Equine Medical and Surgical Urogenital Disease

what might hematuria indicate?

bleeding somewhere within the urinary tract, but timing is important

• right after exercise is often related to cystolithaisis

• in cases of urethral rents in geldings, the bleeding happens at the end of urination

what might pigmenturia indicate?

pigment originates from outside of the urinary system (from muscle or RBC breakdown) but may still have important renal consequences

what is the general diagnostic approach to renal or urinary pathology in horses?

initial evaluation often includes both bloodwork and urinalysis

further testing selected based on initial findings

when should urine samples ideally be collected?

before administering IV fluids or sedation (especially alpha-2s) as these interventions may alter urine concentration and other findings

what findings on bloods raises concerns about renal disease?

creatinine — most useful routine marker of GFR (more useful than BUN)

hypoalbuminemia — may raise suspicion of protein-losing enteropathy due to glomerular disease, but protein-losing enteropathy is more common in horses

what electrolyte abnormalities may be seen with acute kidney injury?

hyponatremia, hypochloremia, hypocalcemia, normal potassium

what electrolyte abnormalities might be seen with chronic renal failure?

hyponatremia, hypochloremia, hypercalcemia, hyperkalemia

what diagnostic imaging is typically used for assessment of the kidneys?

transabdominal ultrasound to identify structural abnormalities associated with congenital disease, nephritis, CKD, or nephrolithiasis

transrectal palpation of the left kidney can be useful to assess its size or the presence of masses

what diagnostic imaging is typically used for assessment of the bladder?

per rectum palpation allows for assessment of bladder distension, wall abnormalities, tonicity or presence of large cystoliths

transrectal ultrasonography provides detailed evaluation of the wall and contents (can help identify wall thickening, sediment, cystoliths or masses)

cytoscopy allows direct evaluation in horses with stranguria, pollakiuria, or hematuria; can identify cystitis, cystoliths, ulceration or masses; also permits targeted sampling or biopsy

what diagnostic imaging is typically used for assessment of the urethra?

male horses - transcutanous ultrasound to evaluate penile and perineal urethra and identify obstruction (including calculi and proximal urethral distension)

urethroscopy - direct visualization to identify calculi, strictures, inflammation, trauma, masses or sources of bleeding

what are some important causes of acute kidney injury in horses?

nephrotoxic drugs, pigmenturia, renal hypoperfusion/ischemia, and less commonly immune-mediated or idiopathic renal disease

what drugs commonly cause nephrotoxicity/acute tubular necrosis?

aminoglycosides commonly, oxytetracycline less commonly

NSAIDs, especially phenylbutazone and flunixin, in hypovolemic or poorly perfused horses

what else causes nephrotoxicity other than drugs?

severe pigmenturia eg horses with severe exertional rhabdomyolysis may develop myoglobinuria

is NSAID-associated renal dysfunction reversible?

yes, if recognized and treated early

however continued administration can progress to renal papillary necrosis, which represents structural renal injury and carries a poor prognosis

what is the clinical presentation of horses with acute kidney injury?

oliguria and polyuria — USG may be inappropriately isosthenuric, reflecting loss of normal concentrating ability

anuria — severe renal failure that is difficult to reverse medically and warrants referral

what are the key points of treating acute kidney injury?

correct dehydration and hypovolemic, then replace ongoing losses; stop or minimize nephrotoxic drugs wherever possible; monitor serum creatinine, urine output, hydration, electrolytes and acid-base status

why should fluid overload be avoided in horses with AKI?

excessive IVFT can cause renal interstitial edema and potentially worsen RBF and GFR

when are diuretics indicated in horses with AKI?

in oliguric or anuric horses; furosemide is the diuretic of choice after circulating volume and hydration have been adequately restored

when can treatment be reassessed for AKI?

azotemia resolves or remains stable for >24h; serum creatinine shows an appropriate downward trend over first 24-48h, urine output and USG improve, urinalysis abnormalities resolve; hydration, electrolyte and acid-base abnormalities have been corrected

what findings are often associated with CKD in horses?

weight loss, poor body condition, reduced performance, PUPD

how is CKD treated in horses?

supportive rather than curative!

preserve remaining renal function, maintain hydration and nutrition and manage complications

include good quality pasture, increased carbohydrate intake and addition of fat when additional calories are required

what are secondary UTIs commonly associated with?

sabulous cystitis or cystolithiasis, urinary tract obstruction or calculi, urethral or bladder dysfunction (including neurologic disease), urethral dysfunction following dystocia or foaling

what clinical signs are associated with UTIs in horses?

stranguria, pollakiuria, urinary incontinences and changes in urine appearance

how are UTIs treated in horses?

addressing both the bacterial infection and any underlying cause

• TMPS is a reasonable antimicrobial option for uncomplicated UTI

what are the two types of equine uroliths?

