Chapter 64 - Dx techniques and principles or urinary surgery Flashcards
1
Q
What are the most common presenting complaints for horses with urinary tract disease?
A
Weight loss, decreased performance, and abnormal urination.
2
Q
Which clinical signs may indicate urinary tract disease?
A
Stranguria, pigmenturia, pyuria, incontinence, fever, and anorexia.
3
Q
What is the significance of polydipsia in horses?
A
t may indicate renal disease, pituitary dysfunction, or diabetes.
4
Q
How can an owner differentiate between pollakiuria and polyuria?
A
Pollakiuria is frequent urination, while polyuria is increased urine volume often with increased thirst.
5
Q
What does a dropped penis in male horses typically indicate?
A
It often indicates obstructive urethrolithiasis.
6
Q
What histWhat conditions can cause myoglobinuria in horses?regarding changes in urination?
A
Changes in frequency, posturing, and appearance of urine should be noted.
7
Q
What might intermittent urine dribbling from the vulva suggest in younger horses?
A
It may indicate unilateral ectopic ureter.
8
Q
What conditions can cause myoglobinuria in horses?
A
wxercise-associated rhabdomyolysis, crush injuries, and Clostridial myonecrosis.
9
Q
Which medications can cause urine discoloration?
A
Rifampin, phenothiazines, nitazoxanide, and doxycycline.
10
Q
What does hematuria at the beginning of urination suggest?
A
Lesions in the distal urethra.
11
Q
What might persistent urine scalding indicate?
A
Incontinence in horses.
12
Q
How should owners be questioned about water intake?
A
Quantify daily water consumption and note any changes.
13
Q
What are common causes of hemoglobinuria in horses?
A
Infectious diseases, toxins, and immune-mediated hemolysis.
14
Q
What does a “fishy” odor in a horse’s mouth indicate?
A
It may suggest chronic renal failure.
14
Q
What is the primary rule out for hematuria after exercise?
A
Cystolithiasis.
15
Q
What can indicate a renal mass during physical examination?
A
Altered abdominal conformation or gait abnormalities.
16
Q
What might a mass on external genitalia suggest?
A
Possible lower urinary tract disease.
17
Q
What might a mass on external genitalia suggest?
A
Possible lower urinary tract disease.
18
Q
What symptoms may accompany pyelonephritis in horses?
A
Intermittent fevers, lethargy, and decreased appetite.
19
Q
What should be assessed during an examination for incontinence?
A
Whether the horse shows awareness of bladder distension.
20
Q
What is a common complication of anesthesia related to myoglobinuria?
A
Crush injury.
21
Q
What environmental conditions can affect water intake?
A
Temperature, humidity, and level of activity.
22
Q
What are signs of severe renal disease in horses?
A
Anemia, lethargy, and decreased body condition.
23
Q
What does the presence of excessive dental tartar indicate?
A
It may be associated with chronic renal failure.
24
What condition is associated with hematuria and frequent urination in mares?
Cystitis.
25
What clinical sign might suggest the presence of urinary tract neoplasia?
Hematuria or abnormal urination patterns.
26
What should be monitored to assess for polyuria in horses?
Urine output, typically 0.5 to 1 mL/kg/hour.
27
What indicates that a horse is experiencing obstructive urethrolithiasis?
“Renal colic” presentation with a dropped penis.
28
What are potential causes of urinary tract infections in horses?
Urolithiasis or poor hygiene.
29
What might indicate a need for further neurological examination in a horse?
Signs of incontinence or abnormal gait.
30
What could cause pigmenturia aside from hematuria?
Myoglobinuria or drug-induced discoloration.
31
What factors can lead to increased urinary sediment?
Urinary tract infection or renal disease.
32
What might indicate a recent muscle injury or exercise in a horse?
Presence of myoglobin in urine.
33
What could blood in urine at the end of micturition suggest?
Hemorrhage from the proximal urethra or bladder neck.
34
What should be done if urine appears discolored upon bedding?
Investigate potential causes of pigmenturia or hematuria.
