Lower urinary tract diseases Flashcards
Anuria
total lack of urine production
Red flag for acute severe kidney injury or acute kidney failure
Dysuria
difficulty passing urine - often reported with pollakiuria
There can be non-urinary causes for stopping whilst ridden and ‘posturing to urinate’ e.g. gastric ulceration and abdominal pain from other sources
Haematuria
presence of blood in the urine
Note that urine dipsticks cannot differentiate Hb from Mg molecules so are not always detecting haematuria rather pigmentiuria - confirm presence of red cells with microscopy
Oligouria
etymology Greek ‘few’ - reduced urine output
Sometimes absolute, sometimes only noted as a lack of expected urine output GIVEN fluid therapy
Pigmentiuria
change in the usual urine colour spectrum (pale to dark yellow)
Linked to whole blood, Hb, or myoglobin in the urine
Pollakiruria
etymology Greek ‘pollakis = many times’ - increased frequency of urination
Check with owners - is this truly increased volume (actually polyuria) or inncreased frequency. If the latter this is more likely to be bladder pain/detrusor hyperreactivity/cystitis
Stranguria
straining to pass urine
May be mistaken by owners as straining to pass urine, but is actually GI pain - gastric ulcers, meconium impaction (foal), intestinal neoplasia/abscess pulling on mesentery
Hyposthenuria
Urine specific gravity (USG) <1.008
Urine concentration is more dilute than plasma
Indicative of lack of kidney concentrating ability
In fact, it shows active secretion of water and is indicative of CKD, excessive water intake (psychogenic polydipsia), or diabetes insipidus
Isosthenuria
USG: 1.008 < USG > 1.014
Urine concentration is the same as plasma
Kidneys are neither conserving or secreting water
Could indicate a lack of kidney concentrating ability, or normal water intake for that individual
Also, worth checking if sedative drugs have been used to catheterise and obtain the urine sample, as this is the most common artefactual reason for urine that is isosthenuric, rather than more concentrated.
Hypersthenuria
USG > 1.014
Urine is more concentrated than plasma
Kidneys have normal concentrating ability
Maybe seen prior to anuria, and alongside oligouria
Might be a normal finding in horses with low water intake, but is a concern in a hypovolaemic patient, or one where acute kidney injury is suspected or indeed being treated
Approach to stranguria/pollakuria
Unusual owner reported problem
Mostly associated with inflammatory conditions of the bladder or urethra
E.g. urinary caliculi, cystitis, neoplasia
Urinalysis
Visual assessment of the bladder/urethral via endoscopy
If caused by a calculus, might be persistent or intermittent haematuria, perhaps after strenuous exercise
Primary urinary tract infection
Primary cases are very rare - check for inciting cause before dispensing antimicrobials
Normal flora of the vulva and sheath are protective
Bladder has usual mucous lining to protect
Inflammation/trauma (calculi, sabulous material) are usually the inciting cause because they interfere with usual protective mechanisms
Secondary cystitis causing stranguria/pollakuria
Urethra damage
○ Breeding
○ Parturition
○ Iatrogenic
Abnormal anatomy
Urolithiasis
Bladder paralysis
Bladder neoplasia
Sterile inflammatory cystitis that leads to opportunistic infection
Clinical signs alongside stranguria
Can be variable
Urine dribbling and staining from the detrusor hyperreactivity
Scalds the skin of the perineal area and medial aspect of pelvic limbs
The smell of stinky urine/ammonia
Proving the presence of urinary infection
Quantitative culture
○ Catheter not free catch
○ >10 leukocytes per high power field
§ 10,000 CFUs/mm
Gram -ve: E. coli, klebsiella, enterobacteriaceae
Gram +ve: staphylococcus, streptococcus, pseudomonas, (rarely Corynebacterium renale)
Treatment of stranguria/pollakuria
Underlying cause
If genuine septic cystitis - justifiable use of antimicrobials
○ TMPS is concentrated in the urine - excellent first choice and practically can be given for an extended course if needed as PO medicine
○ Aminoglycoside + penicillin next choice but much less practical
Causes of haematuria
Renal: idiopathic haemorrhage, neoplasia, cystic structures
Bladder: stones, idiopathic haemorrhagic cystitis, bacterial cystitis, neoplasia
Urethra: neoplasia, colliculus seminalis (geldings) inflammation
NB - urinary calculi - could be intermittent haemorrhage after exercise
Investigation of haematuria
Endoscopy identifies pathology in the urethra and bladder
Also enables assessment of where blood is coming from by watching ureters:
○ If from both kidneys - bilateral haematuria - probably haemolysis
○ If from one kidney - unilateral disease
○ Ultrasound kidneys as likely to see neoplasia, kidney stone, idiopathic renal haemorrhage, cystic change?
Urolithiasis
Not diet induced
Horses eat forage and excrete calcium via kidneys
○ Calcium carbonate
○ Calcium phosphate
Mucus from renal pelvis and ureters provides protection
Mostly yellow, spiculated and fragment
Sometimes grey, smooth, and don’t fragment as easily - perhaps more phosphate?
By far most likely in the bladder
Very rare to have urethral or indeed ureteral obstruction
More common in geldings (3:1) vs mares
Which shows that not as a consequence of UTI since this is more prevalent in mares (short wide urethra)
Nephroliths
Clinical signs
○ Pain when ridden
○ Biting sides
○ Etc.
Dx: U/S kidneys (transrectal and transabdominal) to rule in/out
Can be incidental, or provoke infection etc.
May have increased urine protein/creatinine ratios
Tx: leave alone or consider nephrectomy if not azotaemic
Cystoliths
Commonly haematuria after exercise
Stranguria/dysuria
Signs of concurrent UTI
Possible low grade colic
Mares and geldings/stallions similar prevalence
○ Transrectal palpation and ultrasonography
○ Cystoscopy
Very difficult to use diet or oral salts to dissolve or reduce size
Ammonium Cl used - but unpalatable at any real level of administration
Salt (NaCl) - induces PUPD to some degree - not necessarily that helpful!
Stone removal via perineal urethrotomy and cystoscopy-guided stone removal
Urinary incontinence
Most problems relate to neurological dysfunction or are idiopathic
Often by the time the horse presents
○ Detrusor weak
○ Enlarged bladder
○ Owner noticed overflow incontinence
Rare for there to be an obstruction but occasionally, causes eventual bladder atony and overflow incontinence
Causes of incontinence
Sabulous cystitis
Sacrococcygeal injury
Bladder calculi
EHV myeloenceohalitis/opathy
Polyneuritis equi
Sacral abscessation
Sacral neoplasia
Causes of sacral trauma
Falling over backwards after rearing or pulling away from handler
Rearing and sitting down on the sacrum
Getting stuck under gates, in trailers or lorries, stocks or racing stalls
