Equine Renal Flashcards

Question

Acute tubular necrosis (ATN)

Answer 1

A physiologic hallmark of ATN is a failure to maximally dilute or concentrate urine (isosthenuria). This defect is not responsive to pharmacologic doses of vasopressin. The injured kidney fails to generate and maintain a high medullary solute gradient, because the accumulation of solute in the medulla depends on normal distal nephron function. — (Failure to excrete concentrated urine even in the presence of oliguria is a helpful diagnostic clue in distinguishing prerenal from intrinsic renal disease; in prerenal azotemia, urine osmolality is typically more than 500 mOsm/kg, whereas in intrinsic renal disease, urine osmolality is less than 300 mOsm/kg.)

Answer 2

Mechanical obstruction of the urinary collecting system, including the renal pelvis, ureters, bladder, or urethra, results in obstructive uropathy or postrenal AKI. If the site of obstruction is unilateral, then a rise in the serum creatinine level may not be apparent due to contralateral renal function. Although the serum creatinine level may remain low with unilateral obstruction, a significant loss of GFR occurs, and patients with partial obstruction may develop progressive loss of GFR if the obstruction is not relieved. Causes of obstruction include stone disease; stricture; and intraluminal, extraluminal, or intramural tumors.

Answer 3

Ureteric obstruction — stone disease, tumor, fibrosis, ligation during pelvic surgery Bladder neck obstruction — benign prostatic hypertrophy [BPH], cancer of the prostate [CA prostate or prostatic CA], neurogenic bladder, tricyclic antidepressants, ganglion blockers, bladder tumor, stone disease, hemorrhage/clot Urethral obstruction — strictures, tumor, phimosis Intra-abdominal hypertension Renal vein thrombosis

Answer 4

— Tubular obstruction from crystals (eg, uric acid, calcium oxalate, acyclovir, sulfonamide, methotrexate, myeloma light chains) — Ureteral obstruction - Retroperitoneal tumor, retroperitoneal fibrosis (methysergide, propranolol, hydralazine), urolithiasis, or papillary necrosis — Urethral obstruction - Benign prostatic hypertrophy; prostate, cervical, bladder, colorectal carcinoma; bladder hematoma; bladder stone; obstructed Foley catheter; neurogenic bladder; or stricture

Answer 5

``` Monitoring: — Therapeutic drug monitoring — Blood pressure — Central venous pressure — Urinalysis — Electrolytes — Creatinine — Etc ```

Answer 6

- Depends on underlying event. Length of time present - Severe ischemic failure, AIN carry worst prognosis - ATN prognosis good if basement membrane intact - Patients recover but may not be able to fully concentrate urine

Answer 7

Infrequently recognized in horses Primarily a problem in older patients Many older patients have renal lesions: large renal reserve prevents clinical signs — Requires 2/3 to % of functional parenchyma be lost Underlying causes can be congenital or acquired

Answer 8

``` Gradual weight loss Poor performance Pendent edema PU/PD Excessive dental tartar Oral ulcerations Stunted growth Abdominal pain ```

Answer 9

Two broad classes of causation: — Primary glomerular disease • Glomerulnephropathy, glomerulopathy, renal glomerular hypoplasia, amyloidosis — Tubulointerstitial disease • Incomplete recovery from ARF, pyelonephritis, nephrolitiasis, hydronephrosis, renal dysplasia, papillary necrosis (rare)

Answer 10

``` — Chronic interstitial nephritis in most common cause: ATN Drug induced Obstruction NSAID toxicity Pigmenturia Ischemic causes Nephrolitiasis ```

Answer 11

``` As for ARF but include: - BUN:Cr usually > 10 with CRF — Red cell parameters: CRF patients frequently anemic — Albumin: < 2.5 gm/dl — More electrolyte abnormalities — Blood gas parameter: acidosis common — Hypercholesterolemia/ hyperlipidemia — Rectal exam and US to evaluate renal size ```