35
What can be inferred from a horse that exhibits excessive urination during exercise?
Possible renal disease or increased water intake due to exertion.
36
What is a common cause of recurrent colic in horses with urinary issues?
Urolithiasis may present as abdominal pain.
37
What clinical sign is often observed in mares with a history of dystocia?
Potential urinary incontinence.
38
What clinical findings are associated with severe renal disease?
Ventral edema and a strong urine odor.
39
What diagnostic tool is essential for understanding a horse’s water consumption?
Monitoring daily water intake over multiple days.
40
hat type of clinical signs might a horse with urolithiasis present?
Stranguria, abnormal micturition posture, and colic-like symptoms.
41
What is the typical range for normal daily water intake in a 500-kg horse?
22.5 to 27.5 liters per day.
42
Which infectious disease can lead to hemoglobinuria in horses?
Equine infectious anemia.
43
What is the relationship between urine scalding and incontinence in mares?
Urine scalding often results from the prolonged contact of urine with the skin due to incontinence.
44
What would a horse’s appetite changes suggest in the context of renal disease?
It may indicate renal dysfunction or chronic renal failure.
45
What should be evaluated to differentiate between normal and abnormal urination patterns?
Frequency, volume, and appearance of urine during micturition.
46
Which laboratory findings are important in assessing renal disease?
Changes in blood urea nitrogen (BUN) and creatinine levels.
47
what type of urinary appearance might suggest myoglobinuria?
Dark red or brown urine following strenuous exercise.
48
What does hematuria at the end of urination often indicate?
Hemorrhage from the proximal urethra or bladder neck.
49
What can be a sign of chronic pain related to urinary issues in horses?
Intermittent signs of colic or behavioral changes.
50
How might a horse with a renal mass present differently than one with urinary tract infection?
A renal mass may show altered abdominal conformation, while UTI might have more obvious signs of discomfort during urination.
51
What should be assessed if a horse shows signs of urinary urgency?
Possible urinary tract infection or bladder distension.
51
What is a common cause of exercise-induced pigmenturia?
Rhabdomyolysis.
52
what can the presence of oral ulcers indicate in a horse with urinary issues?
Possible chronic renal failure or systemic disease.
53
How does a horse with incontinence often position itself?
It may show signs of restlessness or attempts to posture without voiding.
53
What does prolonged posturing to urinate suggest?
Possible obstructive urolithiasis or urinary tract irritation.
54
What indicates that a horse's bladder might be distended?
the horse appears restless or shows abdominal muscle use to relieve pressure.
55
Which non-infectious factors can contribute to hematuria?
Trauma, exercise-associated bladder mucosal trauma, or neoplasia.
56
What type of urine appearance can suggest a urinary tract infection?
Cloudy urine with excessive sediment.
57
What should be done if pigmenturia is suspected?
Differentiate between myoglobinuria, hemoglobinuria, and normal pigment changes.
58
What does it mean if a horse has both hematuria and signs of colic?
Possible underlying urinary tract obstruction or irritation.
58
What type of bacteria might cause a urinary tract infection in horses?
Commonly, Escherichia coli or other gram-negative bacteria.
59
How can one differentiate between normal urination and incontinence?
Incontinence is characterized by involuntary urine passage without posturing.
60
What dietary changes could influence a horse’s urinary health?
Increased protein intake may lead to higher nitrogen waste and potential renal strain.
61
What does a sudden change in urine color post-exercise often indicate?
Potential myoglobinuria from muscle damage.
62
What is a common condition associated with excessive thirst and urination in older horses?
Pituitary pars intermedia dysfunction (PPID).
63
What should be investigated if a horse displays signs of repeated colic?
Possible urinary tract issues such as urolithiasis.
64
What are potential complications of untreated urolithiasis in horses?
Urinary obstruction, bladder rupture, and systemic infection.
65
What should be included in the management plan for horses with urinary tract disorders?
Hydration assessment, dietary modifications, and monitoring of urine output.
65
What initial examination should be performed on male horses suspected of urinary tract disease?
