Diagnostics Flashcards by Jacy Lauzon

Why does the plasma protein concentration affect the total serum calcium concentration?

Serum calcium is bound to albumin, such that changes in serum total protein concentration can cause equivalent changes in serum total calcium (but not serum ionized calcium) concentration.

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The ELISA heartworm test detects antigen from:

A) Microflora
B) Adult female worms
C) Adult male worms

B) Adult female worms

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In dogs, the ultrasonographic appearance of a gallbladder mucocele resembles which cut fruit?

The kiwi fruit

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What is the diagnostic test of choice for evaluating the magnitude of proteinuria in a dog or cat?

Urine protein to urine creatinine ratio (UP:UC or UPC ratio)

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When measuring the following parameters in the same patient, which can be expected to be significantly different (e.g. more than 25%) in venous blood samples compared to arterial samples? PCO2, PO2, HCO3-, pH

Only PO2 is appreciably different - typically 50% lower in venous samples compared to arterial

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Your heparinized blood gas sample shows marked hypernatremia that is inconsistent with the clinical picture. Which error likely occurred when obtaining the sample?

blood was drawn into sodium heparin rather than lithium heparin.

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Grossly, hemorrhagic pericardial effusion can most reliably be differentiated from peripheral blood in which way?

It rarely clots (exceptions: cardiac rupture or severely hemorrhaging neoplasm)

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Should brain tissue submitted for rabies testing be refrigerated or frozen?

Refrigerated

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Heat precipitation or electrophoresis of urine is used for detecting which characteristic substance in cases of multiple myeloma?

Bence Jones proteins

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What are the hallmark clinical pathologic findings of hemorrhagic gastroenteritis in dogs?

Increased hematocrit (50-80%) with normal to low total protein.

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What is the diagnostic test of choice for salmonellosis (‘‘parathyroid’’) in chickens?

Direct bacterial culture, to allow identification of the Salmonella species

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When drawing blood from a ferret for hematologic and biochemical panels, which two venipuncture sites are commonly used that provide the appropriate sample volume (about 1.5mL)?

The jugular vein and the cranial vena cava

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How would you confirm a tentative diagnosis of myasthenia gravis?

Identify the presence of serum acetylcholine receptor antibodies; edrophonium (Tensilon) testing is considered obsolete.

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What is the anticoagulant of choice in test tubes used for coagulation testing and blood typing?

Citrate (Blue top tube)

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How can you explain that an animal with ketonuria has a negative ketones result on urine dipstick?

High level of beta-hydroxybutyrate. Urine dipstick ketone squares react to acetoacetate, but not beta-hydroxybutyrate.

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Why is the blood glucose reading falsely low if left at room temperature for longer than 60 minutes?

Because of red blood cell glycolysis

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In dogs, approximately which proportion of nephrons must be nonfunctional before abnormal concentrating ability of the kidneys is evident?

2/3 need to be non-functional (versus 3/4 for azotemia)

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Which common characteristic of large animal urine can cause a false positive result for urinary protein?

Strongly alkaline urine

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What is the organism most commonly isolated from cat bite abcesses?

Pasteurella multocida is the bacterium most often cultured from abscesses of cats caused by the bite of other cats.

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If you make a radiographic diagnosis of hypertrophic osteopathy of a patient’s radius, what is your next diagnostic step?

Thoracic and abdominal radiographs, looking for a mass.

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Knowing a patient’s serum electrolyte levels, how can you calculate the anion gap?

Anion gap = (Na+ + K+) - (Cl- + HCO3-)

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How can you explain that hyperlactatemic calves have a normal blood lactate measurement?

They predominantly have high circulating d-lactate levels, whereas analyzers measure l-lactate.

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If your patient’s pH is high and the pCO2 is decreased, which type of acid-base disturbance does the patient have?

Respiratory alkalosis

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What is the diagnostic blood test of choice, and the expected abnormality, in a case of organophosphate intoxication?

Serum acetylcholinesterase levels
Low levels (Less than 50% normal) are consistent with intoxication.

