Urinary Tract Problems & PUPD in the Horse Flashcards
what is the water maintenance requirements in the horse
40-60 ml/kg bwt/day
what would a polydipsic horse be drinking a day
>100 ml/kg/day
what is a normal urine output
15-30 ml/kg bwt/day
15l for a 500kg horse
what are the ddx for PUPD (5)
- psychogenic PUPD
- secondary renal medullary washout
- endocrine: Cushing’s syndrome
- chronic renal failure
- diabetes insipidus (rare)
what are the causes of psychogenic PUPD
boredem/change of environment/feed
what is secondary renal medullary washout
inability to concentrate urine due to loss of sodium in renal medulla
how does cushing’s cause PUPD
direct inhibition of ADH
glucosuria
how does chronic renal failure lead to PUPD
increased water intake to maintain glomerular filtration rate
what are the types of diabetes insipidus
central vs nephrogenic
both very rare
what are the ways water is lost in equine
urine +/- 20%
feces +/- 75%
sweat
what is the normal colour of adult urine
pale yellow to brown
what is the normal colour of foal urine
pale yellow
what is the normal viscosity of adult urine
viscous (mucoid)
what is the normal viscosity of foal urine
watery
what is the normal transparency of adult urine
slightly turbid
what is the normal transparency of foal urine
translucent
what is the specific gravity of adult urine
1.006-1.050 (usually 1.020-1.050)
what would the specific gravity be if BUN elevated
>1.020 if BUN increased
what is the normal specific gravity of foal urine
1.001-1.027
what is the pH of adult urine
6.5-8.0
what is the pH of foal urine
6.0-7.0
what is the RBC/hpf in adult horse
<5 cells/hpf
what is the RBC/hpf in foal
none
what is the WBC/hpf in foal
0-3/hpf
what is the WBC/hpf in adult
<5cells/hpf
what are PUPD diseases in congenital/young horses (6)
- patent urachus may follow septicemia in neonates
- ectopic ureters – seen in fillies
- rectovaginal fistula
- rectourethral fistula
- polycystic kidneys
- renal agenesis
what are middle aged diseases that can cause PUPD (2)
- urolithiasis (more common in males)
- neoplasia
- bladder neoplasia rare (SCC, transitional cell carcinoma)
- externial genitalia (SCC, fibrosarcoma, melanomata)
what are the diet changes that may cause urinary diseases
important to establish any recent changes
change from pasture to stabling causes dramatic drop in water intake
is forage high in Ca? what supplements?
is water intake adequate?
presence of salt blocks?
what role does the environment play in urinary diseases (5)
- recent change of environment or use?
- any recent trauma? ortho/neuro damage
- more than one individual affected? (ex. EHV, equine protozoal myeloencephalitis)
- access to toxic plants (oak/acorns, exposure to alfatoxins)
- receiving NSAIDs?
what specific complaints from the owner might indicate renal involvement
- weight loss and PUPD
- lethargy or loss of athletic performance
what will the clinical exam entail (9)
- full exam
- collect blood sample prior to sedation
- detailed exam of external organs
- rectal palpation
- collection of sterile urine sample
- bladder/renal ultrasound
- bladder endoscopic exam
- peritoneal fluid collection
- neurological exam
what are clinical signs of urinary diseases (5)
- weight loss common
- can appear lame if external genital pain
- depression if azotemic: pre, post, or intrinsic renal failure
- fever: sheath infection, cystitis, urolithiasis or pyelnonephritis
- anemia: hematuria, CRF
what would the ddx of a mass on the sheath be (4)
- sarcoid (nodular, fibroblastic)
- SCC
- habronemiasis
- melanoma (cytobrush sample or biopsy)
what would the ddx of a mass on the perianal or perivulvular mass be (5)
- SCC
- abscess
- post service injury
- fibrosarcoma
- lymphoma (US + aspirate or biopsy)
how would you examine the penis
acepromazine 0.05 mg/kg IV/IM
most reliable for penile relaxation
xylazine 0.3-0.5 mg/kg IV
wait 5-10 mins
what are the components you can evaluate with the rectal exam (3)
- left kidney (right = retroperitoneal) (size, any associated pain)
- ureters
- bladder (size, tone, wall thickness, presence of calculi, is a cystolith palpable?)