External examination of the urethra below the anus while lifting the tail.
66
What findings might suggest a diagnosis of verminous nephritis?
Signs of hematuria along with a history of strongyle infections.
67
What systemic signs can be associated with chronic renal failure?
Ventral edema, poor coat quality, and lethargy.
68
What indicates urethral obstruction during a rectal examination?
Moderate-to-severe distention of the urethra.
69
Why is symmetry of the perineum important in rectal examinations?
Deformities may indicate proximal urethral rents.
70
How is the urethral sphincter described in relation to the mare's anatomy?
It feels similar to the cervix of a mare but is located more caudally.
71
What features of the bladder should be assessed during palpation?
Size, wall thickness, and presence of cystic calculi or sediment.
72
What is dysuria and how does it affect bladder palpation?
It often results in a small bladder that may be entirely within the pelvic canal.
73
How can a cystolith be palpated effectively during a rectal exam?
The hand should be inserted wrist-deep to avoid missing it beneath the forearm.
74
What condition is indicated by an atonic bladder in horses?
Sabulous urolithiasis, which is the accumulation of urine sediment.
75
What aspect of the bladder's anatomy is important for proper examination?
The apex should be freely movable within the abdomen.
75
What should be palpated to differentiate sabulous urolithiasis from cystoliths?
The size of the bladder and the indentability of the sediment with pressure.
76
What abnormality might occur if the bladder apex adheres to the umbilicus?
A tubular bladder that cannot be freely manipulated.
77
What is an osteochondroma and how can it affect the urinary bladder?
A bone tumor that can cause tears in the bladder and hematuria if it exceeds 20 mm in height.
78
What findings may suggest acute renal failure during kidney palpation?
Enlarged or painful left kidney.
79
How might chronic renal failure affect kidney palpation findings?
The kidney may appear smaller, irregularly shaped, and firmer.
80
What is azotemia and how is it identified in serum chemistry?
Increased BUN and creatinine levels indicating decreased renal function.
81
What are the three potential origins of azotemia?
Prerenal, intrinsic renal disease, and postrenal obstruction.
82
How is prerenal failure characterized in relation to BUN and Cr levels?
Reversible increases associated with renal hypoperfusion.
83
What is the significance of measuring glomerular filtration rate (GFR)?
It helps assess the severity of renal function impairment.
84
What are two indicators of acute kidney injury (AKI)?
A rise in creatinine of 0.3 mg/dL or a 50% increase from baseline.
85
How does NSAID administration affect renal blood flow?
It can diminish the protective vasodilatory response, increasing the risk of renal damage.
86
What are the typical laboratory findings in horses with chronic kidney disease (CKD)?
Azotemia, hypercalcemia, and hypophosphatemia.
87
How can BUN and creatinine ratios assist in dietary assessment?
Ratios above 15:1 suggest excessive protein intake.
88
What difference in electrolyte levels is noted between prerenal and intrinsic renal failure?
Electrolyte concentrations remain normal in prerenal failure, but are abnormal in intrinsic renal failure.
89
What changes in potassium levels can occur with acute kidney injury (AKI)?
Potassium levels can be low, normal, or increased, with significant hyperkalemia in severe cases.
90
What is the impact of urea accumulation in renal failure?
Urea is a uremic toxin that contributes to tissue dysfunction at elevated levels.
91
Why is creatinine considered a reliable marker of renal function?
Its levels rise when glomerular filtration decreases, with minimal tubular reabsorption.
92
How does muscle mass relate to creatinine production?
About 1% of muscle creatine is converted to creatinine daily.
92
What is spurious hypercreatininemia and when might it occur?
It’s a temporary elevation in creatinine in neonatal foals, resolving quickly after birth.
93
What role does urine output play in assessing renal function in foals?
Adequate urine output indicates normal renal function despite high creatinine levels.
94
How should glucose levels be interpreted in relation to glucosuria?
Glucosuria must be interpreted alongside serum glucose concentrations.
95
What are common causes of hyperglycemia in horses?
Stress, exercise, sepsis, pituitary dysfunction, or diabetes mellitus.
