Page 357 - Feline Cardiology

372 Section L: Comorbidities

compounded into liquid form, with meat or fish consultation with the veterinarian or technician. This
flavors that many cats like, is another popular option. approach helps to identify congestive heart failure
Transdermal preparations, on the other hand, have early if it recurs. When it does not recur, the patient is
not proven to be reliable with cardiovascular drugs in an optimal situation: benefiting from being free of
and are not recommended (MacGregor et al. 2005). signs of congestion while also receiving lower dosages
• Identify diuretic resistance. of diuretics and thus, a lower risk of adverse effects.
• Measure urine specific gravity, which should be • For patients with a history of congestive heart failure,
<1.030 in any cat receiving diuretics. If it is ≥1.030, minimize diuretic need through low-sodium diets.
the diuretic effect is likely incomplete or absent. These may be commercially prepared (e.g., Purina
Discussion with the owner about compliance is CV) or home-cooked provided the home cooking
then warranted, and if compliance is good, the pos- follows a recipe formulated by a veterinarian who is
sibility of the tablet not reaching the stomach board certified in gastroenterology or nutrition (e.g.,
should be considered and addressed with having the www.balanceit.com, www.petdiets.com, professional
owner give a morsel of tasty food, or a 5 cc bolus of textbooks (Strombeck 1999; Hand et al. 2000)). Diets
tap water by syringe, after diuretic administration. formulated for chronic kidney disease may be consid-
If this aspect of medication administration is satis- ered because they also are sodium-restricted and, in
factory as well, then diuretic resistance may be contrast to canine renal diets, renal diets for cats are
present, and adding a second diuretic such as hydro- generally not severely protein-restricted (Freeman
chlorothiazide or torsemide (Uechi et al. 2003) may et al. 1997). The protein content of a feline diet should
be beneficial (see Chapters 19 and 29). contain a minimum of 6.5 g/100 kcal (Freeman et al.
• Identify systemic hypertension and treat if present 1997). As a basic principle, sodium-restricted diets
and if attributed only to renal disease (i.e., rule out are only initiated gradually (the owner weans the cat
the “white coat effect” and obtain an accurate diagno- onto the lower sodium diet over several days to weeks)
sis of systemic hypertension, see Chapter 21). and never at the expense of appetite. If the cat refuses
Uncontrolled systemic hypertension may lead to to eat the low-sodium diet, then a different diet should
worsening renal lesions and further concentric left be tried. Some cats find a low-sodium diet to be more
ventricular hypertrophy, which is undesirable, par- palatable if it has been supplemented with a sprinkling
ticularly if the cat’s underlying heart disease is hyper- of potassium chloride (e.g., “No Salt” salt substitute;
trophic cardiomyopathy (see Chapter 21). 100% potassium chloride available in many super-
markets), but other cats dislike this taste.
• With good client comprehension, taper diuretic to • Differentiate between advanced chronic kidney
lowest effective dosage. This delicate balance mimics
Comorbidities the titration that human congestive heart failure disease and an acute-on-chronic process: anemia,
hyperphosphatemia, and small kidneys (exceptions:
patients may undergo in order to achieve optimal drug
polycystic kidney disease, lymphoma cause renomeg-
dosage. A fundamental requirement is an astute owner
who understands that gradually reducing diuretics
carries risks and benefits. A reduction of 10–20% in aly) suggest chronic kidney disease. Their absence
offers the possibility of an acute, potentially revers-
diuretic dosage, no sooner than 2 weeks apart, and to ible superimposition on the chronic process, and
as little as 1 mg/kg furosemide PO q 24h in cats with therefore the potential to regain renal function with
congestive heart failure caused by mild structural treatment of the acute disorder (e.g., pyelonephritis).
heart changes (e.g., moderate atrial enlargement), • Manage anemia (in cats, PCV <20%). With chronic
helps reduce prerenal azotemia and serum electrolyte kidney disease, anemia can arise due to chronic
changes; it also risks the recurrence of congestive illness, erythropoietin deficiency, uremic gastrointes-
heart failure. Thus, this measure can be considered tinal blood loss, or a combination of these factors.
when the cat is stable, comfortable, has a normal Correction of anemia when concurrent heart disease
resting respiratory rate and effort, and appears overtly is present results in a lower risk of cardiac arrhyth-
normal at home in the owner’s opinion. It is preferably mias and improved tissue delivery of oxygen.
done in conjunction with transition to a low-sodium • Removal of large-volume, recurrent body cavity effu-
diet so that the reduced sodium intake requires a lesser sions in chronic states: periodic centesis/drainage may
quantity of sodium needed to be excreted through be superior to higher-dose diuretics for both efficacy
diuretic-induced natriuresis. During the tapering and lesser degree of adverse effect. The limitation of
process, the owner can record daily or twice daily frequency is dictated by client means (ability to return
resting respiratory rate (should be <30/minute) and to the hospital, financial cost) and the cat’s tolerance
respiratory effort, which can be reviewed by phone of the procedure. In some cats this approach provides