Urinary Tract Disorders Flashcards
Blocked horse signs
- Lethargic, mild colic
- Usually relatively acute
- Can have scrotal-prepuce swelling (will feel cold, no pain)
- Cannot see if urinating
Differentials for scrotal swelling, lethargy, and history of mild colic?
- Blocked (urethral obstruction)
- Testicular torsion
- Inguinal hernia
- Trauma
- Edema
- Others: parasites, neoplasia, ascites, foreign body, etc.
Diagnostic tests for the donkey that had a urethral obstruction
- Palpation under sheath WNL (no neoplasia, foreign body)
- Testicular ultrasound showed edema
- Abdominal ultrasound was WNL
- Rectal examination: full bladder, normal accessory reproductive glands
What drug do you need to be careful with with stallions?
- Acepromazine
- Downside is priapism
Potential signs on CBC with urethral obstruction
- Hemoconcentration (dehydrated, lethargic)
2. Mild inflammation (mature neutrophilia and hyperfibrinogenemia - relatively non-specific)
Potential signs on chemistry with urethral obstruction
- SEVERE HYPERKALEMIA*** (VERY SIGNIFICANT)
- Mild hypochloremia
- Mild hyponatremia
- Azotemia
Pre-renal azotemia evidence
- High USG
- High PCV, high TP
Renal azotemia evidence
- Should have a low USG
- Should be isosthenuric
- Rest of electrolytes depend on chronicity
Post-renal azotemia evidence
- Should be normal urine but can’t show up
- Bloodwork will show hyperkalemia
- Block in the bladder or a ruptured bladder
Colic vs dysuria stance
- See on slides
First Treatment priority for Urethral Obstruction
- DEAL WITH HYPERKALEMIA FIRST
- fluids with glucose to get potassium inside of the cells
- Don’t want to give too many fluids because you can risk rupturing the bladder
Treatment options for relieving urethral obstruction (after hyperkalemia resolved)
- Cystoscopy: urethral urolith and tear (long scope)
- Remove with forceps (difficult)
- Perineal urethrostomy** (most cases)
- Will want to give a few days of antibiotics as well as anti-inflammatory medication due to trauma
- Fluid therapy to resolve hemoconcentration and hyperkalemia
Which signalment of horse is most likely to get a calculi?
- Geldings are 75% of cases
What is the most common type of calculi found in a horse?
- Calcium carbonate***
- MUST REMEMBER THIS
- They are very spiculated
Most common locations for horses do get calculi
- Bladder (60%)
- Urethra (24%)
- Kidneys (12%)
- Ureters (4%)
- Can lead to complete (more likely with a urethral obstruction) or partial obstruction (more common with bladder stone)
What type of diet is associated with urolith formation?
- Alfalfa
Diagnosis of renal uroliths
- DIFFICULT
- Colic is rare
- Ultrasound (but difficult to see)
- May not be azotemic if the other kidney is functioning
- Microscopic hematuria
Treatment for renal uroliths
- Remove affected kidney if no azotemia
What is the most common sign of a bladder stone?
- Hematuria (post-exercise)!!!!
Other clinical signs for bladder stones
- Dysuria
- Pyuria
- Incontinence
- Colic
Diagnosis of bladder stones
- Rectal palpation (depends on fullness of bladder - won’t feel in a full bladder)
- Cystoscopy (easy to see)
Treatment for a female with a bladder stone?
- Manual extraction
- Can take it out with your hand
- They can put the stone in a bag and hammer to collect it
- Also exploratory laparotomy
Treatment for a male with a bladder stone?
- Perineal urethrostomy
- Also exploratory laparotomy
Clinical signs of urethral stones
- Dysuria, pollakiuria, colic
Diagnosis and of urethral stones
- Clinical signs
- Endoscopy
Treatment of urethral stones
- Endoscopy
- Removal and perineal urethrostomy
Cystoscopy overview
- urethra, bladder, and ureters
- Sedation
- Empty bladder
- Should see urine coming out on both sides
Ultrasonography Overview
- Bladder and kidneys (kidneys VERY DIFFICULT TO IMAGE)
- Transrectal or transabdominal
What can you visualize with ultrasonography of the bladder?
- Urine
- Mass
- Ruptured bladder
- Stone
What can you visualize with ultrasonography of the kidneys?
- Size, echogenicity, masses, cyst, etc.
Palpable structures for rectal exam (urinary system)
- Bladder: size, wall thickness, masses, calculi, tone
- Palpate empty
- Caudal pole of the left kidney
- Ureters are NOT NORMALLY palpable
Where do obstructions and calculi normally form?
- Anywhere in the urinary tract (usually bladder followed by urethra)
At what point in the disease do clinical signs appear for calculi?
- Pretty late
Why do you want to reduce alfalfa in the diet for calculi?
