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newSchoolWorks.com › VoTechWorks › Health & Personal Services › Veterinary Technology / Vet Assistant › Veterinary Assistant Clinical Rotation (9-Month Track) › Lesson 5
HLT-VET42-08 · Lesson 5 · 24 clock hours · field

Specimen Collection and In-House Laboratory Support

Objective. Students will correctly collect, label, and prepare blood, urine, fecal, and skin cytology specimens under supervision, and operate in-house diagnostic equipment according to manufacturer and clinic protocols.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

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Why Specimen Quality Matters

Every laboratory result a veterinarian uses to diagnose, treat, or monitor a patient depends on one thing first: a properly collected and prepared specimen. A mislabeled tube, a hemolyzed blood sample, or a poorly made smear can delay diagnosis or, worse, lead to the wrong treatment decision. As a veterinary assistant working under technician supervision, you are responsible for the steps that happen before any machine or microscope is involved — and those steps matter enormously for patient safety and diagnostic accuracy.

Blood Specimen Collection and Preparation

Blood is most commonly collected by a licensed veterinary technician or veterinarian; your role in many clinics is to prepare the tubes, restrain the patient safely, and process samples immediately after collection.

Tube selection: Color-coded Vacutainer tubes contain different additives. EDTA (lavender top) is used for complete blood counts (CBC) because it prevents clotting while preserving cell morphology. Red-top or gold-top tubes (serum separator tubes) are used for chemistry panels. Always confirm tube type before drawing — using the wrong tube invalidates the sample.

Blood smear preparation: Place a small drop of fresh EDTA blood near one end of a clean glass slide. Hold a spreader slide at roughly a 30–45-degree angle, back it into the drop until blood spreads along the edge, then push forward in one smooth motion. A good smear has a feathered edge where cells spread into a monolayer. Label the frosted end immediately with patient ID, date, and your initials.

Hemolysis prevention: Mix EDTA tubes gently by inversion — never shake. Process samples promptly; prolonged delay or improper handling causes hemolysis (red cell rupture), which falsely elevates potassium and interferes with many chemistry values.

Urinalysis: Collection, Dipstick, and Sediment

Urine can be collected by free catch, catheterization, or cystocentesis (needle aspiration directly from the bladder — performed only by a licensed technician or veterinarian). Your role includes labeling, dipstick testing, and preparing the sediment.

Dipstick: Dip the strip in fresh urine, tap off excess on the container rim, and read each pad at the manufacturer's specified time. Record results immediately. Urine left sitting causes pH to rise and casts to dissolve, so analysis should happen within 30–60 minutes of collection, or the sample must be refrigerated and warmed before testing.

Specific gravity with a refractometer: Place one drop on the prism, close the cover, and read the scale at the sharp line dividing light from dark. Rinse and dry the prism between samples. Specific gravity reflects urine concentration; it is an important kidney function indicator.

Sediment preparation: Centrifuge a standard volume (typically about 5 mL) at the clinic's specified speed and time. Pour off the supernatant, resuspend the pellet, place a drop on a slide, and apply a coverslip. Examine under low power first to scan, then high power to identify casts, crystals, cells, and organisms. Document findings in the patient record.

Fecal Flotation

Fecal flotation is used to detect intestinal parasite eggs and oocysts. Mix a small, fresh fecal sample with flotation solution (a high-density salt or sugar solution). Parasite eggs, being less dense than the solution, float to the surface. After the prescribed standing or centrifugation time, touch a coverslip to the surface, transfer it to a labeled slide, and examine promptly — some eggs collapse if left too long.

Always wear gloves and wash hands thoroughly; many intestinal parasites (for example, Toxocara roundworms) are zoonotic. Dispose of all waste according to clinic biohazard protocols.

Skin Cytology: Scrape and Tape Prep

Skin scrape: Used to detect mange mites such as Demodex or Sarcoptes. Apply a drop of mineral oil to the lesion, scrape firmly with a scalpel blade held perpendicular to the skin until capillary ooze appears (deep scrapes are needed for Demodex). Spread material onto a labeled glass slide and apply a coverslip. Note the site and technique in the patient record so the veterinarian can interpret findings in context.

