Final Flashcards
T/F: you should always interpret abnormalities on blood panels in light of your clinical picture
True
How can you compartmentalize the CBC? Chem?
CBC:
-erythron
-leukom
-thrombon
Chemistry+urine+blood gas:
-protein metabolism
-energy metabolism
-renal
-minerals
-electrolytes and acid base
-liver
-muscle
-pancreas and GI
How should you interpret proteins?
In context of the chemistry- look at protein metabolism
What is the difference between hematocrit and PCV?
Hematocrit is calculated by machine
-disagree in cases of IMHA due to agglutination. MCV will also be affected if HCT is affected (MCV used to calculate the hematocrit)
-In the case of IMHA, trust the PCV not the hematocrit
What values should you look at to determine if an anemia is regenerative?
Reticulocyte count, percent, morphological changes
What is a test you can send out blood for to farther classify an anemia?
Iron panel
What should be the proportion between hemoglobin and hematocrit?
Hemoglobin X 3 = hematocrit (+/- 1-3)
-when this is not the case, this is likely due to hemolysis
How can you differentiate in vitro vs in vivo hemolysis?
In vivo- patient may have icterus which would indicate actual hemolysis in the patient
What is one reason that a patient with a systemic infection may have a low lymphocyte count?
Stress
-can have simultaneous corticosteroid and inflammatory leukogram
What should you do if you are worried about an erroneous platelet result?
Do a blood smear
In what species is enlarged platelets (increased MPV) normal?
Cat
What is the cause of giant platelets? What will they look like on a CBC?
Due to megakaryocyte replenishing of platelets (due to consumption in most cases)
-will appear as an increased RBC count
What can decreased fibrinogen indicate?
Impaired liver function, impaired coagulation, inflammation
T/F: globulins are measured for a Chemistry
False- just total protein minus albumin
How do you determine if fibrinogen is increased due to inflammation or due to dehydration?
PP:F Ratio (PP- fibrinogen)/Fibrinogen
-In horses <15 is inflammation, >20 is dehydration
-In cattle <10 is inflammation, >15 is dehydration
If between the two values, both are probably present
How can serum protein electrophoresis help you better determine a patients protein status?
To better determine what is happening with globulin proteins, specifically beta 2 and gamma
-cancer may cause monoclonal increase, vs if polyclonal more likely from infectious process
How can you evaluate energy metabolism?
Look at carbohydrates and lipids
Why may animals with diabetes have low glucose in the urine?
Due to osmotic diuresis
-always have to keep in mind the hydration status of the patient
What is included in the primary vs secondary renal panel?
Primary: creatinine, BUN, UPC on urinalysis, SDMA (dont rely on only this, often reflects other values)
Secondary: Albumin, Minerals, Electrolytes, acid-base
What mineral is very affected by increased or decreased GFR?
Phosphorus
What does 3/4 loss of renal loss lead to? 2/3?
3/4: azotemia
2/3: Isosthenuria
What makes up the primary and secondary renal panel?
Primary: calcium, phosphorus, magnesium
Secondary: Albumin, ALP, Renal Profile
What calcium is reflected on a blood panel?
Total calcium
-composed of ionized calcium (50-55%), protein bound calcium (35-45%), and complexed calcium (5-10%)
T/F: if albumin is lost, calcium should drop proportionally
True
What is the synonym for total CO2?
Bicarb
-used to calculate ion gap (sum of positive things minus negative things)
Can you tell anything about respiratory alkalosis or acidosis on a chemistry?
NO
-can only look at metabolic components
What does a lot of chloride mean? too little?
Excess chloride: metabolic acidosis
Too little chloride: metabolic alkalosis
** chloride behaves as an acid. If chloride decreases bicarb will increase to compensate
T/F: Uremic acids are the same thing as BUN
False- they are the other acids that are not measured on blood panel
-ex: citrates and sulfates
How do you calculate corrected chloride? Why do you do this?
To determine if the chloride is following the sodium. Can help you determine if there is a true alkalosis or acidosis.
(average Na/measured Na) X measured Cl
What are the main things you look for on the liver panel?
Liver injury (ALT,AST, GDH, SDH, LDH)
Liver function (Albumin, BUN, Glucose, cholesterol, coag factors, conjugated bilirubin, fibronogen, ammonia, bile acids, RBCs)
Cholestasis (indicated by increased GGT, ALP)
T/F: in horses you can use ALT and AST as a marker of liver function
F- because very influenced by red blood cells
T/F: you can have a patient with liver dysfunction without liver injury
TRUE
-also can have lots of liver injury with a functional liver
How can liver dysfunction lead to anemia?
The liver plays a large role in iron metabolism
Should you worry about liver enzymes being low?
NO- should only care when they are above the reference interval
With bad muscle injury, what may you see on urinalysis?
Myoglobin
What are the markers of the exocrine pancreas?
Lipase, amylase, Trypsin-like immunoreactivity (TLI), pancreatic lipase immunoreactivity (PLI), cobalamin, folate
What are the two things that can cause increased lipase or amylase?
Decreased GFR (usually more mild changes) or increased acinar pancreatic damage
What causes increased TLI and PLI? Decreased?
Increased: acinar pancreatic damage, decreased GFR
Decreased: chronic pancreatitis, acinar atrophy
What does decreased cobalamin and increased folate indicate?
