RUT: practice questions (week 13)

upper urinary tract, AKI, glomerular disease, surgery for kidney + ureter, bladder surgery, surgery for urethra

The glomerular membrane has selective permeability. In a healthy kidney are plasma proteins able to pass through the glomerular membrane?

No → membrane is impermeable to them

What type of proteinuria is associated with immune mediated hemolytic anemia?

Pre-renal

What type of proteinuria is associated with hypoalbuminemia?

Renal (glomerular)

What two breeds are most commonly associated with Glomerular amyloidosis?

Abyssinian + Shar-Pei

You have diagnosed a patient with protein losing nephropathy caused by an immune mediated glomerular nephritis. How you would explain to your client why kidney disease is causing peripheral edema in their dog?

-Because the kidney filters are damaged, essential proteins from the blood (specifically a vital protein called albumin) are leaking out of the bloodstream & getting lost into the urine (protein-losing nephropathy)

-Albumin acts like a sponge inside the blood vessels; its main job is to hold onto water & keep it safely circulating inside the blood system

-As the amount of albumin in the blood drops, the blood vessels can no longer hold onto that fluid effectively & water seeps out of the blood vessels & collects in the surrounding body tissues most noticeably in the lower legs + paws, causing the soft swelling (peripheral edema)

A male dog presents with urethral obstruction caused by a calculus lodged immediately caudal to the os penis. Which anatomical feature best explains this location?

The os penis creates a relatively fixed distal narrowing

During primary repair of a completely transected urethra, which surgical approach is most likely to minimise postoperative stricture formation?

Precise, tension-free mucosal apposition with preservation of blood supply

Before unilateral nephrectomy, what information is most important for deciding whether removal is safe?

Function of the contralateral kidney

An azotemic cat has unilateral obstruction. What interpretation is most appropriate?

The opposite kidney is also likely to have disease

What best distinguishes a subcutaneous ureteral bypass (SUB) from a ureteral stent?

A SUB bypasses the entire ureter → connects renal pelvis to bladder via a SQ port

During surgery near the bladder neck, what structure is most important to identify + protect?

Trigone + ureteral openings

A dog has abdominal free fluid after road-traffic trauma. What result most strongly supports uroabdomen?

Fluid creatinine/potassium > serum creatinine/potassium

What closure is most appropriate after an uncomplicated cystotomy?

Appositional absorbable monofilament engaging submucosa

A male cat with complete urethral obstruction is bradycardic + hyperkalemic. What is the best immediate priority?

Stabilize + establish urinary decompression

What imaging study is the first choice for defining a suspected urethral lesion?

Retrograde positive-contrast urethrography

What procedure creates a permanent urinary outlet rather than temporary access?

Urethrostomy

What surgical principle most directly reduces the risk of postoperative urethral stricture?

Precise, tension-free apposition

What are some of the history findings that may be consistent with chronic kidney disease (CKD) in small animals?

PU/PD, weight loss, not doing right, loss of muscle mass, hyporexia

-all gradual or intermittent signs

What are some of the history findings that may be consistent with acute kidney injury (AKI) in small animals?

Sudden anorexia, V/D (± blood), lethargy, oliguria or anuria, collapsed

-all signs have very sudden onset

What are some of the physical exam findings that may be consistent with chronic kidney disease (CKD) in small animals?

Low BCS, muscle wasting, unkempt hair coat, dehydration, hypertension, new heart murmur

What are some of the physical exam findings that may be consistent with acute kidney injury (AKI) in small animals?

Renomegaly + pain on abdominal palpation, bradycardia, dehydration, oral ulcers (uremia)

What clinicopathological parameters can help differentiate CKD from AKI in small animals?

-CKD: Normocytic normochromic non-regenerative anemia (due to decreased erythropoietin production)

-AKI: severe hyperkalemia + metabolic acidosis

-AKI will show an acute increase in serum creatinine of ≥ 0.3 mg/dL (or ≥ 1.5-fold increase) within 48 hours, while CKD will show stable, persistent elevations in creatinine + SDMA w/o rapid swings

-CKD shows bilateral shrunken kidneys on US, while AKI shows normal to enlarged kidneys on US

What clues should we look for on a urinalysis when differentiating CKD from AKI in small animals?

Granular casts, renal epithelial cells, pyuria/bacteriuria, glucosuria = all indicate AKI

What is the new biomarker to detect CKD earlier in cats?

FGF-23

What does a change in creatinine >0.3mg/dL indicate in small animals?