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Name the most common laboratory test abnormalities identified in acute canine Anaplasma phagocytophilum infection.

Thrombocytopenia, lymphopenia, elevated serum alkaline phosphatase and/or amylase activities.

In the pregnant female dog, mineralized fetal skeletons can be detected radiographically as early as how many days after the luteinizing hormone (LH) peak?

45 days

What is the Morgan line?

It is a radiographic finding that represents the formation of enthesiophytes on the caudal aspect of the femoral neck, medial to the trochanteric fossa. It occurs as a result of early degenerative joint disease of the coxofemoral joint.

What does serum protein electrophoresis do?

It quantifies the individual protein fractions that make up the total protein content of serum.

Gamma glutamyl transferase (GGT) is the liver enzyme most sensitive to cholestasis for all feline liver diseases except one. Which disease, and which enzyme is superior for it?

Hepatic lipidosis; alkaline phosphatase.

Which specific test is used for asserting the function of the intrinsic coagulation pathway?

Activated partial thromboplastin time

What are the 4 ECG characteristics of atrial fibrilation?

1) No P waves 2) Undulating baseline 3) Normal QRS complexes 4) Irregularly irregular rhythm

Mycobacteria all have which specific microscopic staining characteristic in common?

They are acid-fast staining

After what approximate period of time from the onset of anemia would you expect a maximum erythropoietic response from the marrow?

7 days

What is the fecal flotation medium of choice for demonstrating Giardia cysts?

Zinc sulfate

The prothrombin time evaluates which pathways of secondary hemostasis?

Extrinsic and common pathways

When testing serum bile acids in horses, only 1 sample is taken as compared to dogs and cats in which 2 samples are taken. Why only 1 in horses?

Because horses lack a gallbladder, there is no advantage in measuring a postprandial sample.

What is the mechanism of hypercalcemia leading to low urine specific gravity?

Hypercalcemia interferes with the action of antidiuretic hormone and renal concentrating ability.

What is the anticlinal space and where is it found in the cat and dog?

It is the narrowest thoracic intervertebral disk space. It is found between the 10th and 11th thoracic vertebrae (the 11th thoracic vertebra is the anticlinal vertebra).

Blood zinc levels must be measured on blood drawn specifically into special tubes. Why?

Other tubes have rubber tops that contain zinc, causing falsely elevated results.

Which diagnostic test might produce abnormal test results consisting of positive sharp waves and fibrillation potentials?

Electromyography (EMG), a test used for assessing patients with suspected myopathic or denervation disorders.

What are the 2 characteristics of an alveolar pattern on thoracic radiographs?

1) Air bronchograms 2) Silhouetting (loss of distinction between lung and surrounding soft tissue)

Urine cortisol: Creatinine is infrequently used for diagnosis of hyperadrenocorticism in dogs. What is its main flaw?

Poor specificity (many nonadrenal disorders cause a (false) positive result).

Which in vitro phenomenon may cause false elevation of serum or plasma concentration?

Platelet activation during in vitro clotting, or failure to separate serum or plasma from red blood cells within an hour of collection. Hemolysis rarely causes artificial hyperkalemia (common mistake), except in individuals with unusually high intraerythrocytic potassium concentrations (e.g. Akita, Shiba Inu, Tosa Inu breed dogs).

Which serum electrolyte abnormality is suggested by absence of a P wave on an electrocardiogram?

Hyperkalemia

There are 3 modes of echo display in diagnostic ultrasound. A standard abdominal ultrasound would be done in: A) A-mode B) B-Mode C) M-Mode

B) B-Mode

Synchronous diaphragmatic flutter in horses is suggestive of which serum biochemical abnormality?

Hypocalcemia

What is the diagnostic purpose of placing a rebreather bag over the mouth and nose of a horse?

Movement of extracellular potassium to the intracellular space (response to acute alkalosis, or administration of insulin or glucose)

Which two hematologic findings on smears of peripheral blood suggest immune-mediated red blood cell damage?

Spherocytosis and agglutinated red blood cells

What is the clinical significance of a fractured hair shaft on microscopic examination of a hair specimen?

