Hematopoietic Disease Flashcards
What do dark mucous membranes suggest?
- Increased PCV
Clinical signs of a horse with anemia
- Pale mucous membranes
- Tachycardia
- Tachypnea
- Systolic heart murmur
- Lethargy
- Exercise intolerance
- Pale slera
Severity of anemia
- Mild: 30-33%
- Moderate: 20-29%
- Severe: 13-19%
- Very severe: <13%
What is the limit for anemia of chronic disease severity?
20%
Should not be lower than 20%
If it is, it’s something else
1st step to assessing anemia
- Regenerative vs non-regenerative
What is unique about horse blood that makes it hard to assess regeneration?
- Lack reticulocytes
Regenerative disorders
- Hemorrhage and hemolysis
Non-regenerative disorders
- Anemia of chronic disease, neoplasia, chronic renal disease, bone marrow issues, chronic inflammation
Hemorrhage signs
- If external, hopefully fairly obvious
- Not as obvious if internal hemorrhage
- Look with ultrasound or tap
- Might not see if there is a big hematoma
- Can have blood loss into the GIT, but not as common
- Not as obvious in the feces
What are the three general principles of hemorrhage control?
- Stop the hemorrhage
- Volume replacement (balance with hemodilution)
- Maintain oxygen carrying capacity
Common cause of internal hemorrhage/hemoabdomen in brood mares
- Uterine artery hemorrhage
Treatment for hemoabdomen in broodmares
- Keep relaxed
- Can give acepromazine to decrease blood pressure and decrease anxiety
- Can nasal canula oxygen
What do you want to give if sending to a referral hospital?
- Hypertonic saline
- Increase osmolarity of blood and will suck volume in
- Lasts about 3-4 hours
- Give a couple of liters
- Make sure you’ve stopped the hemorrhage first
Signs of acute internal hemorrhage
- Sweating
- muscle fasciculations
- Tachycardia
- Tachypnea
- Pale mucous membranes
- Cool extremities
What are the three causes of dark red urine?
- Myoglobin, hemoglobin, and whole red blood cells
Signs of intravascular hemolysis
- Hemoglobinuria
- Hemoglobinemia
- Increased indirect (unconjugated) bilirubin
Red blood cell is destroyed and is filtered through kidney
Signs of extravascular hemolysis
- Only increased unconjugated (indirect)
- Surface of RBC is destroyed and goes to bone marrow, liver, or spleen
Which is more common in horses: intravascular or extravascular hemolysis?
- Extravascular by far
Causes of hemolysis
- Immune mediated (most common out here)
- Oxidative hemolysis
- Infectious diseases (equine piroplasmosis and equine infectious anemia)
- Toxins (Clostridium, oak, DMSO)
- Iatrogenic (hypotonic or hypertonic fluids)
- Miscellaneous (liver disease, DIC)
What are two tests used to diagnosis immune mediated hemolysis?
- Autoagglutination
- Coombs test
How do you differentiate autoagglutination from rouleaux?
- Mix 1 part blood with 4 parts saline to allow rouleaux to disperse
- Autoagglutination stays clumped together
Significance of positive autoagglutination?
- IMHA
What to do if autoagglutination is negative but you still suspect IMHA?
- Coombs test
Important aspects of IMHA pathology
- Look for an underlying cause
- Usually secondary to something
- Other concurrent immune-mediated abnormalities are possible
Treatment for immune-mediated hemolysis
- Discontinue current medications
- Diurese (VERY important in intravascular hemolysis as the free hemoglobin can cause tubular disease)
- Corticosteroids (can be helpful if immune mediated especially)
- Maintain oxygen carrying capacity (consider transfusion if showing clinical signs)
- Treat underlying problems
Differentials for oxidative hemolysis and which is most common?
- Red maple leaf toxicity (Acer rubrum)** (most common by far)
- Wild onion (need a lot)
- Phenothiazine (rarely used anthelminthic)
- nitrate (rare in horses)
Red Maple Leaf toxicity Diagnosis general
- History
- Clinical signs
What specific bloodwork changes would suggest red maple leaf toxicity?
- Blood methemoglobin levels
- Heinz bodies
How do you visualize Heinz bodies?
- Stain a blood smear with new methylene blue
Treatment for red maple leaf toxicity (3 aspects)
- Maintain oxygenation of tissues (transfusion ideally if needed; caution as they can get profound reperfusion injuries)
- Diurese to protect kidneys
- Decontaminate (activated charcoal and pass a stomach tube; mix in water with these guys)
- Make sure you treat other horses that were possibly exposed
Equine Infectious anemia overview
- Retrovirus
- Lentivirus
Infected cell type in Equine Infectious anemia
- Tissue macrophages and dendritic cells
How long does EIA last?
- Lifelong
How does EIA result in anemia?
- Likely stimulates an antibody response
What do most horses look like with EIA?
- super healthy
- They can still have sufficient virus to act as reservoirs
Horses with chronic EIA?
- Pitting edema
- Weight loss
- Recurring fevers
- Thrombocytopenia and anemia
How is EIA transmitted?
- Biting flies (Tabanids, Chrysops)
What type of vector are biting flies for EIA?
- Mechanical vectors
- Spread the virus by getting blood on their mouthparts
How far can tabanids fly for EIA?
- 200 yards
- If test positive and owners elect to quarantine, rule is they must be 200 yards from another horse
Diagnosis of EIA (screening and confirmatory test)
- Screening test: Agar gel immunodiffusion (AGID or Coggins)
- Confirmatory test: ELISA assays
Coggins test
- Positive antigen protein in central well
- Samples from the horses
- If the horse has ANTIBODY circulating to EIA, then it meets the antigen and creates a line of precipitation
ELISA assays for EIA
- More sensitive
- Less specific
- Confirm results