Pharmacology Quiz 28 Quiz InstructionsThis quiz consists of 20 multiple-choice questions.You will be awarded 5 marks for each correct answer. Question 1: In chronic cadmium exposure in mammals, which of the following is considered the primary critical target organ where the metal accumulates and eventually precipitates pathological changes?LiverKidneySpleenBrain Question 2: What is the specific organic chemical form of selenium found in the accumulator plant Morinda reticulata, which is responsible for equine selenosis?SelenomethionineSodium seleniteSelenocystathionineDimethyl selenide Question 3: Based on studies of chloramphenicol-propylene glycol toxicity in horses, why is it recommended to include a separate vehicle control group in pharmacological trials utilizing propylene glycol?To increase the solubility and bioavailability of chloramphenicolTo differentiate the intrinsic toxic effects of the solvent itself from those of the active drugTo stimulate the host's primary immune response prior to drug administrationTo prevent the degradation of blood proteins during long-term storage Question 4: What is the primary neurological mechanism responsible for the classic clinical manifestation of laryngeal hemiplegia and pharyngeal dysfunction in chronic equine lead toxicosis?Microvascular thrombosis of the pulmonary capillariesSegmental demyelination of the recurrent laryngeal and other regional motor nervesBilateral necrosis of the brainstem motor nucleiDiphtheritic inflammation of the laryngeal mucosa Question 5: In the clinical diagnosis of equine lead poisoning, what is the specific clinical advantage of determining the erythrocyte zinc protoporphyrin level?It is directly proportional to acute copper levels in the liverIt indicates the degree of previous lead exposure and is independent of the immediate blood lead levelIt helps clinicians differentiate between lead and selenium toxicosisIt measures the rate of biliary excretion of heavy metals in the horse Question 6: In horses subjected to intensive tick control programs consisting of multiple inorganic arsenical treatments, a specific encephalopathy has been described. What clinical signs are associated with this chronic syndrome reported by Seddon?Laryngeal hemiplegia, pharyngeal paralysis, and aspiration pneumoniaCircling movements, depression, hyperexcitability, and maniaEpiphyseal enlargement, sterile joint effusion, and lamenessProfuse hematuria, anuria, and uremic breath Question 7: Which diagnostic procedure is utilized to confirm lead poisoning in horses by comparing urinary lead concentrations before and after administering a specific chelating agent?Intravenous injection of 7.5 mg/kg of Ca EDTAIntravenous injection of 75 mg/kg of Ca EDTAOral administration of 45 g of Ca EDTASubcutaneous injection of 150 mg/kg of Ca EDTA Question 8: What is the recommended preventative concentration of sodium arsenite to be added to drinking water for horses in areas endemic for selenium toxicosis?0.5 parts/10^65 parts/10^650 parts/10^6500 parts/10^6 Question 9: Chronic zinc toxicity in newly weaned foals results in a juvenile osteodystrophy characterized by swollen joints, sterile joint fluid, and which specific degenerative cartilage lesion?Epiphyseal osteoporosisOsteochondritis dissecansFibrous osteodystrophyAnkylosing spondylitis Question 10: Which of the following is considered a classical clinical sign of acute fatal selenium poisoning (selenosis) in horses, occurring just prior to death?Symmetrical exudative dermatitis of the flankHead pressingBilateral laryngeal hemiplegiaSevere chemical stomatitis with loosening of teeth Question 11: Match the heavy metal or compound (Column I) with the hallmark clinicopathological presentation in horses (Column II):I. Phenylmercuric acetateII. Methylmercury chlorideIII. Zinc oxideIV. Lead acetate (in young foals)Column II:1. Symmetrical exudative dermatitis and proprioceptive neurological dysfunction2. Severe progressive chemical stomatitis with mandibular periostitis3. Juvenile osteodystrophy with osteochondritis dissecans4. Laryngeal hemiplegia due to recurrent laryngeal nerve demyelinationWhich of the following represents the correct matching?I-2, II-1, III-3, IV-4I-1, II-2, III-4, IV-3I-2, II-1, III-4, IV-3I-4, II-3, III-2, IV-1 Question 12: Match the diagnostic tissue concentrations or criteria (Column I) with the corresponding heavy metal intoxication in horses (Column II):I. Hair concentration exceeding 5 parts/10^6II. Whole blood levels exceeding 6 parts/10^6 associated with joint lamenessIII. Renal cortical level exceeding 200 parts/10^6 linked to critical dysfunction in mammalsIV. Blood levels exceeding 0.35 parts/10^6 regarded as diagnosticColumn II:1. Zinc2. Lead3. Cadmium4. SeleniumWhich of the following options represents the correct match?I-4, II-1, III-3, IV-2I-2, II-3, III-1, IV-4I-4, II-2, III-3, IV-1I-1, II-4, III-2, IV-3 Question 13: Match the acute single oral toxic doses or ranges in horses (Column I) with the corresponding heavy metal or salt (Column II):I. 125 mg/kgII. 3.3 to 6 mg/kgIII. 