Unit 1 Flashcards
What is the Packed Cell Volume (PCV) (a.k.a. Hematocrit)
The percentage of blood volume that is composed of red blood cells rather than plasma
Where are red blood cells produced
bone marrow
What is the Total Protein (TP)
The quantity of protein contained in plasma. Under normal circumstances, protein is maintained in the bloodstream because protein molecules are larger than openings in blood vessel walls. If vessels are abnormal, protein can leak out of vessels.
What is the main function of the protein in the plasma?
is to influence fluid movement to maintain plasma volume within the vessels
What is normal PCV and TP in adult dogs and cats
Adult Dogs: PCV: 35-55%, TP: 5- 7 g/dl Adult Cats: PCV: 27-47%, TP: 5-7 g/dl (numbers can vary slightly depending on the population and laboratory, and will be lower in neonates and pediatrics)
When should you perform a PCV and TP test?
Any animal presenting for emergency care that is not completely healthy
What are causes of low PVC?
- Anemia (blood loss, red cell destruction, poor bone marrow production)
- Fluid overload
What are the causes of high PVC?
- Dehydration/ Plasma fluid loss
- Abnormal red blood cell production (a rare condition called polycythemia)
- Splenic contraction (The spleen stores RBC)
What are causes of high TP?
- Dehydration (fluid lost from plasma while protein remains)
- Excessive production of globulin protein (an immune protein)(Example: feline infectious peritonitis, chronic inflammatory disease)
Causes of High PCV with normal TP
- Normal for breed
- Splenic contraction
Causes of High PCV with low TP
Splenic contraction and/or dehydration with protein loss (this pattern characteristic for hemorrhagic gastroenteritis – a severe, acute GI bleeding disorder)
Causes of high PVC and high TP
Dehydration
Causes of low PCV with normal TP
Anemia from red blood cell destruction (example: Immune-mediated hemolytic anemia)
Causes of low PVC with low TP
Anemia from blood loss, or excessive fluid administration and overhydration
Causes of low PCV with high TP
Anemia and protein overproduction (example: feline infectious peritonitis)
What are white blood cells (WBC)
Blood cells vital to immune function in the body. There are various types of white blood cells with different functions.
Where are WBC made?
Most WBC are made in the bone marrow; however, lymphocytes are made in lymphoid tissue such as lymph nodes.
What are the types of WBC
neutrophils, lymphocytes, eosinophils, basophils
Neutrophils
Sudden response to acute infection. Short (4-6 hour) life span. Largest proportion of WBC
- “Segmented”: Mature adult neutrophils
- “Band”: Immature or young neutrophils – increase occurs with active or sudden infection
Lymphocytes
Provides “memory” to the immune system to respond rapidly to repeat invaders. Present in low numbers.
Eosinophils
Important in allergic or parasitic disease. Very low or absent normally.
Basophils
Similar to eosinophils, function in allergic or parasitic response. Very low or absent normally.
What are normal WBC and platelet counts in dogs and cats?
Dogs: WBC: 6,000-11,000/uL Platelets: 200,000-500,000/uL Cats WBC: 5,000-11,000/uL Platelets: 200,000-500,000/ul
What part of the spun blood in the hematocrit tube contains WBC and platelets?
The “Buffy coat”, which is the thin white band between the red blood cell and plasma layers.
How are WBC estimated on an emergency blood smear?
On 40X magnification on an area of the slide with a single layer of cells, count the number of WBC seen and multiply by 1600 to estimate total WBC count.
*Note: The WBC count will naturally be higher at the far edge of the smear, so counts at the far edge of the slide may be higher.
How are platelets estimated on an emergency blood smear?
On 100X magnification on an area of the slide with a single layer of cells, count the number of platelets seen in one high-powered field and multiply by 15,000-20,000 to identify a platelet estimate.
Causes of low WBC
- Rapid onset or early active infection consuming WBC (sepsis, pneumonia, pyometra)
- Reduced bone marrow production (parvovirus, bone marrow injury or toxicity)
Causes of high WBC
Active or chronic infection or inflammation, beyond the acute phase of rapid WBC use.
Excessive bone marrow production (bone marrow cancer)
*Note: Elevated WBC count does not always mean “infection”, and antibiotic therapy is not always indicated.
Causes of low platelets
- Consumption (active bleeding)
- Poor production (bone marrow disease)
- Destruction (immune-mediated thrombocytopenia, drugs)
- Sequestration (platelets hang out in peripheral vessels)
Causes of high platelets
Many diseases, and not usually a primary problem that needs to be addressed
What are Blood Chemistries
Measurements of parameters in a plasma or serum sample that provide information on function of various organ systems (kidneys, liver, gastrointestinal tract), proteins, and electrolyte values.
Which parameters are commonly measured cage-side for emergency management of dogs and cats?
Sodium (+/- Chloride) Potassium Calcium Glucose Urea nitrogen (BUN), +/-creatinine
At admission, when should you perform chemistry tests?
Any animal that is not completely healthy (although costs of testing should be discussed with the owner). Depending on severity of illness, tests are sometimes done as cage-side tests with immediate results, and at other times are performed by submitting blood to the laboratory for more complete results but without immediate availability of results.
With inpatient testing, when should you perform chemistry tests?
