Pathology of the Lower Urinary Tract Flashcards
What is the lower urinary tract? What are most diseases of the LUT associated with?
conduit for transport of urinary waste from the kidney to the exterior, made up of paired ureters, the urinary bladder, and the urethra
obstruction and infection
How does gender affect predilection for LUT disease?
MALES: prone to obstruction due to urethra anatomy (sigmoid flexure, urethral process, and os penis are narrow)
FEMALES: prone to infection due to short urethra and its proximity to external environment and rectal flora
What is an ectopic ureter? What does this predispose an animal to?
ureter terminates at the urethra or vagina rather than at the trigone at the bladder
(usually an incidental finding)
- hydronephrosis
- hydroureter
- UTI
- pyelonephritis
What is urolithiasis? What is the difference between uroliths/stones and urethral plugs?
presence of calculi made up of precipitated urinary solutes, urinary proteins, and proteinaceous debris in the urinary passages
- UROLITHS/STONE: minerals predominate, round/spherical hard structures
- URETHRAL PLUG: masses of sandy sludge with a higher organic (protein) component
What are 4 major causes of urolithiasis?
- defective metabolism of a substance
- metabolic disease
- high levels of a substance in the diet
- infection
What are 2 common examples of defective metabolism causing urolithiasis?
- uric acid in dalmations
- cystine in dogs and cats due to defective proximal tubular resorption from GF
What are 2 common types of calculi formed due to metabolic diseases?
- calcium oxalate - hyperparathyroidism, hypercalcemia
- ammonium biruate - severe/chronic liver disease/portosystemic shunts
What are 2 common examples of high levels of substances in the diet causing urolithiasis?
- silicic acid in native pastures (ruminants)
- mineral imbalance (calcium, phosphorus, magnesium)
What kind of urolith is commonly formed in response to infection? How is it typically formed?
struvite in dogs and cats
ureases from Staph/Proteus induces supersaturation
What are 4 other minor causes of urolithiasis?
- urinary pH
- reduced water intake
- urine supersaturation
- foreign body (suture, grass awn, catheter)
What are the gender, species, and dog breed predilection for urolithiasis?
male > females, especially castrated individuals
cattle, sheep, dogs, cats > horses, pigs
Dachshunds, Dalmatians, Cocker Spaniels, Basset Hounds, Poodles, Schnauzers, small terriers
Why are uroliths difficult to determine by gross observation?
color and shape vary and may be inconsistent, even among calculi of similar composition
What are the common sites of lodgment of urethral calculi in cattle, rams, dogs, and cats?
CATTLE: ischial arch and proximal end of the sigmoid flexure
RAMS: urethral process (veniform appendage)
DOGS: proximal base of the os penis
CATS: entire length of the urethra
What 3 things happen at the site of calculi lodgment? What does this cause?
- local pressure necrosis
- ulceration of the mucosa
- acute hemorrhagic urethritis/cystitis
hematuria, dysuria
Nephrolith, goat:
Bladder stones, dog:
Urethral plug, ram:
+ hydronephrosis
Hemorrhagic cystitis, dog:
Urolithiasis, cat:
Urolithiasis, Dalmation:
urate calculi
Urolithiasis, urethral process necrosis:
What can obstruction of the urethra eventually lead to if it is not managed?
rupture of the urethra with accumulation of urine the subcutis
Urolithiasis, goat:
- hydroureter (distended)
- hydronephrosis
- pyelonephrosis
- huge urinary bladder
What is the main cause of ammonium biurate crystal urolithiasis? How does this happen?
acquired portosystemic shunts due to severe, chronic liver disease
- hepatic fibrosis compresses portal veins causing hypertension
- since blood cannot reach the liver, new blood vessels form from the portal vein to connect to the vena cava
- this allows blood to bypass the liver, leaving ammonia un-metabolized and able to accumulate in the urine
What are the 4 normal antibacterial properties of the bladder?
- repeated voiding
- protective urothelial mucus coating
- mucosal IgA
- high urea and organic acids
What are 3 risk factors for cystitis?
