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Hydronephrosis 483

Acute and Chronic Treatment Possible Complications Prevention
Medical options: • Generally, medical therapy results in only Limit prenatal exposure to toxins, viral infec-
VetBooks.ir kg PO q 12-24h, then tapered to lowest • Complications of shunt placement include Technician Tips Diseases and Disorders
tions, and vaccines.
• Prednisone (↓CSF production) 0.25-0.5 mg/
transient improvement of clinical signs.
effective dose
mechanical failure (breakage, migration,
• Furosemide (↓CSF production; Na-K
infection, and overdrainage.
the external jugular veins in these patients
cotransport inhibition) 0.5-2 mg/kg PO q and disconnection), functional obstruction, • Avoid excessive restraint and compression of
12-24h, taper to lowest effective dose (can increase intracranial pressure).
• Acetazolamide (↓CSF production; car- Recommended Monitoring • Counsel owners on monitoring for
bonic anhydrase inhibitor) 10 mg/kg PO • Signs of acute decompensation: coma, gastrointestinal ulceration if the animal is
q 8h seizures, behavior changes being treated with glucocorticoids.
• Omeprazole (↓CSF production; proton • Seizure control • After surgery for shunt placement, monitor
pump inhibition) 0.7 mg/kg PO q 24h; the skin over the shunt for signs of pressure
10 mg PO q 24h for dogs weighing < 20 kg PROGNOSIS & OUTCOME necrosis, especially in small-breed dogs with
or 20 mg q 24h PO for dogs weighing > tendency for thin skin.
20 kg • Congenital: guarded; prognosis also is
• Mannitol (hyperosmolar therapy, decrease influenced by coexistence of other neural Client Education
blood viscosity) 1 g/kg IV tissue abnormalities • Clinical signs of acute decompensation
• Antiepileptic drug therapy for seizure • Acquired: prognosis depends on underlying • Guarded prognosis and likelihood of residual
control cause neurologic deficits with therapy
Surgical: indicated for worsening of clinical • Importance of maintaining the pet in a
signs that do not respond to medical therapy: PEARLS & CONSIDERATIONS protective environment
• Ventriculoperitoneal shunt
• Ventriculoatrial shunt Comments SUGGESTED READING
• Every attempt is made to determine the Estey CM: Congenital hydrocephalus. Vet Clin North
Drug Interactions underlying cause. Am Small Anim Pract 46:217-229, 2016.
Prolonged use of corticosteroids, furosemide, • Early shunt placement is advocated to lessen
and acetazolamide can cause potassium deple- residual neurologic deficits and behavior AUTHOR: Joan R. Coates, DVM, MS, DACVIM
EDITOR: Karen R. Muñana, DVM, MS, DACVIM
tion and other systemic disorders. abnormalities.

Hydronephrosis Client Education
Sheet

BASIC INFORMATION ASSOCIATED DISORDERS • Abdominal mass (kidney, bladder, prostate,
• Renal failure ± uremia granuloma)
Definition • Hypertension • Urethral mass (by rectal palpation)
Dilation of the renal pelvis and calices (pyel- • Urinary tract infection • Prostatomegaly
ectasia) in one or both kidneys resulting in Clinical Presentation • Dehydration
atrophy of the renal parenchyma, which typi- • Halitosis (uremia)
cally results from ureteral (or rarely urethral) DISEASE FORMS/SUBTYPES • Oral ulcerations (uremia)
obstruction • Reversible or irreversible
• Unilateral or bilateral Etiology and Pathophysiology
Epidemiology • Illness varies depending on whether obstruc-
SPECIES, AGE, SEX HISTORY, CHIEF COMPLAINT tion is unilateral or bilateral, degree and
Dogs and cats of any age and either sex Often an incidental finding (patient is clinically duration of obstruction, and pre-existing
normal); signs can include renal function.
RISK FACTORS • Vague abdominal pain (if renomegaly) • Clinical signs can be absent, chronic, or
Any cause of ureteral (or urethral) obstruction, • Polydipsia/polyuria (with chronic kidney acute; acute signs are more likely when
whether mechanical or functional: disease [CKD]) obstruction is complete.
• Bladder atonia/hypotonia • Anorexia and vomiting (uremia) • Obstruction results in increased hydro-
• Blood clots • Pollakiuria, stranguria, dysuria, hematuria static pressure in renal pelvis, collecting
• Celiotomy (inadvertent ligation/fibrotic • Urinary incontinence (if ectopic ureter) ducts, and distal tubules, causing tubular
entrapment of ureter) • Oliguria or anuria (urethral obstruction or, dilation with flattening of the tubular
• Congenital ureteral stenosis or stricture rarely, bilateral ureteral obstruction) cells.
• Ectopic ureter • Concurrently, renal vasculature and blood
• Prostatic carcinoma PHYSICAL EXAM FINDINGS supply are compromised. Renal blood flow
• Reflex dyssynergia Often normal; abnormalities can include progressively decreases, arterioles constrict,
• Retroperitoneal mass/fibrosis/infarction • Abdominal discomfort or back pain (severity capillary pressure decreases, and many
• Trauma related to rapidity of obstruction rather than arterioles collapse, resulting in parenchymal
• Ureteral fibroepithelial polyps degree of obstruction) atrophy.
• Urinary tract neoplasia • Renomegaly • Changes may become irreversible after 14-45
• Urolithiasis (common cause) • Distended bladder (if urethral obstruction) days.

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