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33 Cards in this Set
- Front
- Back
Characterization of disease
-define |
-why is the animal sick?
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Characterization of disease
-requires what |
-investment in diagnostic tests and post mortem exams
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Case definition
-define |
-description of an animal that meets your requirements for receiving treatment or for treatment success/failure
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Reason for a case definition
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-must define a disease before you can effectively treat it
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Case definition
-challenges |
-develop your own ability to recognize disease
-make sure you are comfortable with normal *then help clients define disease |
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Case definitions need to be characterized as:
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-important
or -misleading |
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BRD
-example case definitions |
-depression
-nasal discharge -ocular discharge -rumen fill/appetite -rectal temp -auscultation *images in ppt |
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BRD
-depression scoring system |
-0 = normal, no signs of depression
-1 = slower than pen mates but perks up when approached and does not appear weak, actively follows your movements with a raised head -2 = stands with head lowered, will perk up when approached but will return to depressed stance, moves slowly and falls towards back of group, may display signs of weakness such as incoordination --3 = obviously very weak, difficulty in moving with group, raises head only when approached closely |
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Why is it so difficult to visually ID BRD positive cattle?
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-prey species
-look at humans as predator so want to hide disease from doctor |
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Caudal vena caval syndrome
-describe |
-liver abscesses located near the vena cava erode the blood vessel and eventually the lungs get bathed in blood
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Tendencies of production animal vets
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-call less animals ill
*wrong |
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Tendencies of individual animal vets
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-call more animals sick
*wrong |
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BRD
-what do we know about diagnosing |
Clinical illness scores + rectal temp > 40C (104F)
-63% specificity Lung evaluation at harvest: gross evaluation -90% specificity |
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BRD
-what does a rectal temp of <105F tell us |
-there are some who can't get a difference between outcome success and failure
-population could reflect true population fatality rates |
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BRD
-typical rectal temp cut-off |
- >104F = probably will need intervention for treatment
- <104F = most respond spontaneously |
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Stethoscope
-exam findings |
-crackles and wheezes = likely significant
-hear nothing = likely significant because there is no air flow (consolidation) -hear nothing abnormal = possibly still abnormal |
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Stethoscopes
-false sounds may come from |
-environment
-hot cattle |
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diagnostic equipment necessary for physical exam
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-stethoscope
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Ultrasound
-use in BRD diagnosis |
-98% specificity
-use with auscultation -ultrasound waves can't go through air, so if lots of lung tissue is seen ---> consolidation |
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Ultrasound
-limitations |
-experience
-can't see consolidation if attached to pleura |
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Blood work
-will this give you a perfect BRD diagnosis? |
-no
-CBC and biochem show little benefit in acute respiratory disease diagnosis |
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Blood work
-only significant finding |
-fibrinogen (will not predict pneumonia)
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Blood work
-problems with reference intervals |
-normal for adult middle-aged cows
-mature bulls ---> lower WBCs -calves ---> high GGT |
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Why is GGT high in calves?
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-high in milk and colostrum
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Infrared thermography
-function |
measure heat of dorsal planum
-calves with >10% consolidation 22.9C -calves with <10% consolidation 18.7C |
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Infrared thermography
-limitations |
-a lot of potential environmental confounders
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Advanced imaging
-best specificity |
Radiographs < CT < MRI
*none are perfect |
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Necropsy
-benefits |
-visual assessment
-histology -culture |
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How to diagnose and individual animal with BRD with everything at your disposal
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-excellent physical exam
-ancillary diagnostic tests as required |
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How to diagnose a population with BRD with everything at your disposal?
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-create a case definition (understand limitations)
- |
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What is important for being able to diagnose disease?
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-educate and be educated by staff
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Why are adult feedlot cattle with BRD different from calves?
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less pronounced:
-effort -nasal discharge -ocular discharge |
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What age group of cattle should you practice physical exams on?
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-adults
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