Owners can administer subcutaneous fluids as the disease progresses. Fluids may be infused with a conventional intravenous
(IV) administration set and needle or through the new subcutaneous fluid catheter (Endo-Sof subcutaneous catheter— Global
Veterinary Products). The catheter is surgically implanted near the dorsal midline. A fitting that accepts a standard IV line
is sutured to the skin (Figure 1). I recommend this catheter when owners or cats are needle averse. They're not tolerated by all cats, but can be extremely
helpful, even life-saving, for others. A phosphate binder (PhosLo, 1/4 tablet or 167 mg b.i.d.), appetite stimulant (cyproheptadine,
2 mg b.i.d.), hypotensive agent (amlodipine, 0.6 to 1.0 mg once a day), and erythropoietin (100 U/kg one to three times per
week) are prescribed on an as needed basis.
Diagnosing and treating hypertension
When assessing cats with chronic renal disease, it's also important to monitor them for systemic hypertension. This disease
is often associated with renal failure; however, it's not limited to this stage of renal disease. Retinal detachment, hyphema,
cardiovascular accidents, and seizures may occur secondary to hypertension in cats with renal insufficiency.
Two major types of equipment are available for measuring blood pressure in cats. Inexpensive, dependable Doppler units detect
systolic blood pressure and are widely used because they are simple to operate (Figure 2) (Vet-Dop—Vmed Technology;Model 811-B—Parks Medical). Oscillometric units are more expensive, but they determine systolic,
diastolic, and mean blood pressure (Memoprint—S+B medVET; Cardell BP Monitors, Sharn Veterinary Inc.).Although some clinicians
prefer to know all three values, the systolic measurement is adequate for determining hypertension in cats (and dogs).
Hypertensive cats should be treated with a hypotensive agent. ACE inhibitors may be used, but their hypotensive effect is
not as efficient as the calcium channel blocker amlodipine (0.6 to 1.0 mg once a day). Administer the drug for two days,
then reassess the patient's blood pressure. The desired systolic range is 130 to 150 mm Hg. Adjust the dosage according to
the response. More than 90% of the time, systemic hypertension is secondary to either hyperthyroidism or chronic renal disease.
Hypertensive patients should be tested for these diseases and treated appropriately.
Diagnosing and treating heart disease
As a veterinary school graduate in 1972, I was taught that heart disease was rare in cats. However, that was only because
we didn't have the tools to detect it. A screening lead II electrocardiogram (ECG) is now part of my annual feline exam, as
detailed in the article, "Healthier patients are an annual visit away,"
Initially, I used ECGs as public relations tools. By performing the ECG in front of clients and providing them with a portion
of the tracing, I tried to demonstrate the important role of annual exams in detecting health problems. In addition, I wanted
to show them how thorough I was in my examinations. After performing screening ECGs for a few months, I began to find heart
abnormalities in cats more frequently than I anticipated. I find an ECG abnormality or an audible murmur on auscultation in
about 1 out of 25 seemingly healthy cats. This forced me to better understand ECG interpretation—a skill that eluded me while
I was in veterinary school. It also increased my appreciation of the value and limitations of ECGs. I don't expect to make
a specific diagnosis from the ECG. Instead, I use it as a tool to identify cats with heart disease. I use the stethoscope
in the same manner.
When I diagnose a cardiac abnormality with either auscultation or an ECG tracing, I inform the owner that heart disease is
present and recommend thoracic radiographs and an echocardiogram. Radiographs allow me to assess the cardiac silhouette, lung
fields, tracheal position, the pleural space, and the major vessels. However, they're not sensitive enough to diagnose early
heart disease or specific heart diseases. Therefore, an echocardiogram is essential to make a conclusive diagnosis and determine
effective treatment (Figures 3a, 3b, & 4).
Figure 3a & 3b. Lateral and dorsoventral thoracic radiographs of a 2-year old cat with a history of syncope. The cardiac silhouette
is with in normal limits.