What are the kidneys?
The main organ responsible for conservation and the production of urine
What are the role of the kidneys?
- Blood pressure (cardiac output)
- Conservation of certain molecules
- Excretion through the production of urine
What is the adrenal gland responsible for?
Production and secretion of ACTH to the pituitary gland to the hypothalamus.
Key features of water balance regulation?
- Very tightly regulated
- 15% deficit or surplus of TBW is fatal.
- Regulation takes place in the kidney
What can overhydration (possibly caused by fluid therapy) lead to?
Overhydration leads to a flooding of cells with sodium.
Which hormones help with the conserving and release of water in the kidneys and how?
Renal water absorbtion regulated by production of antidiuretic hormone (ADH) by the HPA and, in the longer term by aldosterone from the adrenal cortex.
ADG acts on the collecting ducts of the kidney to increase water uptake therefore concentrating the urine
Which products do the kidneys preserve?
- water
- glucose
- amino acids
- sodium
- chloride
- bicarbonate
- calcium
- magnesium
- most proteins
(Stockholm and Scott, 2008)
Which products do the kidneys excrete?
- urea
- creatinine
- phosphate
- potassium
- hydrogen
- ammonium
- ketones
- bilirubin
- haemoglobin
- myoglobin
(Stockholm and Scott, 2008)
Apart from conserving and excreting products, what else is the kidney responsible for?
- synthesising erythropoietin
- regulate acid- base
- renin secretion
- calcium and phosphorus homeostasis
- BP regulation
Define urine that is ‘Hyposthenuric’
More dilute than plasma, if ADH is present
Define urine that is ‘Isothenuric’
same concentration as plasma if insufficient renal tubules are functional or the animal has primary polydipsia
Define ‘Hypersthenuric’
More concentrated than plasma, if ADH is present and the renal tubules are functional
Which techniques can be used to take a urine sample?
- Voided or free catch
- Table collection
- Manual expression of the urine
- Urinary catheterisation
- Cytocentesis (ultrasound guided aseptic technique)
Key features of specimen packaging?
Collection cups/vials must be leak proof and should be delivered to the lab within an hour of collection. The urine can be refrigerated (which can result in crystals) to prevent bacterial growth
What is the process of taking a urinalysis?
- Look at the physical properties
- Perform a reagent (dipstick) test
- Evaluate under a microscope
Advanced diagnostics include:
- CBC and chemistry panel
- Bacterial culture (blood agar plate)
- Urine cytology
What are the physical properties of urine?
- Colour (pigmenturia=abnormal colour could be due to blood or myoglobin if a reddish colour)
- Clarity (farm animals have natural mucous making urine appear cloudy)
- Specific gravity
- Odour (pear drop smell is linked to ketonemia)
Which products do we test for when doing a reagent test strip?
- pH - expected value for species
- Protein
- Glucose
- Ketone
- Blood
- Bilirubin
- Nitrate
the above should not be present
What would you look for during microscopic evaluation?
- RBC
- WBC
- Transitional epithelium
- Casts
- Crystals
- Bacteria
- Yeast
- Fungi
- Parasites
Which bacterium could be present in urine?
Pseudomonas and E-coli
A dog whom is polydipsic and polyuria, what should be checked during a physical examination?
- TPR
- Feel the peripheral lymph nodes (submandibular)
- Alopecia? Particularly on the ventral abdomen
- Thinning of the skin?
What is classed as polydipsia?
total water consumption inc food, exceeding 100ml/kg/day
What is classed as polyuria?
Urine production exceeding 50ml/kg/day
Define ‘azotemia’
Occurs when BUN and creatinine are increased- often occurs in cats
3 types: Prerenal (dehydration/haemorrhage), Renal (chronic or acute renal failure) or postrenal (Obstructed urine flow)
What are exertional myopathys?
A syndrome of muscle fatigue, pain or crumping associated with exercise (horses).
Most commonly produces necrosis of striated skeletal muscle known as exertional rhabdomyolysis.
clinical signs: excessive sweating, tachypnoea, tahcycardia, reluctance, myoglobinuria and refusal to move