It indicates external trauma (e.g. excessive licking or scratching), which narrows the differential diagnosis by ruling down endocrine and other atraumatic causes of alopecia.

When collecting a blood sample for a complete blood count, an adequate sample volume must be drawn into the anticoagulant tube. Otherwise, which false result can be expected?

Decreased hematocrit because of excess volume of EDTA solution related to sample volume.

What are the characteristics of anemia typically seen in ''anemia of chronic disease''?

Normocytic normochromic non-regenerative anemia

Does acute respiratory distress syndrome increase, decrease or not affect PaO2:FIO2?

Decreases it (can be less than 200)

With ultrasonography, portal veins are distinguished from hepatic veins by which feature?

Presence of hyperechoic walls (portal veins)

Which substance is typically present in abnormally high concentrations in chylous effusions?

Triglyceride

What are 2 options for assessing the cardiac rhythm of a patient with arrhythmias that occur only sporadically?

1) Holter monitor (portable continuous ECG recorder - Lasts 24h) 2) Event monitor (portable ECG monitor that the owner triggers when an episode occurs, to record the ECG instantly - lasts 7 days or more) 3) In-hospital monitoring with ECG (télémétrie)

A cat's liver biopsy specimen is pale and it floats in the formalin solution of the biopsy jar. What is the most likely diagnosis?

Hepatic lipidosis

What is the mechanism by which von Willebrand factor enables blood clotting?

von Willebrand factor is an adhesive protein that is required for platelet-collagen binding

Legg-Calvé-Perthes disease is also known as:

Aseptic necrosis of the femoral head

What is the hallmark radiographic sign of diskospondylitis?

Vertebral end plate lysis

The combination of proteinuria, hypoalbuminemia, hypercholesterolemia, and peripheral pitting edema is pathognomonic for:

Nephrotic syndrome

In dogs, codocytes, or target cells, have been specifically linked with the hypercholesterolemia of which endocrine disorder?

Hypothyroidism

Which biochemical test is used for assessing the average serum glucose concentration over the preceding 2 to 3 weeks?

Fructosamine

Calcium oxalate monohydrate crystals and calcium oxalate dihydrate crystals in dogs: which one is more suggestive of ethylene glycol toxicosis?

Monohydrate (''picket fence'' shape): ethylene glycol Dihydrate (''envelope'', ''Maltese cross'' shape): Nutritional or artifact of refrigeration or less commonly ethylene glycol

A patient's azotemia responds rapidly and completely to fluid replacement therapy alone. Is the azotemia more likely renal or prerenal origin?

Prerenal

A patient has ascites, and fluid analysis reveals that it is a pure transudate. What is the differential diagnosis?

Severe hypoalbuminemia is the most common cause; others include prehepatic portal hypertension and cyst rupture. Most other cases of transudative ascites produce a modified transudate.

If youe are looking for Demodex canis mites in a dog, do you want to do a superficial or deep skin scraping?

Deep. Demodex mites live deep in the hair follicles.

If you are looking for Sarcoptes mites, do you perform a deep or a superficial skin scraping?

Superficial

Wood's lamp examination is fast and inexpensive when searching for dermatophytosis; however, its major disadvantage is?

Poor sensitivity. For example, only 50% of the most common dermatophyte in dogs and cats, M. canis, fluoresces.

If the patient's blood pH is low and the blood HCO3- is decreased, which type of acid-base disturbance is present?

Metabolic acidosis

What is the optimal serum concentration of IgG in a 24h-old foal?

More or equal to 800 mg/dL

What is the characteristic brain histologic finding of rabies?

Negri bodies in neurons

A patient has an intraocular pressure of 7 mmHg. What is the most likely diagnosis: Normal, Uveitis or Glaucoma?

Uveitis (Less than 10mmHg) (Normal: 10-30 mmHg; Glaucoma: more than 30 mmHg)

What causes the ''tracheal stripe sign'' on thoracic radiographs and which disorder does it suggest?

Gas in the esophagus; megaesophagus, or just aerophagia.

Why is it advantageous that the body removes iron from the circulation during anemia of inflammatory disease?