Exocrine pancreatic insufficiency
How should you approach toxicology cases?
Look into what body systems are affected, onset time, morbidity and mortality
-history is critical- analysis is expensive so must have very defined differentials
What are the main categories of toxicants in small animal? Large animal?
Small animal: human or veterinary medicines and foods, insecticides and rodenticides, house and garden products
Large animal: metals and minerals, toxic plants, mycotoxins, feed additives and contaminants
What does 16 ounces equal?
1 pound/pint
How many pints are in a quart?
2
How much does 1 milliliter weight?
1 gram
What does percent equal?
gram or mL per 100 grams or mL
What is 1 fluid ounce equivalent to?
30 mL
What is 1 ppm equivalent to?
1 mg/kg
How do you determine a mg/kg dose in feed?
ppm in feed X percent BW eaten per day
What organ system do insecticides target?
Nervous system
What insecticides target the sodium or chloride channels?
Pyrethroids, avermectins, fipronel
What insecticides target acetylcholine receptors?
Organophosphates, Carbamates, Neonicotinoids
-mainly cause parasympathomimetic signs (pupil constriction, hypersalivation, decreased HR)
How can you diagnose Organophosphate or Carbamate Toxicity?
Give preanesthetic dose of atropine (0.01-0.04 mg/kg IV). If signs resolve this is not the cause
-If no change, give antidotal dose (0.2 mg/kg)
-can also measure acetylcholinesterase activity of heparinized whole blood and/or brain tissue to confirm (70% reduction of activity is reasonably diagnostic)
What is the treatment for cholinesterase inhibitor toxicity?
Atropine is the first treatment to counteract signs
-be careful not to overdose and cause atropine toxicity (treat with diazepam)
-give initial dose of 0.1-0.5 mg/kg. can give 1/4 IV and rest IM or SQ to prevent overdose
2-PAM (pralidoxime) secondarily
-regenerates of AChE
-20-50 mg/kg early
-works against nicotinic signs
Are there any anecdotes for pyrethrins? What species is the most affected?
NO- must do empiric treatment (decontamination)
Cats are the most affected
What are the 5 main Rodenticides that you worry about in small animals? What do they target?
- Bromethalin: targets nervous system, no anecdote. Important to calculate amount ingested and decontaminate
- Vitamin K Antagonists: target hematopoietic system, treat with vit K.
- Cholecalciferol: targets kidney
- Strychnine: targets nervous system (causes tetanic seizures)
- Zinc Phosphide: changes to a volatile gas and causes respiratory problems
How should a DVM act if there is a suspected metal or mineral toxicosis?
-obtain history, review signs, assess site
-perform physical
-review unique characteristics of metals and minerals that may be involved
-prioritize suspected toxicants
-collect appropriate samples for testing. Collect from animal and the environment
-confirm with toxicology testing
What are the possible metal toxicities, what are their sources, and what do they target?
Lead: acute and chronic exposure from many sources. Has multi system effects (CNS, GI, kidneys)
Sodium: CNS toxicity from water deficiency (can be affected by ionophores)
Copper: in copper wire, chronic exposure via feed additive with acute released from liver especially in stressed sheep
Zinc: in galvanized meal, metallic nuts and bolts. Has hematopoetic effects
Arsenic: in soils, ores, and ash of treated wood, targets GI tract
Iron: in drugs, fertilizers, and metal objects that rust. Target GI tract and liver
Selenium deficiency: chronic from deficient soil, targets muscle
How do you treat lead toxicity?
Calcium EDTA 75 mg/kg
-3 days of and 3 days off dosing
-not allowed to use in Food animals as it remains in meat for years
T/F: in tox cases, you should only treat animals with clinical signs
True in most cases
What are seven important mycotoxins that can contaminate animal feed/food?
Aflatoxin: hot, dry season, mainly in corn, GI and liver target
Vomitoxin: cool, set season production mostly in small grains, GI target
Zealenone: co exists with vomitoxin, repro system target
Slaframine: produced in clover, limited cholinergic effect
Penitrem A: in rotting dairy products, garbage, neurotoxic
Roquefortine: in rotting compost, garbage, neurotoxic
Fumonisin: moldy corn products, neurotoxic
**food/feed contaminations can also include bacteria and their toxins
T/F: There is no diagnostic test for mycotoxins in biological samples from animals exposed
True- must save the food
Describe the toxicity of bulbs
-includes daffodils, tulips, iris, hyacinths, crocus, amaryllis, gladiolas
-toxicity: not well characterized, usually not lethal. Includes irritant resins, alkaloids and/or insoluble calcium oxalate
-clinical signs: mostly in dogs, onset time <1 hr. Causes salivation, vomiting, diarrhea
-treatment: decontamination, multiple doses activated charcoal, cerenia
What is the mechanism of action of bulb toxicosis?
Contact irritant, allergen, centrally acting emetic, decreased protein synthesis
Describe onion and garlic toxicity
Also a bulb
-toxic in all forms (toxic dose 0.5% body weight or 5 g/kg)
-cats and cattle affected more than dogs
-MOA: metabolism to disulfides cause oxidative damage to RBCs–> lysis
Signs: odor on breath, vomiting, anemia, hemoglobinuria
Treatment: decontamination and symptomatic
Prognosis is dose dependent
What system is affected by Christmas plants?
