple Primary Rumen Tympany (前胃迟缓伴气胀)
  2. Traumatic Reticuloperitonitis / Hardware Disease (创伤性网胃腹膜炎)
  3. Acute Rumen Lactic Acidosis / Grain Overload (急性瘤胃酸中毒 / 瘤胃积食) Correct answer.
  4. Right Displaced Abomasum with Volvulus (皱胃右方变位伴扭转)

Explanation

Ingestion of excessive rapidly fermentable carbohydrates causes overgrowth of Streptococcus bovis and Lactobacillus spp., producing massive amounts of D- and L-lactic acid. This drops rumen pH below 5.0 (normal 6.2–6.8), kills normal ciliate protozoa, causes chemical ruminitis, metabolic acidosis, and osmotic fluid shift into the rumen.

Question 27Ruminant metabolism, herd evidence and reproductive health

In dairy cow clinical examination, simultaneous auscultation and percussion (叩诊结合听诊) over the left flank along a line between the 8th and 12th ribs elicits a characteristic high-pitched, metallic resonant 'ping' sound. What is the most likely diagnosis?

  1. Cecal dilation and torsion (盲肠扩张与扭转)
  2. Left Displaced Abomasum (LDA / 皱胃左方变位) Correct answer.
  3. Traumatic pericarditis (创伤性心包炎)
  4. Rumen impaction with sand (瘤胃砂石积食)

Explanation

Left Displaced Abomasum (LDA) occurs when the gas-distended abomasum migrates from the ventral abdominal floor upward between the rumen and the left abdominal body wall. Simultaneous auscultation and percussion over the left 8th–12th intercostal spaces produces a pathognomonic resonant high-pitched acoustic 'ping' (steel band sound).

Question 28Ruminant metabolism, herd evidence and reproductive health

In 2-month-old lambs and calves grazing on selenium-deficient soils, animals exhibit stiffness, trembling, reluctant movement, arched back, and sudden death. Necropsy reveals chalky white bilateral symmetrical streaks in the myocardium and skeletal muscles. What is the diagnosis?

  1. Clostridial Blackleg / Emphysematous Gangrene (气肿疽)
  2. Bovine Malignant Catarrhal Fever (恶性卡他热)
  3. Nutritional Myodystrophy / White Muscle Disease (营养性肌营养不良 / 白肌病 - 硒与维生素E缺乏症) Correct answer.
  4. Tetanus / Clostridium tetani infection (破伤风)

Explanation

White Muscle Disease (白肌病 / Nutritional Myodystrophy) is caused by deficiency of Selenium (Se) and/or Vitamin E. Deficiency impairs the antioxidant glutathione peroxidase system, leading to cellular lipid peroxidation, calcium influx, and Zenker's hyaline/chalky white necrosis in skeletal muscle and myocardium.

Question 29Ruminant metabolism, herd evidence and reproductive health

In a nonpregnant cow, which listed hormone released through the uterine luteolytic mechanism contributes to regression of the corpus luteum? Do not assume every domestic species uses the identical physiological pathway.

  1. Progesterone (孕酮 / 黄体酮)
  2. Prostaglandin F2alpha (PGF2alpha / 前列腺素F2alpha) Correct answer.
  3. Luteinizing Hormone (LH / 促黄体素)
  4. Human Chorionic Gonadotropin (hCG)

Explanation

In non-pregnant domestic mammals (cattle, sheep, mares, sows), pulsatile secretion of Prostaglandin F2alpha (PGF2alpha) from the uterine endometrium acts on the ovary to cause structural and functional luteolysis of the corpus luteum, dropping progesterone levels and allowing a new estrous cycle to begin.

Question 30Ruminant metabolism, herd evidence and reproductive health

In veterinary obstetrics, how is Dystocia (难产) primarily classified based on etiology?

