Equine Urinary Tract Disorders

Question 1

What specific history should we take for urinary disorders?

Answer 1

Measure water intake over 24hrs
Abnormal urination?
Abnormal colour?
Any other problems?
Weight loss

Question 2

What specific physical examination should we do for urinary disorders?

Answer 2

Rectal to feel bladder - size/wall thickness/uroliths/masses
Rectal to feel caudal pole of left kidney
Examine penis (sedate)
Pass urinary catheter if suspect an obstruction

Question 3

What are we looking for on haematology?

Answer 3

Leukocytosis (inflammation/infection)

Anaemia - chronic (renal) disease

Question 4

What are we looking for on biochemistry?

Answer 4

Urea/creatinine
Azotaemia (creatinine slightly more specific for renal dysfunction)
Do not increase until >75% nephrons non-functional
Little use in evaluation of early/minor changes
Once elevated, doubling urea/Cr = 50% decline in remaining function

Question 5

How do we get a sample for urinalysis?

Answer 5

Usually caught midstream (container on a stick) or obtained by catheterisation
Most horses will urinate when placed in freshly bedded stable
Not cystocentesis in horses
If pigmenturia, note timing and duration of passage of discoloured urine

Question 6

What tests can we run for urinalysis?

Answer 6

Urine specific gravity
Biochemistry (Reagent strip analysis)
Sediment analysis (casts)

Question 7

Describe the three dilutions of urine seen using urine specific gravity.

Answer 7

Hyposthenuria (USG < 1.008) = urine is more dilute than serum
Isothenuria (USG 1.008-1.014) = urine and serum of similar osmolality
Hypersthenuria (USG > 1.014) = urine more concentrated than serum

Question 8

How can we use ultrasound to diagnose a urinary tract disorder?

Answer 8

Transrectally/transabdominally
Uroliths in kidneys and sometimes bladder
Size and architecture of kidneys

Question 9

How can we use cytoscopy to diagnose a urinary tract disorder?

Answer 9

Very useful to investigate abnormal urination
Examine urethra, bladder, watch/sample urine coming from ureters (may identify a unilateral renal problem)
Sedation including ACP if male

Question 10

Describe the water deprivation test.

Answer 10

PUPD - to test for diabetes insipidus/psychogenic polydipsia
Weigh horse, measure urea/creatinine/USG
DO NOT PROCEED if increased or USG > 1.008
Water remove and USG/urea/creatinine checked regularly
Test stopped when: 24hrs reached / USG goes above 1.020 / azotaemia / clinical signs of dehydration / loss of 5% bodyweight

Question 11

How can we tell where haemorrhage is from using haematuria?

Answer 11

Throughout urination = from kidneys/ureter/bladder
Beginning of urination = from distal urethra
End of urination = from proximal urethra

Question 12

What differential diagnoses can we see with PUPD?

Answer 12

Renal failure
Pituitary Pars Intermedia Dysfunction (PPID)
Primary/psychogenic polydipsia
Central/nephrogenic diabetes insipidus (lack of ADH)
(Diabetes mellitus)

Question 13

What is acute renal failure?

Answer 13

Abrupt reduction in glomerular filtration - leads to:
Failure of kidneys to excrete nitrogenous wastes, causing azotaemia leading to uraemic syndrome / disturbances in fluid, electrolyte and acid-base homeostasis

Question 14

What can cause pre-renal failure?

Answer 14

Decreased renal perfusion without associated cell injury
From conditions causing decreased cardiac output/increased renal vascular resistance, e.g. dehydration, diarrhoea, endotoxaemia, septic shock +/- use of NSAIDs

Question 15

What can cause intra-renal failure?

Answer 15

Ischaemic or toxic damage to the tubules
Tubular obstruction (e.g. from casts)
Acute glomerulonephritis
Tubulointerstitial inflammation

Question 16

What can cause post-renal failure?

Answer 16

Obstruction or disruption of urinary outflow (e.g. uroliths)

Question 17

What are the clinical signs of acute renal failure?

Answer 17

Vague and non-specific
Lethargy
Inappetence
Dehydration
Signs of primary problem e.g. colic

Question 18

How do we diagnose acute renal failure?

Answer 18

Oliguria
Azotaemia
USG
Casts in urine - show damage
Rule in/out pre-/post-renal causes
If intra-renal, ultrasound +/- biopsy

Question 19

How can we treat acute renal failure?