GI tract
-but Christmas trees can cause hepatic nephrosis, and nephrosis (due to phenols and pine oils)
Which toxins are the most toxic to cats of the following list:
1. tulips
2. Onions
3. Mistletoe
4. Pine
Onions and pine
What are the main cardiotoxic plants?
-Christmas kalanchoe, oleander, foxglove, lily of the valley
-cardioactive steroids (digoxin and oleandrin)
What is the lethal dose of oleander?
0.005% of body weight
What is the mechanism of action of cardiotoxic plants?
All parts of the plant are toxic, and all animals are susceptible
-GI irritants
-inhibition of NA/K ATPase pumps
-increases intracellular sodium and calcium –> positive ionotrope
-increased extracellular potassium leads to a decreased resting membrane potential and impaired conduction
-causes bradycardia and dysrhythmias
What are the clinical signs associated with cardiotoxic plants?
-anorexia, hypersalivation, vomiting/diarrhea, colic, depression/lethargy, marked weakness
-various arrythmias: Bradycardia/AV block/tachycardia
-weak irregular pulses
-death usually from asystole and Vfib
How can you diagnose cardiotoxic plant toxicosis?
-history, clinical signs, presence of plant in GIT
-clin path shows hyperkalemia
-serum analysis/urine analysis for specific toxin (immunoassays for digoxin and digitoxin)
-ECG abnormalities
What is the treatment for cardiotoxic plants?
Activated charcoal, atropine and glycopyrrolate (to increase HR), lidocaine
In small animals can use Digibind (antibody to bind digitalis and others)-very expensive
What are some other cardiotoxic plants can affect cattle and horses?
-Dogbane, common milkweed can end up in haybales
-diagnose same way as small animals (unlike to do ECG though)
Describe tobacco poisoning in small animals
Frequently occurs from puppies licking ashtrays
-alkaloid toxicity
-effects on CNS, GI, indirectly cardiovascular
-can be toxic at 1 mg/kg
-signs include nausea, salivation, irritation of mouth and stomach, weakness, staggering, resp problems, erratic heart rate and BP
-treatment: remove residual tobacco, assist resp, stabilize heart and BP
What occurs with Yew toxicosis?
-all parts of plant are toxic (taxine alkaloid)
-direct affect on myocardium with depression of AV node conduction–> bradycardia, hypotension and diastolic cardiac arrest
-fast onset (15 min-24 hr)
-signs: dyspnea, bradycardia, convulsions, trembling, diarrhea, incoordination, depression, lethargy, SUDDEN DEATH
-can often diagnose with necropsy by analyzing GI contents. Other options are taxine analysis of stomach contents
-treatment: atropine, activated charcoal, saline cathartic
-guarded prognosis even if they don’t die right away
What are the toxic shrubs we discussed? How do they cause toxicosis?
Rhododendron, Azaleas, Mountain Laurel
-contains grayanotoxins (all parts of plants toxic), sheep and goats most likely to be affected
-causes heart arrythmias and vomiting through stimulation of the vagus nerve (decreases HR)
-diagnose mainly through clinical signs. Die due to heart effects
What is the treatment for rhododendron, azalea and mountain laurel?
-stop vomiting with acepromazine
-then give activated charcoal and a saline cathartic
-appropriate drugs for arrythmias (lidocaine for tachycardia, atropine for bradycardia)
Describe buckeye toxicosis
-all parts are toxic
-aesculin is toxin
-unknown MOA
-clinical signs: goose stepping (hypermetra), ataxia, muscle tremors, paralysis, hyperesthesia
-diagnose on necropsy of stomach contents
-treat with sedative until signs resolve
-morbidity not mortality problem
What species does black walnuts affect?
Horses- can be used as bedding and horses can ingest
-causes enhanced constriction of blood vessels of the woof wall which can lead to laminitis
-diagnose through analysis of wood shavings in bedding (dark, chocolate brown color)
-treatment: activated charcoal, cathartics, mineral oil, acepromazine, DMSO, pain meds, prazosin (vasodilator)
What part of oak trees causes toxicity problems?
Acorns
-tannic acid causes inactivation of phenols and denatured proteins
-causes gastroenteritis and ulceration as well as severe kidney damage (proximal tubule damage)
-only tends to cause problems in cattle
-clinical signs: ventral edema, dyspnea, black diarrhea, colic
-diagnosis: evidence of renal failure (elevated BUN/creatinine, decreased sodium, chloride, calcium, increased magnesium)
-treatment: fluid therapy, electrolyte replacement, vitamin B, transfaunation, calcium hydroxide
-major differential is pigweed
How can you avoid acorn toxicosis?
Pasture management
Which maple tree is the most toxic?
Red maple in horses
-causes oxidative damage and heinz body formation, methemoglobin formation and hemolysis
-clinical signs: cyanosis, heinz body anemia, methemoglobinemia
-long onset (1-2 days after ingestion)
-lesions: icterus with hepatic, centrilobular necrosis, splenomegaly, reddish-black kidneys (similar to copper)
How do you diagnose and treat maple toxicosis?
