Page 334 - Problem-Based Feline Medicine

326 PART 6 CAT WITH WEIGHT LOSS OR CHRONIC ILLNESS

● Metyrapone has given mixed results and is diffi- prevented by not giving long courses of exogenous cor-
cult to obtain. ticosteroids.
● L-depronyl has little information available on use
in cats, and no proven efficacy.
GLOMERULONEPHRITIS (PROTEIN-
Radiation therapy with ablation of the pituitary tumor LOSING NEPHROPATHY)
has given mixed results.
Classical signs
Adrenalectomy. Because of the difficulties of med-
ical therapy, surgery has been considered the treat- ● Rare disease seen most frequently in
ment of choice. However, this is changing with the young male cats.
success of trilostane treatment. Where a single adrenal ● Weight loss with a good appetite early in
tumor is present, the removal of the affected adrenal disease.
gland is recommended. With PDH or bilateral adrenal ● Often marked subcutaneous edema and
tumors, bilateral adrenalectomy is recommended. ascites.
While surgery can provide successful treatment, the ● ± polydipsia and polyuria.
risk of a fatal peri-operative hypoadrenal crisis, ● ± vomiting and/or diarrhea.
renal failure or surgical complications are great.
The procedure should only be performed by an expe-
Pathogenesis
rienced surgeon. Consideration of the diabetic state
must be given, and peri-operative and post-operative Glomerulonephropathy can arise from one of two
treatment with glucocorticoids is essential. Gluco- mechanisms:
corticoids are needed in all cases. Short-term treat- ● Primary glomerulonephritis has antibodies tar-
ment will be needed after unilateral adrenalectomy, geted directly against the glomerular basement
because the contralateral gland will be temporarily membrane.
atrophied. Long-term treatment will be needed after ● Secondary glomerulonephritis has deposition of
bilateral adrenalectomy, and should also include min- immune complexes within the glomeruli that have
eralocorticoids. arisen elsewhere in the body.
– This is the most common form in cats.
– It tends to be membranous or membrano-pro-
Prognosis
liferative in nature.
Without successful treatment, the prognosis is poor. – It may be associated with many different condi-
Where PDH is present, successful bilateral adrenalec- tions (see below), but in most cases the underly-
tomy will reduce the signs of hyperadrenocorticism, ing cause cannot be found.
but the risk of a hypoadrenal crisis is high and tumor ● Diseases that may be associated with secondary
expansion will eventually lead to neurological signs. glomerulonephritis in cats include infection
If adrenal tumors are successfully removed the hyper- with FeLV, FIV, FIP, Mycoplasma spp., or
adrenocorticism should resolve, and the diabetic state Ehrlichia spp., chronic pyoderma, chronic gin-
may become less insulin resistant or even resolve. givitis, dirofilariasis, endocarditis, pancreatitis,
Early studies with trilostane appear to show that while pyometra, neoplasia or other immune-mediated
it may ameliorate signs of hyperadrenocorticism, it diseases.
may not alter the need for exogenous insulin in cats
Deposition of immune complexes within the glomeru-
that are also diabetic.
lus leads to the initiation of inflammation and this
results in proteinuria (protein-losing nephropathy).
Prevention
Clinical signs
Since hyperadrenocorticism is usually caused by pitu-
itary or adrenal tumors, its development cannot be pre- Rare condition seen most typically in young male
vented. Iatrogenic hyperadrenocorticism can be cats.