- stagnation of urine
- incomplete voiding (common in spinal cord lesions)
- urothelial trauma
What are 4 causes of cystitis?
- bacterial infection (females!)
- chemicals (cyclophosphamide)
- urolithiasis (obstruction)
- trauma
What enteric bacterial commonly cause cystitis? What are the specific renal pathogens of cattle, pigs, and horses?
E. coli > Staphylococcus spp. > Proteus spp. > Klebsiella spp. > Enterococcus spp. > Streptococcus spp.
CATTLE: Corynebacterium renale
PIGS: Actinobacillus suis
HORSES: Klebsiella spp.
What is a common chemical cause of cystitis in horses?
Blister beetle infestation in alfalfa hay, which produce cantharidin that is toxic to the epithelium and causes ulcerative and hemorrhagic cystits
What is a common chemical cause of cystitis in dogs and cats?
cyclophosphamide, a chemotherapy/immunosuppressant, is able to cause ulcerative and hemorrhagic cystitis
What are the 3 major causes of feline lower urinary tract disease (FLUTD)?
- feline idiopathic interstitial cystitis***
- infection
- urolith/urethral obstruction
What are 6 risk factors for developing feline lower urinary tract disease (FLUTD)?
- middle-aged neutered cats
- overweight cats that undergo little exercise
- cats with little to no access outside
- dry diet
- multiple animal household
- STRESS
Feline lower urinary tract disease:
huge, red, hemorrhagic bladder
Feline lower urinary tract disease, bladder:
Feline lower urinary tract disease, urethral plug:
How is chronic cystitis classified? What are the 2 major types?
based on pattern and type of inflammatory response
- FOLLICULAR: disseminated submucosal lymphoid nodules
- POLYPOID: polyps composed of connective tissue mixed with mononuclear cells (must be differentiated from tumors)
How does emphysematous cystitis appear grossly? What is it commonly associated with?
multiple, small, clear, air-filled bulla in the mucosa of the urinary bladder
diabetes mellitus - glucosuria supports the growth of glucose-fermenting bacteria
What are 3 major neoplasms of the urinary bladder?
- transitional cell carcinomas - dogs > cats
- transitional cell carcinomas, hemangiomas, and hemangiosarcomas in cattles due to chronic Bracken fern poisoning
- botryoid rhabdomyosarcoma - young large breed dogs
What are the most common sites of transitional cell carcinoma? What dogs are predisposed? What is the metastatic ability of this type of neoplasm?
bladder neck and trigone
older dogs, Scottish Terrier
40% of these tumors have metastasized to the lymph nodes, lungs, and bone by the time of clinical diagnosis
What are the 4 classifications of transitional cell carcinoma?
- papillary and non-infiltrating - no invasion of the stroma (better prognosis)
- papillary and infiltrating - most common
- non-papillary and non-infiltrating - carcinoma in-situ
- non-papillary and infiltrating - most common to metastasize
TCC with unilateral hydronephrosis:
TCC, papillary vs. non-papillary:
Diffuse TCC:
What is botryoid rhabdomyosarcoma? What dogs are predisposed? What does it commonly cause?
grape-like neoplasm arising from the trigone or bladder neck from embryonic myoblasts
young, large breed dogs —> St. Bernards overrepresented
obstruction
- one case of hypertrophic osteopathy
Botryoid rhabdomyosarcoma:
- young dogs
- St. Bernard!
- trigone, bladder neck
What causes enzootic hematuria? What is its toxic principle?
chronic ingestion of Bracken fern (Pteridium aquilinum) in cattle
Ptaquiloside, a carcinogenic and immunosuppressive toxin, leaving the cattle prone to BPV-2 infection
What does the toxin from Bracken fern cause?
- papilloma formation
- TCC
- hemangiomas
- hemangiosarcomas
- HEMATURIA
Enzootic hematuria:
- Bracken fern (Ptaquiloside)
- papillomas
- hemangioma/sarcoma
- TCC
Enzootic hematuria, TCC:
+ ulceration
Bracken fern!
