Clinical Pathology Chapter 7
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- It is sometimes necessary to treat an anemia with blood replacement therapy (blood Transfusion)
- In giving a blood tranfusion, it is necessary to consider the possibility of Blood transfusion reactions related to RBC antigens.
- All RBC contain many different types of antigens on ther surface. (AB can receive AB+O)
- Some of these antigens are :blood group" antigens
- In humans, there are 3 basic groups/typs A,B, AB
- Type O is not a blood group per se; it is the absence of any other blood antigens (universal doner)
- Human Blood always contains antibodies (isoantibodies) against the antigens of the other blood groups.
In dogs, there are a total of 7 blood group antigens are called DEA (dog erythrocytic antigens)
These antigens are labeled DEA 1-7
DEA 1 antigens are broken down into 2 subgroups
- DEA 1.1 (40-40% of the dog population)
- DEA 1.2 (10-20% of the dog population)
The DEA 1 subgroup antigens (especially DEA 1.1) are the most important antigens because
they have strong antigenicity and cause the most serious problems during transfusion
Unlike humans, dogs do not have
naturally occuring antibodies to other blood groups, thus a first time incompatible transfusion when neither the donor or the recipient has had a previous transfusion is ok.
If the recipient or donor has been transfused before, one or both may have developed antibodies, setting up for a transfusion reaction.
If this happens what are the 2 possible consequences that could occur
- The recipient has antibodies that attack the donors RBC's
- The donor has antibodies which attack the recipients RBC's (usually a minor reaction)
Transfusion Reactions result in either
- Hemolysis (the primary reaction)
- Agglutination 9 RBC clump togehter)
Tranfusion Reaction of Hemolysis
Hemolysis is the breakage of RBC's in the bloodstream, leading tot he release of free hemoglobin into the plasma. It is the most significant of the transfusion reactions.
When the Tranfusion Reaction of Hemolysis is looked at under the microscope
- It is seen macroscopically as red plasma or serum (Hemoglobinemia)
- Often leads to hemoglobinuria
- Free hemoglobin severely damages kidney cells leading to renal failure
- Excess bilirubin produced by the liver also damages cells
When agglutination occurs
- RBC's are tied together (clumped) by their surface antigens and antibodies
- May only be detectable microscopically but can be seen macroscopically in severe cases
- Agglutinated cells in the bloodstream can clog small vessels and lead to blood clots
although all of the DEA antigens are capable of stimulating formation of antibodies,
DEA 1.1 and DEa 1.2 have the greatest stimulation potential.
Acute hemolytic transfusion reactions only occur in
DEA 1.1 and 1.2 Negative dogs. As these dogs do not have naturally occuring antibodies, a reaction will only be seen after sensitization of the dog through exposure to DEA 1.1 or 1.2 positive blood (antibody production takes 7-10 days after exposure.)
The normal lifespan of compatible transfusion erythrocytes in dogs is
approximately 21 days. In an acute hemolytic transfusion reaction, the lifespan of incompatible transfused erthrocytes ranges fro minutes to 12 hours.
Although DEA 3-, 5- , and 7-negative dogs can develop antibodies to DEA 3,5, and 7 positive red cells, these blood groups do not
incite severe hemolytic reactions. Rather, transfusion of incompatible blood is hemolyzed more rapidly (within 4 to 5 days than compatible blood would be (so-called delayed hemolytic reaction)
DEA 2,4,and 6 are clinically insignificant as to transfusion reaction.
Ideally all transfused blood would be
- DEA 1.1 and DEA 1.2 negative ( no antigens)
- Certain breed are particularly suitable as blood donors because there is a low frequency of DEA 1.1 and DEA 1.2 antigens in this breed. Large number of Labrador retrievers, on the other hand, are DEA 1.1 positive.
It is estimated that what percentage of dogs are DEA 1.1 positive
40-60% of all dogs are DEA 1.1 positive. Identifying a particular dog as DEA 1.1 positive or negative at birth greatly simplifies future transfusions and or breeding decisions.
A DEA 1.1 positive dog can receive
both DEA 1.1 positive and negative blood. A dog that is DEA 1.1 negative should not receive DEA 1.1 positive blood.
Antibodies may develop in bitches resulting from a transfusion of incompatible blood groups.
Since antibodies are present in the colostrum, bitches with isoantibodies to a given blood type should
not be bred to a sire possesing that blood group if they are expected to nurse the resulting puppies.