  1. Infectious dystocia and Non-infectious dystocia
  2. Nutritional dystocia and Hormonal dystocia
  3. Maternal dystocia (e.g., pelvic stenosis, uterine inertia, uterine torsion) and Fetal dystocia (e.g., fetal oversize, malpresentation, malposture) (母体性难产与胎儿性难产) Correct answer.
  4. Genetic dystocia and Traumatic dystocia

Explanation

Dystocia is fundamentally classified into Maternal causes (母体性难产: uterine inertia, narrow pelvic birth canal, cervical non-dilation, uterine torsion) and Fetal causes (胎儿性难产: absolute/relative fetal oversize, monsters, abnormal fetal presentation, position, or posture).

Question 31Ruminant metabolism, herd evidence and reproductive health

In a dairy herd, several calves born from dams infected during early gestation (40–120 days) are unthrifty and seronegative for antibodies but persistently shed large quantities of Bovine Viral Diarrhea Virus (BVDV). Later, these calves develop severe mucosal disease with erosions throughout the alimentary tract, coronary band inflammation, and fatal watery diarrhea. What is the epidemiological status of these calves?

  1. Genetically immune resistant calves that cleared the infection completely
  2. Calves suffering from acute primary Rinderpest infection
  3. Persistently Infected (PI / 持续感染PI牛) calves that developed immune tolerance to non-cytopathic (ncp) BVDV in utero, developing fatal Mucosal Disease upon superinfection or mutation to cytopathic (cp) BVDV (宫内免疫耐受形成的持续感染牛，突变后发生黏膜病) Correct answer.
  4. Calves suffering from Foot-and-Mouth Disease carrier state

Explanation

When a pregnant cow is infected between 40 and 120 days of gestation with a non-cytopathic (ncp) BVDV strain, the fetal immune system recognizes the virus as 'self', creating an immunotolerant, Persistently Infected (PI) calf. PI cattle shed massive amounts of virus for life. If a PI animal is superinfected with or the virus mutates into a homologous cytopathic (cp) strain, fatal Mucosal Disease (黏膜病) ensues.

Question 32Ruminant metabolism, herd evidence and reproductive health

A beef herd experiences an outbreak of severe respiratory disease with coughing, high fever, and extended necks. Post-mortem examination reveals massive serofibrinous pleurisy with abundant pleural effusion and severe pulmonary hepatization characterized by wide, pale, gelatinous interlobular septa alternating with dark red consolidated lobules ('marbled lung' / 大理石样变). What is the pathogen?

  1. Mycoplasma mycoides subsp. mycoides (Contagious Bovine Pleuropneumonia / 牛传染性胸膜肺炎 / 牛肺疫) Correct answer.
  2. Pasteurella multocida Type B (Bovine hemorrhagic septicemia)
  3. Bovine Respiratory Syncytial Virus (BRSV)
  4. Mycobacterium avium subsp. paratuberculosis

Explanation

Contagious Bovine Pleuropneumonia (CBPP / 牛肺疫) is caused by Mycoplasma mycoides subsp. mycoides. The pathognomonic lesion is severe fibrinous pleuropneumonia with markedly widened, edematous interlobular septa enclosing lung lobules in various stages of red and grey hepatization, creating a striking 'marbled' appearance (大理石样变).

Question 33Ruminant metabolism, herd evidence and reproductive health

Several fast-growing feedlot lambs on a high-grain concentrate ration are found dead in the morning without prior signs. Necropsy reveals rapid post-mortem decomposition, focal encephalomalacia, excess pericardial fluid with fibrin clots, marked glucosuria (urine positive for glucose), and soft, pulpy, autolyzed kidneys ('pulpy kidney disease' / 软肾病). What is the causative pathogen and toxin?

  1. Clostridium chauvoei producing alpha toxin
  2. Bacillus anthracis producing lethal factor
  3. Clostridium perfringens Type D producing Epsilon toxin (D型产气荚膜梭菌产生epsilon毒素引发羊肠毒血症) Correct answer.
  4. Listeria monocytogenes producing listeriolysin O

Explanation

Ovine Enterotoxemia (Pulpy Kidney Disease / 羊肠毒血症) is caused by Clostridium perfringens Type D. High carbohydrate intake promotes rapid bacterial proliferation in the small intestine, producing lethal Epsilon protoxin activated by trypsin. Epsilon toxin increases endothelial permeability, causing severe brain edema, pulmonary edema, glucosuria, and rapid renal cortical liquefactive autolysis ('pulpy kidney').

