Kidney Disease Flashcards
What is the normal water intake out urine output in horses?
15-20 L (90 L if hot)
5-15 L, difficult to see - owners will likely observe consistently soaked bedding
How can a rectal exam be used in diagnosing kidney disease?
can palpate the caudal border of the left kidney
What are the most common ways of obtaining a urine sample from horses? What is important to note about urine appearance in comparison to small animals?
- free catch (horses will likely urinate when put in a fresh stall)
- feathering
- catheter
will likely be viscous due to the normal presence of more mucus
What is the expected tonicity of equine urine? How is that measured?
USG = 1.025-1.050 on refractometer
- hyposthenuric = < 1.008
- isosthenuric = 1.008-1.014
- hypersthenuric = > 1.014
What is the pH of equine urine? What does this cause? When is glucose seen? How is blood measured on dipstick? Bilirubin?
herbivores = alkaline (7-9)
protein trace
usually absent - seen following exercise, sedation (Dex, Xylazine), and with PPID
usually false positive
What sediment is normally seen in horse urine?
- calcium carbonate crystals (circles)
- mucus
What hematology changes are expected in horses with kidney disease? What is the preferred biochemistry value evaluated?
low-grade anemia
- creatinine is most sensitive to kidney damage
- BUN (70% lost)
- electrolytes
What is acute renal injury? What are the 3 major causes?
rapid fall in GFR associated with uremia
- pre-renal = dehydration, vasomotor issue, septicemia (decreased renal blood flow)
- renal = toxic, intrinsic damage to kidney structures
- post-renal = obstruction to urine outflow, uroliths
What is the most common finding with acute renal injury?
acute tubular necrosis
What 3 drugs cause toxic (renal) damage?
- aminoglycosides (Gentamycin, Amikacin) and oxytetracycline
- NSAIDs - treat laminitis and uveitis
- biphosphonate - treats lameness
What 3 diseases are associated with toxic (renal) damage?
- myopathy, hemolysis - myoglobin and hemoglobin filtration damage tubules
- immune-mediated - complexes
- leptospirosis
What clinical signs are associated with acute renal damage?
often caused by predisposing issue with uremia 3 days later —> more obscure
- depression
- anorexia
- rarely febrile
How do the 2 renal values compare when diagnosing acute renal damage?
- creatinine = freely filtered, increases with 75% decreased GFR
- BUN = less accurate due to reabsorption
(SDMA?)
urine and serum creatinine, or BUN/Cr are not reliable and cannot differentiate renal vs. pre-renal
What is expected on USG in renal and pre-renal damage?
RENAL = 1.008-1.016 (concentration potential is lost)
PRE-RENAL = > 1.025
How is urine cytology used to diagnose renal disease?
- RBC, WBC = infectious
- casts = tubular damage
What is the most common change in serum electrolytes seen with acute renal damage? What are 3 other possible observations?
hyponatremia and hypochloremia
- variable changes in potassium - high with anuria/oligura, high and decreases with rehydration is pre-renal, high with rehydration is renal
- magnesium changes
- metabolic acidosis
What are the 3 general steps in treating acute kidney disease?
- fluids
- Furosemide
- pressors
What must be done before treating acute kidney damage? What is the first step in treatment?
correct pre-renal factors, predisposing disease, and intravascular volume deficit
- if diuresis is present: give fluids
- no diuresis (anuric, oliguric): Furosemide, vasopressors (for low BP)
What does the prognosis of pre-renal acute kidney damage depend on?
(HEMODYNAMIC) ability to resolve predisposing issue
good prognosis = issue resolved, urine produced, creatinine decreased over 24-72 hours
When is prognosis of renal acute kidney damage considered favorable, guarded, and grave?
(NEPHROTOXIC)
FAVORABLE = diuresis, normalized creatinine and maintained w/o fluids
GUARDED = anuria, oliguria
GRAVE = uremic encephalopathy
What does the prognosis of post-renal acute kidney damage depend on?
(OBSTRUCTIVE)
- obstruction relief
- hyperkalemia correction
How is acute kidney damage prevented?
- hydrate patient receiving potentially nephrotoxic drugs
- monitor creatinine, urine output, and enzymuria closely
What is chronic kidney disease? What horses most commonly are affected? What disease is associated?
chronic, irreversible, slowly progressing ( > 3 months) structural and functional reduction in GFR
older horses
primary, immune-mediated glomerulonephritis
What are the 3 most common signs of CKD in horses? What else is seen?
- weight loss
- PU/PD
- ventral edema
- inappetence and depression
- fetid breath, gingivitis, tartar
- oral and intestinal ulcers
- decreased performance
- hematuria, encephalopathy
What is commonly seen on hematology in patients with CKD?
- anemia
- hypoalbuminemia
What are kidney values like in patients with CKD? What 3 values are seen on biochemistry?
azotemia - BUN/Cr > 10:1
- hyponatremia, hypochloremia
- hyperkalemia, hypercalcemia
- metabolic acidosis
What is seen on UA in patients with CKD?
- isosthenuria
- proteinuria
- sediment
What diet is recommended in patients with CKD? What should be added?
good quality pasture and carbohydrates (C-H)
- fat
- salt
- omega 3 fatty acids
What treatments are recommended in patients with CKD?
- treat inciting cause
- replace fluids, electrolytes, nutrients, and protein
- treat hypertension with Benazepril
- vitamin B
- anabolic steroids
In what horses with CKD is there a poor prognosis?
- USG < 1.015
- creatinine > 10 mg/dL
What is characteristic of renal tubular acidosis?
renal injury leading to metabolic acidosis and hyperchloremia
What horses may have a genetic disposition to develop renal tubular acidosis? How do they present?
Friesians
- depression, anorexia
- tachycardia +/- arrhythmia
- weakness, ataxia
- intermittent abdominal pain
How is renal tubular acidosis diagnosed? How is UA affected?
- metaboilc acidosis = bicarbonate < 10 mmol/L, or pH < 7.25
- hyperchloremia = Cl > 110 mmol/L
urine pH will be alkaline despite acidosis
How is renal tubular acidosis treated?
- correct acidosis with initial IV isotonic sodium bicarbonate, then maintenance oral sodium bicarbonate
- correct hypokalemia
What is the top differential diagnosis for PU/PD horses?
psychogenic water drinking due to boredom
ALSO:
- iatrogenic
- PPID, EMS
- ARF, CKD
- endotoxemia, sepsis
- DI, DM
- psychogenic salt consumption
What is the most common cause of ectopic ureters? What is the most common presentation?
abnormal embryonic development
filly with lifelong history or urinary incontinence and hindlimb/tail urine scalding (tend to smell)
How are ectopic ureters diagnosed? Treated?
- speculum, endoscopy
- contrast studies
- ultrasound
- UA, blood work
surgical reimplantation or nephrectomy
How is the treatment of ectopic ureters determined?
- unilateral vs. bilateral
- presence of UTIs
- impaired kidney function
What is a urachus?
fetal connection of the bladder and allantoic fluid that closes and regresses at birth
What are the 3 most common clincial signs associated with patent urachus?
- urine leaking from umbilicus
- moist umbilicus
- pollakiuria
What are 3 treatments for patent urachus? What needs to be monitored?
- antimicrobial topicals
- Gomez method
- surgical removal of the infected navel structures (removing source of further infection) and closure of the opening between the urachus and the bladder
presence of navel imfection