Potential bacterial pathogens require iron for rapid growth and multiplication

How can autoregulation be differentiated from rouleaux formation?

Through examination of a saline-diluted wet preparation of fresh blood; if clumping is still present, autoagglutination is confirmed.

On a fresh blood smear, what are the morphologic features of toxic changes in neutrophils?

1) Diffusely basophilic cytoplasm 2) Foamy vacuolation of cytoplasm 2) Döhle bodies 4) Abnormal nuclear shapes

A suckling neonatal animal has a urine specific gravity of 1.009. Is this indicative of renal dysfunction?

No, suckling neonatal animals normally produce a very dilute urine with a specific gravity less than 1.010.

Small numbers od Howell-Jolly bodies are a normal finding in which large animal species?

Equine

Why do immature neutrophils (''bands'') appear quickly in the blood during acute inflammation in cattle?

Cattle have a small bone marrow reserve of mature neutrophils.

Name 2 disorders which can cause a normal anion gap metabolic acidosis in dogs.

Diarrhea, renal tubular acidosis, dilutional acidosis (rapid saline administration), hypoadrenocorticism

What is the diagnostic test of choice for leptospirosis in dogs?

Microscopic agglutination test (MAT)

Name 2 causes of increased anion gap metabolic acidosis.

Ethylene glycol toxicity, diabetic ketoacidosis, uremic acidosis, lactic acidosis (e.g. due to cardiovascular collapse during shock)

What are the reservoir animal species for Francisella tularensis subspecies tularensis?

Lagomorphs (rabbits and hares)

What is a species-specific characteristic of the differential count on the leukogram of cattle and sheep?

The number of lymphocytes exceeds the number of neutrophils in healthy animals

Urine specific gravity in which range is said to be isosthenuric?

1.008-1.012. The kidney is neither concentrating, nor diluting the urine. With severe dehydration, specific gravity up to 1.020 is still consistent with isosthenuria, since plasma osmolality may be markedly increased.

Glomerulonephritis can cause severe proteinuria leading to a hypercoagulable state due to the loss of which protein?

Antithrombin III

The presence of a positive antinuclear antibody (ANA) test, pathologic proteinuria, and polyarthritis should lead to the suspicion of this disease.

Systemic lupus erythematosus

What are Howell-Jolly bodies?

Nuclear remnants that were not extruded from the red blood cell during maturation. Occasionally an insignificant finding in the RBCs of healthy dogs and cats - higher numbers may be seen in animals with regenerative anemia, decreased splenic function, or in association with abnormal erythropoiesis.

In Horner's syndrome, how can a lesion be localized pharmacologically to determine if it is preganglionic or postganglionic (of the lower motor neuron portion of the pathway)?

Application of dilute direct acting sympathomimetic to both eyes reveals minimal pupillary dilation if the lesion is preganglionic, and rapid, marked dilation if the lesion is postganglionic.

Creatinine Kinase (CK) and aspartate aminotransferase (AST) are associated with muscle damage in large animals. Which enzyme has the shorter half-life?

CK (2h in horses, 4h in cattle)

Acantholysis is noted on a skin biopsy. What is the most common cause of this finding?

Autoimmune disease (e.g. pemphigus)

What is the diagnostic test of choice for exocrine pancreatic insufficiency in cats and dogs?

Serum trypsin-like immunoreactivity (cTLI, fTLI)

Sequential radiographs allow evaluation of fracture healing in small animals - especially in cases requiring surgical stabilization. Generally, how often should such follow up radiographs be taken?

Every 4-6 weeks, until healing is complete

Would a lower frequency (e.g. 3 MHz) ultrasound transducer give you more or less penetration for viewing deep abdominal structures?

More - higher frequencies are attenuated more than lower frequencies; therefore, increasing the frequency decreases penetration.

With a higher ultrasound transducer frequency, does the image resolution increase or decrease? Why?

It increases. High frequency sound waves penetrate poorly because they are attenuated by tissue.

What is the most common cell population in healthy bronchoalveolar lavage fluid?

Macrophage (70-80% of cells)