1 to 3 gIV. 10 to 20 mg/kgColumn II:1. Sodium selenite2. Copper sulphate3. Mercuric chloride4. Sodium arseniteWhich of the following represents the correct matching?I-2, II-1, III-4, IV-3I-1, II-2, III-3, IV-4I-2, II-4, III-1, IV-3I-3, II-1, III-4, IV-2 Question 14: Match the historical veterinary study or finding (Column I) with the primary author(s) listed in the text's references (Column II):I. Suppressed anamnestic response to tetanus toxoid by chloramphenicol in humansII. Propylene glycol intoxication in horsesIII. Suppression of antibody synthesis by chloramphenicol in experimental modelsIV. Diagnostic use of serum protein electrophoresis in the horseColumn II:1. Myer and Usenik2. Daniel et al.3. Coffman4. Weisberger et al.Which of the following represents the correct matched pairs?I-2, II-1, III-4, IV-3I-1, II-2, III-3, IV-4I-2, II-3, III-1, IV-4I-4, II-1, III-2, IV-3 Question 15: Consider the following statements regarding the immunological effects of chloramphenicol therapy in Streptococcus zooepidemicus-challenged horses:I. An increase in the gamma-globulin fraction is a normal component of the immune response in challenged horses.II. Maintenance of a constant serum chloramphenicol level at 4 times the MIC (approximately 6 micrograms/ml) results in a failure of the gamma-globulin fraction to rise.III. Constant therapeutic levels of chloramphenicol are hypothesized to interfere with mammalian host cells or eliminate the antigenic stimulus.IV. Propylene glycol, when used as a chloramphenicol solvent, has no clinical or physiological effects of its own and does not require a control group.Which of the statements are correct?I, II, and III onlyI and IV onlyII and IV onlyI, II, III, and IV Question 16: In foals, when toxic levels of both lead and zinc are ingested concurrently, several interactions alter the clinical and pathological progression of the disease. Evaluate the following statements:I. Co-ingestion leads to the complete absence of typical lead poisoning signs, with typical zinc poisoning signs dominating.II. Zinc administration increases the accumulation of lead in the liver and kidney.III. Zinc administration decreases the deposition of lead in the bones and its uptake by the brain.IV. Co-ingested zinc results in higher whole blood lead concentrations compared to administering lead alone.Which of the statements are correct?I, II, and III onlyI, II, and IV onlyII and IV onlyI, III, and IV only Question 17: Consider the following statements regarding chronic selenium poisoning (alkali disease) in horses:I. It occurs far more readily when horses ingest organic selenium from plant sources.II. It can develop on seleniferous soils even when the selenium feed level is in excess of 5 parts/10^6.III. Classic signs include softening, scaling, and transverse cracking of the hoof wall distal to the coronary band.IV. Loss of hair from the mane and tail is a characteristic clinical feature.Which of the statements are correct?I, II, III, and IVI, II, and III onlyIII and IV onlyI and II only Question 18: Assertion: Grazing horses near smelters may ingest significantly higher amounts of lead than estimated from forage contamination measurements alone.Reason: Horses frequently pull out forage by the roots and consume the roots along with the attached soil, which contains up to 16 times higher concentrations of lead than the herbage.Both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion.Both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.The Assertion is true, but the Reason is false.The Assertion is false, but the Reason is true. Question 19: Assertion: In horses, lifetime consumption of soft drinking water is associated with enhanced cadmium uptake and accumulation in the kidneys.Reason: Cadmium is an essential trace element that actively stimulates myocardial fibrosis and arteriosclerosis under soft water conditions.The Assertion is true, but the Reason is false.Both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion.Both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.The Assertion is false, but the Reason is true. Question 20: Based on the comparative pharmacokinetics of mercury compounds in horses, trace the physiological sequence of events following the oral administration of phenylmercuric acetate (an aryl-mercurial) versus methylmercury chloride (a short-chain alkyl-mercurial). Which metabolic and distribution sequence explains why phenylmercuric acetate causes primarily localized stomatitis, while methylmercury causes severe central proprioceptive ataxia?Phenylmercury undergoes rapid C-Hg bond cleavage leading to high systemic inorganic mercury excretion and high kidney accumulation of inorganic Hg with virtually no organic brain deposition, whereas methylmercury maintains a stable C-Hg bond, persists as organic mercury, and crosses the blood-brain barrier.Phenylmercury remains highly stable as an organic compound in the circulation and selectively deposits in buccal mucosa, whereas methylmercury is instantly cleaved to inorganic mercury in the liver.Both compounds are completely excreted within 24 hours of administration, but phenylmercury is locally corrosive to the teeth while methylmercury undergoes renal activation.Phenylmercury undergoes hepatic conjugation to bypass renal excretion, whereas methylmercury is poorly absorbed and exerts its neurotoxic effects through systemic hypoxia.
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