Isoantibodies- an antibody that occurs naturally against foreign tissues from a person of the same species.
The nursing puppies will develop
isoerythrolysis and may be susceptible to disease or even die due to hemolytic anemia.
When do u blood type for cats?
What are the 3 blood antigen groups
- A, B, AB
- Similar to but not identical to humans.
Most cats posses the
A antigen, but about one third of those have naturally occuring, low-titered, anti-B antibody.
87% of domestic cats are blood type A
All type B cats have a naturally occuring, highly tittered anti-A antibody. Cats with B erythrocytes will exhibit
an immediate and catastrophic systemic anaphylactic reaction when transferrewith the A blood because of their naturally high tittered anti A antibody.
Reactions signs include
apena, ion, vomiting, severe neurological depression, as well as hemolytic signs (hemoglobinemia and hemoglobinuria)
Those cats with A erythrocytes and natural low- titered anti B antibody will exhibit
only a mild reaction when transfused with the B blood, but even this can make a difference in recovery rates in a medical situation and the transfused erythrocytes have a short life span.
Cats with type AB blood
Do not develop transfusion reactions based on type A or type B incompatibility, and can receive either type A or type B blood.
What is feline Neonatal Isoerythrolysis
- A recognized cause of fading kittens in pedigree cats is neonatal isoerythrolysis, where kittens have a different blood type from their queen, and , on suckling her milk, receive antibodies against their own red blood cells.
- the destruction of the cells will cause jaundice, brown urine, and rapid death.
Where do cats get the two genes from
One from the mother (in the egg) and one from the father (in the sperm).
The genes from blood type A are
dominant over blood type B.
Animals can be crossmatched to determine if the donor or receipient has antibodies against the other's RBC antigens.
A Major crossmatch tests
whether the recipient has antibodies against the donor.
a minor crossmatch test
whether the donor has antibodies against the recipeint
Major and miner crossmartching may be done by
manual separating samples of the donor and recipient serum and cells, washing the cells with saline, then exposing each to the opposing serum.
a reaction is accuring when
Hemolysis and /or agglutination is visibly apparent in te tubes.
Cross Matching procedure
Slide one- Donor control. Place one drop of donor plasma and one drop of donor RBC. Should show no agglutination.Slide two- Recipient control. Place one drop of recipient plasma and one drop one drop of RBC on glass slide. Should show no agglutination.Slide Three- Place one drop of donor plasma and one drop of recipients RBC, minor CrossmatchSlide Four- one drop of recipients plasma and one drop of donor RBC- Major crossmatchGently rock slide side to side. Examine for agglutination or clumping on slide with cover slip under the microscope at 40x. Incompatible blood will show agglutination.
Saline Slide Agglutination test is used to diagnose
- Ammune Mediated Hemolytic Anemia
- Place one drop of saline solution and one drop of RBC from LTT and rotate side to side.
- The blood typing cards (rapid Vet-H) identify DEA 1.1 positive and negative dogs and for blood types A, B, and AB in cats.
- To do this you Place one drop of diluent in each well.Dispense one drop Positive control in positive Control well.Stir well for 10 seconds using a new stirrer for each one. Dispense one drop negative control in negative control well.Stir that well for 10 seconds using a new stirrer. Dispense one drop patient sample in patient well with pipetteStir that well for 10 seconds using a new stirrer. Pick the card up and rock and tilt by wrist action for 2 minutes. Position card at a 30-45 degree angle.
- If the test was run correctly, visible gross agglutination should have occurred in the well marked Positive Control.
- If the patient sample shows gross agglutination, the patient is DEA 1.1 positive.
- If no agglutination is visible, the patient is DEA 1.1 negative.
What is Biopsy
- refers to teh removal of a small or large solid piece of tissue.
- for the purpose of establishing a diagnosis via histopathological examination.
A biopsy sample must be fixed in
10% formalin for 24 hours and requires and extensive and complicated processing (>12 hours)
A cytology smear refers to the removal and examination of a group of
- cells from a living animal for the purpose of establishing a diagnosis.
- Samples are smeared on a slide and stained: no processing
- Commonly read by practicing veterinarians
- Lsee accurate but is fast, easy and low cost
Several collection procedures
- Imprints - pressing exracted tissue on a slide for the purpose of obtaining cells
- Scraping- scraping the lining of a structure with an instrument for the purpose of obtaining cells.