-diagnosis through history and clin path (decreased PCV, increased bilirubin, AST, SDH, BUN, creatinine)
-treatment: activated charcoal, saline cathartic, blood transfusions, ascorbic acid (antioxidants), fluid therapy, pain meds (NO STEROIDS)
-causes more morbidity than mortality
What are the cyanogenic plant sources?
Prunus (cherries) and sorghum species
What happens with cyanide toxicity?
-glucuronidation in the rumen causes separation of the sugar from cyanide
-most toxic in the wilting stage when the cyanide becomes volatile
-can cause sudden death in ruminants, especially goats
-prevents oxygen from leaving the blood leading to cherry red blood, and inability of oxygen to be used by tissues (brain is very sensitive to low oxygen)
-ddx: nitrate poisoning (but blood will be brown in that case)
-clinical signs: bright red mucous membranes, CNS signs, coma, sudden death
-treat with thiosulfate, nitrite, B12
What happens behind the scenes in a clin path lab?
-test validation
-test comparison
-quality management
-reference intervals
-development of new methodologies and applications
Describe how reference intervals are obtained?
Ideally by sampling at least 120 individuals within a population (several breeds, equal male/female, all ages)
-take average of population and take 2 standard deviations above and below to determine interval
-can have reference intervals for different life sages
-reference intervals vary with equipment, methodology, location and patient
T/F: reference interval is very specific to the region you are in and equipment you are using
True
What should you do if there is not a reference interval available for the species you are working with?
Can compare to reputable sources on the internet
What is the minimum animals accepted to determine a reference interval?
40- often done in minor species as its hard to find 120 normal animals for a study
-with exotic animals, may have to reduce numbers farther and do fancy statistics to increase clinical relevance
What are the 3 types of lab errors?
- Preanalytical (46-68%)
- Analytical (7-13%)
- Post-analytical (19-47%)
What are some examples of pre-analytical errors?
-inappropriate test request
-order entry error or error on request form
-misidentification or labelling error
-inappropriate container or sample
-insufficient volume
-inadequate transport or storage
-sample processing before analysis
If you have a small or fractious patient, how can you prioritize tests?
Based on differentials
-only have a limited amount of blood, cant run all the tests with not enough blood
What can excess EDTA in a purple top tube cause?
Errors in morphology (lots of echinocytes)
-decreased MCV and HCT
-hypocalcemia,hyperkalemia
What is the concern for lack of blood in a citrate tube?
Will dilute the sample and lead to false clotting results
How can you avoid preanalytical errors?
-SOPs
-training of personnel
-communication with clients
What are the sources of analytical errors?
-instrument malfunction
-reagent problems
-methodology
-operator error
How can you prevent analytical errors?
-SOPs
-training
-automation
-monitoring results
-certification
What are the sources of post-analytical error?
-Failure in reporting
-Improper data entry
-inappropriate reference intervals used
-incorrect interpretation of results (some people think this is analytical)
What would happen if a chemistry is accidentally run in a purple top instead of a red top?
-will look like hypocalcemia due to EDTA binding the calcium, EDTA contains potassium so that will be increased
What happens if too much time is passed before plasma separation?
Glucose will be consumed for cells to stay alive
What would occur if a sample is exposed to air for too long?
CO2 will be lost leading to an increased anion gap
What can occur if your sample is too old?
Decreased white blood cells, neutrophils, increased bands, increased or decreased lymphocytes
-Dohle bodies present
What can cause a falsely elevated platelet number? falsely decreased?
-elevated: ghost cells and certain organisms
-decreased: platelet clumps
What order should you collect blood tubes?
- Blood culture
- Light blue- coag
- Red top for chemistry
- Yellow top
- Green top
- Purple top for hematology
- Grey top for glucose/lactate
What are the major steps to progress towards a toxicological diagnosis?
- Observe and examine the patient: look for signs, severity and systems involved
- History: timeline, environment, epidemiology
- Preliminary rule out list- sample collection
- Aid the diagnosis: clin path, other pathology (necropsy or histopath), imaging and electrophysiology
- Revise and prioritize rule outs, select tox tests to be done
T/F: case mortality always follows morbidity
False
What is the smell of cyanide? Selenium?
Bitter almond smell, garlic
What is super important in tox cases?
Must document everything! These cases might end up in court
What is important to put on sample labels for tox testing?
Collection date, case, animal or environmental source, description, and clinician taking the samples
-never store samples in the same container
What should you collect ante-mortem in tox cases?
-whole blood, serum, plasma, urine, feces, vomit, stomach contents from lavage
-also maybe milk, hair, nails, feathers, swabs of suspect material, meconium, amniotic fluid, tissue biopsies
Why can you not use rubber stoppers for suspect zinc intoxication?
There is zinc in the rubber stopper which may lead to false elevations in levels
-use royal blue tubes
What samples are the most important to take post-mortem?
Brain, liver, kidney, urine, GI contents
-can collect up to 10 samples- better to have them then not
What samples can you take from the environment?
-feed, water, suspect bait, soil, plant material
What does ppm in feed equivalent to?
(mg drug/kg body weight)/% body weight eaten as food per day (decimal)
How many ounces are in a gallon?
128
Do you have to take a patient in right away for bromethalin, ethylene glycol, or warfarin toxicosis?
