DEAR DR. MILLER:

We've had a terrible time with our dog. She's had this very stubborn bladder infection. All kinds of antibiotics and medicines have been tried, but none of them worked very well. What antibiotic is really the best for a bladder infection? --H.G.

On some occasions, infections in the urinary bladder respond well to the comparatively ancient sulfur drugs. In other cases, even the usually effective gentiamicin doesn't do the job.

There are many reasons for a poor response when treating urinary infections, and the choice of appropriate drugs depends on many factors, too. For example, some antibiotics, gentamicin in particular, can be damaging to the kidneys. Your own veterinarian (possibly in consulation with a colleague when the case is particularly difficult) is the logical one to lean on for the most appropriate treatment and eventually cure.

DEAR DR. MILLER:

When we came back from our vacation, Henry Hoser, my snake, was dead. Could he have died from a broken heart? I think he might have been too lonesome because before that trip we were always very close. I know he didn't starve to death because he had a big meal the day before we left. --A.N.

Henry Hoser's heart would hardly have broken under the circumstances, even though snakes do occasionally have heart problems including enlargements and congestive heart failure.

While there's no way to know how lonesome your coldblooded comrade actually was, it's unlikely that grief was a major factor in his demise.

DEAR DR. MILLER: We're planning on getting another cokatiel to mate with Cocky, and we're going to build an outside aviary for them. how big does it have to be? Should we build them a nest, or would they rather do it themselves? --F.R.

The minimum size for your outside aviary should be four feeet wide and twelve feet long. Most psittacine pairs would prefer a ready-built nesting box to a do-it-yourself project.