- Leads to formation of calcium carbonate crystals
Renal azotemia
- Azotemia + isosthenuria
Blood work from a horse in acute renal failure
- Hemoconcentration and hyperproteinemia
- Marked neutropenia
- Moderate azotemia
- Hyponatremia and hypochloremia
Urinalysis from a horse in acute renal failure
- Isosthenuria (<1.008)
- Protein +
- Sediment: granular casts and few RBCs
Urinalysis collection for ARF
- First in stall (collect your sample)
- Observe urination
- Color: timing
- Turbid: Ca2+ carbonate
- USG
Hyposthenuria
- <1.008
- indicates that you have renal function still
Isosthenuria
- 1.008 - 1.015
- can go up to 1.020
Concentrated
- > 1.015
Urinalysis tests
- pH
- glucose
- blood
- bilirubin
- ketones
Normal horse urine pH
7-9
Normal glucose levels in horse urine
- None
- If there’s glucose that indicates tubular dysfunction
What can blood signify on the urinalysis strip?
- myoglobin, hemoglobin, RBC
What does bilirubin indicate on the urinalysis strip?
- Hemolysis
Ketones on the UA
- Not used
How quickly to measure urine sediment?
<1 hr
Sediment exam
- WBC, RBC (should be low)
- Bacteria (normal in free catch)
- Casts (none)
- Crystals
Normal horse crystals
- calcium carbonate and phosphate
High GGT on a horse urine meaning
- High GGT could indicate tubular damage
Fractional clearance electrolytes
- measure in urine and serum
- don’t do this a lot
Which part of the kidney is most sensitive to hypoxic injury?
- Medulla (10-20%)
- e.g. with flunixin
Which part of the kidney is most susceptible to toxins?
- Cortex (80-90%)
- e.g. with gentamicin
NSAID toxicity effect on the kidneys
- Afferent artery gets 20-25% of blood supply regardless
- Local release of prostaglandin E2 keeps the artery wide open
- Flunixin is a COX inhibitor and blocks prostaglandin
- If you have a dehydrated animal and give flunixin, the kidney will get significantly less blood
- GGT may be high here but you would have blood in the urine (?)
Gentamicin toxicity effect on the kidneys
- Nephrotoxic but different mechanism
- Tubules of the kidney
- Giving gentamicin IV, receptors in the tubules on the surface that pick up the gentamicin
- Uptake by tubules through those receptors
- Might see GGT high in the urine due to tubular damage
What is the dosing of gentamicin to reduce nephrotoxicity?
- Gentamicin once a day high dose
- Gentamicin comes in and gets absorbed; rest is peed out and doesn’t get into the tubules
Clinical signs of Acute Renal Failure
- Signs usually related to the clinical problem, NOT acute renal failure
- Not suspected unless renal function evaluated (azotemia, urinalysis*****)
- Identify patients at risk
- Associated with oliguria - anuria (rare)
- may be lethargic
Blood work signs of acute renal failure
- +/- hyponatremia, hypochloremia, and hypernatremia
Urinalysis results with ARF depend on what?
- Portion of the kidney affected
Urinalysis in ARF
- USG: ISOTHENURIA!
- RBC
- Proteinuria
- Granular casts
- GGT
Treatment of Acute Renal Failure
- Treat the primary cause
- Fluids!
- Dopamine to increase blood pressure
What fluid rate should horses in ARF be on?
- 2x maintenance
- AT LEAST 2L/HR
- Usually $500 a day on fluid alone
Monitoring for acute renal failure
- check on/off fluids
- Check creatinine again 24 hours after stopping fluid
- If it’s still high, can indicate permanent renal damage
Prognosis of ARF
- varies with damage
Is ARF reversible or not?
- Yes, reversible
Clinical signs in a horse with chronic renal failure
- VERY nice
- Submandibular mass (bigger while on pasture, smaller in stall) - EDEMA
- BCS: 2.5/9
- Rough hair coat
Paraphemosis in a horse with CRF
- Scrotum is big
- Penis is prolapsed
- Too weak to hole the penis in place :(
- Polyuric
Dfdx for Polyuria
- Renal failure
- Psychogenic
- PPID
- Endotoxemia
- Diabetes
- Drugs
What is the most common cause of PU/PD in horses?
- Psychogenic
Ventral edema causes
- Decreased oncotic pressure
- Increased hydrostatic pressure
- Decreased lymphatic drainage
- Increased capillary permability
What are the three most likely causes of weight loss in horses?
- Parasites
- Nutrition
- Dentition
Polyuria in horses definition
- > 50 mL/kg/day of urine
- ~25 L urine/day in a 500 kg horse
Diagnosing polyuria in a horse
- DIFFICULT
- 24 hr urine collection
- Water consumption: polydipsia
Polydipsia things to consider
- Diet
- Environmental temperature
- Workload
What would USG be if you were psychogenically drinking?