Answer 12

``` Treat any acute component as ARF Supportive care, IV fluid support Adequate feed, decrease protein Unlimited water access Oral Naa Or NaHC03 Avoid NSAlDs and steroids Remove calculi if present Pyelonephritis: antimicrobial therapy All efforts are palliative ```

Answer 13

``` Pyelonephritis Cystitis Idiopathic renal Urolithiasis Sabulous bladder Urethral rent Blister beetle toxicosis Trauma ```

Answer 14

``` Lower Urinary Tract - Altered urine flow - Urine scalding - Dysuria - pollakuria - Gross hematuria - Calculi at end of urination Upper urinary tract - Fever - Weight loss - Signs of systemic illness - Other like LUTI ```

Answer 15

``` Urinalysis — > 20 organisms/hpf, > 10 WBC/hpf in mid-stream catch or catheterized sample Ultrasound Chemistry screen Hematology with fibrinogen Urine culture ```

Answer 16

Neurologic disorders — EPM, EHV-I, cauda equine neuritis, botulism Urolithiasis Foaling trauma Poor perineal conformation Common organisms: — E. coli, Proteus spp, Klebsiella spp, Pseudomonas spp.

Answer 17

• Treat any associated ARF/CRF • Antimicrobial therapy based on urine culture and sensitivity — TMS, penicillin, ceftiofur sodium

Answer 18

``` Uncommon Strongylus vulgaris Halicephalobus gingivalis (deletrix) Dioctophyma renale Klossiella equi ```

Answer 19

Urethral rents that occur on the convex surface of the urethra at the level of the ischial arch cause hematuria in geldings and hemospermia in stallions. Urethral rents communicate with the corpus spongiosum penis (CSP). Hemorrhage through the rent into the urethral lumen occurs when pressure within the CSP increases at the end of urination or during ejaculation. The 5-10-mm rent is identified endoscopically on the convex surface of the urethra, near the level of the ischial arch. Urethral rents often heal without treatment.

Answer 20

Urinary calculi or stones may form in any part of the equine urinary tract, but the most common site is the bladder (cystic). Calculi are formed by material dissolved in the urine (solutes) being precipitated upon a collection of bladder or other cells, such as tubular epithelial, renal papillary or red or white blood cells. Usually only one calculus occurs at a time, often composed of calcium carbonate.

Answer 21

The factors favoring this precipitation are not well understood but include urine pH; alkalinity increases the formation of carbonate calculi; and the concentration of urine solutes. — This can be affected by diet, water intake and loss. — If the diet or water has a high mineral content, urine solute content increase. — A high-concentrate, low-roughage ratio may allow the deposited solute to cement together more easily

Answer 22

All breeds and both sexes are equally likely to develop calculi, athough in mares they become very large before symptoms appear. — These are similar to those seen in cases of cystitis, which often is present at the same time. — Affected individuals urinate more frequently, with straining and dribbling of urine. — Less commonly there may be mild recurrent colic, loss of condition and stilted gait. Occasionally a calculus passes into the male urethra, causing acute obstruction of urine flow.

Answer 23

``` Diagnosis of cystic calculi involves: — Urine analysis (the changes are similar to those of cystitis) — Rectal examination — Passage of urinary catheter — Ultrasound of the bladder — Urinary tract endoscopy ```

Answer 24

Surgical removal of the calculus is the only effective method of treatment. The approach and type of surgery is determined by the size of the stone and the sex of the patient. Some cases may also require treatment for concurrent cystitis. — Pyridium! Urinary acidification may be attempted but is often unrewarding.

Answer 25

Inflammation of the bladder with an accumulation of calcium carbonate sludge at the bottom

Answer 26

Incontinent horses due to neurologic dysfunction dribble urine because effective detrusor contraction is absent and bladder contents are not subject to muscle contraction and forced ejection from the body, as occurs in a normal state. The neurologic circuitry that mediates the micturition reflex is complex, and examples of disease processes that can interfere with various segments of the reflex loop include herpes myelitis, polyneuritis equi (cauda equine syndrome), and equine protozoal myeloencephalitis.

