Lower UT diseases

Question 1

Give four reasons why females are more predisposed to lower UTI than males

Answer 1

1. Shorter, wider urethra that opens into non-sterile vagina
2. Urethral opening much closer to anus than males
3. Possible trauma incurred during parturition, mating
4. Hormonal fluctuations of oestrus can alter the environment in the vagina and urethra
   - less glycosaminoglycan production when oestrogen is high
   - more alkaline urine during oestrus, which is preferred by bacteria

Question 2

Give two reasons why males are more predisposed to urethral obstruction by calculi

Answer 2

1. Longer, narrower urethra - more likely to get stuck

2. External structures that can hinder stone passage - prostate, os penis etc

Question 3

Why is ectopic ureter reported 20X more in bitches than male dogs?

Answer 3

Because the ectopic termination into a distal site of the urinary tract causes uncontrolled leak of urine (incontinence). In males, the distal urethral sphincter prevents this, so ectopic ureter may never be discovered

Question 4

Where does an ectopic ureter usually empty in a bitch?

Answer 4

Vagina or urethra

Question 5

What is the urachus?

Answer 5

The tube-like communication between the allantoic cavity and bladder in the developing foetus

Question 6

What are three potential congenital abnormalities of the urachus and their potential consequences?

Answer 6

1. Failure to close = leakage of urine to the peritoneum or outside world can predispose to infection of bladder or liver
2. Rupture may cause uroperitoneum
3. Partial closure can cause urachal cyst formation between urachus and umbilicus

Question 7

What is the technical name for a bladder diverticulum caused by remaining urachal tissue?

Answer 7

Vesicourachal diverticulum

Question 8

What are two potential causes of bladder diverticuli other then persistant urachal tissue?

Answer 8

Obstruction to urine outflow

Weak patch in bladder wall musculature > balooning

Question 9

What are three potential consequences of duplicate bladder?

Answer 9

Dysuria
Urinary incontinence
Abdominal distension

Question 10

What is the name of the condition where the urethral groove fails to close to form the penile urethra?

Answer 10

Hypospadias

Question 11

What is the most common developmental anomaly of the urethra?

Answer 11

Urethro-rectal fistula

Or vagino-rectal fistula

Question 12

Under what circumstances might hydroureter occur without a distal obstruction?

Answer 12

Peritonitis - SNS activity inhibits ureteral peristalsis, causing urine buildup and hydroureter

Question 13

What is bladder eversion? Which surface of the bladder is facing out?

Answer 13

It is invagination of the bladder through the urethra

The mucosal surface is facing out

Question 14

What is bladder prolapse?

Answer 14

Bladder herniates through a tear in the vagina. Its serosal surface faces the outside.

Question 15

Other than bladder eversion and prolapse, what can prolonged straining (e.g parturition) cause in female animals?

Answer 15

Uterine prolapse, vaginal prolapse

Question 16

What are two possible mechanisms for bladder atony?

Answer 16

1. Neural injury that blocks tonic PNS stimulation via the sacral plexus e.g intervertebral disc prolapse
2. Prolonged urine outflow obstruction causing long term bladder dilation e.g calculi, prostatic hyperplasia, neoplasia

Question 17

How does bladder hypertrophy occur? What is a good presumptive test at post mortem exam?

Answer 17

Chronic PARTIAL obstruction of urine outflow

Try to stretch at PME - if can stretch, unlikely hypertrophic

Question 18

In the event of a complete block to urine passage, which anatomic structure determines whether or not the bladder is likely to rupture?

Answer 18

The vesicoureteral valves in the bladder trigone

Question 19

If the valves remain closed what is the likely outcome?

Answer 19

Increase in pressure in bladder > compression of mural veins > venous congestion > venous infarction of wall > rupture

Question 20

If the valves open what is the likely outcome?

Answer 20

Distension and atony of bladder, hydroureter and hydronephrosis - longer time frame

Question 21

What factors other than urine supersaturation might predispose to urolith formation?

Answer 21

Retention of urine, allowing it to concentrate
Bladder diverticuli preventing full evacuation
Favorable pH e.g acidic for calcium oxalate and urate, alkaline for struvite
Decreased concentration of crystal inhibitors e.g glycosaminoglycans, citrates

Question 22

What might lead to supersaturation of urine with solute?

Answer 22

1. Abnormal metabolism e.g purine metabolism in Dalmations increasing saturation of urine with uric acid
2. High dietary solute intake e.g high mineral content pasture
3. Decreased water intake causing concentrated urine

Question 23

What is the usual nature of the obstruction in FLUTD? What does it cause?

