2 – Toxicology Diagnostics Flashcards
What are some things to consider regarding available evidence if you think an animal has been poisoned?
- Circumstantial: owner history
- Clinical observations
- Pertinent physical exam findings
- Pathology
- Samples available to submit: antemortem vs. postmortem
What are the 2 overarching goals of testing?
- Confirming exposure to a toxic dose
- Monitoring clinical signs resulting from poisoning (case progression)
What are some things to consider when making a decision for diagnostic testing?
- Cost money
- Not all poisons have a specific test
- Not all labs run all tests
- “fishing expeditions” are rarely fruitful
- Rule ins and rule outs
What samples will you take from live animals?
- Blood
- Vomitus, gavage fluid
- Urine
- Liver biopsy
- CSF: high degree of skill required
- Feces
- Hair, milk
What samples will you take from deceased animals?
- Blood (ex. anthrax, but can’t do a CBC)
- Stomach/rumen/GI contents
- Liver, kidney
- Brain
- Ocular fluid
- Urine
- Feces
- Fat
- Retina
What are some commonly submitted samples?
- Serum
- Liver
- Stomach contents
- Feed
- Urine
- *better to collect more and not need it
- *often submitted in conjunction with tissue for histo
What are some less common, but important samples to submit? (ex. neuro case)
- Whole blood
- Brain
- Ocular fluid
What are some pre-analytical errors?
- Sample collection
- Sample transportation (weather, temperature and packaging)
- *OUTCOME: inaccurate results and misdiagnosis
What are some errors with sample collection?
- Wrong sample
- Liver: insufficient amount
- Blood/serum/plasma: insufficient volume or hemolysis
What does hemolysis do?
- Compromises interpretation of iron, zinc, magnesium and chemistry panel
What are some causes of hemolysis?
- *delayed separation of serum from clot
- Freezing whole blood
- Inadequate centrifugation
- Wrong needle/synringe
- Inadequate volume collected
- Vigorous mixing
- **exception: hemolysis from poisoning
What is the order of tube collection?
- Blood cultures
- Citrated tube (PT/PTT, light blue)
- Trace mineral tube (dark blue)
- Serum (red)
- Plasma (green)
- EDTA (lavender)
What is the in clinic: point-of care blood work? “Emergency panel: 4 tests”
- Blood glucose
- Total protein
- BUN
- PCV
- *helpful starting point
o Hypoglycemia
o BUN: kidney problems
o PCV: plasma colour, anemia
In clinic: CBC, chemistry and urinalysis
- Minimum database
- Send-out tests may have expert interpretation
- Helpful to narrow DDx for monitoring patient progress
o Anemia
o Organ damage
o Treatment efficacy
In clinic: urinalysis
- Suspected renal damage
o Pigment: myoglobin, Hg, RBC
o Things that should not be there
In clinic: blood gas analysis
- Venous vs. arterial
- Ionized and total calcium: hyper and hypo-calcemia
- Acid-base status
- Electrolytes
- Glucose
- Lactate
In clinic: imaging
- T-FAST: looking for air and fluid (pulmonary edema and bleeding)
- A-FAST: looking for free abdominal fluid or hemorrhage
- Radiographs
- Abdominal ultrasound
In clinic: coagulation panel
- Not all clinics, but many emergency clinics
- Prothrombin time (PT): extrinsic + common pathway
- Partial thromboplastin time (PTT): intrinsic + common pathway
- Considerations: fill up to line, clean venipuncture
Vet diagnostic lab (VDL): metals and mineral
- Inductively coupled plasma mass spectrometry (ICP-MS)
- *heavy metals and trace minerals
- In general: submit plasma/serum and/or liver
o 2mL
o 2-5g or 0.2 g (4 pokes) - *lead in live animal=need whole blood
o Heparinized whole blood
o Tissue
o *90% of lead is bound to RBCs
VDL: pesticides, samples to submit
- Any suspect bait material
- Stomach contents
- Whole blood and brain: AChE activity
VDL or government: water analysis
- Algal toxins
- Metals and trace minerals
- Nitrate
- Drug/pesticide residues
- *some provincial labs offer farm water testing for free
VDL: feed analysis
- Metals and trace minerals
- Nitrates and cyanide
- Mycotoxins
- Drug, pesticide residue
- *biggest concern=representative sampling
What is important to consider to get a representative sample for feed analysis?
- Sampling can affect the results
- Contaminants are not typically uniformly distributed in sample
- *submit what the animal consumes
- *sample from multiple areas and create a composite sample
Poisonous plants
- Many do not have a specific test
- Many labs don’t offer extensive poisonous plant testing (need to send to USA)
- Plant ID can be challenging
- Take pictures! (ex. red maple=always has red stems)
Drugs
- Human OTC tests available
o Different urinary metabolite for marijuana
o Reliable for: cocaine, benzodiazepines, amphetamines, barbiturates - Non-targeted tests or drug panels at VDLs
o Blood, stomach contents, urine
VDL: unknown exposures
- Some labs have non-targeted screening tests
o Not quantitative
Sample packaging: 3 containers
- Primary container: leak proof, plastic containers
- Secondary container: leak proof, contains absorbent materials
- Tertiary container: rigid (cardboard box)
Weather conditions: cold weather
- Room temperature gel packs (not frozen): those that do not require chilling
- Chilled (not frozen) gel packs for samples that need to be chilled
Weather conditions: hot weather
- Cold packs and absorbent material
- Cold backs: separate from sample
- Insulated shipping container
How can you make the most of your submission?
- *lack of info hinders interpretation
o Changes to feed or environment
o Medications or supplements
o Treatments attempted
o Vaccination status
o Duration of problem, onset - COMPLETE history
- Pertinent physical exam and/or necropsy findings
- *best lab: California
