w/c 23/June/14 Flashcards
Immune mediated disease can be organ specific or non-organ specific. Examples of each
Organ specific: Myasthesia gravis, IM neutropenia Non-Organ specific: Systemic Lupus Erythematosus
Role of infection in immune-mediated disease
Infection is thought to influence autoimmune disease at several levels. -> Break-down of vascular or cellular barriers, allowing exposure of self-antigens. -> Promotion of cell death by necrosis causing inflame = bystander activation -> Molecular mimicry = cross reactivity
What is by stander activation
Promotion of cell death by necrosis, causing inflammation
Vasculitis often characterises what type of IM disease
Non organ specific
Blood smear of 5 YO Neutered female dog that presents with lethargy and PCV of 20%
PCV for dog should be 37-55%
Blood smear shows Spherocytes (extra vascular haemolysis)
Ghost cells (intravascular haemolysis)
Polychromatosaia = reticulocytes = regenerative
= IMMUNE-MEDIATED HAEMOLYTIC ANAEMIA
Coombes Test
- primary reagents
- problems with test
If acute IMHA is suspected
Normally sent away test.
Primary Reagent: Polyvalent anti-dog or anti-cat IgG, IgM and C3 antiserum (direct antiglobulin test)
FALSE NEGATIVES AND FALSE POSITIVES CAN OCCUR
If ulcer that you suspect is due to underlying IM disease. Appropriate test =
Biopsy ACROSS inteface with normal tissue not just middle of ulcer/
Antinuclear antibody test =
Indirect immunofluorescence or immuno-peroxidase test.
Hep-2 cells
Which vinca alkaloid is sometimes used for the treatment of IM thrombocytopenia
Vincristine and Vinblastin are Vinca alkaloids that bind to tubulin, blocking polymerisation also break down newly formed microtubules- increased release of PLTs from megakaryocytes.
WATCH TOXICITY: GI, neurological
In which part of the cell cycle do the following drugs work a) vinca alkaloids b) calcineurin c) corticosteroids
a) Vinca Alkaloids: M phase
b) Calcineurin: G1
c) Steroids: S phase
Azothiaprine summary
Greater decrease of cellular than humoral immuinity.
Hepatic metabolism
Therapeutic index of Chlorambucil
Narrow therapeutic in cats.
Slowest acting, least toxic of all alkalating agents.
Administered without food.
Start off treatment for IM disease as prednislone, if IMHA or aggressive IM disease consider what adjuvant treatment?
Rickettsial/Protozoal infection: Doxacycline
If aggressive IM / IMHA consider adjuvant azothiaprine in dogs, chlorambucil in cats.
If dog with IMHA is on prednisalone and chlorambucil how do you go about tapering dose down
CBC and UA should be monitored every 7-14 days.
Corticosteroids should be tapered over 3-4 month period following remission.
20% decrease every 4 weeks.
DO NOT ALTER ADJUNCTIVE Rx at same time!!
Steroids may be stopped all together if clinical remission persists.
What is different about RBC in camelids?
Camelids have ellipital RBC’s.
Anucleate in mammals but nucleated in birds and reptiles
RBC sites of production
Liver/ Spleen in foetus
Swaps to bone marrow in neonates
Growing animals: Marrow of all bones
Life span of Erythrocyte in a) dog b) cat c) horse/cow
a) dog: 100 days
b) Cat: 70 days
c) Dog/Horse: 150 days
What is the difference between haematocrit and PCV
Both same information but Haematocrit (HCT) calculated by machine.
Hamatocrit is less acurrate.
Microcytic rbc’s indicitive of
PSS, Fe deficiency, hepatic failure.
AKITAS
Macrocytic RBC
In regeneration- polychromatophils.
Some poodles
Also in FeLV affected cats
Myelodysplasia
Common artifact in stored blood
Difference between reticulocytes and polychromatophils
These are the same cells.
Reticulocytes: Stained with New Methylene Blue, RNA precipitates forming aggregates
Polychromatophils: Diff-quick stain= larger bluer cells
Why should reticulocyte count be corrected
The same number of reticulocytes will take up a larger percentage in a very anaemic animal.
Reticu % x patient PCV/normal PCV
Regenerative if >1% corre in dog.
