Week 6 Flashcards
How do we lose fluid?
Urine
Faeces/diarrhoea
Vomit
Blood loss
Third space loss (body cavities)
Inflammatory exudate
Insensible losses
- e.g. sweating & breathing (fluid lost but only to a small degree)
What are the 3 major compartments within the body where fluid is stored
Define dehydration and give an example
Define hypovolaemia and give an example
What are the signs of hypovolaemia
What are the signs of dehydration
Define shock
What are the 4 types of shock
Label the types of shock
How can we recognise the 4 types of shock
Gives some signs of fluid loss, clinical signs and reason in cattle
Gives some signs of fluid loss, clinical signs and reason in dog/cat
What are the types of fluids
Crystalloids
- isotonic, hypertonic & hypotonic
Colloids
Transfusion products
Describe isotonic fluids
Used for fluid resuscitation
for both hypovolaemia & dehydration
they equilibrate across membranes rapidly to restore both intravascular & extravascular spaces
effect on intravascular volume expansion can be shirt lived
Give examples of isotonic fluids
Hartmann’s:
- contains sodium, chloride, potassium, calcium, lactate +- magnesium
- useful in most patients
- esp. metabolic acidosis
sodium Chloride (saline):
- 0.9% sodium chloride only
- less balanced in terms of electrolytes & quite acidifying
Dextrose solutions (D5W):
- 5% glucose in 0.18% saline
- dangerous fluid type because glucose is rapidly metabolised leaving 0.18% sodium chloride which is basically water & thus hypotonic
- dont use, if you need glucose supplementation add glucose to saline or Hartmanns
Give examples of hypertonic fluids
Saline in various strengths (usually 7.2%)
- draws fluid into intravascular space (only use IV)
- fluid drawn from interstitial space so dont use in dehydrated patients
- works rapidly (useful for hypovolaemic shock)
- low volumes required so useful for large animals
- draws fluid from brain so useful in head trauma
- sodium can be dangerous so only use 1/2x per 24h & always follow with isotonic fluids
Give examples of hypotonic fluids
usually saline (0.45% NaCl)
- rarely used
- main use would be hypernatraemia (high sodium in blood) to dilute it
- be careful how quickly you reduce hypernatraemia
* sodium balances across BBB
* if you drop Na quickly –> osmotic gradient into brain –> flood brain causing cerebral oedema
Describe colloid fluids
controversial
contain macromolecules which mimic albumin (protein) in blood to provide oncotic pressure
should provide constant buff to intravascular volume by helping retain fluid
but has been shown to increase risk of death & acute kidney injury in dogs
Describe transfusion products
What are the routes for fluid administration
intravenous
- rapid & continuous
* useful for dehydration & hypovolaemia
Intraossesous
- almost as fast as IV but difficult to place & complications (rare) can be severe
- isotonic fluids only
Subcutaneous
- reliant on good subcutaneous blood supply to redistribute fluid so only for mild dehydration
Oral
- relies on functioning GIT
- often used in LA
- can be combined with nutrition via feeding tubes
- use isotonic
- too much water is bas
Rectal
- effective in horses
- only for dehydration & not in diarrhoea
Intraperitoneal
- reliant on good peritoneal blood supply
- can be painful
- rarely used
How do you calculate rate of fluid administration
How can you reduce risk of a reaction when using transfusion products
How can you check if fluid is working (5 parameters and change you expect to see)
What are signs of fluid overload
- What is the problem?
- Hypovolaemic or dehydrated?
- Which fluid type?
- Rate?
- Diarrhoea –> fluid loss +- metabolic acidosis
- dehydrated
- Hartmanns
- picture
What are some common pitfalls of fluid therapy
Describe normal gross appearance of urine and what the following (abnormal) can indicate:
- dark colour
- red
- brown/green
- brown
- orange/blue
- cloudiness
- fishy odour
- sweet odour
What can glucose in urine indicate
What can bilirubin in urine indicate
What can ketones in urine indicate
What can blood in urine indicate
What can proteins in urine indicate
What are normal USG ranges in dog, cattle, horse, cats
What USG in dogs is hyposthenuric, isosthenuric and hypersthenuric
What cells in urine sediment exam are normal in small numbers
erythrocytes
leukocytes
epithelial cells
Name the structures found in urine sediment
What is this
Struvite
What is this
Struvite
What is this
Calcium oxalate dihydrate
What is this
What is this
Struvite
What is this
Calcium carbonate (equine)
What is this
Cystine crystals (canine)
What is this
Cast (red blood cell)
What is this
Red & white blood cells
What is urolithiasis
stony secretions in bladder or urinary tract
Where in urinary tract are blockages with uroliths most common in male sheep?
sigmoid flexure
glans penis
neck of bladder
vermiforme appendage
Is obstructive urolithiasis more or less common in female sheep then male sheep?
More common in males due to longer & narrower urethra
Why does obstruction with uroliths cause lethargy, penis flexing & fever (pyrexia)
lethargy due to pain
penis flexing because animal is trying to pass urine
fever due to inflammation
What are the potential causes of urolithiasis if not successfully treated
bladder rupture
toxin build up
How can you confirm diagnosis of urolithiasis
ultrasound
blood test
- urea, creatinine & potassium
How can you treat urolithiasis in rams
catheterisation & then surgery
or change diet
In what form do aquatic organisms excrete nitrogenous waste
ammonia
In what form do reptiles/birds excrete nitrogenous waste
uric acid
Describe features of uric acid
Made in liver
Highly insoluble:
- water conservation
- storage in eggs
Tubular secretion via reptilian-type nephrons
Excretion is independent of:
- urine flow rate
- tubular water reabsorption
- hydration state
Describe gout & its causes in birds & reptiles
Hyperuricemia (excess uric acid) => precipitates out of blood into organs and joints => gout (visceral and articular)
Causes:
- renal disease
- high dietary protein - too many AAs => more uric acid
- dehydration - urates produced can’t be flushed => renal gout
- nephrotoxic drugs - damages renal tubules
What are urates
Precipitate:
- uric acid
- protein
- Na+ (carnivorous)
- K+ (herbivorous)
Enters cloaca and mixes with faecal material
Why are birds and reptiles able to excrete urates even when dehydrated?
Uric acid crystals precipitate => no osmotic pressure so does not draw water out with it
Why is urinalysis useless in birds and reptiles?
Due to mixing of urine, urate and faecal material
How does the renal portal system in exotics protect against ischemic necrosis of the kidney?
Blood from tail/caudal body travels to the heart via the kidney
Portal system ensures blood flow to tubules (does not supply glomerulus)
Describe the clinical implications of the renal portal system in exotics
Drug pharmacokinetics:
- if drugs injected into caudal region, goes to kidneys first => damage or excretion
Caudal mesenteric vein:
- contributes to renal portal system
- disease of GIT => kidneys
- toxins from gut
Label the different fish nephrons
what structure is missing from all 3?
Loop of henle missing
Label the reptile nephron