what would this penile mass be
squamous cell carcinoma
what would this penile mass be
squamous cell carcinoma
what would this penile mass be
viral papilloma lesions
what would this penile mass be
melanoma
what would be a ddx for an adult male spraying urine, may be dysuria, swelling of urethral opening
urethral diverticular concretion (bean)
SCC
habronemiasis
how do you treat a urethral diverticular concretion
manual removal
sheath cleaning water based lube only
what are the clinical signs of stranguria (2)
- scalding/urine staining of the dorsal hind legs in males
perineal scalding in mares
- swelling of sheath/distal penis (edema vs infection, purulent discharge from sheath or from vulva)
how do you collect a urine sample
use sterile technique
minimal sedation to reduce changes in urine concentration and content
stallion catheter or mare catheter/foley
in the mare: external urethral orifice
what is a catether useful for in mares
- submit cathetirzed sample for cytology and bacterial culture
- bladder lavage helpful in cases of sabulous urolithiasis –> reduce sediment, 5l hartman’s, indwelling foley catheters in bladder paralysis or LMN bladder
can dipstick distinguish blood vs myoglobin vs hemoglobin in horses
no
cytology required
what might be elevated if there is myoglobinuria
CK/AST
what would be in the urine if there is lower urinary hemorrhage
whole rbcs
what might be in the urine if there is renal damage
renal casts
what could cause proteinuria (3)
- glomerular disease
- pyuria
- bacteriuria
what could be ddx for glucosuria (4)
- elevated with stress
- alpha agonists
- cushing’s syndrome
- equine metabolic syndrome
what crystalluria is normal in the horse (3)
- calcium carbonate
- calcium oxalate
- triple phosphate
what does elevated urea/creatinine indicate
reflects reduced GFR
determine if elevations are due to pre-, post- or intrinsic renal failure
what serum electrolyte changes would indicate post-renal obstruction
increased K+
Na+ decreased
Cl- decreased
what is NAG
n-acetly-B-D-glucosaminidase
what can NAG indicate
urinary increase in acute kidney injury
what can lower albumin indicate
PLN uncommon in horses
what can increased globulin indicate
increased if chronic inflammatory focus
what can elevated WCC, fibrinogen, SAA concentration indicate
likely left shift neutrophilia, elevated fibrinogen and serum amyloid A in urolithiasis
what can anemia indicate
decreased erythropoiesis
decreased RBC lifespan if chronic renal failure
what other clinical pathologies seen in pre renal azotemia
signficant dehydration
endotoxemia
USG >1.030
what other clinical pathologies seen in renal azotemia
often following prerenal causes
renal medullary necrosis
NSAID toxicity esp in hypovolemia
acute kidney injury (AKI) subsequent to dehydration, aminoglycoside use
what other clinical pathologies seen in post renal azotemia
increased K+
decreased Na+
decreased Cl-
what can endoscopic exam of the bladder assess (5)
- is there trauma?
- rule out cystoliths?
- visualize ureters
- are both producing urine?
- rule out neoplasia
what are the clinical signs of urolithiasis (4)
- renal: may cause hematuria or pyelonephritis
- ureter: may cause ureteral rupture and uroperitoneum
- bladder: colic signs, dysuria, and hematuria post exercise
- urethra: acute colic, stranguria, bladder distention, penile swelling
what are clinical signs of nephroliths
- colic
- hydronephrosis
- hematuria
what are the clinical signs of cystic and urethral calculi (5)
- dysuria, stranguria
- hematuria after excerise
- frank blood at end of urination
- urine scalding
- similar signs to colic
how do urolithiasis form
nidus required + supersaturation of urine following urine stasis
what are the two types of urolithiasis (2)
- spiculated, yellow-brownish
- smooth, oval and white
how would you diangose a urolithiasis (4)
- clinical signs
- rectal palpation
- catheterization
- endoscopy
what is shown here
accoustic shadowing
urolithiasis
how would you treat an uncomplicated primary bacterial cystitis
hydration: maintain flow of urine
irrigation of bladder
antimicrobial therapy: renal excretion
what antimicrobials would you use to treat a primary bacterial cystitis
- trimethoprim-sulphadiazine
- penicillins (gentamicin, cephalosporins, ampicillin)
may need >2 week duration based on culture cytology and culture
how would you remove a urolithiasis surgically
xylazine epidural
urethral sphincterotomy may be needed
lithotripsy
laparocystotomy commonest technique in males
how do you treat a urethral calculi surgically
surgical emergency
distal urethral –> attempt to express manually
incision over median raphe under GA
ischial calculi require ischial urethrostomy
how do you treat a urethral calculi (3)
- antibiotics
- urinary acidification: oral asorbic acid (1kg/horse/day), diet with low DCAB, restrict caclium intake
- water intake: maximize, addition of salt to diet
how do you treat sabulous urolithiasis (4)
- freq lavage of bladder with sterile saline to remove sediment
- bethanechol to increase detrusor contraction
- phenoxybenzamine only if UMN sphincter involvement
- aim to promote diuresis: urinary acidifying diet, underlying neurological problem not treatable
what are the clinical signs of bladder rupture (3)
- depression and inappetence
- pass small volumes of urine
- pendulous abdomen may develop
what clinical pathology changes might be seen following a bladder rupture (5)
- azotemia
- hyperkalemia
- hyponatremia
- hypochloremia
- uroperitoneum: peritoneum creatinine > serum creatinine by factor of 2
what can cause bladder ruptures
post partum mares and foals (male foals)
following severe necrotizing cytitis
why is a cystoscopy useful in a bladder rupture
determine original cause of rupture and extent of tear to give prognosis
how are bladder ruptures treated
- small tears: heal by secondary intention
- foals: surgery after correction of electrolyte imbalances (correct fluid therapy!)