- VERY DILUTE
- OVER-diluted (hyposthenuric)
Polydipsia amount in horses
- > 100 mL/kg/day (4x more than they should be)
- ~50L/day for 500kg horse (normal is approximately 25 L)
Polydipsia due to primary psychogenic disease features
- Large volumes of water
- Low USG (<1.005)
- Normal PE
MOST COMMON CAUSE BY FAR*
Polydipsia due to secondary psychogenic disease features
- Renal failure: azotemia
- USG will be isosthenuric
- Often very skinny
- Diabetes is a much less common cause
CBC in a horse with chronic kidney disease
- Mild anemia
Chemistry panel in a horse with chronic kidney disease
- Hypoproteinemia/Hypoalbuminemia
- Azotemia SEVERE
- Hypercalcemia
- Hyponatremia and hypochloremia
- Hyperkalemia
What ratio of urea to creatinine is suggestive of CKD?
> 10:1 urea:creatinine
Calcium and chronicity of CKD
- Higher calcium indicates CHRONIC renal failure
- The higher the calcium, the poorer the prognosis
- They have a lot of calcium carbonate in the diet, so calcium builds up quickly if the kidney isn’t working well
Urinalysis for CKD
- Easy to obtain because of frequency
USG for CKD
- 1.012
Sediment abnormalities in CKD
- may be no abnormalities at this point
Urinalysis strip common abnormalities with CKD
- Proteinuria (+++) due to glomerular filtration problem
- Glucosuria (+++) due to proximal renal tubule problem
Where is the problem with proteinuria? (kidney anatomy)
- Glomerulus
Where is the problem with glucosuria? (kidney anatomy)
- Proximal renal tubule
Potential mechanisms for edema in CKD
- Decreased oncotic pressure (losing albumin through the kidneys)
- Increased hydrostatic pressure (Renin release and elevated blood pressure –> hydrostatic pressure)
Congenital causes of CKD
- <5 years old
- No acute renal failure or others
- Renal agenesis, hypoplasia, dysplasia
Acquired causes of CKD
- Most common***
- Previous injury
- Cause may be unknown
- Flunixin/Gentamicin is a common cause
Why do horses with CRF look bad?
- Uremic signs (accumulation of nitrogenous waste)
- A lot of the nitrogenous waste goes to the gut –> converted to ammonia –> crosses BBB
- Nitrogenous wastes can cause anorexia, lethargy, ammonia
- Ammonia is toxic to the mucosa, especially of the large colon so can lead to soft manure and ulceration
Protein losing enteropathy with renal failure
Ammonia is toxic to the mucosa, especially of the large colon so can lead to soft manure and ulceration
Tartar and oral ulcers and CKD
- AMmonia changes urea in the mouth
- Build up of tartar
- Horses don’t usually build a lot of tartar, so if you see this, check bloodwork
What percentage of horses with CKD get edema?
~43%
- Due to decreased oncotic pressure (hypoalbuminemia)
- Endothelial toxicity secondary to elevated urea and increased vascular permeability
- Increased hydrostatic pressure due to renin release
What % of horses with CKD are PU/PD?
- approximately 40% (??? I THINK)
Pathophysiology of anemia in chronic kidney disease
- Less synthesis of erythropoietin and toxic things in the blood stream decrease life span
- Decreased half life due to friable membrane
- Less synthesis due to decreased erythropoietin
Odor of horses with CKD
- May have a uremic odor
Can CKD be cured?
- No
Things to consider with CKD treatment
- Must consider quality of life
What is the creatinine cut point for a horse being able to live a relatively normal life with CKD?
- Creatinine <5 mg/dL
Water and diet recommendations for CKD
- Water - fresh and AT ALL TIMES
- Diet to maintain body condition: good quality grass, no alfalfa (high calcium), fat, omega-3 fatty acids
Bicarbonate in horses with CKD
- Can supplement if low (<20 mEq/L)
- Orally
- Do the calculations
Breeding in a horse with CKD
- DO NOT DO IT
- Pregnancy can shift the fluids around the body
- If a stallion, probably not an issue
- In a mare, pregnancy is too much for them
Prognosis
- Not so great
- Terminal illness
Monitoring CKD
- Measure CBC/Chemistry
- In 10 days/6 months/2-3 times a year
- If stable, 1x per year
How do you differentiate psychogenic polydipsia from diabetes insipidus?
- Remove the water and retest to see if they can concentrate
- Have to overcome the medullary washout that has happened due to polydipsia
- Have to measure first in 24 hours how much they are drinking, then cut that in half for a few days, then in half again
- Takes a LONG TIME
- MUST monitor for dehydration
- Tacky mucous membranes
- Take a body weight daily (if they lose more than 5%, they’ll stop the water deprivation test)*****
