Urinary System II Flashcards
What is azotemia?
- Increased concentration of urea and creatinine (non-protein nitrogenous wastes) in the BLOOD
o May or may not be related to alteration of renal function
o *COULD indicate a renal problem
What are the 3 causes of azotemia?
- Pre-renal
- Renal
- Post renal
*if not corrected, can eventually lead to renal failure
Pre-renal azotemia
- Decreased blood supply to kidney
o BUN and creantinine are not being delivered to kidney=not being delivered - Kidney function is normal
- Ex. dehydration, heart failure and hemorrhage
Renal azotemia
- Problem in kidney leading to decreased extraction of BUN and creatinine from blood
Post renal azotemia
- Lower UT obstruction causing decreased excretion
If azotemia in blood and low USG, what do you have?
- renal failure
What is renal failure?
- **Impaired renal function associated with azotemia
- 75-80% of renal function is lost
- Acute or chronic
- Can be reversible
What are pre-renal causes of renal failure?
- Shock
- Hemorrhage
- Heart failure
- Severe dehydration
- DIC
What are the renal causes of renal failure?
- Damage to tubules or glomeruli by many industrial or natural toxins and metals
- Acute glomerulonephritis
- Renal infection
What are the post renal causes of renal failure?
- Obstruction within lower urinary tract
*What is the clinical syndrome that renal failure can lead to?
- UREMIA
What is uremia?
- Syndrome associated with multisystemic lesions and clinical signs b/c of renal failure
- *different from azotemia
o Azotemia can be associated with normal renal function
o Uremia indicates renal sickness (acute and chronic renal failure)
o *BUN and creatinine is high in both
What is end stage renal disease or kidney?
- renal function is less than 5% of normal
- animal is in terminal stages of uremia
**What is the morphological diagnosis for an end stage kidney?
- Diffuse renal fibrosis
What is acute renal failure characterized by?
- Rapid onset of oliguria or anuria (decreased or no urine output) and azotemia
o Low urine SG - May result from acute glomerular or interstitial injury OR from acute tubular necrosis
- Often have reduced blood pH (metabolic acidosis)
- *often reversible
What are the common causes of acute renal failure?
- Ischemia: shock, cardiac arrest, trauma, deep anesthesia
- Toxic injury: antimicrobials, chemotherapeutic agents, hemoglobin, myoglobin, ethylene glycol
- Other disease states: infection, hypercalcemia, immune mediated disease
Why do animals that die from acute renal failure die?
- Cardiotoxicity of elevated serum potassium
- Metabolic acidosis
- Pulmonary edema
- *reflected clinically by signs
What signs clinically reflect the alterations that occur during acute renal failure?
- Polyuria and polydipsia
- Vomiting and diarrhea
- Ammoniacal-smelling breath
- Array of non-renal lesions
What does the kidney look like grossly with acute tubular necrosis?
- Pale
- Cortex is ‘bulging’ or convex appearance
- (histo to confirm: necrotic tubules)
- *may not see if animal dies quickly
Chronic renal failure
- Similar to acute BUT longer duration and IRREVERSIBLE
- Most common renal disorder in dogs and cats
- Usually progressive loss of renal function
- Usually high blood phosphate and low Ca, normal to low potassium
What are the 2 changes that MAY also be seen with chronic renal failure (and NOT seen with acute renal failure)?
- Non-regenerative anemia
- Soft bones (fibrous osteodystrophy)
What is the differences in urine output between chronic and acute renal failure?
- Chronic: increased
- Acute: decreased
What does chronic renal failure look like grossly in the kidney?
- Pale
- Misshapen
- Irregular surface reflecting fibrosis
- *shrunken kidney
What are the 2 main mechanisms by which uremia produces lesions?
- Vascular endothelial injury
- Alteration in Ca/P balance
What are the 3 potential things that vascular injury can cause?
- Thrombosis, ischemia, necrosis, and hemorrhage
- Increased vascular permeability (edema)
- Leakage of urea and its conversion to cause ammonia by bacteria leading to ULCERATION
What happens to Ca and P levels with chronic renal failure?
- Low Ca
- High P
- *chronic renal failure causes DECREASED Vit D production leading to DECREASED gut ABSORPTION of Ca
What are the consequences of low Ca and high P? (3)
- PT hyperplasia (bilateral white masses on thyroid gland) and increased PTH
- Fibrous osteodystrophy (ie. If can bend a rib)
o Release of Ca from bone and with time Ca is replaced by fibrous tissue - Widespread mineralization (white gritty spots everywhere)
What could white masses on the thyroid be?
- Parathyroid tissue=bilateral masses and have renal failure
- Thyroid tissue=solitary, unilateral mass
What are some things that can occur in dogs (and other animals) with renal failure?
- Tongue tip necrosis
- Ulcerative uremic glossitis
- Uremic gastritis
- Intercostal mineralization
- Enlarged maxilla
- Pulmonary edema
- Uremic colitis
Tongue tip necrosis
- More common in dogs
- *result of vascular injury leading to ischemia and necrosis
Ulcerative uremic glossitis
- Secondary to release of urea and its conversion to ammonia
- Little inflammation but mainly necrosis
- *mainly in dogs and cats, but also other species
- Ischemia could also be a mechanism
- Can also get ulcers on gingiva
Uremic gastritis
- Mainly in dogs and cats (large animals get colitis)
- Necrosis and hemorrhage secondary to vascular injury
- Gastric folds are wet and thickened secondary to edema
- Ulceration
- *cause upset stomach with vomiting and may be diarrhea
- Review stomach if have renal failure=mineralization
Intercoastal mineralization
- Dogs mainly
- Result of chronic uremia
Enlarged maxilla due to fibrous osteodystrophy
- Enlarged and filled with fibrous tissue
- Jaw becomes rubbery and easy to bend (can bend ribs and bone too)
- Teeth in maxilla and mandible become very lose
What is pulmonary edema and uremic COLITIS in large animals due to in chronic renal failure?
- Vascular injury
Why are the lesions of uremia important?
- May tell you to look at the kidney more closely