96
What anatomical structure might be palpated for tears in cases of kidney disease?
The ureters, which can be palpated for enlargement or obstruction.
96
What enzymes can differentiate myoglobinuria from hematuria or hemoglobinuria?
Creatine kinase (CK) and aspartate aminotransferase (AST) activities.
97
What is the importance of the rectal examination in diagnosing urinary tract disease?
It allows for direct assessment of urinary structures and potential obstructions.
98
What condition may cause a horse’s left kidney to be felt above the uterus?
A rare congenital defect or malposition.
99
What is a critical factor in interpreting serum chemistry profiles for renal function?
Recognizing that azotemia is a laboratory diagnosis indicating renal dysfunction.
100
What can cause a marked increase in creatinine in acute conditions?
Sudden decreases in renal blood flow and glomerular filtration.
101
How might chronic inflammatory lesions affect total protein concentration?
They may alter total protein more significantly than AKI itself.
102
What should be monitored over time in horses with chronic renal disease?
Both BUN and creatinine levels to assess disease progression.
103
What is the minimum database required for diagnosing urinary tract disorders in horses?
A complete blood count (CBC), serum chemistry profile, and urinalysis.
104
What laboratory findings support an inflammatory or infectious disease process?
Elevated white blood cell (WBC) count, fibrinogen, and serum amyloid A concentrations.
105
How does elevated globulin concentration relate to inflammation?
It indicates chronicity (weeks to months) of an inflammatory response.
105
What is the packed cell volume range that indicates mild anemia in horses with chronic renal failure?
25% to 30%.
106
What are the major parameters to assess renal function in horses?
Blood urea nitrogen (BUN) and serum creatinine (Cr) concentrations.
107
Why are BUN and Cr considered insensitive indicators of renal function?
Values may not exceed reference ranges until GFR is reduced by 75% or more.
108
How is azotemia defined?
Increases in BUN and Cr detected on a serum chemistry profile.
109
What happens to BUN and Cr values during renal dysfunction?
Small increases indicate deterioration in GFR, with doubling interpreted as a 50% decline in function.
110
What are the three types of azotemia?
Prerenal, intrinsic renal, and postrenal.
111
What is prerenal failure associated with?
eversible increases in BUN and Cr due to renal hypoperfusion.
112
What is the definition of AKI?
An increase in Cr of 0.3 mg/dL or a 50% increase from baseline.
112
What term has been introduced to increase awareness of subclinical renal damage?
Acute kidney injury (AKI).
113
What are some biomarkers being investigated for early indicators of renal damage?
Kidney injury molecule-1 in urine.
113
What does the term chronic kidney disease (CKD) emphasize?
Early detection and intervention of chronic renal disease.
113
How is oliguria defined?
Urine output of <0.5 mL/kg for at least 6 hours.
114
How does renal blood flow differ between the cortex and medulla?
The cortex receives a greater portion of total RBF than the medulla.
115
What effect do NSAIDs have on renal blood flow and potential damage?
They can abolish renoprotective responses and increase the risk of renal damage.
116
What is the significance of the BUN
ratio in diagnosing renal failure?
It can help differentiate types of renal failure, with higher ratios indicating prerenal failure.
117
What BUN
ratio is indicative of prerenal failure?
A ratio of 10 or more.
118
What findings are characteristic of horses with intrinsic renal failure?
Hyponatremia and hypochloremia.
119
How does Cr behave differently than BUN during acute disorders?
Cr typically increases more than BUN during acute disorders.
120
What is spurious hypercreatininemia in neonatal foals?
Markedly elevated Cr concentrations after birth with normal renal function.
121
What is the renal threshold for glucose in horses?
Likely lower than 160–180 mg/dL.
122
How can one differentiate myoglobinuria from hematuria or hemoglobinuria?
By measuring creatine kinase (CK) and aspartate aminotransferase (AST) activities.
123
What does persistent azotemia indicate during treatment in horses?
Greater volume of gastric reflux, abnormal rectal findings, and higher mortality risk.
