|Many cats are living longer lives, and unfortunately, are acquiring diseases that were not commonly seen in the recent past. Hypertension (high blood pressure) is one of these diseases. The increase in blood pressure affects many organs, particularly the liver, eyes, kidneys, and heart. Hypertension hastens the progress of these diseases and substantially predisposes your cat to blindness.We have only recently been measuring blood pressures in dogs and cats, so our database is not as complete as in humanoids. We are at the beginning stages of understanding if an elevated blood pressure is the result of a disease, a cause of a disease, or has no bearing on a disease.
High blood pressure can be primary, where the cause is unknown. In most animals though, it is secondary to some other disease.
We have a short Quicktime video on the use of our doppler blood pressure monitor. It will take a few minutes to download-you need Quicktime from www.apple.com to view it.
The are two main factors that determine blood pressure.
Abnormally high blood pressure causes blood vessel damage, particularly in the eye, kidney, heart and brain. These damaged blood vessels will bleed, cause clots, fluid buildup, and tissue death. The mechanism for this is complex.
Hypertension also places excessive strain on the cardiac (heart) muscle. The heart has to pump against more pressure (vascular resistance), causing further deterioration. As it progresses the heart enlarges and a murmur might be heard with the stethoscope.
There are no specific set of symptoms of high blood pressure. That’s why its called the silent killer in people. What might appear are the symptoms of the disease that is causing the high blood pressure in the first place.
The primary symptom in cats some owners notice is a sudden onset of blindness, as evidenced by dilated pupils and bumping into objects. Cats that were apparently fine just a day or two earlier are now completely blind. Prior to the onset of blindness an owner might notice other symptoms. These might include weight loss, excess drinking and urinating, vomiting, change in appetite (up or down) and fast heart rate. Monitoring some of these parameters ahead of time is possible to look for subtle signs of diseases. This is explained in our In Home Exam section and our Wellness section.
Feline hypertension is almost always secondary to other problems, namely hyperthyroidism and kidney failure. The majority of cats with these two diseases will eventually develop hypertension. Any cat that has been diagnosed with one or both of these diseases should be monitored for hypertension every 3-6 months.
As in people, hypertension is a silent disease. You don’t feel ill, and there are no obvious symptoms until it is too late. Fortunately, we have sophisticated medical equipment that will help us make this diagnosis.
Low blood pressure can be of significance in animals. Usually this is encountered during anesthesia. Our Doppler unit allows us to monitor the blood pressure during anesthesia and make corrections as needed. We also encounter low blood pressure during shock, trauma, bleeding, and from certain medications.
Underlying treatment of the disease that is causing the hypertension is sometimes all that is needed to prevent hypertension. Use of K/D food, with its decreased salt (sodium chloride) might be beneficial, but this is unproven. If hypertension still persists after treating the primary problem then we sometimes will use specific medication to lower the blood pressure:
Blind cats need to be placed on a drug called Norvasc to rapidly lower the blood pressure. There is a chance of regaining sight with the use of this drug, especially if utilized as soon as blindness is noted. Cats that are on this drug should have their kidney tests monitored 2 weeks after starting Norvasc, then every 3 months.
The best treatment for hypertension and its associated blindness is prevention. Any cat over 8 years of age, or diagnosed with kidney disease, diabetes mellitus or hyperthyroidism, should be monitored periodically for hypertension. This will allow diagnosis of the problem before it causes blindness.
All pets with hypertension should have their blood pressure checked every 3 months. In addition, blood panels, thyroid tests, urinalysis, and eye exams should be performed every 3-6 months.