Page 258 - Problem-Based Feline Medicine

250 PART 4 CAT WITH URINARY TRACT SIGNS

monitor calcium and phosphate regularly when Restrict access to cholecalciferol-based rodenticides.
using calcitriol therapy.
Avoid diets or dietary supplements that are unusually
● See Chronic renal failure in The Thin Inappetent
high in vitamin D, such as liver or cod-liver oil.
Cat (page 336) for details of treatment of chronic
renal failure.
NEOPLASIA (RENAL NEOPLASIA
In cats with idiopathic hypercalcemia, dietary mod-
OR LYMPHOMA)
ification may be partially or fully effective in a minor-
ity of cats. Dietary modification is worth trying
Classical signs
initially, as the only other reported therapy to be effec-
tive is long-term corticosteroids. ● Inappetence, weight loss and lethargy.
● Dietary modifications reported to have variable suc- ● Enlarged kidney/s or abdominal mass on
cess include use of a high-fiber diet (Hills w/d) to palpation.
reduce availability of calcium for intestinal absorp- ● ± Vomiting.
tion, or use of a less-acidifying diet (Hills k/d) to ● ± Polyuria, polydipsia.
reduce bone turnover. ● ± Dysuria, inappropriate urination,
● Prednisone (2–3 mg/kg PO q 24 h) has been pollakiuria, stranguria.
reported to be partially or fully effective in normal- ● ± Respiratory signs.
izing both total and ionized serum calcium in the ● ± Lymphadenopathy.
small number of cats reported, however therapy was ● ± Palpable cervical or abdominal mass.
required long term (> 12 months).

Clinical signs
Prognosis
Neoplasia is a cause of polyuria in cats.
If hypercalcemia is unresponsive after aggressive treat-
ment, the prognosis is poor. Lethargy, anorexia and/or weight loss are typical,
regardless of the cause.
In contrast to dogs, cats are reported to have a good
prognosis following ingestion of cholecalciferol-con- Renal, gastrointestinal, respiratory or neuromuscular
taining rodenticide, if appropriate fluid and diuretic ther- signs may occur, and in part reflect the underlying cause.
apy are instituted. Hypercalcemia associated with lymphoma is rare in
cats but does occur (see page 245, Hypercalcemia).
Hypercalcemic cats may have polyuria and polydipsia
Prevention
which may be associated with inappropriate urination,
Do not use calcium-containing intestinal phosphate and/or have signs of lower urinary tract disease,
binders. including dysuria and pollakiuria, which is commonly
associated with calcium oxalate urolithiasis.
Be aware of the risk of hypercalcemia and soft tissue
calcification when using calcium supplementation Vomiting may occur associated with the underlying
and calcitiol therapy in hypocalcemia. neoplasm, hypercalcemia or uremia.
Avoid inappropriately high doses of calcitriol or Other signs include unilateral or bilateral renal enlarge-
other vitamin D preparations, and monitor calcium ment on palpation, or an abdominal, cervical or tho-
and phosphate concentrations carefully when using racic mass.
these products. Moderately increased ionized calcium
does not contraindicate use of calcitriol in chronic renal
Diagnosis
failure, as low doses of calcitriol (2.5 ng/kg q 24 h) do
not significantly increase intestinal calcium absorption. Serum creatinine and urea concentrations may be
Increased serum phosphate concentration is a con- increased if the neoplasia is associated with renal
traindication for calcitriol use. failure.