124
What can cause hyperkalemia in horses with acute kidney injury?
Oliguric to anuric acute renal failure or uroperitoneum.
125
What is the typical outcome for adult horses with severe azotemia?
They do not survive.
126
What changes in serum electrolyte concentrations are typical with prerenal failure?
What changes in serum electrolyte concentrations are typical with prerenal failure?
127
What specific electrolyte abnormalities might be found in horses with CKD?
Hypercalcemia and hypophosphatemia.
128
How can CKD affect protein concentrations in horses?
Total protein concentration may remain normal, but hypoalbuminemia can develop.
129
What is a potential complication of CKD related to gastrointestinal health?
Intestinal ulceration leading to hypoproteinemia.
130
What is the primary route of elimination for creatinine?
Urine, via glomerular filtration with little tubular reabsorption.
131
What does an increase in BUN indicate in relation to uremic toxins?
Progressive increases contribute to tissue dysfunction, especially above 75 mg/dL.
132
What can influence the BUN
ratio in horses with acute disorders?
Dehydration and hypovolemia.
132
How does chronic renal failure (CRF) impact the prognosis in equine patients?
The severity of azotemia is a key prognostic indicator.
133
What type of renal damage can occur despite prerenal failure?
A degree of permanent nephron loss.
134
What is the clinical significance of changes in Cr with treatment?
A decrease of 30% or more in Cr within 24 hours is a reasonable treatment goal.
135
Horses in colic are often alkalotic or acidotic?
alkalotic because of pain and hyperventalation, but with more serious disease such as endotoxemia metabolic and lactic acidosis may be present
136
With 1arey renal disease you have mild metabolic acidosis or alkalosis?
With primary renal disease, mild metabolic acidosis may also be detected, but acidosis is usually not severe until marked azotemia (Cr >10 mg/dL) develops with either oliguric AKI or end-stage CKD.
137
What are two methods of urine sample collection in horses?
Midstream catch during voiding and urethral catheterization.
138
What device can be used to collect urine from geldings or stallions?
A modified gallon plastic bottle cut at the bottom and secured below the sheath.
139
What should be done to prepare the penis before catheterization in male horses?
Clean the end of the penis and remove smegma from the urethral sinuses.
140
What is a common challenge when catheterizing male horses?
Resistance may be felt when passing the catheter over the ischial arch and urethral sphincter.
141
Why is catheterization in mares less complicated than in males?
Mares do not have a urethral diverticulum, simplifying the catheter passage.
142
What is the purpose of measuring urine specific gravity?
To estimate urine tonicity based on the number of particles in urine.
143
Why is urine osmolality (Uosm) considered more accurate than specific gravity?
Uosm accounts for larger molecules like glucose and proteins that can skew specific gravity results.
144
What are the three categories of urine tonicity based on specific gravity?
Hyposthenuria (<1.008), isosthenuria (1.008–1.014), and hypersthenuria (>1.014).
145
What is the expected specific gravity range for normal equine urine?
Typically between 1.025 and 1.040.
146
What effect does prolonged water deprivation have on urine specific gravity in horses?
It usually results in a specific gravity greater than 1.045.
147
How does the urine tonicity of neonatal foals differ from that of adult horses?
Foals often have hyposthenuric urine due to a high milk diet.
148
What urine specific gravity indicates prerenal failure?
Greater than 1.020 with Uosm over 500 mOsm/kg.
149
What urine specific gravity suggests intrinsic renal failure?
Typically less than 1.020 and Uosm under 500 mOsm/kg, despite dehydration.
150
What is a significant complication when collecting urine samples?
Catheter tips may advance into the seminal vesicle duct in male horses.
151
What should be monitored in urine to help differentiate between renal failure types?
Urine specific gravity and osmolality.
152
What can cause urine to appear milky white during collection?
The presence of calcium carbonate crystals and mucus, especially toward the end of urination.
153
Figure 64-2. Asymmetry of the perineum in two geldings with proximal urethral rents causing hematuria immediately after urination. (A) Note widening of the perineum. (B) Note an indentation of the perineum.
