Ask Dr. Richards: 02/04

Question: About two weeks ago our 17-year-old cat, Goldie, went blind (at least thats when we first noticed her bumping into things). Our veterinarian said Goldie has detached retinas, which may have resulted from very high blood pressure, which, in turn, may have been an effect of her kidney disease. (Goldie has had chronic kidney failure for several years, but shes been doing OK.) She prescribed an anti-hypertension medication to lower the blood pressure, and suggested that if the blood pressure comes down, then theres a chance the retinas will come back in place and give Goldie some vision again – although maybe not a full recovery. Can detached retinas come from renal-related high blood pressure? And do you think Goldies vision might return?

Answer: Yes, renal disease can indeed cause high blood pressure – hypertension – which can cause retinal detachment.  Complete detachment of the retinas in both eyes is usually the case with sudden-onset of blindness, and if so, the likelihood of permanent blindness is quite high. The best chance for vision return will be to lower the blood pressure as soon as possible so the retinas have a chance to reattach. Even then, though, recovery of vision is doubtful.  

Nonetheless, administering antihypertensive medication is definitely in order because high blood pressure negatively impacts other organs as well, including the kidneys, brain and heart. Your veterinarian will decide which medication or combination of medications to try, and there will likely be some trial-and-error involved before the right therapy can be found for your cat. Perhaps shell suggest feeding a reduced sodium diet too, but this alone rarely helps, and many cats dont like to eat them.

Hypertension in cats is usually secondary to disease elsewhere in the body: Kidney disease is arguably the leading cause, but other conditions, including hyperthyroidism and diabetes mellitus, can cause it as well. Primary, or essential, hypertension – the most common form of high blood pressure in people – appears to be rare in cats, at least at this moment in time.

Unfortunately, hypertension is under diagnosed. Many veterinarians dont routinely measure blood pressure in cats because its not the easiest thing to do. Cats are notoriously excitable in veterinary clinics, and it takes a lot of practice, time, patience and the right equipment to measure cats blood pressures accurately. But I believe that any cat with a condition commonly associated with hypertension (namely kidney disease and hyperthyroidism) should have its blood pressure routinely measured. Some veterinarians deem it prudent to perform routine measurements in all cats over 10 years of age or so, even in the absence of these conditions, to make sure they dont miss the rare case of primary hypertension. 


Question: My cat is infected with feline leukemia virus and hes due for his vaccines. I think the vaccines are for panleukopenia, feline herpesvirus, feline calicivirus (the three-way shot) and rabies. My friend said she heard somewhere that cats infected with feline leukemia virus shouldnt be vaccinated. Is this true? 

Answer: I suggest vaccinating cats infected with feline leukemia virus (FeLV) or feline immunodefiency virus (FIV) just as one would if they werent infected, assuming theyre healthy, of course; sick cats should never be vaccinated. But unless his FeLV infection is so advanced that hes sick as a result, your cat should respond to the vaccines you listed as well as would any other cat. Theres no need to give him an FeLV vaccine, though; I would expect it to be as safe to use as in any other cat, but it would certainly do him no good.

But what kinds of vaccines should be used?  Is it better to use modified-live virus vaccines, or would killed-virus vaccines be better choices in cats infected with FeLV – or feline immunodeficiency virus?  Frankly the jury is still out. Unlike killed-virus vaccines, the organisms in modified-live virus vaccines reproduce when administered. In other words, they actually cause a mild infection, but the organisms have been modified in such a way that their disease-causing potential is greatly reduced. Even though modified-live vaccines have an excellent safety track record, some veterinarians fear they could potentially cause the disease theyre designed to prevent if given to a cat with an impaired immune system, a condition that may afflict cats in later stages of FeLV or FIV infection.  Im unaware that this has ever happened in the real world, but it is theoretically possible. I lean toward giving exclusively killed vaccines to FeLV- or FIV-infected cats, but if pressed, I dont really have a strong preference.