POS Flashcards
What is hematocrit
Hematocrit also known as Packed cell volume is a measure of the total amount of RBC’s in the blood. MCHC (Mean cell hemaglobin concentration)
What does MCV stand for
Mean cell volume is a measure of the volume of red blood cells. When RBC count is low cells can be characterized into: normocytic (Mild non regenerative anemia - acute haemorrhage), Microcytic (Extra division of RBC due to Fe defeciency) or macrocytic (Polychromatophils - large purple immature RBC’s, contain ribsomal RNA)
What are the two types of anemia
Regenerative - either haemorrhage or haemolysis
Non-regenerative - Anemia of inflammatory disease/chronic disease, chronic renal failure or Decrease of BM production
What are reticulocytes
Seen with a new methylene blue stain, RNA precipitation. Same as polychromatophils.
What are the signs of regeneration of a smear
Polychromasia
Nucleated RBC’s
Codocytosis (Mexican hats)
What is Leukemia and what are the two types
Leukemia is neoplasia of the WBC’s. Can be acute or chronic. Can be of myeloid origin ( from bone marrow) causing faulty basophils, neutrophils or eisinophils. Can also be of lymphoid origin affecting the production of lymphocytes. enlargement of LN’s would be seen.
What do you use to conduct a biochemistry profile
Serum. Plasma contains anticoagulants that interfere with the test.
What is azotemia
Increase in Nitrogenous waste in circulation
What are the different methods of enteral feeding
Orogastric feeding tube - not tolerated by small animals, only used for neonates
naso-oesophageal feeding tubes - most common in practice. can be done under local anesthetic. However diameter of tube is small so only liquid based diet
oesophagostomy feeding tube - tube directly in the oesophagus. well tolerated by animal and has a wider diameter so can give significant amounts of food.
Percutaneous Endoscopic-Guided Gastrostomy Tube - needed when the oral cavity and oesophagus need to be bypassed. usually for long term cases lasting months.
When is fluid therapy necessary
Hemorrhage Diarrhoea & vomiting Polyuria Sequestrial fluid Hypovalaemic shock General anesthesia Azotaemia ( increases GFR which increases removal of renal toxins)
What are crystalloid fluids and the different types and when they would be used
Water with small molecules that can move freely out of intravascular space.
Isotonic - 0.9% Nacl. distributed evenly between compartments. suitable for shock diarrhoea, diuresis & anesthesia. Complications when too little or too much given
Hypertonic - 7.5% Nacl, draws fluid from interstitium and extracellularly into the intramuscular compartments. Rapid resuscitation with patients in shock. low dose required and can also be used with cerebral oedema. however needs to be followed up by other fluids. Can’t be used with dehydrated patient and can only be used once
Hypotonic - 0.5% Nacl. Only useful with hypernatraemic patients.
What are synthetic colloid fluids and what are their purpose
Consists of water with and large molecules (gelatin and starch) that are used to treat hypovalaemic shock and restore circulating volume. Generates a colloid osmotic pressure –> delays equilibrium of fluid with other compartments. Useful for resuscitation of intravascular volume. possible complications arise when theres dilution of platelets and clotting factors –>coagulopathy
What is mannitol used for
Shifts fluid to the intravascular compartment to be excreted by the kidney. Used for head trauma when theres an increase in intracranial pressure & acute glaucoma.
What is paraentral feeding and what is total and partial PN.
Paraentral feeding is the feeding via fluids via iv. TPN contains 100% of required energy requirements via the jugular vein and Partial paraentral nutrition contains 40-70% energy requirements met
What is the first broad spec anthelmintic group, whats its mode of action and why is more potent in some species
Benzimidazoles (white drench)(E.g Fenbendazole). Decreased oral availability therefore oral only drug. Binds to tubulin of parasite inhibiting glucose uptake causing glycogen depletion and death.
Activity covers adult worms, larvae and arrested larvae & lungworms. Multiple small doses has a greater potency than single large dose. Also hgiher potency in horse/cow as the caecum & rumen act as reservoir
What is the second broad spec group of anthelmentics, whats its mode of action
Imidazothiazines (yellow drench)(E.g levamisole). Cholinergic agonist, causing a spastic paralysis due to neuromuscular junction overload.