Answer 27

Bladders that become paralyzed because of these pathologic processes often show deposition of a sandy, crystalloid sediment, a condition called sabulous cystitis, instead of formed uroliths. Bladder paralysis permits settling of deposits onto the bladder floor, where the material's weight prevents it from being extruded during dribbling of urine from the incontinent bladder. The sediment contributes to inflammation and irritation of the mucosal lining, exacerbating cystitis and most likely, the discomfort of the horse

Answer 28

Treatment of the condition involves lavage of the bladder lumen with isotonic solutions to remove the sediment load, administration of systemic antibiotics chosen with regard for culture results and sensitivity testing of a catheterized urine sample, anti-inflammatories, and urine acidification. Lavage can be achieved through a catheter. Placement of an indwelling catheter for a brief initial period helps lower urine stasis and maintains the bladder in a fairly decompressed state, abating further detrusor damage. Adding acetic acid to decrease luminal pH during lavage is advocated.

Answer 29

The parasympathomimetic drug bethanechol augments contractility of the detrusor smooth muscle. - Bethanechol (20-40 mg or 0.07 mg/kg SQ q 8 hours, 80 mg PO q 8 hours do not give I.V. or I.M.) is not currently available as a proprietary formulation but can be obtained from compounding pharmacies. - Phenoxybenzamine, (0.2-0.7 mg/kg PO, q 6-8 hrs) is an adrenergic antagonist, and may be given to help relax the distal urethral sphincter in cases where the condition is determinedly due to upper motor neuron damage.

Answer 30

(4 mg/kg PO q 8-12 hours), an azo dye compound that acts to confer relief from irritation or spasm of the urinary tract mucosa via local anesthetic activity, may also be administered in the initial management of the cystitis caused by the sedimentary accumulation. This compound discolors urine. — Owners should be warned that it will stain skin and textiles which inadvertently come into contact with the substance. • In humans with urinary tract inflammation the agent alleviates symptoms of dysuria, frequency, burning, and the sensation of urgency.

Answer 31

Mares in which urinary incontinence is from hypoestrogenism may enjoy a better prognosis for response to treatment. Successful management of the condition in such mares has been observed in association with administration of estradiol cypionate or benzoate (5-10 _ g/kg I.M. q 48 hours).

Answer 32

Rare, indicates a failure of normal homeostatic mechanisms controlling water balance Can be caused by either increased water intake or increased urine production Establishing if a horse is really PU/PD can be a challenge Rule out: — Diarrhea — Acute Renal Failure — Horse on High Salt Diet

Answer 33

``` Psychogenic polydipsia Thirst Compulsive salt or glucose consumption Diabetes mellitus Diabetes insipidus Hyperadrenocorticism Sepsis/endotoxemia Iatrogenic Primary renal insufficiency ```

Answer 34

``` History Clinical Examination Clinical Pathology Renal function tests Water deprivation test Modified water deprivation test ADH (vasopressin) stimulation test ```

Answer 35

``` Decreased sensitivity of collecting ducts to vasopressin Rare in horses Hyposthenuria in the face of dehydration Positive response to vasopressin ```

Answer 36

Psychogenic water (common) or salt (rare) consumption Drink 2-3 times that of others horses in same environment Respond to water deprivation by concentrating urine

Answer 37

Most common in neonates Associated with perinatal asphyxial syndrome Very concentrated urine Hyponatremia secondary to increased water retention, 'dilutional' Excessive weight gain Usually resolves, treatment is appropriate fluid restriction

Answer 38

``` Causes: — Neurological diseases — Intramural bladder/urethral disease — Hormonal — Ectopic ureter — Bladder tumor — Adhesions — Urolithiasis — Sorghum toxicity - Etc ```

Answer 39

Depends on underlying problem Upper motor neuron: — Phenoxybenzamine — Bethanacol Lower motor neuron: — Phenylpropanolamine Older mares: — Estradiol

Answer 40

Poor to guarded May fully recover from EHV-I, botulism with time

Answer 41

``` Bladder: — Squamous cell carcinoma, transitional cell carcinoma (RARE) Kidney: — Renal cell carcinoma, lymphosarcoma ```

Equine Renal Flashcards

(66 cards)