Page 344 - Problem-Based Feline Medicine

336 PART 6 CAT WITH WEIGHT LOSS OR CHRONIC ILLNESS

● Systemic hypertension is usually measured using ● Ameliorating the clinical signs and systemic
a Doppler technique (Doppler ultrasonic sphyg- complications associated with renal dysfunction.
momanometry) to assess systolic blood pressure. ● Prevention of further deterioration of renal
● Normal range is technique dependent, however sys- function (progression).
tolic pressures > 200 mmHg indicate severe hyper- – Management of end-stage renal failure by renal
tension. replacement therapy (dialysis or transplant) is
● Retinal examination to detect end organ damage generally prohibitive because of cost, technical
should also be carried out. and ethical considerations.
Proteinuria is a risk factor for progression of chronic Although chronic renal failure is irreversible, many
renal insufficiency in cats, and may be a marker of cats presented in a uremic crisis have superimposed
glomerular hypertension. Median survival times are prerenal azotemia or acute renal failure (so called
significantly reduced if the urine protein/creatinine acute on chronic).
ratio is > 0.43. ● It is very important that appropriate therapy be used
to correct reversible azotemia.
All chronic renal failure cases should receive regu-
● Once reversible azotemia is corrected, more accu-
lar monitoring, involving full clinical examination
rate assessment of the severity of the underlying
(including assessment of body weight), measure-
irreversible chronic renal failure can be made.
ment of systemic arterial blood pressure and analy-
sis of blood and urine samples. This allows early Treatment of progression of chronic renal failure
detection of problems, and assessment of efficacy of involves:
therapy and tailoring of treatment to the individual. ● Identifying and eliminating the inciting cause of
the renal damage.
● Correcting the systemic and metabolic derange-
Differential diagnosis
ments of chronic renal failure.
Pre-renal azotemia occurs secondary to dehydration ● Preventing the intrinsic progression of renal fail-
or circulatory collapse, and the azotemia results from ure (if such progression occurs in the cat).
reduced renal perfusion. – A number of therapeutic maneuvers may be
● Typically urine specific gravity is greater than 1.035. effective slowing intrinsic progression. These
● Pre-renal azotemia concurrent with primary disease include dietary protein restriction, angiotensin-
affecting renal concentrating ability can mimic converting enzyme (ACE) inhibitors, modifica-
renal failure, for example a dehydrated cat with dia- tion of dietary lipid intake and phosphate
betes inspidus. restriction. Evidence for a beneficial effect on
survival for each of these treatments is limited
Acute renal failure.
and therefore currently each case should be
● Therapeutically and prognostically it is important
assessed on an individual basis.
to distinguish between chronic and acute renal
failure. Maintenance of hydration.
● Evidence of chronicity is usually obvious from ● Unrestricted access to water is essential in any cat
the history (polydipsia, weight loss), physical with chronic renal failure to allow thirst to compen-
examination (small kidneys), and diagnostic tests sate for the obligatory polyuria. Additional fluids
(non-regenerative anemia). (oral, subcutaneous or intravenous) may be required
● Due to the gradual decline in glomerular filtration when intake fails to keep pace with diuresis. Home
rate in chronic compared to acute renal failure, administration of subcutaneous fluids are indicated
clinical signs in chronic renal failure tend to be less when the cat is unable to maintain hydration.
dramatic relative to the metabolic derangements. Typically, cats require 75–150 ml SQ q 12–72 h.
Begin a 4–5 kg cat on 150 ml twice weekly, and use
normal saline with 35 mmol (mEq)/L of KCl added.
Treatment
Education of the owner on proper administration
Treatment of chronic renal failure is aimed at: and sterile technique is vital.