In the exam room Mr. Johnson held his cat Jinx in his arms as he explained why he thought Jinx might have gone suddenly blind. The morning had begun like every other day, with Jinx underfoot looking for breakfast. A few hours later, Mr. Johnson heard Jinx meowing urgently and noticed him moving timidly and walking into things. Mr. Johnson felt sure that Jinx couldn’t see and called our hospital right away.
I had Mr. Johnson set his cat on the exam room floor and noticed that Jinx seemed a little uncertain with his steps and was bumping into furniture. I tried to determine if Jinx would react to visual stimuli by dropping a cotton ball in front of him and by moving my finger quickly toward his face, but he seemed oblivious. As I looked into his eyes through his widely dilated pupils, the cause of his problem became obvious: Both retinas had detached from the deeper layers of the eye and billowed forward. The rest of Jinx’s exam was normal.
Of the causes of sudden retinal detachment, when it happens in both eyes, high blood pressure is the most common cause. This was where I wanted to start looking. A normal cat’s blood pressure should be less than 180; Jinx’s was 310. This supported my initial concern – Jinx’s blindness was likely a complication of high blood pressure.
In cats as in people, high blood pressure, or hypertension, often can’t be linked to a specific cause, and treatment is simply directed at lowering the blood pressure. Sometimes, however, hypertension is secondary to another disease process, most often kidney or thyroid disease. Since treatment of the hypertension must be directed at the underlying cause of high blood pressure, it’s important to look for causes of this condition. In Jinx’s case, this meant additional testing, including blood and urine analyses.
Hypertension can lead to many serious complications such as kidney damage, heart problems, stroke and, as in Jinx’s case, retinal damage. Unfortunately, many cats with hypertension don’t exhibit specific symptoms, and it isn’t until these complications occur that the disease is diagnosed. But even at this stage, treatment can help. Given the additional problems that continued hypertension can cause, I started Jinx on medicine to lower his blood pressure right away, even though his final test results wouldn’t be back until tomorrow.
The following day the lab results came in and were normal. There was no underlying thyroid or kidney disease, so I directed Jinx’s treatment at lowering the blood pressure. I had Jinx start on medication to control his blood pressure and discussed a diet change to a lower-salt food. We would monitor his pressure, and make changes in the medication if needed.
A week later, Jinx’s blood pressure had dropped to 160. Even so, I couldn’t guarantee the return of his eyesight; only time would tell if the damage was permanent. In Jinx’s case a short time later we knew that Jinx was a lucky cat – his vision had returned in both eyes, and the continuing medication was keeping his blood pressure under control very nicely.
Dr. Deirdre Brandes is a veterinarian at the Rancho Santa Fe Veterinary Hospital. She can be reached at www.rsfvets.com, or 858-759-8797. The cases described in Veterinary Vitals are true stories, but the author has changed details about the patients to protect their privacy.