Answer 19

Reverse underlying cause
Correct fluid and electrolyte imbalances
If sufficient response, dopamine infusion to improve renal blood flow
Diuretics?
Stop aminoglycosides/NSAIDs where possible - if not, monitor serum concentrations

Question 20

What nursing considerations should we have for acute renal failure patients?

Answer 20

Fluid therapy
Monitor - urine output, signs of oedema
Encourage appetite - variety of feeds, in hand grazing
Monitor complications e.g. laminitis, thrombophlebitis

Question 21

What is the prognosis for acute renal failure?

Answer 21

Depends on underlying cause, duration, response to treatment, development of complications
Can live long-term, but often polyuric and must always have access to water

Question 22

What are some causes of chronic renal failure?

Answer 22

Glomerulonephritis
Immune-mediated
Ischaemia
Toxic insults
Infection

Question 23

What are the clinical signs of chronic renal failure?

Answer 23

Present late in disease course
Lethargy (anaemia)
Anorexia
Weight loss
PUPD
Dental tartar
Azotaemia + inability to concentrate urine (low USG)

Question 24

What nursing considerations should we have for chronic renal failure?

Answer 24

Fluid therapy - to rule out acute renal failure (monitor urine output and signs of oedema)
Access to water
Encourage eating
Diet - reduce protein (avoid alfalfa if possible)

Question 25

Describe urinary tract infections.

Answer 25

Not very common
Primary cystitis uncommon, look for a primary problem (e.g. urolithiasis)
Dysuria
Midstream urine sample, bacteriology
Plus investigate for underlying causes

Question 26

Describe penile squamous cell carcinoma.

Answer 26

Malodorous/swollen sheath
Haematuria if distal urethra involved
Early on = no signs
Urinary tract obstruction uncommon unless tumours are large
Treatment depends on position and extent of tumour - local excision/penile resection
High rate of recurrence, although slow metastasis (inguinal lymph nodes)

Question 27

Who is most likely to get urolithiasis?

Answer 27

Uncommon
More common in males (mares have a shorter, wider urethra, easier to pass)
Adults (mean age 10)
Bladder > kidneys > ureters > urethra

Question 28

What are the types of uroliths?

Answer 28

All calcium carbonate
Type 1 = more than 90%, yellow and spiculated, easily fragment
Type 2 = grey, smooth
Sabulous urolithiasis = accumulation of urine sediment in ventral bladder

Question 29

What are the clinical signs of cystic calculi?

Answer 29

Dysuria
Haematuria
Stranguria
Incontinence
Especially at/after exercise

Question 30

How do we diagnose cystic calculi?

Answer 30

Rectal
Endoscopy
Ultrasound
Must empty bladder!

Question 31

How can we treat cystic calculi?

Answer 31

Laparotomy and cystotomy
Recovery as for colic surgery
But low risk of long-term complications

Question 32

Describe urethral calculi.

Answer 32

Males usually, small cystoliths that have passed into urethra
Dysuria
If blocked - colic, acute post-renal failure, risk of rupture
Perineal urethrotomy

Question 33

How can we try to prevent recurrence of urolithiasis?

Answer 33

Cannot acidify urine so avoid predisposing factors - no supplementary electrolytes, no alfalfa/lucerne, check for UTI

Question 34

Describe urinary incontinence.

Answer 34

Uncommon
Signs exacerbated by coughing/exercise
Similar signs to urolithiasis - more common so investigate for that first
Upper motor neuron (including Equine Herpes Virus myeloencephalitis), lower motor neuron or myogenic disorders
Sabulous urolithiasis (bladder full of sediment)

Question 35

Describe bladder paralysis.

Answer 35

Usually a feature of neurological disease (cauda equina syndrome, herpes virus)
Urinary incontinence, scalding, loss of anal/tail muscle tone

Question 36

What nursing considerations should we have for urolithiasis/incontinence patients?

Answer 36

Cleaning of perineum/hindlimbs
Protection from urine scalding
Management of urinary catheter if necessary
If abdominal surgery - as colic surgery
Monitoring of urination/urine output

Question 37

Describe patent urachus in foals.

Answer 37

Foetus - urine passes from bladder to allantoic cavity via urachus, normally closes at time of parturition
Congenital patent urachus, drip urine from umbilicus, treat with prophylactic antibiotics/surgical resection IF does not close on its own

Question 38

Describe ruptured bladder in foals.

Answer 38

Occurs during parturition, usually in males - progressive dullness over first 72hrs
Results in electrolyte imbalance (hyperkalaemia)
Urine accumulation free in the abdomen
Fluid support then surgery to correct