Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
Now for Remi to develop these signs within a few days of being rehomed, I share your concern that she may have an upper respiratory tract infection (aka cat flu). If dry air were to blame, we'd have expected this to appear sooner for her. That said, we do also have to consider that both allergies or an irritative item (ie grass, seed, etc) getting stuck in her nose could also cause the signs she is showing. Of course though, the development of clinical signs of cat flu within 3-10 days post adoption is just something we very commonly see appear in young cats within days of adoption due to the stress of so much life change dampening the immune system and allowing the causative agent to gain a foot hold. And therefore, there would be a risk to your other cat potentially catching this from her.
With this all in mind and since she has no discharges, we'd wan to use supportive care at this stage.Of course, if she did develop discharges that were snotty (yellow, green, etc), then that would be a sign that bacterial agents are starting to creep in and antibiotics would be indicated.
Now in regards ***** ***** care, your use of the humidifier is good. We will often use steam treatment not just to moisten airways but to also help combat congestion within the nose. So, you can keep using this for her. Though when doing so, consider making her a "steam tent" with her in her carrier, the humidifier near by and a bed sheet over both. That way you can concentrate the steam for more effect.
Further to this, if she is building up mucus in her airway that the steam isn't shifting, you can use a cotton ball moistened with warm water to wipe away crust and mucus. As well, do consider also using saline nasal drops (like Ocean Mist or Little Noses but not anything medicated) to help gently open her nasal passages. To do so, tilt the head back and drop two to three drops in one nostril. Cats hate this, but it helps. After the drops go down, you can let the head up and wipe away any discharge that gets loosened. Then repeat with the other nostril.
Furthermore, it is important to monitor her eating/drinking at this stage; since congested cats who can’t smell their food
often won’t eat or drink. Therefore, if she has any lapse in her normal of appetite, then do tempt her with smelly wet foods (since they are high in water). It may help to warm it up a bit in the microwave to help her be able to smell it.
Just to to rule out allergies as a trigger for her signs, though less common a reason for kitties this young, we can consider starting her on an antihistamine like Benadryl/Diphenhydramine (More Info/Dose: http://www.petplace.com/article/drug-library/library/over-the-counter/diphenhydramine-benadryl). We tend to give this at a dose of 0.25-0.5 mg per pound every 12 hours. When dosing, we tend to aim for the lower end of the dose since this medication can cause drowsiness (just as in people). Though of course, we'd want to check with her vet first if she has any pre-existing issues or is on any medication already.
Finally, since she is from the pound and feline herpes virus is one of our top suspects, I would note that we can also put her on L-lysine. This is an OTC nutritional supplement that can be helpful if feline herpes is the cause for her signs. It is available at vets, pet stores, and even health food stores. It comes in gel, powder, and crushable tablet form and these can be mixed with food. Typically, we will give 500mg daily.
Overall, your lass's signs are suggestive of a viral upper respiratory tract infection being present here. Therefore, at this stage, we'd want to use the above supportive care for her to help her overcome this. At the same time, we will want to monitor your other kitty, since it is possible that this will affect them too. As long as can settle this for her/them, we are happy. But if the discharge turns snotty or isn't settling; then those would be cues that we'd want her to be checked by her vet again to rule out any other potential though less common causes for her signs and potentially have antibiotics dispensed to help address this for her.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best, *****
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