How long an allergic reaction will last?

In the midst of an allergic reaction - how long will it last?

• I unknowingly fed my cat something (a canned seafood recipe wet food) that she is allergic to. This came after my vet gave me the OK to try it out. Her nose is extremely itchy and swollen. She seems to have a bit of a sore on it. I only fed her about 1/3 of the can (it was Wellness CORE). That was around 1 PM on Wednesday. It is now 9 AM on Friday here. I have no experience with a reaction like this, as her last allergic reaction was in 2005, and was the result of a long DIET filled with things she couldn't eat, resulting in a very bad attack with a long duration (and lots of vet visits) rather than one isolated thing. Right now I have her in the cone collar, and I'm taking it off throughout the day so she can eat, be comfortable, go to the litter box, etc. She has pretty good mobility with it, but I really, really don't want this to be an extended thing. My vet said just to watch her and call them up if she worsens. Is there anything I can do? Any idea how long I can expect this to last?

• Answer:

  Encourage her to drink. Put ice cubes in the water dish - tends to fascinate cats. If the vet won't give you something to stop the reaction, then I don't think there is much you can do except wait. If you haven't had it done yet, I would suggest that you have allergy testing done on her to find out what she is allergic to. I believe that they pull a blood sample to use for the test. It is pricey, but it would prevent future problems, which as she ages could get worse. I do applaude you for trying to feed her high quality food however.