Equine urinary tract infections & urolithiasis

Question 1

Urinary Tract Infections in horses:

Answer 1

Cystitis, nephritis

Uncommon in horses

Mares at higher risk due to their Short urethra.

If recurrent: look for a functional deficit.
Secondary to urolithiasis and some other conditions (lower motor neuron dysfunction, backpooling of urine due to anatomy etc.).

Question 2

Suspect urinary tract infection in horses when:

Answer 2

• Frequent, strained urination
• Frank blood in urine
• Urine scalding

Look for:
* Cystic calculi
* Bacteria, WBC, RBC in urine

Question 3

Urolithiasis in horses.

Answer 3

The presence of macroscopic concretions of urine crystals within urinary tract.
* Calcium carbonate

Is an Uncommon disease with a Prevalence of 0,004-0,5%.

Location of concrements:
* Bladder
* Kidneys
* Urethra
* Ureters

Males (geldings) are predisposed due to Longer and less distensible urethra.

2 types of equine urinary tract concrement:
* Type 1: Yellow-green, uneven surface.
Most common.

• Type 2: White-gray, smooth surface.

Answer 4

Urolithiasis Pathophysiology in horses.

Is Not completely understood. Mineralization around nidus. Concrements maybe also a result of tissue damage or Also as a result of CKD!

• Calcium carbonate crystals
• Calcium oxalate crystals
• Struvite

Other components
* Mucoproteins
* Leukocytes
* Epithelial cells

Question 5

Clinical signs of urolithiasis in horses.

Answer 5

Depends on site of formation and degree of obstruction.

Dysuria
Stranguria

Tenesmus
Hematuria

Urine scalding
Colic

Partially dropped penis
Repeated posture to urinate

Stiffness of hindquarters
Weight loss

Question 6

Diagnosis of equine urolithiasis should include:

Answer 6

Rule out chronic kidney disease.

Palpate transrectally.

Ultrasound: the whole urinary tract, incl kidneys.

Culture some urine for Staphylococci, Streptococci.

Cytoscopy of the urinary tract.

Question 7

Endoscopy/cyctoscopy of the equine urinary tract.

Answer 7

Videoendoscope size <12mm diam, 1m long. Aseptically.

Catheterize first to Remove urine.

Insufflate with air for Better visualization of bladder and mucosa.

Uretral openings at 10 and 2 o’clock. Watch for Urine draining (once in every minute).

Dilated ureters can indicate Obstructive or be Congenital.

Question 8

Urolithiasis tx in horses.

Answer 8

Surgery or Fragmentation (Manual, Laser, Shock wave)

Catheter for 5-7 days (when urethral calculi have been removed) to Reduce stricture formation.
Broad spectrum AB + NSAIDs.

• Uroperitoneum may develop
• Reoccurrence common

Diet won’t dissolve them because horses don’t have struvites!

Question 9

Prevention of urolithiasis in horses.

Answer 9

Acidification of urine (but this may be impossible to achieve)
Via Oral supplementation
* Ammonium chloride
* Ammonium sulphate
* Ascorbic acid (Vitamin C) (500 gr per day according to one source so this is a huge amount and may not be feasible)

Decreasing intake of minerals
* calcium, phosphorous, magnesium

Low calcium diet
* Feed Grass hay
* No lucerne (alfalfa)

Question 10

Sabulous cystitis in horses is

Answer 10

Chronic inflammation of the bladder caused by
accumulation of excessive urinary sediment
(calcium carbonate crystals).

Caused by bladder dysfunction.
* Lower motor neuron: pudendal nerve, detrusor muscle and external urethral sphincter dysfunctions.
Or
* Upper motor neuron: muscle spasticity and bladder
overfill.

But Often, no neurological deficits present – idiopathic bladder paralysis.

Possible that Chronic lumbar pain predisposes – if won’t posture to urinate normally, sediment accumulates, detrusor muscle gets damaged.
* Geldings predominate

Question 11

Tx of sabulous cystitis.

Answer 11

Treatment: high volume lavages, antimicrobial
treatment, NSAIDs. IV etamsylate if bleeding in bladder.

Outcome: may resolve completely or require
repeat treatments at certain intervals. Complete resolution rare.

Option 2 is Large volume lavage with NaCl mixed with DMSO (6-9
liters at the time). DMSO is a chemical solvent.