Page 963 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

938 CHAPTER 7

VetBooks.ir is at least 50% smaller than normal. Renal failure ultrasonographic examination can identify neph-
Renal hypoplasia is a condition where renal mass
roliths of significant size. Diminished unilateral
will develop if renal mass is <30% or if concurrent
renal disease affects renal function. or bilateral entry of urine into the bladder from
ureteral openings may be evident endoscopically.
Renal dysplasia is an abnormal differentiation of Successful dietary and/or medical procedures to dis-
renal tissue that develops secondarily to in-utero solve nephroliths have not been reported in horses.
exposure to teratogens. Bilateral and unilateral dis- Unilateral nephrectomy is the treatment of choice if
ease have been reported. There are no specific treat- the remaining kidney is normal.
ment options for any of these conditions and the
long-term prognosis is poor. Interstitial nephritis
Interstitial nephritis or tubulointerstitial disease is a
Renal pelvis calculi common sequela of AKI. Depending on the degree
Nephroliths (Fig. 7.20) that develop within or adja- of damage and the number of affected nephrons,
cent to the renal pelvis can partially or completely CKD may develop following an episode of AKI.
obstruct the upper urinary tract. As the passage of The degree of renal interstitial change influences
urine is obstructed, hydronephrosis develops. It is the severity of clinical signs and the prognosis for
believed that a nidus of damaged renal tissue is most short- and long-term recovery.
often the initiating factor in nephrolith develop-
ment. If upper urinary tract obstruction is bilateral, Immune-mediated
CKD will develop. glomerulonephritis
Diagnosis is based on history and clinical signs. Glomerulonephritis can be defined as a disease
In unilateral disease, azotaemia may not be present, characterised by intraglomerular inflammation and
but urinalysis may reveal pigmenturia and/or micro- cellular proliferation associated with haematuria.
scopic haematuria. Transabdominal and transrectal When antigen–antibody complexes are deposited in
the glomeruli of kidneys, they cause a local inflam-
matory response and vasculitis. Most often it is seen
7.20 following streptococcal infections. Antigens against
equine infectious anaemia have also been associated
with glomerulonephritis. Circulating immune com-
plexes of other chronic diseases such as leptospiro-
sis, Borrelia burgdorferi and herpesvirus infections
probably also lead to glomerular deposits. Persistent
deposition of complexes leads to irreversible damage
and CKD. Definitive diagnosis is via histopathologi-
cal and immunofluorescence examination of renal
biopsies or necropsy samples.
Treatment should aim at removal of the initiating
cause of the glomerulonephritis and CKD treatment
as described previously. Immunosuppressive therapy
with corticosteroids has been successfully used in
other species although their affect in equine glomer-
ulonephritis has not been proven.

Pyelonephritis
Definition/overview
Fig. 7.20 Nephrolith 1 cm in diameter (arrow) in the Pyelonephritis is a suppurative bacterial infection
right kidney. of the kidney (Fig. 7.21). It is an uncommon cause