Answer 23

Gritty, rubbery plug of protein, cell debris and struvite crystals especially in urethra of male cats

Causes oliguria, dysuria, stranguria and haematuria

Question 24

Name 5 of the usual defences of the lower urinary tract to infection

Answer 24

1. Voiding of urine
2. Acidity of urine especially carnivores
3. Factors that inhibit bacterial attachment including Tamm Horsfall mucoprotein, surface glycosaminoglycans
4. Sloughing of mucosal epithelial cells that have adherent bacteria
5. Urinary oligosaccharides may detach adherent bacteria

Question 25

What are 5 factors that predispose to lower UTI?

Answer 25

1. Incontinence > constant wetting of perineum 2. Glucosuria or proteinuria > bacterial substrate 3. Disruption/overgrowth of vaginal or distal urethral flora e.g following antibiotic therapy 4. Incomplete urine voiding or urine stasis 5. Urinary catheter 6. Impaired immune defense e.g Cushings, corticosteriod use

Question 26

What are three bacterial species that are only pathogenic when in the lower urinary tract?

Answer 26

Corynebacterium renale C. pilosum C. cystitidis

Question 27

What are two features of bacteria that enhance their pathogenicity in the urinary tract?

Answer 27

1. Having of fimbriae which mediate attachment | 2. Having urease which splits urea to ammonia and can make the surrounding environment more alkaline promoting survival

Question 28

Name one iatrogenic cause of cystitis

Answer 28

The chemotherapeutic drug cyclophosphamide causes sterile, haemorrhagic cystitis Can get TCC with prolonged therapy

Question 29

Five descriptors of the lesions of cystitis?

Answer 29

``` Catarrhal (serous exudate on surface) Fibrinopurulent Haemorrhagic Necrotising Ulcerative ```

Question 30

What causes emphysematous cystitis?

Answer 30

Production of CO2 by glucose-fermenting bacteria in the wall of the bladder E.g secondary cystitis in diabetes mellitus

Question 31

What is chronic follicular cystitis? Which species?

Answer 31

Cystitis characterised by multifocal 1-4mm cream-white nodules in the bladder mucosa, which correspond to aggregates (follicles) of lymphocytes in the superficial submucosa. Dogs. If nodules are red - "chronic active"

Question 32

What is chronic polyploid cystitis? Which species?

Answer 32

Bladder mucosa thrown into folds corresponding to submucosal fibrous tissue infiltrated by mononuclear leukocytes. Nodules may be sessile or pedunculated. Biopsy required to discriminate from tumour. All species.

Question 33

What is a von Brunn's nest?

Answer 33

A downgrowth of hyperplastic bladder epithelium into the submucosa, in response to chronic irritation. Typically undergo glandular metaplasia and produce mucous, or become cystic

Question 34

Are primary or secondary tumours more common in the bladder? Why - what are two predisposing factors.

Answer 34

Primary Because: - chronic irritation due to cystitis or infection can predispose - mucosa is exposed to carcinogenic substances concentrated in the urine

Question 35

What are two examples of urinary carcinogens?

Answer 35

Cyclophosphamide metabolites, tryptophan metabolites

Question 36

What is the usual location and behaviour of a TCC?

Answer 36

Usually located at the trigone of the bladder - may grow into lumen (papillomatous, polyploid) or into the wall (sessile) 50% metastasise

Question 37

What is enzootic haematuria?

Answer 37

A syndrome of persistent haematuria and anemia in cattle (+ occasionally sheep) associated with haemorrhagic cystitis and bleeding tumours of the lower UT. Due to chronic ingestion of bracken fern or mulga rock fern + oncogenic bovine papillomavirus infection.

Question 38

What are the scientific names for bracken fern? What is its toxin called?

Answer 38

Pteridium aquilinum Pteridium esculentum Ptaquiloside

Question 39

What is the scientific name for mulga rock fern?

Answer 39

Cheilanthes sieben

Question 40

What is the initial effect of ptaquiloside consumption on the body?

Answer 40

Causes bone marrow suppression and subsequent thrombocytopaenia > small or large haemorrhages in the mucosa of the lower UT, causing microscopic haematuria

Question 41

What happens if ptaquiloside is ingested long term?

Answer 41

Dilation of submucosal capillaries in lower UT, chronic cystitis and hyperplasia +/- metaplasia of cystic mucosa - leading to tumour development

Question 42

If an animal with enzootic haematuria has macroscopic haematuria, how far along is the cancer?

Answer 42

Most likely has ulcerated, bleeding tumours that are bleeding into the lumen of the bladder

Question 43

Is there a single tumour type typical of ptaquiloside toxicity?

Answer 43

No - may even be multiple types in same specimen including papillomas, fibromas, haemangiomas, haemangiosarcomas and transitional cell carcinomas