Diagnostics Flashcards
Two goals of testing?
- confirm exposure to toxic dose
- Monitoring clinical signs resulting from poisoning
Decision whether to do diagnostic testing
-Money
-not all poisons have specific tests
-not all labs run all tests
-“fishing expeditions” are rarely fruitful
-rule ins and rule outs
Sample selection options for live animals
-can also sample food/water, suspected sources, soil, plants
Sample selection for deceased animals
-can also sample food/water, suspected sources, soil, plants
Most commonly submitted samples
-serum
-liver
-stomach contents
-feed
-urine
Less commonly submitted samples (but very important)
-whole blood= lead poisoning
-brain= neuro issues
-ocular fluid= neuro issues
Errors with sample collection
-wrong sample
-liver- insufficient amount
-blood/serum/plasma- insufficient volume, hemolysis
Errors from sample transportation
-poor packaging
-weather
Issues with Hemolysis
-compromises interpretation of iron, zinc, magnesium, and chemistry panel
Causes of hemolysis
-delayed separation of serum from clot
-freezing whole blood
-inadequate centrifugation
-wrong needle/syringe
-inadequate volume collection
-vigorous mixing
What is an exception for having/using hemolysis?
Hemolysis that occurs from poisoning
Order of tube collection
What can be done in clinic to check for toxicity?
- Emergency panel
- CBC, Chemistry, Urinalysis
- Blood gas analysis
- imaging
- Coagulation panel
What is an emergency panel bloodwork?
- Blood glucose
- Total protein
- BUN
- PCV
Why check blood glucose?
Some toxins cause hypoglycemia
Why check BUN?
Kidney problems
Why check PCV?
-can see plasma colour and look for anemia
In clinic initial tests
-CBC
-Chemistry
-Urinalysis
**in house testing to help narrow DDx list
*send out tests to have expert interpretation
What are the key things that CBC, chemistry and urinalysis can tell you about patient?
-anemia
-organ damage
-treatment efficiency
Why urinalysis?
Suspect renal damage
-Pigment indicates myoglobin vs hemoglobin vs RBCs
-Check for proteins, glucose, cells, certain types of crystals
Blood gas analysis
Venous vs. arterial
-Check for ionized and total calcium (hyper or hypocalcemia)
-Check for electrolytes (Na, K, Mg), glucose, lactate, acid-base status (pH, pCO2, HCO3, base excess)
Imaging possibilities
T-FAST
A-FAST
Radiographs
Abdominal ultrasound
T-FAST scan
Air, fluid
-B-lines: wet lung problems; pulmonary edema, bleeding
A-FAST scans
-checking for free abdominal fluid or hemorrhage
Coagulation panel
Determine:
- Prothrombin time (PT): extrinsic and common pathway
- Partial thromboplastin time (PTT): intrinsic and common pathway
Specific considerations for coagulation panel
-fill up to the line
-need clean venipuncture
Detecting metals and minerals at Vet Diagnostic labs
Use inductively coupled plasma mess spectrometry (ICP-MS)
-generally use plasma/serum and liver
-Lead poisoning detected in RBCs (whole blood)
What is needed of plasma and liver for metal and mineral detection?
Plasma: 2ml
Liver: 2-5g fresh or frozen- ship on ice packs
Liver biopsies: at least 0.2g
Detection of lead
90% of lead bound to RBCs
-use heparinized whole blood (green top)
-ship on ice packs
-tissues (liver, kidney)
Testing of pesticides in diagnostic labs
High performance liquid chromatography, liquid chromatorgraphy mass spectrometry, gas chromatography mass spectrometry
What samples do you submit for pesticides?
-any suspect bait materials
-stomach contents (strychine, OP/carbamates, metaldehyde, sodium fluoroacetate, zinc phosphide)
-whole blood (organophosphates/carbamate poisons)
-brain (organophosphates/carbamate poisons)
Water analysis
Test for algal toxins (20ml of stored water at -4 C , metals and trace minerals, nitrate, drug/pesticide residues, farm water testing for free
Feed analysis in diagnostic labs
Methods: LC.MS, ICP-MS, colorimetric methods
-detect metals, trace minerals, nitrates, cyanides, mycotoxins (0.2-2 kg of feed in resealable bag), drug/pesticide residues
Representative sampling
*biggest consideration in feed analysis
-contaminants are not usually uniformly distributed in sample so sample what the animal consumes or from multiple areas and create composite sample
Poisonous plants
-Many plants don’t have a specific test and extensive plant testing not present at many labs
-USA has some plant testing
**take pictures
Drug detection
-Human OTC test kits but there are limits
*human marijuana test detects different urinary metabolite than dogs
*however can be used for cocaine, benzodiazepines, amphetamines, barbiturates
-there are non ttargeted tests or drug panels at some labs
Unknown exposure detection in labs
Labs may have non targeted screening tests
-use a catalogue of hundreds of compounds
-not quantitative
Shipping your samples
- Primary contained: leak proof, plastic containers
- Secondary contained: leak proof, contains absorbent materials in case of leakage
- Tertiary contained: rigid, cardboard box
Shipping samples in cold weather
Use room temperature gel packs (not frozen) for samples that don’t need chilling
Use chilled (not frozen) gel packs for samples that need to be chilled
**keep packs separate from sample
Shipping samples in hot weather
Pack sample with cold packs and absorbent material
-cold packs should be separate from sample
-insulated shipping contained (styrofoam box)
What needs to be supplied with the sample?
-complete history (changes in feed, medications, supplements, treatments attempted, vaccine status, duration of problem)
-pertinent physical exam and or necropsy findings