Acute kidney injury → decrease in GFR

How does GFR decrease in pre-renal azotemia?

Decreased blood flow to the kidneys

How does GFR decrease in renal azotemia?

Nephron loss or due to AKI/CKD

How does GFR decrease in post-renal azotemia?

Backpressure of urine in nephrons (eventually leads to renal azotemia)

What is the biomarker to detect acute tubular injury in small animals?

Urine Cystatin-B

What are the biomarkers that tell us there is something up with the kidneys, but cannot differentiate between acute/chronic/pre-renal/renal disease?

BUN, Crea, SDMA

What are the three categories of AKI etiologies in small animals?

1. Hemodynamic AKI → renal hypoperfusion leads to renal injury

2. Intrinsic renal injury → toxins, infectious, immune-mediated

3. Obstructive AKI → obstruction of ureters or urethra

If a patient with suspected AKI presents to your clinic, what actions would you take to assess patient stability before searching for or treating the underlying cause?

-Check perfusion parameters

-Check BP → could be dangerously high or low

-Check K+

-Urine output monitoring

-POCUS to check for effusion or uroabdomen

What is the most common renal neoplasia in cats?

Lymphoma

What is the most common renal neoplasia in dogs?

Carcinoma

How would you treat feline renal lymphoma?

Chemotherapy → CHOP protocol

How would you treat any renal neoplasia besides feline lymphoma?

Surgical removal of tumor + affected kidney if unilateral

-chemo often ineffective against renal tumors

What diagnostic tests are indicated for diagnosing all causes of AKI in small animals?

Diagnostic imaging → radiographs (obstruction/neoplasia/mets), POCUS (effusion, pelvic dilation), abdominal US (obstruction, pyelonephritis hints, thrombi)

What is the most common infectious cause of AKI?

Pyelonephritis (E. coli)

What are the pros vs. cons of MAT (microscopic agglutination test) for diagnosing Leptospirosis as a cause of AKI in small animals?

Pros: “gold standard” when paired (up to 50% of cases are missed with just one titer)

Cons: 5-7 days to get back from lab, vaccine interference, titers only rise 7-14 days post-infection (when antibodies are made), serovar cross-reactivity from vaccine

What are the general treatment considerations for any small animal patient presenting with AKI?

-IV fluids

-Treat underlying disease

-Analgesia, anti-emetics, abx, nutrition as needed

How would you diagnose pyelonephritis in small animals?

Urine culture (cystocentesis)

A dog presents to you with suspected AKI. Blood creatinine is <1.6mg/dL. Bloodwork shows nonazotemic, but history tells you that AKI is occurring due to the presence of oliguria/anuria as well as a progressive nonazotemic increase in blood creatinine by >0.3mg/dL within 48 hours. What IRIS AKI grade would you give to this patient?

Grade I

A dog presents to you with suspected AKI. Blood creatinine is 1.7-2.5mg/dL. Upon looking at the dog’s history, you notice he already has had documented AKI as well as static or progressive azotemia (increase of >0.3mg/dL) as well as measured oliguria (<1mL/kg/h) or anuria over a 6-hour period. What IRIS AKI grade would you give to this patient?

Grade II

Grades III-V of IRIS AKI grading all present as moderate to severe AKI, which is classified as documented AKI & increasing severities of azotemia + functional renal failure. What will the blood creatinine levels look like for each of the three grades?

Grade III → 2.6-5.0mg/dL

Grade IV → 5.1-10.0mg/dL

Grade V → >10.0mg/dL

What does the USG typically look like in a patient with AKI (unless it is pre-renal)?

Isosthenuria

What are some of the atypical/unconventional diagnostic tests you should run in an attempt to identify a specific cause of AKI in small animals?

-Serum ethylene glycol levels

-Serum cholecalciferol levels

-Lepto testing

What is the daily maintenance fluid requirement for most mammalian species (except cats)?

50mL/kg/day

What is the daily maintenance fluids requirement for cats?

40mL/kg/day

How fast should fluid deficits be replaced in order to restore normal renal blood flow in AKI patients?

4-6 hours

What is the most important factor to monitor when rehydrating an AKI patient with IV fluids?

Urine output → if anuric even after rehydration, this is a bad sign (stop fluids!)

-urine flow should increase to 2-5mL/kg/hr

What specific therapy can we use concurrently with IV fluids in oliguric/anuric AKI patients for increasing urine output within 20-40 minutes?

Furosemide (loop diuretic) → 2mg/kg IV