>0.4% corec in cat
Can do faecal occult blood test if Melena is not obvious. What do you need to do to avoid false positives
Meat free diet for 5 days otherwise test will be positive.
High sensitive, not very specific.
Immune mediated haemolysis pathogenesis
Anti red cell antibodies (IgM, IgG, IgA)
Lysis of red cells more common with IgM but IgG and IgA = phagocysed.
How to differentiate Rouleaux from Agglutination
Royleaux: Start repelling each other = ‘stack of coins’ - normal finding due to shape of RBC. Can be due to disease
Agglutaintion= Grape lke structure (1 drop saline + 1 drop EDTA)
Ghost cells
Repnants of RBC that have lost haemoglobin.
Membrane only.
Associated with deposition of complement and intravascular haemolysis
i.e. red plasma = indicitive of intravascular haemolysis
Spherocytes identification
Central pallor is normal due to biconcave shape.
Spherocytes are smaller in diameter and darker (lots of Hb)
Indicitive of extravascular haemolysis
Increased bilirubin is more indicitive of intra/extra vascular haemolysis?
Inc bilibubin is more indicitive of extravascular haemoylysis
May have neutrophillia/monocytosis (due to marrow upreg)
Diagnosisd of Mycoplasma haemofelis
Diagnosis: PCR- excellent
Blood smear: NOT RELIABLE/
Babesia pathogenesis
USA>UK
Tick borne disease
Pyriform bodies in red cells.
Treatment: Imidocarb.
V. severe if not diagnosis
TRAVEL HISTORY?
Heinz body formation
Denatured haemoglobin = Heinz body.
Cats more vunerable than dogs.
Low Numbers UNREMARKABLE IN CATS.
Oxidative injury (onion, paracetamol, prop glycol, vit K)
When would you expect horses to have Eccentrocytes
Haemoglobin has uneven distribution within the cell = eccentric distribution.
Seen most in dogs but due to oxidative damage
HORSES WITH RED MAPLE TOXICOSIS
Schistocyte
Shear injury product: Schistocytes/Keratocytes
i.e. Tumours (narrow vessel)
Haemangiosarcoma
Acanthocytes
Surface projections of variable length.
Projections are uneven spaced on surface.
Associated with splenic disease (haemangiosarcoma)
Causes of non regen anaemia
Kidneys: Norm produce EPO (CRF = Decreased production)
EPO injections (may develop antibodies)
Endocrine (hypothyr, hypoadren)
FeLV (70% anaemic cats)- subgroup C
Aplatic Anaemia
All precursors wiped out = ALL CELL LINES. platelts, granulocytes etc
Fat, plasma cells, mast cells are left.
Need core biopsy.
OESTROGEN TOXICITY? Testicu tumour
Phenobutazone
Leydig cell tumour =
Think derm (alopecia) as release +++ oestrogen
Also non regen anaemia due to oestradiol tox on bone marrow
How does storage of blood and smears differ?
Blood= store in fridge until anaylsis
SMERARS= STORED AT ROOM TEMP
How does the Signalment help refine cause of anaemia
Young animal: Lower PCV than adults anyway but more like parasitic
Old animal: Bleeding tumours?
How long does it take to develop a regenerative anaemia
3-5 days.
Check for polychrosia (diff quick) , corrected reticulocyte (new methyle blue, RNA precipitate) count
If Haemorrhage is susepected as the cause for the regenerative anaemia then what further tests would you do
Platelet count (manual)
Diagnostic imaging (thoracic/abdo)
Faecal lungworm
ACTH stim tests (if melena)
Abdo/ Pleural fluid sampling
Why would you do a ACTH stim test for cases where you suspect haemorrgage (e.g. melena)
Gastrointestinal hemorrhage. Melena and/or
hematemesis have been reported in both typical
and atypical Addison’s cases. Gastrointestinal
ulcers may form as a result of the hypovolemia
due to aldosterone deficiency (poor perfusion
and vascular stasis within the intestines)
If Haemolysis is suspected what further tests (for cases of regen anaemia)
Urinalysis - bilirubin? Haemoglobinura (with intra vascular haemoylsis may cause renal damage)
- Screen for tick bourne disease, Mycoplasia (cats)
When would bone marrow biopsy be most indicated
Bone marrow aspirate / core biopsy are most indicated if no underlying cause has been found and there is moderate->severe anaemia
OR if more than one cell line affected
Poor prognostic indicates for IMHA are…
Young to middle aged Cockers, Springers, Bearded collies.