Not technically because it takes a long time for onset
What are the main principles behind decontamination?
Remove, dilute, eliminate
-however, stabilization of vital signs has first priority
-then move to decontamination to prevent further absorption
-also is important in asymptomatic animals
-there are not very specific anecdotes in most cases
What are the major methods of decontamination?
Emetics or gastric lavage:
- contraindicated for volatile compounds, solvents, corrosives, convulsing patients
Activated charcoal
-not useful for metals or alcohols
Washing/dilution/ion trapping
What is included on the ProCyte Dx scatterplot? What is the difference with the ProCyte one?
The hematology values with a chart next to each to show you how far from the reference value you are
-a plot showing your red blood cell and platelet information as well as your WBC information
-with ProCyte one the scales of the plot is a bit different
What are the red vs purple vs blue dots on the RBC procyte plot?
Red- mature red blood cells
Blue- platelets
Purple- reticulocytes
If you see any orange, these are white blood cells
If you see dots between the red blood cell and platelet clouds, what may these be?
Fragments of red blood cells (schistocytes)
-occurs with DIC, intravascular hemolysis, hemangiosarcoma’s, iron deficiency anemia, vasculitis
*indication to look at smear
What do the different colors indicate on the WBC plot?
Red=monocytes
dark blue=lymphocytes
Light blue=basophils
Green=eosinophils
Purple=neutrophils
Orange=RBCs that were not lysed
What are the mononuclear cells vs granular cells?
Mononuclear-monocytes and lymphocytes
Granular cells: basophils, eosinophils, neutrophils
What should you do if the clouds are blending?
Look at blood smear!
-if there are distinct lines between large populations of cells, concern for leukemia
What can occur with the scatter plot when you have a left shift?
Nucleus becomes less segmented (looks C shaped)- can be confused with monocytes by the analyzer
-also the marrow accelerates maturation process, leading to lack of granules- makes cloud shift up and to the left
What percent of cases can the procyte misclassify cells in?
about 15% of cases
- therefore always look at the blood smear when available
Should you be concerned about enlarged platelets on a scatter plot?
-Normal to have large platelets in cats
-in dogs, this is an indication of an active thrombopoiesis
-can be an accident in production or could be due to bone marrow disease (nothing is pathognomonic)
What can you see on the plot in cases of marked platelet clumping?
Curve in the distribution
Compare and contrast POC vs reference labs
POC: quicker turnaround, specific technology to ensure minor training and maintenance, often cost-effective
Reference lab: slower turnaround, quality assurance and control management programs ensure quality of results, specialist operation of equipment
What things do you need to be aware of when running hematology tests?
-some systems only have electronic controls (self calibrators)
-all assays have a degree of error (so dont over interpret changes in lab data)
-understand capabilities and limitations of your system
-all instruments are different. cannot compare values from one lab directly to another
Who is ultimately responsible for faulty equipment in a vet clinic?
The veterinarian
What are causes of increased BUN besides azotemia?
GI bleeding
What are the most common causes of increased phosphorus?
-decreased GFR (hypovolemia or glomerular damage)
-tubular disease–> decreased vit D synthesis –> decreased iCa –> increased PTH –> renal secondary hyperparathyroidism
When do you have a risk of tissue mineralization?
When P X Ca > 80-90
-usually occurs in foci of inflammation
What is the main thing that household chemicals cause when ingested by animals?
GI irritation (diarrhea, vomiting, anorexia)
When does activated charcoal not work?
For anything ingested that contains metals, alcohols, or volatiles
What are the most toxic cleaning products?
Bleaches, disinfectants, dishwater detergent, oven cleaners, drain cleaners, toilet bowl cleaners
When should you be concerned about products based on the label?
If they say “warning”, “caution”, or “danger: poison”
-means that the toxic dose is fairly low
What are the 4 types of detergents (surfactants)?
Nonionic: the safest
Anionic: can be irritating
Cationic: most toxic. Includes those with quaternary nitrogens
Amphoteric: not common in home. Combo of anionic and cationic (second worst)
Why can cationic surfactants be neurotoxic?
The structure of quats are the same as acetylcholine
What clinical signs can be seen with detergents?
-vomiting, diarrhea
-hemolysis with anionic
-neurologic and GI signs with cationic: muscle tremors, bladder atony, acidosis, shock
-contact with eye can lead to corneal ulcers, prolonged skin contact can cause dermatitis
Can you use activated charcoal, emesis, lavage, or catharsis for irritant cleaners?
NO
-dilution is ideal
What are alkalides?
Drain cleaner
T/F: you can mix cleaning agents
FALSE
-can cause acid base reactions
Why are pine base cleaners and phenol disinfectants of particular concern for cats?
Contain alcohols
-cats cant process them due to inability to perform glucuronidation
What can alkali substances cause?
Liquefactive penetrating necrosis
Which disinfectants can be inhaled leading to respiratory problems?
Solvents and bleach
Which alcohols are FDA approved for antiseptic use?
Isopropyl alcohol and ethanol
-methanol can cause CNS depression and hypothermia if absorbed through the skin
Whats the problem with fertilizers?
-contain iron which can cause hepatic damage and GI damage
-treat with dilution (irrigation with water or milk)
What are the most dangerous pesticides?