VetBooks
154
Figure 64-3. Relationship between glomerular filtration rate (GFR) and serum creatinine (Cr) concentration. When renal function is normal, a large decrease in GFR results in a minor increase in Cr (arrow 1). In contrast, when renal function is decreased, as with chronic kidney disease, a much smaller decrease in GFR results in a similar increase in Cr (arrow 2).
155
Figure 64-4. A urine collection device for use in male horses and ponies.
156
What is the typical pH range of equine urine?
The pH of equine urine is usually alkaline, ranging from 8 to 9.
157
What is the normal urinary protein concentration in horses?
Normal horses typically have urinary protein concentrations less than 100 mg/dL.
158
What is the typical renal threshold for glucose in horses?
The renal threshold for glucose is estimated to be between 160 and 180 mg/dL.
159
What unusual finding might indicate proximal tubule dysfunction?
Glucosuria without hyperglycemia suggests primary proximal tubule dysfunction.
160
What condition is bilirubinuria associated with in horses?
Bilirubinuria is associated with intravascular hemolysis, hepatic necrosis, and obstructive hepatopathies.
161
How should sediment be prepared for examination?
Centrifuge 10 mL of fresh urine at 1000 rpm for 3 to 5 minutes, discard the supernatant, and resuspend the pellet in a few drops of urine.
161
What type of crystals are most commonly found in equine urine?
The majority of crystals in equine urine are calcium carbonate crystals.
162
What does pyuria indicate in urine analysis?
Pyuria (more than 5 WBCs per hpf) is typically associated with infectious or inflammatory disorders.
163
What changes occur in urine osmolality in intrinsic renal failure?
Urine osmolality values drop below 226 mOsm/kg in intrinsic renal failure.
164
What imaging technique is often used to confirm uroperitoneum?
Transabdominal ultrasonography is commonly used to confirm uroperitoneum.
164
What is a significant finding in peritoneal fluid analysis for diagnosing urinary tract obstruction?
A peritoneal fluid creatinine level more than twice that of serum creatinine indicates obstruction.
165
What clinical signs may indicate postrenal azotemia?
Signs include dysuria, renal colic, and abdominal distention in cases of bladder rupture.
166
What role does urinary sediment examination play in diagnosing urinary disorders?
It helps identify casts, RBCs, WBCs, and bacteria, which are indicative of various urinary tract disorders.
167
What can prolonged dehydration lead to regarding urine concentration?
Prolonged dehydration can lead to concentrated urine with a specific gravity greater than 1.045.
168
What urine characteristic typically indicates renal failure?
Isosthenuria, or the inability to concentrate or dilute urine, indicates renal failure.
169
What is the recommended approach for horses with chronic kidney disease (CKD) and dehydration?
Rehydration with hypotonic enteral fluid therapy is recommended over aggressive IV fluid therapy.
170
What factors must be considered when interpreting urine electrolyte concentrations?
Diet, fluid therapy, and the timing of sample collection must be considered.
171
How does metabolic acidosis relate to aciduria in horses?
Aciduria can occur with metabolic acidosis, but horses often present with hypochloremic metabolic alkalosis instead.
172
What is pyelography and how is it performed?
Pyelography involves injecting a contrast agent directly into the renal pelvis under ultrasonographic guidance.
173
What is a significant limitation of radiography in evaluating adult horses' urinary tracts?
Diagnostic radiographs can only be obtained in small foals or Miniature horses.
174
What types of conditions can retrograde contrast radiographic studies help identify in foals?
Ruptured bladder, ectopic ureter, or urorectal fistula.
175
What is the advantage of using ultrasonography over radiography in equine kidney evaluation?
Ultrasonography can provide real-time imaging and assess kidney size, shape, and echogenicity.
175
What echogenicity changes in kidneys might indicate acute kidney injury (AKI)?
The kidneys may appear normal or enlarged, often without detectable parenchymal detail.
176
What distinguishes nephroliths from normal renal pelvis echogenicity on ultrasound?
