Chai wrote:oh sure p-dog...find out about new jersey, but don't worry about my poor feral cat with the URI.
Had nothing to add to CowDoc's cautions. I can tell you that we know that some cats who get FURDC (feline upper respiratory tract disease, nomenclature borrowed from the bovine folks, who see a similar syndrome) have troubles with chronic rhinitis (inflammation of the nasal passages) down the road, and there's nothing to be done about it. Could be involvement at the first infection of Bordatella bronchiseptica, the pimary recognized agent of kennel cough in dogs and a close relative of a bug that causes atrophy of the bones of the nasal sinus in pigs. Also, as CowDoc noted, infection with feline herpesvirus can lead to reappearance of clinical signs during stressful times (just like lip sores in people with herpes) and there's not a whole lot you can do about it. Some folks think that using L-lysine in the face of a herpes outbreak can help reduce shedding of virus and may help with clinical signs, but there's no solid evidence to support it.
I do worry about indiscriminate use of antibiotics vis-a-vis the veterinary community's putative role in induction of antibiotic resistance, but I've never heard of erythromycin specifically inducing resistance. (By the way, erythromycin is notorious for causing GI upset and diarrhea in pretty much everything but cows.) (Also, by the way, metronidazole can rarely cause central nervous system toxicity, so look out for your feral cat looking neurologic.
See? Nothing to add, just pessimism. And maybe L-lysine, which you can get at a supplement store. 250-500 mg -- probably the low end of that range, given his size, but it's a very safe supp and he should be all right with it. Not sure how it tastes, they gave up on the stuff at the shelter before I started working with the URI cats there.