what are congenital causes of urinary incontinence (2)
- ectopic ureters
- hydroureters
what are neurological causes of urinary incontinence (4)
- LMN damage may occur secondary to sabulous urolithiasis
- cauda equine damage
- infectious causes of cauda equina neuritis
- traumatic injury to spinal cord or brain causing LMN or UMN damage
what are anatomical defects that can cause urinary incontinence (2)
- mares may have pooling of urine in the repro tract
- accumulation of urine within the sheath in males if unable to exteriorize the penis
what are the sympathetic nerves that innervate the bladder
hypogastric nerves from the lumbar vertebrae
what are the parasympathetic nerves that innervate the bladder
pelvic nerve from sacral vertebrae
what does the sympathetic innervation in the bladder cause
detrusor relaxation, internal sphincter contraction
filling and continence
what does the parasympathetic innervation in the bladder cause
detrusor contraction
emptying bladder
what is the somatic innervation of the bladder
pudendal nerve from sacral vertebrae
what is the somatic innervation of the bladder control
external sphincter
what is cauda equine syndrome
meninges end at S2/S3 vertebral junction
caudal nerve roots extend further
cauda equine = nerve roots and SC located caudal to LS junction
sacrococcygeal nerve roots (pudendal, caudal rectal, pelvic and coccygeal peripheral nerves, part of sciatic and gluteal nm)
damage to this region may occur in isolation or be part of multifocal problem
what are the signs of cauda equine and the ddx (8)
- traumatic damage
- neuritis of the cauda equina (polyneuritis equi)
- EHV-1 myeloencephalitis
- sorghum-sudan grass toxicity
- equine protozoal myeloencephalitis
- sacrococcygeal vertebral osteomyelitis
- rabies
- neoplasia
what might cause equine LMN incontinence
may be linked to cauda equina neuritis
primary or secondary sabulous urolithiasis (sediment crystalliuria, recurrent discomfort and infection)
what are the signs of LMN incontinence
incomplete bladder emptying
overflow of small quantities urine from large flaccid bladder
what would LMN neurological incontinence affect
detrusor and urethral sphincter atony
urinary retention and overflow incontinence
large, atonic bladder easy to express
where would a UMN neurological deficit be that causes incontinence
lesion in suprasacral or brain stem
where would a LMN deficit be that would cause neurological incontinence
lesion in sacral, pelvic or pudendal nerves
what would a UMN neurological incontinence look like
urethral sphincter tone exaggerated and loss of coordination micturition
urinary retention and overflow incontinence
large, firm bladder difficult to express
what is renal tubular acidosis
alkaline urine and systemic acidosis
inability to excrete H+ ions in the distal convoluted tubule (Type 1)
or
fail to resorb bicarbonate ions from proximal convoluted tubule (type 2)
what are the clinical pathologies of renal tubular acidosis
hypercholermia
low potassium
metabolic acidosis
what are the clinical signs of renal tubular acidosis (4)
- depression, weakness and ataxia
- loss of condition
- tachypnea and tachycardia
- primary and secondary forms
how is renal tubular acidosis treated
bicarbonate deficit = bwt x 0.6 x base deficit (mmol)
correct bicarbonate deficit
longterm oral supplementation based on blood gases and response to treatment