Question 34Ruminant metabolism, herd evidence and reproductive health

A flock of goats in Northwest China experiences high mortality (up to 80%) characterized by high fever, necrotic erosive stomatitis (foul breath, crusted lips), purulent oculonasal discharge, severe watery-to-bloody diarrhea, and broncho-pneumonia. Post-mortem reveals 'zebra stripes' (斑马纹状出血) along the mucosal folds of the large intestine and colon. What is the diagnosis?

  1. Contagious Caprine Pleuropneumonia (CCPP / 羊传染性胸膜肺炎)
  2. Contagious Ecthyma / Orf (羊口疮 - Parapoxvirus)
  3. Ovine Brucellosis (羊布鲁氏菌病)
  4. Peste des Petits Ruminants (PPR / 小反刍兽疫 - Morbillivirus) Correct answer.

Explanation

Peste des Petits Ruminants (PPR / 小反刍兽疫, Morbillivirus) is a catastrophic Class I viral disease of sheep and goats (especially severe in goats). It produces erosive necrotizing stomatitis, purulent catarrhal respiratory discharge, severe enteritis with linear mucosal hemorrhages along the colorectal folds ('zebra striping' / 斑马纹), and high mortality.

Question 35Swine population medicine, infection and production systems

Nursery and growing pigs (6–12 weeks old) present with progressive emaciation, dyspnea, pallor, rough hair coat, and generalized enlargement of superficial inguinal lymph nodes (lymphadenopathy enlarged 3–5 times). Histopathology reveals marked depletion of lymphoid follicles with infiltration of histiocytes and multinucleated syncytial cells containing intracytoplasmic inclusion bodies. What is the causative pathogen?

  1. Porcine Circovirus Type 2 (PCV2 / 猪圆环病毒2型 - PMWS断奶仔猪多系统衰竭综合征) Correct answer.
  2. Swine Pox Virus (猪痘病毒)
  3. Porcine Parvovirus (猪细小病毒)
  4. Haemophilus parasuis (猪副嗜血杆菌)

Explanation

PCV2-associated systemic disease can involve wasting, enlarged lymph nodes and characteristic lesions in the relevant age group. Detecting PCV2 alone is not sufficient to establish that it caused the complete clinical syndrome. Histopathology, antigen or nucleic-acid findings in the appropriate lesions and the whole herd pattern contribute to diagnosis.

Question 36Veterinary pathology, specimens and interpretation

In cellular biochemistry, which rate-limiting enzyme catalyzes the irreversible committed step of glycolysis, converting fructose 6-phosphate to fructose 1,6-bisphosphate?

  1. Hexokinase (己糖激酶)
  2. Phosphofructokinase-1 (磷酸果糖激酶-1 / PFK-1) Correct answer.
  3. Pyruvate kinase (丙酮酸激酶)
  4. Glucose-6-phosphatase (葡萄糖-6-磷酸酶)

Explanation

Phosphofructokinase-1 (PFK-1) is the primary rate-limiting and committed enzyme of glycolysis. It phosphorylates fructose 6-phosphate to fructose 1,6-bisphosphate using ATP and is allosterically regulated by ATP, AMP, citrate, and fructose 2,6-bisphosphate.

Question 37Veterinary pathology, specimens and interpretation

Regarding comparative nitrogen metabolism across domestic species, what is the primary end product of protein catabolism in avian species (chickens, ducks) compared to ureotelic domestic mammals (pigs, cattle, dogs)?

  1. Urea (尿素)
  2. Free ammonium ions (游离铵根离子)
  3. Creatinine (肌酐)
  4. Uric acid (尿酸) Correct answer.

Explanation

Avian species and terrestrial reptiles are uricotelic organisms that excrete excess nitrogen primarily as insoluble Uric Acid (尿酸) to conserve water, whereas domestic mammals are ureotelic and synthesize urea in the liver via the ornithine-urea cycle.

