Page 970 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Urinary system 945

VetBooks.ir weakness are the most common presenting com- are not well understood. Tissue damage, cystitis,
remaining suture material, supersaturation of urine
plaints. Appetite is usually good until advanced
stages of the disease, at which point depression and
pose to calculus development. A genetic predisposi-
lethargy may also be noted. Pollakiuria, stranguria with certain minerals and urine stasis may predis-
and haematuria may be observed. Earlier in the dis- tion is possible.
ease process the clinical signs may be confused with Cystic calculi are mainly composed of calcium
those of cystic calculi. carbonate crystals. If calcium carbonate crystals are
mixed with calcium phosphate crystals, the struc-
Differential diagnosis ture of the calculus becomes stronger than that of
Differential diagnoses include urolithiasis, cystitis, calcium carbonate crystals alone. Most calculi are
renal failure, bladder paralysis, urinary tract trauma, sphere-shaped stones. An accumulation of crystal-
colic and neoplasia of other organ systems. loid sludge (sabulous urolithiasis) can also occur
(Fig. 7.24). The latter is usually associated with
Diagnosis bladder paralysis and urine stasis.
Physical examination is usually non-specific. On
urinalysis macroscopic or microscopic haematuria Clinical presentation
and neoplastic cells are often observed. Urine SG is Stranguria, pollakiruia and haematuria are the
usually normal (>1.020). The bladder should be pal- most common presenting complaints. Haematuria
pated p/r and if the bladder is distended with urine, may be more pronounced following exercise. Signs
it should be emptied, prior to further evaluation. of systemic disease such as fever, depression or
A thickened, irregular bladder wall or obvious mass anorexia should not be present. Other signs include
may be palpable. Transrectal and/or transabdominal tenesmus, colic, incontinence and urine scald-
ultrasonography can be used to further evaluate the ing. Urinary incontinence is common in sabulous
bladder. Cystoscopy can be used to evaluate the blad- urolithiasis.
der mucosa and to obtain a biopsy. Anaemia from
chronic haematuria or anaemia of chronic disease Differential diagnosis
may be identified on a complete blood count (CBC). Differential diagnoses include cystitis, oestrus,
Hypoproteinaemia may be present from chronic pyelonephritis, calculi in other parts of the urinary
blood loss or chronic inflammatory disease. tract, renal failure, bladder rupture and neoplasia.

Management
Surgical excision and chemotherapy have had vari-
able success in the treatment of bladder tumours. 7.24
Bladder carcinomas are locally very invasive and
have also been reported to metastasise to other
organs. The prognosis is grave.

CYSTIC CALCULI

Definition/overview
Cystic calculi (cystoliths) are the most common uro-
liths in horses and are usually identified in adults.

Aetiology/pathophysiology
It is believed that a nidus in the form of organic
debris is needed as a base for calculus formation. Fig. 7.24 Sabulous urolithiasis (yellow debris)
Risk factors for the development of cystic calculi associated with cystitis.