Nephroliths cast an acoustic shadow, while the renal pelvis does not.
177
What does increased echogenicity of the renal cortex suggest in the context of chronic kidney disease (CKD)
It indicates structural changes associated with renal dysfunction.
178
Which imaging technique is recommended for examining the bladder and urethra?
Transrectal ultrasonography using a linear array transducer.
179
What is the typical appearance of normal distal urethral mucosa in male horses during endoscopy?
pale pink with longitudinal folds.
180
What condition should be closely examined if a horse presents with hematuria at the end of urination?
Urethral rent or injury.
181
What radiopharmaceutical is commonly used for scintigraphy in horses?
99mTc (technetium).
182
What does a significant variability in gamma camera images compared to GFR measurements indicate?
Different depths of the equine kidneys may affect image accuracy.
183
In what situation might CT and MRI be used in horses?
To provide detailed anatomical images of urinary tract problems in smaller patients.
184
What can the presence of cystic calculi indicate during ultrasonographic examination?
Possible urinary obstruction or bladder disease.
184
What feature helps differentiate a cystic calculus on ultrasound?
It has a highly echogenic surface and produces an acoustic shadow.
185
What anatomical detail can be evaluated using renal scintigraphy in horses?
Split renal function or individual kidney function.
186
What are the diagnostic benefits of using endoscopy for urinary tract examination?
It allows direct visualization of abnormalities such as calculi, inflammation, and tumors.
187
what is a common finding in horses with chronic renal disease during imaging?
Small kidneys with increased echogenicity.
188
What does a renal scintigraphy study assess in equine patients?
Renal blood flow (RBF) and glomerular filtration rate (GFR).
189
Figure 64-5. Transabdominal ultrasonographic images of the left kidney (deep to spleen) of two horses with acute kidney injury resulting in acute renal failure. (A) Enlarged left kidney (23.3 cm in length).
(B) Renal cortex is more echogenic than normal.
190
Figure 64-6. Transabdominal ultrasonographic images of the left kidney of two horses with chronic kidney disease. (A) Left kidney of a yearling with chronic interstitial nephritis that developed 11 months following treatment with an aminoglycoside antibiotic and flunixin meglumine for a leg wound. Note the generalized increase in echogenicity of the renal parenchyma in comparison to the spleen. (B) Left kidney of the same yearling with the probe directed in a different plane, revealing a large nephrolith adjacent to the renal pelvis. (C) Left kidney of a stallion with an obstructive ureterolith causing hydronephrosis; note the small nephrolith in the center of the image producing an acoustic shadow. (D) Left kidney of the same stallion imaged in a plane rotated 90° revealing hydronephrosis consequent to obstructive disease. (E) Left kidney of the same stallion following relief of ureteral obstruction by electrohydraulic lithotripsy. Note that the kidney is small and the renal parenchyma has a diffuse increase in echogenicity because of renal fibrosis. (
191
Figure 64-7. Ultrasonographic images of the left (A) and right (C) kidneys and cross-sectional gross pathology of the left (B) and right (D) kidneys of a 19-year-old Arabian mare with chronic renal failure consequent to polycystic kidney disease. (
192
Figure 64-9. Endoscopic images of an abnormal ureteral opening (A) and a nephrolith in the renal pelvis (B) of a stallion with chronic kidney disease.
193
Figure 64-10. Nuclear scintigraphic dorsal image (cranial at top and caudal at bottom) of the kidneys of a horse with chronic hematuria arising from the left kidney. The study revealed considerably less radiopharmaceutical uptake and elimination by the left kidney and provided support to the theory that nephrectomy of the left kidney would not result in a substantial loss of remaining renal function. LT, Left; RT, right.
194
Figure 64-11. Contrast-enhanced computed tomographic images of the kidneys (excretory urography) of a normal Miniature horse. (A) The transverse plane image shows nearly homogeneous uptake of the contrast agent in both kidneys. (B) The reconstructed dorsal plane image provides even greater detail of the intrarenal distribution of the contrast agent within the right kidney (left side of image).