Rodenticides, insecticides
-herbicides are fairly non-toxic, but can still cause problems in animals
What percent of pesticides are herbicides?
50%
What is the mechanism of action of herbicides?
Designed to work on things unique to the plant
-cause excess nitrate or cyanide accumulation in plants
-why they are not terribly toxic
How can animals experience herbicide related toxicosis?
-animal gained access to undilute herbicide, drank from spills or run of puddles
-herbicide application to unpalatable plants makes these plants more palatable leading to toxicosis from the plants
What are the most noteworthy herbicides leading to toxicity?
-glyphosate (possibly carcinogenic)
-2,4 D
-paraquat
-atrazine
What are the effects of glyphosate in animals likely due to?
The surfactant present in them
-not very toxic at all but can cause some minor GI irritation
-treat with dilution
What is glufosinate?
A relative of glyphosate which is much more toxic(not nearly as common)
-irreversibly inhibits glutamine synthetase which can lead to hyperammonemia
-if it penetrates the CNS can be neurotoxic
Describe the toxicity associated with phenocy/chorophenoxyacetic acid
Disrupts growth hormone balance and protein synthesis in plants
-2, 4 D is a formulation of this (can cause rear limb paresis? extremely rare and not a lot of evidence)
-dogs have decreased ability to excrete these
-signs include muscle weakness with rigidity (myotonia) due to inhibition of voltage gated channels in skeletal muscles
-treat through decontamination (activated charcoal)
Describe the toxicity of paraquat
-requires a licensed operator to apply this to fields
-oral LD50 very low
-accumulates in the lungs and causes lung fibrosis, and can cause direct kidney tubular damage
-clinical signs: fulminating pulmonary edema, hemorrhage, interstitial pneumonia, kidney damage, hepatic necrosis and death
What is the difference with toxicity related to diquat?
-does not require license to apply
-does not accumulate in the lungs, but instead the eye of dogs
-can also cause GI damage and kidney damage due to superoxide formed
What is the unique product you can use to treat paraquat/diquat toxicity?
-N acetylcysteine, vitamin E and C
What is the potential concern with fungicides?
-generally not very toxic
-possibly increased mutagenic and carcinogenic potential
Describe the toxicity associated with triazine (atrazine)
-persists in water for a very long time (years)
-does not cause a ton of toxicity
-can lead to hyperesthesia in cattle, as well as muscle tremors with exposure to concentrated product
What is one of the classic signs from intoxication with alkaloids?
Biliary hyperplasia
-will see classic cholestasis pattern (elevated GGT, ALP, bilirubin, ALT, GDH)
What is the first test you should request in a potential tox case?
Clin path
What are causes of increased ALP?
Cholestasis, bone turnover, stress
What are some causes of hypocalcemia in dogs on Chemistry?
-hypoalbuminemia
-pancreatitis
-ethylene glycol
What are some indications on chemistry of ethylene glycol intoxication?
High anion gap, very low calcium, bad acidosis
What is the anectote for ethylene glycol if you catch it early enough?
Ethanol/fomepizole
What type of crystals are seen in the urine and kidneys in the case of ethylene glycol intoxication?
Calcium oxalate- picket fence shaped
-can see from other causes as well
What two lung patterns can commonly be seen together in the same patient?
Interstitial and alveolar patterns
What does an alveolar pattern look like?
Homogenous, uniform opacity
-varies from solid and opaque to white and fluffy (depending on how filled the alveoli are)
-classic signs: lobar sign and air bronchograms
-can also see silhouette effect/border effacement of the heart
What is a lobar sign?
Interface between fluid filled lung and gas filled lung
-can be confused with a pleural fissure line (thin opacity between two gas filled lungs)
If you have multiple patterns in a patient, which is most likely to be the dominant pattern?
Alveolar
-radiographic appearance tends to change quickly
What are the main causes of alveolar patterns?
-pneumonia: aspiration, bronchopneumonia, or hematogenous
-edema: cardiogenic or noncardiogenic
-hemorrhage: trauma or coagulopathy
What is unique about the pattern seen with atelectasis?
It is technically an alveolar pattern, but not due to fluid filling but instead alveolar collapse
-occurs due to prolonged lateral recumbency
Describe a linear interstitial pattern (unstructured)
-overall increase in hazy, linear opacities
-vasculature is smudged but visible
-can be artificially created by expiratory or underexposed radiograph
Describe the progression of early signs of congestive heart failure on radiographs?
Unstructured interstitial pattern rapidly moving to an alveolar pattern
-often focused in perihilar and caudal areas, but often more widespread
What are the causes of a linear interstitial pattern?
-artifact
-geriatric change
-pulmonary edema
-hemorrhage
-pneumonia
-neoplasia (bronchoalveolar carcinoma in cats)
-fibrosis (westies predisposed)
Describe a nodular/structured interstitial pattern
-relatively circumscribed nodule or mass
-single or multiple
-varying sizes- miliary implied many tiny nodules (can look like severe bronchial pattern)
-main differentials: neoplastic and fungal disease
Describe a bronchial pattern
-thickened bronchial walls visible in periphery and hilus
-causes end-on thickened bronchi that look like donuts
-longitudinal version looks like railroad tracks
What are the main differentials for a bronchial pattern on a radiograph?