Females >Males
Prog Guarded, esp if haemoglobinaemia.
Pulmonary thromboembolism occur as complication.
CAN occur secondary to neoplasia, infec, drug treatment.
Primary INHA in cats is rare but can occur.
Decrease in what element can cause haemolysis
Hypophosphatemia can cause haemolysis.
Also shear injury
Meylophtiasis
Neoplasia.
Bone marrow is crowded out by neoplastic cell lines such as lymphoma, multiple myeloma, leukaemias, mast cell tumours.
Intravascular haemolysis is normally Ig_ mediated
Extravascular haemolysis is normally Ig_mediated
Intravascular: IgM (poss IgG)
Extravascular: IgG
Examples of Inherited haemolytic anaemias
Pyruvatekinase (PK) deficiency
Phosphofructokinase (PFK) deficiency
Why would you consider asprin/clopridogel in combination with prednisalone + azothiaprine (NOT CATS) in dog with IMHA?
Pulmonary thromboembolism is a common cause of death/ sudden onset dyspnoea in dogs.
Cats: use chlorambucil instead of azothiaprine
Common aetiology and sequalae for hypophosphataemia
Diabetic ketoacidosis
Leads to haemolysis and heamorrhage.
More common in cats.
Ideal weight for donor cat and dog
Cat: >4.5kg
Dog >25kg
Full biochem and haem repeated monthly
PCV/Total protein each donation
Vaccination but not <14 days before donation
Should not have previously had a transfusion themselves
Volume of blood taken for tranfusion (cats/dogs)
15-20% of estimated blood volume
Estimate blood volume: Dog: 80-90ml/kg
Cat: 55-65ml/kg
Dogs can donate every 3 weeks but analyse serum iron.
Canine donation procedure
12 hour fast in case of sedation and to decrease likelihood of lipaemic serum
Pre donation PCV/TP
Jugular
Try to collect over 5-10 minutes.
Max volume 525g (greater = risk of clot formation)
Feline donation procedure
12 hour fast in case of sedation and reduce risk of lipaemic serum
Pre donation PCV/TP
Sedation: Ketamine/Midazolam
Dog blood types, which one do we test for
Dog erythrocyte antigen 1,3,4,5,7
Test for DEA 1 as if DEA 1 +VE blood given to DEA 1 -VE patient sensitisation occurs (antibodies form) within 1-2 weeks
Can result in transfusion reaction
Can happen with all blood types but DEA 1 = most serious
Feline blood types
Type A, B or AB (RARE)
Cats have naturally occuring proteins to blood proteins they don’t have.
Why is testing ALL feline blood prior to transfusion more important than testing dog blood
Rare for dogs to have naturally occuring antibodies
Cats naturally have antibodies against alloantibodies to blood proteins they don’t have (A,B, AB)
Type AB cats can get either (but ideally AB, then A if not avaliable)
Most serious blood tranfusion reaction in cats occurs when
Type B cats recieving type B or AB blood = peracute sometimes fatal
Type A cats recieving type B blood = similar reaction in DEA-1 negative sensitised dogs
When is dog blood cross matching required
When recepient has been transfused mroe than 4 days previously.
There is a history of a transfusion raction
Receipients transfusion history unknown
Test for agglutination (blood typing)
Used in emergencys
Take serum + EDTA samples from donor AND recipient
Centrifuge for 5 min then seperate serum and plasma
Have 4 slides (donar control, major cross match, minor cross match, recipient control)
Positive agglutination = INCOMPATIBILITY
Negative agglutination = NOT A GUARENTEE BUT MAJOR REACTION UNLIKELY
Major / Minor crossing
Major cross: recipient antibodies to donon erythrocyte antigen
Minor cross; recipient antigen to donar antibodies
Volume of blood required to raise the recipient PCV by 1%
2ml/kg of blood raises the recipient PCV by approx 1%.
What anticoag is not used for auto-transfusion
Auto-transfusion is a last result.
Heparin should not be used as an anticoag as it has a long half life and causes platelet activation
Why should plasma not be frozen in a dometic freezer?