Very short half life. available as injection, oral or pour on with the latter having the longest residual action (24hours)
What is the third broad spec anthelminitic drug group, whats its mode of action, what does it act against and why can it be used metaphalacticly and prophylacticly
Macrocyclic lactones (clear drench)(avermectins). Opens specific glutamate chloride channels in the post synaptic membrane causing a flaccid paralysis.
Broad spec killing gut worms (including arrested larvae), lungworms and arthropods. Has a persistent effect so therefore can be used in 2 different ways.
a) Metaphylaxis - treating animals going out on to dirty pasture (minimise EXPECTED outbreak of disease)
b) Prophylaxis - Prevent initial contamination of pasture (prevent disease)
What is praziquantel
Anthelmintic that acts by disrupting tegument of the helminth altering permeability, causing an iniflux of calcium ions causing muscle spasms. Causes worm to release gut wall and then is digested.
What are the possible reasons for anthelmintic treatment failure
Under dosing Poor treatment technique Use of incorrect drug Underestimating body weight Inadequate maintenance of equipment Reintroduction onto heavily contamintae dpasture Resistance Failure to follow manufacturers guidance
What is the problem associated with anthelmintic resistance
By time Anthelmintic resistance is detectable the allele frequency is >25% and resistant parasite population is >5% & by time clinical failure of anthelmintics the allele frequency is >50% and resistant parasites is >95%
How can anthelminitic resistance be measured
- Drench test - Anthelmintic treatment to a group of animals & F.e.c of 10 samples post treatment
- Fecal egg count reduction tests - Comparing f.e.c before and after treatment with untreated controls. Resistance is indicated if treatment doesnt reduce F.e.c by >95%
What is ‘COWS’ and what are their guidelines
Control of worms sustainably
- Work out a Strategy
- Treat cattle in quarantine & turn out onto dirty pasture (polution)
- Test for Anthelmintic resistance on farm
- Administer wormer efficiently
- Dose only when needed
- Select appropriate wormer
- Preserve susceptible worm population (Refugia). Some calves are left undosed. This allows them to produce eggs of susceptible worms, diluting the population of resistant ones. Also resistance can come at a cost of fitness, therefore can be out-competed by susceptible worms.
- Reduce dependence on worming. Use grazing management, targeted treatment by F.e.c & quarantine appropriate stock
What is an antigen-specific antibody used for and give 3 examples
Can be useful when determining: Exposure of an individual/herd to a specific pathogen (BVDV), response to vaccination and diagnosis of antibody mediated hypersensitivity.
- ELISA - Can be used to detect antigen or antibody. Generally if infection had occured in <7days then will look for infectious organism whereas >7days will look for antibodies. So if testing for antigen will have serum antibodies added to well with known antigen, enzyme linked antibody will then bind to any antibody-antigen complexes causing substrate change.
- Immunofluorescence - Same principle as ELISA except instead of enzyme linked antibody will have fluorecent marker.
- Virus neutralising assay - Culture cells deliberately in the presence of virus in question, with and without presence of serum. If patient has no Ig’s then cells become infected and will either be lyses (cytopathic viruses) or will show cytopathic effects. The virus neutralising titre is the greatest dilution in which serum prevents the cells from becoming infected. An advantage of this is that it shows the Ig’s are biologically active
Explain and allergy test
A serology based test measuring allergen specific IgE. A labelled recombinant Fc-epsilon receptor to detect atopic dermatitis or flea allergic dermatitis.
Important to detect specific IgE and not any other antibodies because the reactivity of another Ig wouldnt necessarily indicate a hypersensitivity, therefore giving a false positive.
What is serum protein electrophoresis used for diagnostically
Can tell you if theres a monoclonal gammopathy (Large narrow increase, myeloma) or polyclonal gammopathy (wide peak indicating multiple proteins and a chronic infection)
How can you evaluate T cell responces
- Invitro can be measure by measuring cytokine release following stimulation by specific antigen (bovine IFN gamma ELISA).
- Can be measure invivo by performing a delayed hypersensitivity test. this is the basis of bovine TB testing in uk. ( single intradermal comparative cervical tuberculin)
How are antibodies used as detection reagents
Used to detect pathogen in an clinical sample.
a) Sandwich ELISA (faecal/biological fluids)
b) Immunofluorescence (smears/tissue sections)
c) Immunohistochemistry - tissue section on slide, then an enzyme labelled antibody against the cell surface markers.