Question 38Veterinary pathology, specimens and interpretation

In general veterinary pathology, what type of necrosis is characterized by preservation of the basic structural tissue architecture for several days with loss of cellular nuclei, commonly observed in renal or myocardial infarcts?

  1. Coagulative necrosis (凝固性坏死) Correct answer.
  2. Liquefactive necrosis (液化性坏死)
  3. Caseous necrosis (干酪样坏死)
  4. Enzymatic fat necrosis (酶解性脂肪坏死)

Explanation

Coagulative necrosis (凝固性坏死) occurs when protein denaturation predominates over enzymatic lysis, preserving the ghost outline of cells and structural tissue boundaries for several days, typical of ischemic infarction in solid organs (kidney, heart, spleen).

Question 39Veterinary pathology, specimens and interpretation

In veterinary vascular pathology, which combination of three pathological factors constitutes Virchow's Triad (魏尔啸三联征) predisposed to intravascular thrombus formation (血栓形成)?

  1. Hypoglycemia, hypokalemia, and metabolic acidosis
  2. Endothelial injury, alterations in blood flow (stasis/turbulence), and blood hypercoagulability (内皮损伤、血流异常与血液高凝状态) Correct answer.
  3. Arterial hypertension, tachycardia, and peripheral vasodilation
  4. Leukocytosis, thrombocytosis, and lymphopenia

Explanation

Virchow's Triad consists of: (1) Endothelial injury (exposing subendothelial collagen), (2) Abnormal blood flow (stasis or turbulence), and (3) Hypercoagulability of blood. These three factors interact to initiate pathological intravascular thrombosis.

Question 40Veterinary pathology, specimens and interpretation

In cellular pathology, what reversible degeneration is characterized by the accumulation of neutral fat triglycerides in the cytoplasm of parenchymal cells, presenting grossly as an enlarged, yellowish, greasy liver?

  1. Cellular cloudy swelling (细胞颗粒变性 / 混浊肿胀)
  2. Hyaline degeneration (玻璃样变性)
  3. Amyloidosis (淀粉样变性)
  4. Fatty degeneration / Steatosis (脂肪变性 / 脂肪沉积) Correct answer.

Explanation

Fatty degeneration (steatosis / 脂肪变性) refers to the abnormal accumulation of triglycerides within the cytoplasm of parenchymal cells (especially hepatocytes). The affected organ becomes enlarged, pale yellow, friable, and has a greasy feel on cut section.

Question 41Veterinary pathology, specimens and interpretation

In chronic granulomatous pathology of animals infected with Mycobacterium bovis (bovine tuberculosis), what specialized multinucleated giant cells with nuclei arranged in a horseshoe pattern at the cellular periphery are typically observed?

  1. Foreign body giant cells (异物巨细胞)
  2. Touton giant cells (图顿巨细胞)
  3. Langhans giant cells (朗汉斯巨细胞) Correct answer.
  4. Aschoff giant cells (阿少夫巨细胞)

Explanation

Langhans giant cells (朗汉斯巨细胞) are formed by the fusion of activated epithelioid macrophages in response to chronic persistent antigens like Mycobacterium bovis. They are histologically characterized by multiple nuclei arranged in a peripheral horseshoe or semi-circle arc.

Question 42Veterinary pathology, specimens and interpretation

In veterinary bacteriology, what structural component is found exclusively in the cell wall outer membrane of Gram-negative bacteria (革兰氏阴性菌) and acts as an endotoxin (内毒素) triggering systemic fever, shock, and DIC in septic animals?

  1. Thick peptidoglycan murein layer (厚层肽聚糖)
  2. Teichoic acid (磷壁酸)
  3. Lipopolysaccharide / Lipid A (脂多糖 / 类脂A) Correct answer.
  4. Ergosterol membrane lipid (麦角固醇)

Explanation

Lipopolysaccharide (LPS / 脂多糖), specifically its hydrophobic Lipid A component, is embedded in the outer leaflet of the outer membrane of Gram-negative bacteria (e.g., E. coli, Salmonella). When bacteria lyse, Lipid A is released as endotoxin, activating macrophages via TLR4 to release massive inflammatory cytokines.