Needs to be at -30
Max for 12 months then factors start deterorating
If dometic freezer will start deterorating immediately
Only indication for plasma is ..
Provision of clotting factors (assessed using PT or PTT times)
Animals at risk of bleeding diathesis.
Used pre operatively in animals with inherited coagulopathies such as haemophillia A or Von Willebrands (USE CRYOPRECIPITATE- concentrated fraction of plasma)
Patients suffering rodenticide poisoning
Difference between Cryoprecipitate and Cryosupernatant
Cryoprecipitate: Conc fraction of plasma containing von Willebrand factor, factor VIII, XI and XII, fibrinogen.
Cryosupernatant: Contains vit K depedent clotting factors, albumin and antithrombin.
Rodenticide tox, vit K defi, hypoalbuminae
Blood products should be administered at what rate
Over 4-6 hour period.
NOT WITH HARTMANNS/SEPERATE CATHETER as calcium leads to crystal formation.
RATE: 0.5-1ML/KG/HR FOR first 30 mins then increased if no reaction
Most common transfusion reaction to FOREIGN PLASMA PROTEINS
Swelling of the face = angiodema.
Can also cause urticaria and erythema of the skin.
Tx: Antihistamine drops (chlorpheamine IV)
If worsens= steroids.
If rectal temp rises by 1 degree = stop transfusion
If compatible red cells are given the transfusion should last approx
4-6 weeks.
Example of a non-immunological transfusion reaction
Volume overload.
Most commonly cats as they have underdiagnosed cardiac abnormalities.
Seen as tachypnoea and crackles.
Jugular distension or detection of a new mumur.
Tx: oxygen and furosamide
TPR should be preformed every ___ minutes for the first hour of tranfusion and then
TPR every 15 minutes for first hour of tranfusion and then every hour afterwards
What endocrine condition do we need to monitor for if large volumes of blood are given
+++ CITRATE WILL CAUSE HYPOCALCAEMIA
Causes of haemorrage in horses (external blood loss)
- External wound involving large artery (prox/distal limb)
- Guttural pouch mycosis (erodes int. carotid artery)
- Post surgical haemorrhage (e.g. castration, can be internal haemorrhage but rare)
- GI parasitism (S. vulgaris)
- Haematuria (pyolonephritis, cystitis)
Which artery can sometimes rupture before, or more commonly after parturition in the horse (more common in older mares)
Uterine artery rupture- normally middle uterine artery.
Clinical signs: Sweating, colic, tachycardia.
Blood either lost into abdo cavity or retained within broad ligament
Immune mediated haemolytic anaemia in horses, pathogenesis
Primary: Uncommon autoimmune process
Secondary: Antibodies attach to RBC membrane because of alterations in RBC membrane because of primary infection, neoplasatic, or other immune medaited process.
Drugs
Treatment of of immune-mediated haemolytic anaemia
Discontinue all treatments if possible (consider feed supplements/additives)
Blood transfusion may be nec.
Immunosuppression (most commonly dextamethasone, prednisalone)
Red maple toxicity presentation
Horses= oxidative damage= Heinz body formation (precipitations of oxidatively denatured haemoglobin on RBC membrane)
Toxin found in wilted leaves can cause intravascular and extravascular haemolysis and methaemaglobinaemia (chocolate brown)
Treatment of Equine infectious anaemia
Exotic to the UK.
Caused by equine infectious anaemia virus (Lentivirus)
Persistant infection = no treatment.
Horses remain life long carriers
Anaemia due to chronic disease pathogenesis (3 things)
- Iron sequestration ‘anti-bacterial’ mechanism
- Defective erythropoeitin response
- Decreased RBC life span
TREAT PRIMARY DISEASE
Colostrum is mainly comprised of
Mainly IgG, some IgA and IgM.
Normal foals suckle within 1-3 hours after birth and consume 1-2Litres.
<4g/L of IgG = Failure of Passive Transfer
4-8g/L of IgG = Partial Failure Passive Transfer
Treatment of Failure of Passive Transfer
<4g/L = fpt 4-8g/l = Partial FPT
If foals less than 12-18 hrs of age = oral colostrum unless disease.
