By Dr. Jody Kaufman
High blood pressure can be a problem for humans as they age. The same is true for dogs and cats. High blood pressure (hypertension) can result from problems in other systems. Kidney disease is one example.
When kidney function is impaired, fewer metabolic waste products are excreted. Their build-up becomes toxic and leads to the signs of kidney failure. The body, in its wisdom, has mechanisms to increase blood pressure so that more fluids and waste products are pushed through the kidney. That would be great except that it’s structurally damaging to the kidneys. This feedback loop also occurs in other systems, where compensatory mechanisms backfire and cause further damage. In essence, kidney problems can lead to high blood pressure, but high blood pressure can damage the kidneys.
What can we do to help? The combination of blood pressure medicines and special diets can be beneficial in stabilizing blood pressure as well as kidney function.
Certain heart conditions can also cause elevated blood pressure. Hyperthyroidism occurs fairly commonly in middle-aged and older cats. These patients have a “hyperdynamic” metabolism, so that the typical hyperthyroid cat will have lost weight, have a racing heart, and a heart murmur in many cases. They can also have hypertension, which usually resolves once the thyroid is under control.
One of the dangers of hypertension is retinal detachment. We see it most commonly in elderly cats, many of whom have a combination of thyroid and kidney disease. They present with very dilated pupils and a sudden onset of partial or complete blindness. Vision can be restored in some cases if the problem is caught early.
The majority of patients with high blood pressure show no outward signs, and significant damage can occur if it isn’t brought under control. Therefore we are recommending a simple blood pressure screening for our patients once they are middle aged or older. This can easily be done during an annual exam.