Tape prep: Press a length of clear acetate tape firmly against the skin lesion, then press the tape sticky-side-down onto a drop of stain (commonly Diff-Quik) on a slide. This technique helps identify surface bacteria, yeast (Malassezia), or superficial parasites. Document the lesion site and your collection technique.

Operating In-House Analyzers and the Centrifuge

Before operating any analyzer, review the manufacturer's standard operating procedure (SOP) posted at the machine. Run quality control (QC) samples as scheduled — typically daily or each time a new reagent lot is opened — and record results in the equipment log with date, your initials, control level, and whether results fell within the acceptable range. Never report patient results if QC is out of range; notify the supervising technician.

For the centrifuge: balance tubes by placing equal-weight tubes opposite each other in the rotor. Never run an unbalanced centrifuge — imbalance damages the machine and can be a safety hazard.

Labeling and Documentation

Every specimen label must include at minimum: patient name and/or ID number, species, owner name, date and time of collection, test requested, and collector initials. Unlabeled or incompletely labeled specimens must not be processed — return them to the supervising technician. Document all procedures in the patient record as directed by clinic protocol.

Key terms9

EDTAEthylenediaminetetraacetic acid; the anticoagulant additive in lavender-top Vacutainer tubes that prevents clotting by binding calcium, preserving blood cell morphology for CBC analysis.
HemolysisThe rupture or destruction of red blood cells, which releases intracellular contents into the plasma and can falsely alter many chemistry values; caused by rough handling, improper tube use, or delayed processing.
Specific gravityA measure of urine concentration compared with pure water, assessed with a refractometer; reflects the kidneys' ability to concentrate or dilute urine.
Fecal flotationA diagnostic technique that mixes feces with a high-density solution so that parasite eggs and oocysts, being less dense, float to the surface for microscopic collection and examination.
Urine sedimentThe cellular and particulate material collected at the bottom of a centrifuged urine sample, examined microscopically for casts, crystals, red blood cells, white blood cells, and microorganisms.
Skin scrapeA collection technique in which mineral oil and a scalpel blade are used to scrape skin firmly enough to detect subsurface parasites such as Demodex mites; material is transferred to a slide for microscopic examination.
Tape prep (cytology)A technique using clear acetate tape pressed onto a skin lesion to collect surface material such as yeast, bacteria, or superficial parasites, then transferred to a stained slide for examination.
Quality control (QC)The process of running samples with known values through a diagnostic analyzer on a scheduled basis to verify that the instrument is performing within acceptable accuracy limits before patient samples are run.
Feathered edgeThe thin, gradually tapering end of a properly prepared blood smear where red blood cells are spread into a single layer, allowing optimal microscopic examination of cell morphology.