195
What type of instruments are crucial for urinary tract surgeries?
Long-handled and standard-sized instruments.
196
What retractors are commonly used for accessing the urinary tract in adult horses?
Broad-bladed self-retaining retractors like Finnechetto or Balfour retractors.
197
What role do flexible rubber urethral catheters play in surgery?
They facilitate anastomotic procedures and intraoperative stenting.
198
What is the recommended time frame for removing stents after ureteral surgery?
Within 5 to 7 days post-surgery.
199
What tools assist in repairing ureteral defects during surgery?
Magnifying loupes, operating microscopes, and adequate lighting.
200
How is synthetic absorbable suture material absorbed in the body?
Through hydrolysis.
201
What alternative closure method is suggested for hollow organs like the bladder?
Absorbable staples, oversewn with continuous-inverting suture patterns.
202
What can accelerate the absorption of synthetic absorbable sutures?
Exposure to alkaline urine.
203
Which inhalant anesthetic is considered nephrotoxic?
All fluorinated gas anesthetics.
203
What is the typical voiding pressure in adult ponies?
Approximately 90 mm Hg.
204
How do all anesthetics generally affect glomerular filtration rate (GFR)?
They tend to decrease GFR.
205
What is the impact of halothane on renal function?
It has minimal formation of toxic waste products, making it relatively safer for renally impaired horses.
206
What is a common effect of inhalant anesthetics on the kidneys?
Peripheral vasodilation leading to renal hypoperfusion.
207
What pharmacologic agents can enhance renal perfusion during anesthesia?
Dobutamine and dopamine.
208
What broad-spectrum coverage is recommended for perioperative antibiotics?
Against aerobic gram-positive and gram-negative organisms.
209
What should guide the selection of antimicrobial agents for urinary tract infections?
Culture and susceptibility results.
210
Why are potentiated sulfonamides favored for UTI treatment in horses?
They are excreted largely unchanged in urine.
211
What is the advantage of ceftiofur in treating resistant urinary pathogens?
It has broad-spectrum activity and a long-acting formulation.
212
what is a major risk associated with fluoroquinolone use in juvenile horses?
Damage to articular cartilage.
213
What urinary concentration is achieved with procaine penicillin G in horses?
Exceeds 60 mg/mL for 48 hours.
214
Which suture sizes are adequate for high-pressure urinary tract closures?
USP size 3-0, 2-0, or 1-0.
215
Why is chloramphenicol not commonly approved for use in horses?
It poses a risk of aplastic anemia, and its use is restricted.
216
What is the recommended dosage of chloramphenicol for treating complicated UTIs in horses?
25–50 mg/kg PO every 6–8 hours.
217
Which multidrug-resistant organisms are a concern in horses with urinary tract infections?
Enterococcus spp.
218
What is the recommended dosage of vancomycin for persistent UTIs after catheter removal?
7.5 mg/kg IV every 8 hours.
219
What emerging antibiotic is gaining interest for treating multidrug-resistant UTIs?
Fosfomycin.
220
What dosages of fosfomycin have been reported to produce effective serum and urine concentrations?
10 or 20 mg/kg.
221
How does phenazopyridine alleviate lower urinary tract pain?
It acts as a topical local anesthetic on the ureteral, bladder, and urethral mucosa.
222
What color does phenazopyridine turn urine, and what is a practical concern of this?
It turns urine orange, which can stain hands and clothing.
223
What alternatives may be considered if NSAIDs and phenazopyridine are insufficient for pain management?
Intermittent α2-receptor agonists, opioids, or a continuous-rate infusion of lidocaine.
224
What should be considered when formulating an analgesic plan after a nephrectomy?
The loss of residual functional nephrons increases the risk for nephrotoxicity from NSAIDs.
225
For how long is phenazopyridine typically administered post-surgery?
2 to 3 days.
226
Bladder is the strongest of weakest tissue of the body?
The bladder is considered one of the weakest tissues in the body.
227
What is the recovery/regenerative capacity of the bladder?
These tissues regain nearly 100% of their normal strength within 14 to 21 days