Question 43Veterinary pathology, specimens and interpretation

Which of the following major veterinary pathogens is an anaerobic, Gram-positive, spore-forming rod (芽孢杆菌) whose neurotoxin blocks the release of inhibitory neurotransmitters (GABA and glycine) at interneurons, causing spastic paralysis and 'wooden horse' posture (木马样姿势)?

  1. Clostridium botulinum (肉毒梭菌)
  2. Clostridium tetani (破伤风梭菌) Correct answer.
  3. Bacillus anthracis (炭疽杆菌)
  4. Listeria monocytogenes (单核细胞增生李斯特菌)

Explanation

Clostridium tetani (破伤风梭菌) produces the neurotoxin tetanospasmin under anaerobic wound conditions. Tetanospasmin is transported retrogradely to spinal inhibitory interneurons (Renshaw cells), where it cleaves synaptobrevin, preventing the release of GABA and glycine, leading to uncontrolled motor neuron firing and generalized spastic muscle rigidity ('sawhorse' or 'wooden horse' posture).

Question 44Veterinary pathology, specimens and interpretation

In veterinary virology, why are enveloped viruses (包膜病毒, such as African Swine Fever Virus, Canine Distemper Virus, and Avian Influenza Virus) generally more susceptible to environmental lipid solvents, detergents, and ether than non-enveloped naked viruses (e.g., Canine Parvovirus, Foot-and-Mouth Disease Virus)?

  1. Their genetic material consists exclusively of unstable double-stranded DNA
  2. Enveloped viruses lack an inner protein capsid structure entirely
  3. They reproduce solely by binary fission in extracellular spaces
  4. Their viral envelope consists of a host-derived lipid bilayer containing glycoprotein spikes that are easily dissolved and destroyed by detergents and ether (脂质双分子层包膜易被有机溶剂和去污剂溶解破坏) Correct answer.

Explanation

Enveloped viruses acquire a lipid bilayer membrane from host cellular membranes during budding. Organic solvents (ether, chloroform) and lipid-dissolving detergents disrupt this lipid envelope and detach viral attachment glycoproteins, neutralizing viral infectivity. Non-enveloped viruses have a rigid protein capsid that is highly resistant to lipid solvents.

Question 45Veterinary pathology, specimens and interpretation

In the replication cycle of animal viruses, what is the correct chronological sequence of stages from initial cellular encounter to the production of progeny virions?

  1. Attachment (Adsorption) -> Penetration -> Uncoating -> Biosynthesis -> Assembly and Maturation -> Release (吸附 -> 侵入 -> 脱壳 -> 生物合成 -> 组装成熟 -> 释放) Correct answer.
  2. Penetration -> Uncoating -> Attachment -> Biosynthesis -> Release -> Assembly
  3. Uncoating -> Biosynthesis -> Attachment -> Penetration -> Assembly -> Release
  4. Attachment -> Biosynthesis -> Uncoating -> Penetration -> Assembly -> Release

Explanation

The replication cycle of animal viruses follows a strict sequential pathway: (1) Adsorption/Attachment to specific host surface receptors, (2) Penetration (via receptor-mediated endocytosis or membrane fusion), (3) Uncoating of the viral genome, (4) Biosynthesis of viral mRNA, non-structural and structural proteins, and viral genome replication, (5) Assembly and maturation of virions, and (6) Release (via lysis or budding).

Question 46Veterinary pathology, specimens and interpretation

When an animal is vaccinated or naturally exposed to a viral pathogen for the very first time, which antibody isotype appears earliest in the primary humoral immune response (初次体液免疫应答)?

  1. Immunoglobulin G (IgG)
  2. Immunoglobulin M (IgM) Correct answer.
  3. Immunoglobulin A (IgA)
  4. Immunoglobulin E (IgE)

Explanation

In the primary immune response, naive B-lymphocytes differentiate into plasma cells that initially secrete pentameric Immunoglobulin M (IgM). IgM appears within days as the first line of humoral defense, followed later by isotype class switching to IgG, which dominates the secondary memory response.