Worked examples4

1. You need to centrifuge a urine sample at 400 × g for 5 minutes to prepare sediment, but the centrifuge display only shows RPM. The rotor radius is 10 cm (0.10 m). What RPM setting should you use?
  1. Recall the relationship: RCF (× g) = 1.118 × 10⁻⁵ × r × N², where RCF is relative centrifugal force, r is radius in centimeters, and N is speed in RPM.
  2. Rearrange to solve for N²: N² = RCF ÷ (1.118 × 10⁻⁵ × r).
  3. Substitute values: N² = 400 ÷ (1.118 × 10⁻⁵ × 10) = 400 ÷ 0.0001118 = 3,578,532.
  4. Take the square root: N = √3,578,532 ≈ 1892 RPM.
  5. Round to the nearest practical setting; set the centrifuge to approximately 1900 RPM for 5 minutes.
Answer: Approximately 1900 RPM at a 10 cm rotor radius produces roughly 400 × g, the target RCF for urine sediment preparation.
2. A urine refractometer reading shows a specific gravity of 1.018 for a canine patient. The scale has marks every 0.002 units. The sharp line falls exactly halfway between 1.016 and 1.018. What value should you record?
  1. Identify the two nearest marks: 1.016 and 1.018.
  2. The interval between them is 1.018 − 1.016 = 0.002.
  3. The line falls exactly halfway, so add half the interval to the lower mark: 1.016 + 0.001 = 1.017.
  4. Record the value as 1.017.
Answer: Record the specific gravity as 1.017, interpolating halfway between the two scale marks.
3. You are preparing five fecal flotation slides and five urine sediment slides for the same morning appointment block — ten specimens in total. Each specimen label requires: patient name, species, owner last name, date, test name, and collector initials. How many individual data fields must be correctly completed across all ten labels?
  1. Count required fields per label: patient name, species, owner last name, date, test name, collector initials = 6 fields.
  2. Multiply by the number of specimens: 6 fields × 10 specimens = 60 total fields.
  3. Confirm: each of the 10 labels must have all 6 fields completed = 60 fields.
Answer: 60 individual data fields must be correctly completed across all ten specimen labels.
4. A daily QC run on the in-house chemistry analyzer gives a glucose control result of 112 mg/dL. The control package insert states the acceptable range is 95–115 mg/dL. Is the QC result acceptable, and can you proceed to run patient samples?
  1. Identify the acceptable range: 95 mg/dL (low) to 115 mg/dL (high).
  2. Compare the result: 112 mg/dL.
  3. Determine whether 112 falls within 95–115: 95 ≤ 112 ≤ 115 — yes, it does.
  4. Conclusion: QC is within range; document the result, date, control level, and your initials in the equipment log, then proceed to patient samples.
Answer: 112 mg/dL is within the acceptable range of 95–115 mg/dL; QC passes, and patient samples may be run. Always document the result in the equipment log before proceeding.

The math in this lesson2

Learners rearrange RCF = 1.118 x 10^-5 x r x N^2 to find about 1,892 RPM for 400 x g.
N-RN.2A-CED.4
Brush up in the math halls at newSchoolWorks.com:
In class: Under technician supervision, prepare fecal flotation, urinalysis (including sediment prep), and blood smears for at least 10 patient samples; label each specimen with patient ID, date, test requested, and collector initials. · Operate the clinic's in-house hematology analyzer or centrifuge following standard operating procedures; document machine QC results in the equipment log. · Practice skin scrape and tape prep cytology collection technique on clinic patients with dermatologic complaints; prepare slides for veterinarian evaluation and document technique used in patient record.
Materials: Vacutainer tubes, syringes, centrifuge, refractometer, urine dipstick strips, fecal flotation solution and equipment, glass slides, coverslips, immersion oil, in-house hematology/chemistry analyzer, specimen labels, laboratory log sheets
Check: Supervising technician reviews 10 labeled specimens for accuracy and preparation quality; all labels must be complete and correctly matched to the patient record, and procedural technique must be rated 'acceptable' on the clinic's lab competency rubric.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Laboratory Procedures
1. A blood sample collected in an EDTA tube is shaken vigorously during transport to the in-house analyzer. Which consequence is most likely?
Laboratory Procedures
2. Which Vacutainer tube is the correct choice for collecting a sample intended for a complete blood count (CBC)?
Laboratory Procedures
3. When preparing a urine sediment slide, you centrifuge the sample, pour off the supernatant, and resuspend the pellet. What is the NEXT step?
Laboratory Procedures / Dermatology
4. A veterinary assistant is performing a deep skin scrape for suspected Demodex mange. Which statement best describes correct technique?
Laboratory Quality Assurance
5. You run the daily quality control sample on the hematology analyzer and the result falls outside the acceptable range. What is the correct action?
Laboratory Procedures / Urinalysis
6. Which of the following is the most important reason to perform urinalysis within 30–60 minutes of collection if the sample is not refrigerated?
Professional Practice / Laboratory Procedures
7. A specimen label is missing the collector's initials but has all other required fields. According to standard laboratory practice, what should happen to this specimen?
Laboratory Procedures / Parasitology
8. During fecal flotation preparation, you notice the flotation solution has been sitting unused and a crust has formed on the surface. Which risk does this most directly create?
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