What is immunophenotyping
Antibodies against cell surface markers can be used to determine cell types present. Can be done on cells in suspension by flow cytometry. An example if this could be a LN aspirate from a dog with lymphoma, determining the cell lineage the cancer
What biochemistry results (enzymes) would indicate damage to the liver
ALT, AST, SDH, GLDH are all directly leaked from hepatocytes and indicate damage or necrosis.
ALT and AST are low in large animals so GLDH and SDH are more reliable indicators. AST and ALT also increase due to muscular injury. (therefore creatine kinase can be used to differentiate muscle damage)
ALP is derived from bile duct epithelium and indicates cholestasis when increased. Also increases in growing animals because its found in bones. steroids can induce increase of isoform in DOGS, any increase in cats is significant, often indicating hyperthyroidism or hepatic lipidosis
GGT is derived from bile duct epithelium. More sensitive indicator of cholestasis in large animals as ALP has wide range.
What biochemistry results would indicate dysfunction of the liver
Bilirubinuria - in the dog, the kidney can metabolize a small amount of haemoglobin into bilirubin, so a reading of +2 can be normal. However in cats and positive reading indicates liver disease as conjugated bilirubin has exceeded renal threshold.
Urea decreases with liver disease
Cholesterol - Increase with cholestasis and decrease due to hepatic failure.
Bile acids - Endogenous test that involves measuring fasting levels and postprandial levels, as the bile acids should be stored in the gall bladder, released after feeding and then undergo enterohepatic recycling. An increase in bile acids shows one of two things, a) decrease in excretion of bile due to obstructive cholestasis or b) decreased bile acid clearance from portal blood due to portosystemic shunt.
What are the 3 main parameters looked at with effusion fluid collected & what are the normal for each
- Total nucleated cell counts (<3 x 10e9/L)
- Cell identification & morphology (mesothelial cells/macrophages)
- Protein concentration (25-30g/L)
Define transudate
Clear water like fluid with Low protein and low cellularity. total protein <25g/L, TNCC <0.5 x 10e9, and mesothelial cells, macrophages and low number of non-degenerate neutrophils can be seen.
Thought to be due to decreased colloid osmotic pressure from hypoalbuminemia (which is due to glomerular or hepatic disease).
Hepatic fibrosis/cirrhosis will cause prolonger portal hypertention and the formation of secondary collateral circulation. Local vasodilators released (NO), causing vasodilation and decreased effective blood flow. Also compounded by Renal retention of Na due to RAAS, End result is expansion of plasma volume and leakage of low protein lymph from intestines.
Define modified transudate
A yellow serosonguinous fluid. Amount of protein is variable (25-50g/L). can expect a TNCC of 0.3-5.5 x 10e9. Cells present will include macrophages, neutrophils, mesothelial cells & small lymphocytes.
Causes include:
cardiac disease causing congestion and an increase in hydrostatic pressure (especially in hepatic sinusoids)
leakage of protein rich lymph
chylous effusions
Define exudate
Turbid fluid thats white/yellow/red. Has high TNCC (3.0 x 10e9) and high total protein (>30g/L). Cells present include macrophages, neutrophils (degenerative and non-degenerative), lymphyctes and eosinophils.
Caused by inflammation of the pleural or abdominal cavity. Can be septic (degenerate neutrophils present and intracellular bacteria) cause or non-septic ( Non degenerate neurtophils and no bacteria e.g FIP)
Describe properties of a hemorrhagic effusion
turbid red.
Total protein >30g/L.
TNCC 1.5-10 x 10e9
Cell types dependent on the type of haemorrhage
An ongoing/iatrogenic haemorrhage will have erythrocytes and platelet clumps present
An acute haemorrhage will have erythrophagia, where macrophages can be seen with intact or partially digested RBC’s inside.