-chronic bronchitis in dogs
-feline asthma
-pulmonary parasites (HW, osleris osleri, roundworm migration)
Describe a vascular pattern
-associated with enlargement of one or both pulmonary vessels
-causes include heartworm disease (arteries affected more), left to right shunts (artery and vein enlarged), venous congestion (vein affected more)
Where do veins lie in comparison to arteries in the lungs?
Ventral and central
-arteries are dorsal and towards periphery
What should you look at when assessing small intestines on a radiograph?
-location
-gas pattern
-intraluminal contents
-diameter
What will obesity do to the small intestines?
They will be more centrally located
-increased contrast
What is a normal variation of the small intestine location in cats?
Right sided distribution
What does plicated bowel indicate?
A linear foreign body
-often will see comma shaped pieces of bowel with tapering
-eccentrically positioned bowel
What should the diameter of the small intestines be in dogs? Cats?
Dogs: less than 1.6 times the mid-body height of the L5 body
Cats: less than or equal to 12 mm
-used as a guideline- must correlate with clinical signs
What is the definition of ileus?
Failure of passage of intestinal contents through bowel lumen
-can be paralytic (adynamic and functional)
-can be obstructive (mechanical, dynamic)
What will you see radiographically with paralytic ileus?
Mild generalized dilation
What are some causes of paralytic ileus?
-peritonitis
-pancreatitis (focal ileus in descending duodenum)
-post-op abdomen
-enteritis
-pain
-anticholinergic drugs
-sedation/anesthesia
-dysautonomia
-GDV and mesenteric volvulus
-electrolyte imbalance
Describe the radiographic features of obstructive ileus
-dramatic dilation
-only the portion of bowel cranial to obstruction will be dilated leading to 2 distinct populations of bowel
Describe the left arm rule
-elbow will represent fundus
-wrist represents pylorus
-fingers handing down represent descending duodenum
What are the main causes of obstructive ileus?
-foreign body
-intussusception
-neoplasia
-stricture
-hernia
-adhesions
Where is aspiration pneumonia classically seen?
Ventral distribution of alveolar pattern
-cranioventral most common
When should you stop antibiotics in pneumonia cases?
A week after you have resolution of pathology on radiographs
What is the classic presentation of HW disease on radiographs?
Enlarged tortuous arteries, larger than veins
-right sided heart enlargement, main pulmonary artery enlargement
What is a fairly common finding in cats with asthma?
Atelectasis of the right middle lung lobe due to mucous plug blocking the airway
What is the most common cause of intussusception in puppies?
Parasites
-can also be caused by parvo however
When should gastric emptying occur after a dog eats?
Within 3 hours, usually quicker
What would make you think that you are dealing with a 360 degree GVD?
Dilated esophagus
-extremely large globoid stomach without classic smurfs hat appearance
-confirm by trying to pass and orogastric tube- if you cant this is your answer
What are the main goals of viral detection?
To prevent introduction at a country, state, or shelter/herd level
-to target care (treatment of secondary infections)
-to limit spread (to both animals and people)
Describe the main options for viral detection?
-can either look for host antibodies or antigen itself
-if targeting antigen, this can be in the form of viral protein, nucleic acid or live virus
What are the main methods for antibody detection?
-ELISAs
-lateral flow assays
-agar gel immunodiffusion (gold standard)
-other agglutination assays
Test contains antigen and patient antibodies react with test antigen- if present there is a reaction visualized. Some tests detect IgM (can detect earlier) while others detect IgG (most cases)
What is the main disadvantage to antibody based tests?
Takes weeks to develop antibody response so often it is too late to prevent outbreaks
How is an ELISA test conducted?
Direct: Plate has target antigen fixed to it, add patient serum, if antibody present it will bind
Indirect: Same as above, but the enzyme resulting in reaction has an antibody bound to it
Competitive: Instead of looking for more color, you look for less of a reaction (means more antibody is present)
Describe the steps of a lateral flow assay
Add patient serum, if antibody is present it will bind with conjugate, regardless of whether antibody is present conjugate will be moved across the pad through wicking action, if conjugate is present it will create a precipitation where the anti-antibody is on the test strip
Ex: FIV test
Describe the agar gel immunodiffusion test
-tests for equine infectious anemia (coggins test) and avian influenza
-antigen lies in center of the plate. If serum is positive a line will precipitate between the two
GOLD STANDARD
What occurs during the hemagglutination inhibition test?
-RBCs in solution form clot in well
-certain viruses will bind to surface of erythrocytes and prevent clotting (flat layer of red blood cells)
-if antibodies are present they will bind to the RBCs and allow the blood to clot as normal
What is the plate agglutination test?
-looks for antigen-antibody complexes on plate
-field test
-mix patient serum with free antigen
How is the lateral flow assay different when detecting viral protein?
Labeled antibodies on plate bind antigen if present
-easy, fast and cheap
-ex: parvo snap test
Describe the capture/sandwich elisa
Antibody fixed to plate instead of antigen
-antibody has regions that will bind to antigen of interest
-second labelled antibody added that you can visualize
Used for BVC serum tests as persistently infected animals wont have antibodies
Describe fluorescent antibody testing
-direct method using fluorescent labeled antibodies that bind to target antigens
Performed with rabies testing
How is immunohistochem different than FAT?
fixed tissue is treated to expose the antigen
-then sections are exposed to an antibody
Used for FIP, Mareks disease
What are the main pros and cons of elisas and lateral flow assays?