For monitoring of response to therapy or deterioration of condition. Certain medical conditions, such as diabetic ketoacidosis or Addison’s disease, may require tests to be performed multiple times a day.
Normal blood chemistry values, dogs and cats
-Dogs: Sodium (Na): 142-155 mEq/l Chloride (Cl): 112-120 mEq/l -Cats: Na: 145-158 mEq/l Cl: 115-123 mEq/l -Both: Potassium (K): 3.5-5.5 mEq/l Calcium (Ca): 9-11 mEq/dl (Ionized Ca 1.0-1.25 mmol/L) Glucose: 80-120 mg/dl BUN: 8-28 mg/dl Creatinine: 0.8-1.6 mg/dl
When does high potassium happen?
Urinary obstruction Bladder rupture and urine in the abdomen Acute kidney failure Accidental overdose Severe tissue damage (rare)
What does high potassium cause?
Irregular heart rhythm and slow heart rate, leading to heart standstill and cardiac arrest
When does low potassium happen?
Chronic kidney failure (cats)
Excessive fluid administration
Diabetic ketoacidosis
What does low potassium cause?
Muscle weakness leading to inability to lift head (cervical ventroflexion) and respiratory failure
When does high glucose happen?
- Diabetes mellitus/ diabetic ketoacidosis
- Stress (cats)
- Excessive intravenous dextrose administration
What does high glucose cause?
Increased urine output and drinking (PU/PD)
When does low glucose happen?
Puppies and kittens with poor food intake (especially toy breeds) Severe systemic infection (Sepsis) Addison’s disease (hypoadrenocorticism) Insulin overdose Liver failure (uncommon)
What does low glucose cause?
Seizures, coma, death
When does high BUN or creatine happen?
Kidney failure
Urinary obstruction or bladder rupture
Severe dehydration
What does high BUN or creatine cause?
Nausea, anorexia, vomiting, diarrhea, respiratory and brain injury
When does low calcium happen?
Dogs with poor nutrition that are nursing puppies
Parathyroid disorders
Antifreeze toxicity
What does low calcium cause?
Tetany (Muscle twitching)
Seizures
Death
When does high sodium and chloride happen?
Severe dehydration
Poor water intake
What does high sodium and chloride cause?
Excessive thirst (PD)
Dementia/ behavior change
Seizures
Coma
When does low sodium and chloride happen?
Excessive water intake
Excessive fluid loss
What does low sodium and chloride cause?
Dementia/ behavior change
Seizures
Coma
How is urine obtained?
For a sterile urine sample, urine must be collected by cystocentesis (needle inserted in the bladder) However, with a critical animal, voided or catheter –collected urine should be saved, ideally prior to any fluid being administered. Fluid therapy can change urine results.
What parameters can be determined from urine?
Pre-treatment urine specific gravity is important to understanding how to interpret kidney test results. For dogs, appropriate concentration in the face of azotemia is >1.025 USG, while for cats, appropriate USG when azotemic is >1.035-1.040. Urine dipstick testing can also be performed cage-side for emergency patients to identify glucose and/ or ketones (diabetes mellitus), blood, pH, and protein. Urine sediment evaluation can reveal crystals (for example, calcium oxalate crystals for antifreeze toxicity), or tubular casts that indicate tubular damage.
How are blood clots formed?
Following tissue injury, blood platelets in circulation travel to the site of injury, adhere to the injury, and recruit other platelets to join the fight by aggregating on the initial platelets. This forms a “platelet plug”. Once the platelet plug is formed, blood-clotting factors that are made in the liver travel to the site of the platelet plug and form a solid clot. When the injury has healed, the body dissolves the clot in a process called fibrinolysis.
How do we measure platelet numbers?
Platelet count (either in a laboratory as a part of a complete blood count (CBC) test or by performing a blood smear and counting platelets)
How is platelet function measured?
By creating a tissue injury and timing how long it takes until a blood clot forms on the surface. Blood clotting should occur within 5 minutes of injury. Tests to measure platelet function include buccal mucosal bleeding time (performed on the inside of the lip) or toenail bleeding time. The risk of either test is that if the platelets are not working, bleeding might not stop.
How are blood-clotting factors measured?
Factors are measured in the laboratory by performing a prothrombin time (PT) and activated partial thromboplastin time (aPTT). These are timed tests, and prolonged results indicate an absence of certain factors. Each of these tests provides somewhat different information about the 12 clotting factors produced by the liver.
For cage-side testing, activated clotting time (ACT) can be performed. The test is performed by filling an activated clotting time tube with whole blood immediately after sample collection. The tube must be pre-warmed, and maintained at body temperature. The tube is gently agitated and formation of a solid clot is the end point. A clot should normally form within 5 minutes. Low blood platelets will cause the test to be falsely prolonged even if clotting factors are normal.
What are clinical signs of low platelets or dysfunctional platelets?
Surface pinpoint bleeding (petechia) or paintbrush bleeding (ecchymoses)
Urinary system bleeding (blood seen in urine)
Gastrointestinal system bleeding (causes melena, or dark, tarry stool)
What are clinical signs of low clotting factors
Bleeding into body cavities (thorax, abdomen) or tissue bleeding. Sometimes this is seen by excessive bleeding following obtaining a blood sample.