- Swab- using a swab or similar device to ontain fluid and secretions which then can be used to make a smear.
Another way to collect specimens is to
- Aspiration- Inserting a hollow needle into a cavity or organ for the purpose of removal of some portion of the contents (fluid, bone marrow, tissue)
- Using a 22-25 gauge needle with 6cc or 12cc syringe. Needles larger than 20 gauge cause blood contamination.
- Insert needle into mass. Avoid the center of the mass.
Staining- After slides are smeared they should
- be air dried completely.
- You should always make 3-4 smears of the same sample, staining two, and keeping the other two unstained in case you want to stain them differently later.
A staining technique
- wright stain
- Gives the best nuclear detail
- Requires multiple steps and considerable time
Identification of bacteria
It's used as a
- predicter of "fertile time" and gestation days in dogs.
- Changes in epithelial cells, along with the presence or absences of other elements like Neutrophils, RBC's and bacteria, help determine which phrase of the estrous cycle a bitch is currently experienceing.
Preparing a vaginal smear
slow rises in estrogen and a sudden spike in lutenizing hormone define the various estrous periods.
Anestrus is characterized by
a predominance of intermediate, round nucleu with basophilic cytoplasm with irregular shaped walls and primarily parabasal cells, large nucleus to small cytoplasm. Superficial cells (cornified cells) are absent or found in very small numbers. Neutrophils are usually absent but may be present in very small numbers.
As serum concentration of estrogen rise during proestrus, it leads to capillary breakage and leakage of red blood cells trhough uterine epithelium, as well as proliferation of the vaginal epithelium. Examination of vaginal smears from the early to late proestrus will reveal a gradual shift from intermediate and (very little) parabasal cells to superficial cells. Typically, red blood cells are present in large numbers and Neutrophils are commonly observed. Large numbers of bacteria are also often present.
The defining characteristic of cytologic estrus is the predominance of superficial cornified cells. Most, but not all, bitches will undergo full cornification, and the smear will reveal a monotonous pattern composed almost exclusively of anucleate superficial cells.
The onset of diestrus is marked by the precipitous decline in the number of superficial and reappearance of
intermediate and parabasal cells. Most commonly, the cellular profile changes within a single day from essentially 100% superficial cells to less then 20% superfiical cells. The significance of identifying the onset of diestrus is that it is a considerably more accurate predictor of the time of ovulation, and hence gestation length, than sexual behavior. Dog's ovulate 5-7 days prior to te onset of diestrus. (7-9 days after the preovulatory LH surge) and hence, gestation length is usually 57+ 1 day from the onset of diestrus day one.
P arabasal cells
- Round small cells with a large nucleus to cytoplasm.
- Diestrus and proestrus, primarily anestrus
- Round and irregular cells with smaller nucleus to even cytoplasm
- 2-3 times the size as parabasal cells
- seen in all stages but estrus
- large irregular shapes with small nucleus and all large cytoplasm.
- Seen primarily in Estrus
- Cells grow from immature parabasal cells to superficial adult cells.
parabasal and intermediate cells, few RBC and no neutrophils. Primary parabasal cells
Primarily intermediate cells, some parabasal, but large amounts of RBC, neutrophils and bacteria.
Superficial cells with no RBC, neutrophils or bacteria
Return parabasal, intermediate cells with few RBC
- Identification of Primary cell type
- Acute vs. sub-acute vs. chronic
- Suppurative (pus), pyogranulomatous (Monocytes increase), granulomatous Eosinophilic (eosinophils)
Neoplasia is a cancer
Benign Vs. Malignant
- Identification of disease- causing organisms
- Bacteria, fungi mites
- Suppurative- 85% neutrophils (infectious)
- Pyogranulomatous - mixture neutrophils, macrophages and lymphocytes (F.B Fungal infections)
- Eosinophilic - 100% Eosinophils (hypersensitivity, MCT)
Neoplastic Cell Types
- Benign- adenoma
- Mammary gland adenoma
- malignant- carcinoma
- Mammary carcinoma, pulmonary carcinoma, etc.
Connective Tisssue Tumors-Sarcoma
- Malignant - "sarcoma"
- Round cell sarcomas
- Mast Cell Sarcoma Basophils
- Spindle cell sarcomas
- Hemangiosarcoma (is a malignant cancer of the cells that form blood vessels)
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