If foal is >12-18 hours old = IV plasma often 2L required
Neonatal erythrolysis can occur in what mares
Normally multiparous mares that have been sensitised to foals RBC’s antigens during preg.
CAN ALSO OCCUR IN MAIDEN MARES
- Foal inherits red cell antigens from sire, different from mare.
- Red cell must be strongly antigenic (Aa, Qa)
- Commonly mule foals (donkey sire x horse dam)
How must the mare be exposed to foals red cell antigen to for neonatal isoerythrolysis to occur?
- Transplacental haemorrhage
- Prior blood tranfusion
- During parurtiion
Antibodies against foals RBC are contained in mares colostrum
Foals develop signs first 4 days of life.
Treatment of neonatal isoerthrolysis
If 24-48 hours of age: Prevent further colostrum ingestion, plasma transfusion to establish plasma transfer of immunity (<4g/L = FPT 4-8g/L = Partial FPT_
Blood transfusion: Mare’s WASHED red cells (NOT PLASMA)
Normal PCV for a) Cattle b) Sheep
a) Cow: 24-46
b) Sheep: 27-45
Cause of haemolytic anaemia in farm animals
Leptospirosis
Postpaturient haemoglobinuria
Bacillary haemoglobinura
Protozoa
Chronic Cu poisoning
Cold water ingestion
Brassica poisoning (rape, kale, cabbage)
Autoimmune haemolytic anaemia
Drug induced
Causes of depressed erythrocyte production in farm animals
Deficiency of Cobalt or Cu
Iron def
Acute bracken posioning (enzootic haematuria)
Fasciolosis
Lymphosarcoma
Renal disease
Anamia of inflamm disease
Enzootic haematuria in farm animal
Acute braken poisoning.
= Depressed erythrocyte production
How does the type of Anaemia differ between a) Copper b) Cobalt ingestion
Chronic copper poisoning: Haemolytic anaemia
Copper and Cobalt DEFICIENCY = Depressed erythocyte production
Blood transfusion of adult cow
First transfusion should be safe.
5L required.
How to differentiate braken poisoning from pyelonephritis
Both cause haemtouria in cattle.
Enzootic haemturia= braken poisoning = most common cause in cattle.
Braken posioning will cause anaemia but pylenephritis may not cause anaemia
Causes of Abomasal ulcer
Sand
Displaced abomasum
Stress
Occult blood in faeces/ black dung
Free air in abdomen
Abdominal pain
Most susceptible breeds for chronic poisoning
Sheep more susceptible than adult cattle.
Calves moderately susceptible.
Texels and Suffolk most susceptible
Causes haemolytic anaemia
c.f. copper deficiency leads to decreased erythrocyte produ
Copper store
Texels/Suffolk most susceptible.
Copper is stored and accumulates in liver.
Some centrilobular necrosis occurs as liver copper conc rises.
At some point there is a sudden release of copper from liver into blood = acute fatal syndrome develops
Pathogenesis of Chronic copper poisoning
Chronic copper poisoning is an acute disease (sudden release from liver store) following chronic absorption and accumulation of copper.
Cause of Chronic Copper poisoning
The diet: Concentrates, Phytogenous (pasture), hepatogenous (liver damaged by PA)
-Accidental overdose (more likely ACUTE poisoning)
Levels >4 are required
Levels >12 may be dangerous dependent on breed (texels/suffolk parti predisposed)
CATTLE PIG FEEDS EXCEED THIS THEFORE CARE
Why should cattle and pig feeds NOT be fed to ewes
Chronic Copper poisoning
Levels >4 ppm required for normal health
Levels >12 ppm may be dangerous
Clinical signs: Jaundice, pallor, haemoglobinura
How should you test for imminent copper poisoning
Blood Cu levels only elevated after release from liver (following continual storage)
BIOPSY LIVER
Necropsy: Swollen yellow liver, gunmental kidneys, jaundice everywhere.
Treatment of Cu poisoning
Ammonium tetrathiomolybdate (ATM)
Somulose 10ml iv
Sodium Calcium Edetate
PREVENTION: kEEP Dietary Copper <10ppm
Cu absorption inhibitors (Mo,Zn, Fe and soil)
Avoid prolonged feeding of conc
Never feed cow/pig concentratates to sheep
