Diagnostic toxicology Flashcards
What is the most important aspect in dealing with toxicosis? What are specific treatment and prognosis based on?
Accurate/confirmed diagnosis
T/F: Diagnosing poisoning is the same as diagnosing other species–by process of elimination
TRUE
How is a tentative diagnosis obtained?
Can be obtained by detailed history, thorough clinical and postmortem examinations
How is a presumptive diagnosis reached? What can sometimes help?
- Can be reached when the history and clinical signs are supported by circumstantial evidence and identification of the source of poisoning
- Sometimes response to a specific antidotal treatment may help making a presumptive diagnosis
How is a confirmed diagnosis reached?
May be reached by using all criteria of diagnosis including laboratory work (sampling, interpretation)
What are the 5 criteria of diagnosis? Which is unique to toxicosis?
- Case history
- Clinical signs
- Postmortem findings
- Laboratory diagnosis
- Laboratory animal tests
- Unique to toxicosis
Case history–5 aspects?
- Looking for the evidence
- Relying on information provided by the owner or caretaker may be misleading
- Make sure that the animal has ingested or has been exposed to the poison at a certain level
- The food and water should be examined for the presence of toxic agents
- Information and questions depend on if the animal is a farm or companion animal
What specific questions should you ask when discussing case history of farm animal toxicosis?
- # of animals
- # of effected
- # dead
- Course of disease
- Type of management
- Feeding
- Vaccination
- Use of herbicides/insecticides
- Past illness
- Presence of poisonous plants
- Detailed clinical signs, postmortem findings, etc.
What questions are included in the small animal case history?
- Is the animal indoors or outdoors
- Use of any drugs, insecticides, pesticides
- Household chemicals
- Vaccination, etc.
Clinical signs–what’s included/not included
- Details of clinical signs
- Complete and thorough clinical examination
- Most diseases do not have pathognomonic signs
Postmortem findings
- Include both gross and microscopic examinations
- Must be done in legal cases
- Negative results are as good as positive results
Laboratory diagnosis (6)
- Clinical pathology
- Chemical analysis
- Positive chemical results consistent with other criteria may confirm diagnosis
- Should be done by a qualified toxicology lab
- Accuracy of chemical results depends on good sampling
- Interpretation of results should be done carefully considering other evidence
- Positive results do not always mean intoxication
- Negative results do not always mean that poisoning did not occur
Laboratory animal tests (6)
- Usually done by the toxicoloy lab
- Administration of the suspected materia (food or water) to a susceptible animal and observing the effects
- Important in bacterial, fungal, plant toxins and feed additives in animal feeds
- It is more relevant to administer the suscpected material to the same species that was exposed to the suspected toxin
- Positive results may be helpful in aiding diagnosis
- Negative results do not eliminate the possibility of intoxication
Submitting specimens for chemical analysis:
Specimens should be accompanied by?
Evaluation?
Ideal specimen?
- Should be accompanied with a complete history, clinical signs, postmortem findings and other information including the vet’s name, address and phone #; owner’s name, address, phone # and animal’s species, breed, sex, age, and weight
- Specimens will be evaluated for toxicants quantitatively and qualitatively
- Specimens should be representing, avoiding dilution, contamination, or putrefaction
What 8 procedures/precautions must be followed when submitting specimens for chemical analysis?
- Specimens should be taken free of chemical contamination or debris
- Specimens should not be washed
- Animal and tissue specimens should be frozen
- Blood samples should be refrigerated while other body fluids should be frozen
- Packaging specimens from different organs separately
- Clean glass or plastic containers that can be tightly sealed should be used
- Waterproof ink should be used when labeling specimens and should include owner’s name, animal’s name, or # and tissue of specimens
- Preservatives must not be added to specimens unless indicated as in case of histopathological examination (this has to be mentioned on the label)
Examples of adequate material amounts (7)
- Serum: 5mL live animal, 10mL dead animal
- Whole blood: 10mL live or dead animal
- Urine: 50mL live or dead
- Vomitus or baits 200g
- Liver, kidney, or fat 100g
- Brain: 1/2 frozen and 1/2 in formalin
- Rumen or stomach contents 500g
6 steps in obtaining a serum sample?
- Use clean, dry syringes, needles, vials or tubes
- Avoid hemolysis by avoiding pressure, aspiration, or shaking of the sample
- Allow enough time (1-2hr) for the blood to clot
- Put tubes with blood in an oblique position to obtain more serum by increasing the SA
- Obtain serum by pouring in another tube, or by centrifugation at 3000 rpm for 15 min and pipetting the serum
- Vials and tubes have to be tightly sealed and labeled, then frozen and transported on ice
Sampling feeds or forage for analysis
- Forages should be cut to length of ~3in
- Sample size should be on quart or kilogram
- Green forage or silage should be frozen, or green forage dried
- Samples should be taken from dif. bales and dif. parts of the bale
- Samples should be packaged tightly and sealed airtight in plastic bags
- All letters/instructions should be sealed in a first class mail envelope attached to the mailing container
Transporting specimens to a laboratory
- Liquids (blood, other) should be shipped in glass or heavy plastic containers that can be tightly sealed
- Tissue specimens can be transported in ziploc plastic bags, glass, or plastic containers
- Samples should be wrapped individually for mailing
- Plastic bags, cardboards and coolers are used for transporting
Sealing of packages for legal or insurance purposes (according to FBI, 1996)
- Pack bulk evidence securely in a box
- Seal box and mark as ‘evidence’
- Place copy of transmittal letter in envelope and mark ‘invoice’
- Stick envelope to outside of sealed box
- Wrap sealed box in outside wrapper and seal in gummed paper and address directly to laboratory (Note attention to specific person if possible)