Pros: quick, less expensive, readily available, can be done in clinic, can see titer changes over time with ELISA
Cons: less specific, risk of false positives, not as likely to be accepted for regulatory purposes, risk of cross reactivity
What are the main pros and cons of AGID and HIs (hemagluttination)?
Pros: specific, gold standard for some tests, often accepted for import and export
Cons: harder to find, longer incubation, labor intensive, more expensive
What are the main pros and cons of FAs and IHC?
Pros: Usually quite specific, FAs are fast and can directly visualize pathogen in site of infection, IHCs provide an option for fixed tissue and you can also visualize location
Cons: rarely antemortem, can be expensive, may be species specific, limited assays available
When do you want to detect the antigen? When is it better to detect antibodies?
Antigen: detecting current infection and detects virus in immunotolerant animals (ex BVD PI)
Antibody: detecting previous/chronic infection (protection against future infection, antibodies past to offspring) and detects vaccines that elicit IgG (good way to see if vaccines are working)
What are the option for nucleic acid detection?
PCR and sequencing
What is the main benefit of real-time PCR?
Quantifies viral load
-can detect both DNA and RNA viruses
What are the basic steps of PCR?
Separation of strands to expose areas for binding
-add in probe with multiple primers
-probe and primers will bind to specific region of DNA to amplify the DNA. Once probe is dislodged by the transcription, it will fluoresce
Why is PCR like golf?
The lower the amount of cycles, the more viral pathogen is present
-used for many different panels: respiratory, abortion, enteric
-also specific diseases like distemper, BVD, equine herpes 1, influenza
What types of sequencing is currently being done?
Whole genome: done with pure viral sample to be able to compare to current viruses affecting a population (used a lot for epidemiology)
Metagenomic: Can start with impure sample, sequence everything in it, then use computer analysis to pick out potentially pathogenic material
What are the main pros and cons of Sequencing?
Pros: large amount of data, ID unknown pathogens, track mutations
Cons: expensive, lots of analysis, best done on pure samples
What are the main pros and cons of PCR?
Pros: fast, sensitive, reliable
Cons: no distinction live vs inactive virus, may miss mutated virus, contamination is an issue, need to know what you are looking for
What are the tests for viral detection?
Viral Isolation
Electron Microscopy
Histopath
This is where we started
What are the goals of viral isolation?
-to grow virus from diagnostic sample and then identify it
-usually tissue samples or body fluids, swabs
-gold standard is it is the only test that proves a viable virus is present capable of causing infection
How are viruses cultured?
-variety of cell lines are available, for best results use cell line similar to what the pathogen targets
-can use embryonated eggs in some cases -inject different areas of embryo depending on pathogen
-most cell lines are embryonic but there are some adult lines, specific organ lines
Once a virus is cultured, what is the next step?
Identification via looking for cytopathic effects and electron microscopy
-can also run FAT, hemagglutination, PCR, or sequencing
What are some examples of cytopathic effects?
Syncytial cell formation, rounding of cells, vaccuoles, plaques (patches of dead cells), intracytoplasmic inclusions
When should you use viral isolation?
-if there is a low viral load (ex: IBR in semen, BVD in milk)
-unknown pathogens
-species without serological or molecular tests
Describe the use of electron microscopy for viral isolation
-transmission electron microscope used
-stain sample with heavy metal salts to visualize surface structures
Used on disease samples or purified virus, can search blindly, can detect primary, secondary or other pathogens
How is histopathology used for viral detection?
-can visualize viral inclusions inside cells
-use standard H and E stain
-usually pathognomonic
-usually indicates a certain stage of infection
What are the pros and cons of viral isolation?
Pros: detection of living virus, detects and identifies unknown virus, sensitive, amplifies and collects live virus
Cons: difficult (special training, cell lines), long wait time, expensive, sensitive to contamination
What are the pros and cons of electron microscopy?
Pros: Visualize pathogen (can identify viral type), will work even if mutated, false positives are rare, see all actors involved
Cons: Expensive, less common, longer turnaround, cant determine if pathogen or bystander
What are the pros and cons of histopath?
Pros: false positives unlikely, inclusions are often distinct and pathognomonic, virus is inactivated (no risk of spread)
Cons: Absence does not equal a negative (may only be present in one stage of infection or may not be seen in sections taken), long turnaround
What type of swabs should you use for viral testing?
Do not use wood as it can inactivate viruses and interfere with PCR
-avoid calcium alginate
-use synthetic product with plastic handles
Safe options: polyester, dacron, nylon, rayon, flocked=catch more virus
What type of test should you run if you want to prove a virus is no longer present on a property?
-do not use lateral flow assay due to risk of false positive
-do not use PCR since it could detect dead viruses on the property
Use viral isolation in this case-sensitive and specific. will only detect live virus but be aware that this is slow
Why is testing for FIP so difficult?
PCR of feces does not differentiate coronavirus from mutated form, neither does indirect FA or lateral flow assays
-Negative ELISA not definitive as they can lose antibodies in severe disease
-PCR on abdominal fluid is fairly definitive, biopsy is best option
