The first thing to address with allergic diseases is diet. The theory is: the fewer allergens the cat is exposed to overall, the less reactive the immune system will be. So I recommend a homemade or limited/novel antigen ("hypoallergenic") canned diet. Chicken beef, fish, wheat, corn and dairy are the top allergy triggers in pets. That might seem to leave very few foods, and that's true. However, in the US at least, Petguard, Merrick, Innova/EVO, and Nature's Variety Prairie all make venison, lamb, turkey, or rabbit varieties of canned food. Here's an article about food allergies; the principles are just the same with any allergic disease.
You'll all get sick of hearing me say it this week, but dry food is absolutely out. The problem is that dry food is heat processed, which distorts (denatures) the proteins. These weird proteins are prime targets for a nasty immune response; and voila! you have an allergy. Dry food also contains many more flavorings, texturizers, and preservatives than canned. I have long been an advocate for decreasing or eliminating dry food, but then I read this cool paper about a cat with inflammatory bowel disease that was put on a hypoallergenic diet, didn't respond, then cleared up immediately and completely when she was put on the canned version of the same
diet. Whoa! So I'm becoming ever more adamant about it.
Antioxidants and Omega-3 fatty acids are both anti-inflammatory and are used in humans with allergies with great benefits.
Other modalities, like flower essences, EFT, homeopathy, acupuncture, herbs, and NAET can be very helpful. NAET in particular (www.vetNAET.com
) works spectacularly well for allergies.
A runny nose is not a typical symptom of allergy in cats. They do not get "hay fever" like we do. Instead, inhalant allergies (to things like pollen and dust in the air) cause skin symptoms; itching, rashes, and crusty areas, particularly around the face, ears, and feet. (This goes for dogs, too.) In most cases, upper respiratory symptoms are due to upper respiratory viruses like herpes, which is a chronic condition that often comes and goes.
Now, all that being said, in a 16-year old cat, the benefits of steroids may well outweigh the potential side effects, most of which take a long time to develop. Always, the cat's comfort is the main consideration. It depends on how severe her symptoms are. Usually I would prefer oral prednisolone (that's predniSOLONE, not prednisone) to depo-medrol, which can cause diabetes. However, with asthma, depo often works better.
So you'll have to weigh the benefits and risks. Natural treatments can often lower the dose needed to control symptoms, so even if she can't get off the steroids, perhaps we can help her be more comfortable with less.