Question 47Veterinary pathology, specimens and interpretation

Which immunoglobulin isotype exists as a dimer linked by a J-chain and a secretory component, providing the primary immunological defense barrier across respiratory, gastrointestinal, and urogenital mucous membranes in animals?

  1. Immunoglobulin D (IgD)
  2. Immunoglobulin G2a (IgG2a)
  3. Secretory Immunoglobulin A (sIgA / 分泌型IgA) Correct answer.
  4. Immunoglobulin E (IgE)

Explanation

Secretory IgA (sIgA) is produced as a dimer by submucosal plasma cells and acquires a secretory component during epithelial transcytosis. It is resistant to proteolytic enzymes and provides mucosal immune exclusion by neutralizing pathogens and toxins before they penetrate epithelial linings.

Question 48Veterinary pathology, specimens and interpretation

In veterinary clinical immunology, what immune mechanism mediates Type I Immediate Hypersensitivity (I型过敏反应 / 速发型超敏反应), such as acute vaccine-induced anaphylaxis or flea allergic dermatitis?

  1. Antigen cross-linking of specific IgE antibodies bound to Fc-epsilon receptors on mast cells and basophils, causing rapid degranulation and release of histamine and leukotrienes (特异性IgE结合肥大细胞/嗜碱性粒细胞，引起组胺释放) Correct answer.
  2. Complement-dependent IgG/IgM cytotoxic lysis of target erythrocytes (II型)
  3. Deposition of circulating antigen-antibody immune complexes in capillary beds (III型)
  4. Sensitized CD4+ and CD8+ T-cell mediated delayed-type cellular reactions (IV型)

Explanation

Type I Hypersensitivity is mediated by allergen-specific IgE bound to high-affinity Fc-epsilon-RI receptors on mast cells and basophils. Re-exposure to allergen causes receptor cross-linking, triggering explosive degranulation of preformed histamine, heparin, and synthesis of leukotrienes and prostaglandins.

Question 49Veterinary pathology, specimens and interpretation

In veterinary diagnostic serology, what is the fundamental working principle of an Indirect Enzyme-Linked Immunosorbent Assay (Indirect ELISA / 间接ELISA)?

  1. Specific capture antibody is coated to bind serum antigens sandwiched by an enzyme-labeled primary antibody
  2. Red blood cells are mixed with viral hemagglutinin to observe visible cell clumping without enzyme substrates
  3. Bacterial colonies are cultured on blood agar plates to measure hemolytic zones
  4. Known viral/bacterial antigen is coated on the plate, target animal serum antibodies bind to the antigen, and enzyme-labeled anti-species secondary antibody is added to generate a chromogenic signal (已知抗原包被，捕获被检血清特异性抗体，再加酶标二抗显色) Correct answer.

Explanation

In an Indirect ELISA (间接ELISA), purified specific antigen is adsorbed onto microwells. When test serum is added, specific antibodies bind the immobilized antigen. After washing, an enzyme-conjugated secondary antibody (anti-species IgG-HRP) is added, which catalyzes a substrate chromogenic reaction proportional to the antibody titer.

Question 50Veterinary pathology, specimens and interpretation

In the surveillance of Avian Influenza (AI) and Newcastle Disease (ND), how is a 4-fold or greater rise in Hemagglutination Inhibition (HI / 血凝抑制试验) antibody titer between paired acute and convalescent sera interpreted?

  1. Indicates complete failure of the host immune system to recognize the antigen
  2. Confirms recent active infection or successful immunological seroconversion (确诊近期存在活动性感染或有效免疫应答) Correct answer.
  3. Indicates toxic chemical contamination of the serum sample
  4. Proves that the animal is suffering from an acute autoimmune hemolytic crisis

Explanation

A rise between appropriately collected paired samples supports a recent antibody response under the relevant assay interpretation. Vaccination, timing, baseline status and the test method affect what that response means. Seroconversion alone does not prove that an animal currently has active infectious disease or caused a particular outbreak.