With a chronic haemorrhage siderophages (haemosiderin containing macrophages) can be seen along with haematoidin (orange-yellow pigment)
What are the modes of action or antibiotics with examples of each
> Inhibition of cell wall synthesis - Penicillins & cephalosporins
> Inhibition of cell membrane function - Polymxins imidazoles
> inhibition of protein synthesis - Chloraphenicol, macrolides, linocosamides, tetracyclines and aminoglycosides
> Inhibition of nucleic acid synthesis - Sulphonamides, quinolones and metronidazole
What bacteria are present in the following areas: oral, liver, lungs, GIT, urinary tract and skin
Oral - Gram -ve and anaerobes
Liver - Gram -ve, anaerobes and staphylococcus
Lungs - Gram -ve & +ve, and atypical (e.g mycoplasma)
GIT - Gram -ve & anaerobes
Urinary - Gram -ve & staphylococcus
Skin - Staphylococcus
What is minimum inhibitory concentration
Lowest concentration of drug that will inhibit bacterial growth
Describe a bacteriostatic drug and give examples
Effects are reversible once drug is removed. Drug concentration at site of infection must be maintained above MIC throughout dosing interval (therefore adherence to the dosing schedule is key) Examples include: > Chloraphenicol > Lincosamides > Macrolides > tetracyclins
What are the two types of Bacteriocidal drugs with examples
- Time dependent - Time above MIC over a 24hr period determines therapeutic success. Thus dosing regime must be followed, also can’t be used with bacteriostatic drugs. E.gs include penicillins and cephalosporins
- Concentration dependent - Peak concentration under curve predicts the therapeutic success. Can be given once a day. E.gs include Aminoglycosides, Metronidazole & Fluoroquinolones
What antibiotics are recommended for atypical bacteria
Atypical bacteria include mycoplasma and chlamydia.
Tetracyclins are the most commonly selected, Macrolides, fluoroquinolones and chloraphenicol can also be used.
Describe pharmokinetic considerations when administering antibiotics and which areas are hard to treat
Distribution of the drug is dependent on the perfusion of that specific tissue. However some tissues have permanently limited drug distribution due to lipid membranes, E.g > Brain > Eye > Prostate > Bronchus > Blood-milk > intracellular
When is surgical antibiotic prophylaxis justified & what class of antibiotic would you recommend
> With high risk dental procedures > Patient with leukopenia > Contaminated surgery > Orthopedic surgery or any major Abdominal/thoracic surgery > Surgical time >90mins
To achieve maximum effect drug must be present at the time of contamination. Likely pathogens from skin (staph) and intestines (anaerobes & gram +ve).
1st gen cephalosporins good choice (if no risk of GI contamination) or 2nd gen (off label)
Why must maximum withdrawal times always be used
Withdrawal times are calculated on healthy patients. With sick patients possible to have decreased clearance & half life, therefore maximum withdrawal is recommended
What is maximum residue limit
MRL is the maximum concentration of residue accepted in EU food product that have received veterinary medicine.
Which antibiotics can not be used on farm animals
> Chloraphenicol (can be used on horses bust document it in the passport to prevent animal going into food chain) - causes aplastic anaemia in humans
Phenylbutazone - aplastic anaemia
Metronidazole - carcinogenic
Will be struck off if used
What 4 ways can bacteria be resistant to antimicrobials
- AM cant reach target due to decreased penetration into the bacterial cells
- AM expelled by special efflux pumps
- AM inactivated by modification before or after cell penetration
- AM target modified or protected by another molecule
Give an example of intrinsic resistance in bacteria
Gram -ve bacteria are resistant to macrolides as their to large to cross the cell wall and gain access to cytoplasmic target
What are the three VFA’s and how are they affected by PH changes in the rumen
Acetate - Predominates at high roughage diet and is the precursor for milk fat
Propionate - Predominates at high concentrate diet and provides energy via conversion to glucose in the liver
Butyrate - Provides energy to the rumen wall and used for body fat
Rumen normally maintained at 6-7 PH, when lowered causes an increase in the propionate:acetate ratio causing decrease in milk fat.
How is cow comfort measured
Approximately 85% of the herd should be laying down 1 hour before feeding.
What is target milk fat and what would a low milk fat in the bulk tank indicate
Ideal is 4.2%. Altered by an increased propionate:acetate ratio caused by increased concentrates. Could indicate SARA
What is the target milk protein and why might it fall
3.4% is ideal. Milk protein is due to overflow of bacteria in the rumen into abomasum. must be sufficient energy to allow bacteria proliferation. After periods of inadequate intake possible for milk protein to fall, difficult to correct quickly