Type I: yellow-green, spiculated calculi that fragment readily (~90% of cases)

Type II - grey-white, smooth calculi that are more resistant to fragmentation and may contain phosphate

both are composed of calcium carbonate and are usually spherical

what clinical signs are associated with urolithiasis?

exercise induced hematuria, stranguria, less common signs include recurrent colic, weight loss, irritability and rarely rectal prolapse

how is urolithiasis treated?

refer for surgical removal (medical dissolution is generally ineffective)

how is risk of recurrence of urolithiasis reduced?

avoid feeding high-calcium feeds (eg legume hays and calcium-containing supplements); increase salt intake to promote water consumption; provide pasture access

what are some indications to examine the penis and male urogenital tract?

preputial or penile swelling, penile or preputial lesions, abnormal urination or urination posture, hematuria, routine health examination or sheath cleaning

what are some true emergencies that require immediate recognition and referral in male horses?

paraphimosis, pripism, penile hematoma, penile wounds/lacerations, spermatic cord torsion (testicular torsion)

what is paraphimosis, how is it diagnosed, and what management steps should be taken immediately?

protruded penis, edema, inability to retract penis; diagnosed by clinical examination

protect and support penis, reduce edema (cold therapy, compression, NSAIDs, attempt manual reduction)

what is priapism, how is it diagnosed, and what management steps should be taken immediately?

persistent erection, turgid penis, inability to retract penis; diagnosed by clinical examination and differentiation from paraphimosis

penile support, compression, analgesia; urgent intervention to preserve function

what is a penile hematoma, how is it diagnosed, and what management steps should be taken immediately?

acute penile swelling, bruising, enlarged dependent penis, inability to retract penis; diagnosed by clinical examination ± ultrasonography

cold therapy, compression bandaging, penile support

what are penile wounds, how is it diagnosed, and what management steps should be taken immediately?

visible wound, swelling, hemorrhage, inability to retract penis; diagnosed by physical examination and assessment of urethral integrity

control hemorrhage, clean wound, reduce edema, support penis

what is spermatic cord torsion, how is it diagnosed, and what management steps should be taken immediately?

acute scrotal pain, colic-like signs, scrotal swelling; diagnosed by physical examination ± ultrasonography

provide analgesia and arrange urgent surgical referral

what are some common non-emergency male reproductive conditions?

penile/preputial massess (SCC, sarcoids, papillomas, habronemiasis), chronic scrotal enlargement, hydrocele, orchitis, epididymitis, and other causes of infertility

what are some true emergencies that require immediate recognition and referral in mares?

uterine torsion, body wall rupture (prepubic tendon rupture), uterine artery hemorrhage, uterine tear, uterine prolapse, bladder eversion, prolapse or rupture

how does uterine torsion typically present, how is it diagnosed, and what management steps should be taken immediately?

late-gestation mare with colic; diagnosed by rectal palpation of broad ligaments ± ultrasound

stabilize mare (analgesia, fluids if required)

how does body wall rupture typically present, how is it diagnosed, and what management steps should be taken immediately?

ventral edema, abnormal abdominal contour, bloody mammary secretions; diagnosed by clinical examination

apply abdominal support bandage; minimize movement

how does uterine artery hemorrhage present, how is it diagnosed, and what management steps should be taken immediately?

postpartum mare with pallor, tachycardia, weakness, colic or collapse; diagnosed by ultrasound ± abdominocentesis

minimize stress, stablize CV status

how does uterine tear typically present, how is it diagnosed, and what management steps should be taken immediately?

post-foaling colic, endotoxemia, peritonitis or shock; diagnosed by vaginal examination ± ultrasound

treat shock/sepsis and stabilize

how does uterine prolapse typically present, how is it diagnosed, and what management steps should be taken immediately?

large uterine mass protruding from the vulva shortly after foaling; diagnosed by visual examination

protect tissue from trauma and contamination

how does bladder eversion, prolapse or rupture typically present, how is it diagnosed, and what management steps should be taken immediately?

prolapsed tissue, depression, azotemia or uroperitoneum after foaling; diagnosed by physical examination ± ultrasound

stabilize mare and protect exposed tissues

what are some common non-emergency mare reproductive conditions?

pneumovagina, perineal lacerations, rectovaginal fistula, cervical lacerations, vaginal lacerations, and granulosa-theca cell tumours (GCTs)

what are some urogenital conditions of the foal that requires immediate recognition and/or referral?

bladder rupture, urachal tear, patent urachus

how does bladder rupture typically present, how is it diagnosed, and what management steps should be taken immediately?

abdominal distension, reduced nursing, lethargy, colic, frequent attempts to urinate with little output; diagnosed by abdominal ultrasound, abdominocentesis, bloodwork showing electrolyte abnormalities

stabilize electrolyte abnormalities and refer for surgical repair

how does urachal tear typically present, how is it diagnosed, and what management steps should be taken immediately?

similar to bladder rupture, often with slower progression of clinical signs; diagnosed by abdominal ultrasound ± surgical exploration

stabilize electrolyte abnormalities and refer for surgical repair

how does patent urachus typically present, how is it diagnosed, and what management steps should be taken immediately?

urine leakage from the umbilicus; diagnosed by clinical examination ± ultrasonography of umbilical structures

umbilical antisepsis, investigate for concurrent infection, medical management where appropriate, persistent cases may require surgery