Expert: Jessica - 5/10/2010

Question
Hi, I'm fostering four 4 week old kittens and their mother and they have URI. They saw the vet about a week ago and were all given Convenia. The kittens are still very congested and I wondering if this is normal.

Answer
Hi Melissa.  Convenia isn't the ultimate antibiotic for a URI.  It's labeled specifically for oral and skin infections in the U.S.  Vets can use it off-label to treat other infections, but medications like Clavamox and Cefa-Drops are preferred for upper respiratory infections.  I have had numerous writers complain that Convenia has not worked for URI's, and my own experience has been consistent with this as well.  I imagine the vet chose Convenia for a couple of reasons, one being that it doesn't pose the risk for diarrhea that most oral antibiotics do, which can be very dangerous to kittens of this age.  Another is that administering oral antibiotics to four week old kittens may pose a slight choking hazard.  Third is that dosing five cats twice a day is quite a feat, and a one-time injection is much more convenient.  However, since the kittens haven't shown much improvement, I would talk to the vet about prescribing a different antibiotic.

That said, a large component of this infection is probably viral, as well, and no antibiotic will cure that.  Most kittens are infected with both a virus, usually feline herpes, as well as a bacterial infection.  What WILL help with feline herpes is an amino acid called lysine.  This can help battle any viral illness, since it's needed to build antibodies against viruses.  But it's especially helpful against herpes because it makes a different amino acid, arginine, unavailable, and herpes needs this to replicate.  Without arginine, the number of herpes virus in the system dwindles, and the symptoms lessen.  The flare up is soon under control, although the cat will become a herpes carrier for life (as are around 90% of cats).  You can buy lysine supplements made especially for cats online or through most vets.  Search for Viralys or Enisyl-F treats, pastes, powders or gels.  Or, you can buy lysine tablets at your local pharmacy.  The effective dose for kittens under 5 pounds is 250mg (1/4 the average tablet) a day.  For adults, it's 500mg.  Preferably, these would be split into two doses daily.  Even 1/4 of a tablet is too big to give to a cat, so it should be ground up and mixed into canned cat food.  250mg is okay to give even to the little babies, since excess lysine is excreted in the urine, but you could even split that dose in half, and it would be effective for the tiny babies.

Good luck with your foster family!

Jessica