Now the reason I have asked all the questions that I have is because anorexia in the cat is most often triggered by underlying nausea or oral discomfort. Now at Silver's age, we'd not be overly worried about severe dental disease, organ/metabolic issues, or tumors of the mouth or anywhere else for that matter. Instead, our most common issues will be things like oral pain from trauma (if she has injured her mouth with something she ate), but mostly nausea from issues like bacterial or viral gastroenteritis, pancreatitis, dietary indiscretion, or ingestion of something non-edible or harmful.
With all this in mind, if it has been 3 days we do need to tread with care here. This is because we do start getting worried about them after a few days of anorexia. This is because of the risk of dehydration, loss of nutrition (which will make her feel weak), and because cats were not well designed for the anorexic lifestyle. When they are off their food, body fat is broken down and released into the bloodstream, causing their liver distress (ie. hepatic lipidosis) that can make getting them better even more difficult for us.
Now if she is turning away from food, then it her signs could include nausea despite not showing any vomiting (often nauseous cats go off their food rather then eat/vomit like a dog would). That said, this can be GI based but it can also be associated with systemic diseases that have an associated nausea.
To rule out nausea as an anorexia differential, you can try her on antacid therapy. There are a number of antacids that are available over the counter and pet friendly. I would advise only treating with one, but the two I tend to recommend are Pepcid (MoreInfo/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) or Tagamet (More Info/Dose Here @http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet). This medication of course shouldn’t be given without consulting your vet if she does have any pre-existing conditions or is on any other medications. Ideally, it should be given about 30 minutes before food to easy her upset stomach.
As well, you will want to try and see if you can get her eating (as I am sure you have been). Favourite foods are allowed or you can tempt her with alight/easily digestible diet. Examples of this would be boiled chicken,scrambled eggs (made with water and not milk), meat baby food (do avoid the ones with garlic powder in the ingredients) or there are also veterinary prescription diets that can be used here (ie Hill’s I/D or Royal Canin’s sensitivity.)
Further to this, if she has been off her food this long and if tempting doesn’t work, then we do have to consider initiating syringe feeds to get food into her. In that case, you may want to try Hill's A/D from your local vet. This is a critical care diet that is comes as a soft, palatable pate. It is calorically dense, so a little goes a long way nutrition-wise and this could just help get some more calories into her even if we can’t get a huge volume of food in. As well, for syringing food, you can use the animal version of Ensure (balanced for animals dietary requirements) called ClinicareCanine/Feline Liquid Diet. It is actually by the same people who make Ensure,but is formulated to meet out pet's dietary needs. Your vet should be able to order it for you but it is available without a prescription. Or even in a pinch, you can try watering down wet kitten food to syringe. In all cases, these will get food in her stave off hepatic lipidosis, and buy you time to uncover the reason for her anorexia and lethargy.
On top off all of this, you do need to keep an eye on her water intake and hydration. To test hydration, there are a few things we can test at home. One is whether the eyes appear sunken, if the gums are tacky instead of wet/moist, and whether the she has a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a wee video on this HERE.( http://www.ehow.com/video_12232503_dog-dehydrated.html) They use a big dog but it makes it easier to see and the principles are exactly the same. If you are seeing any signs of dehydration already, then you do want to have your kitty seen by her vet before this gets out of control for her.
In regards ***** ***** you can do to help stave off dehydration at home (though do note that if she is already then she will likely need more the oral rehydration), encourage her to drink but offering fresh water or even low-sodium chicken broth. As well, wet foods (as mentioned above) are 35%water, so getting her to eat will help us deal with water intake as well. Ifshe isn't amenable to drinking, you may wish to offer unflavored pedialyte via syringe feeding. While we cannot do this if they are vomiting, it may be an option for this situation. A typical maintenance rate for hydration in an animal 48mls per kilogram of her body weight a day. If you do give syringe pedialyte, this should obviously be divided up into multiple offerings through the day rather then all at once. This value will give you the total she needs for the day and is a good starting point to give you an idea of her daily requirement. If she does vomits if you give pedialyte, I would discontinue this as a therapy. (since we don’t want her vomiting because of our intervention).
Overall,when a cat is anorexic and lethargic, it can mean a wide range of underlying issues. Therefore, with this in mind and how long she has been like this already, we do need to be very careful with Silver. So, do try the above with her now. Though if you do not see improvement in 12-24hours or she worsens (vomits, etc), then you do want to get your vet involved at that stage. They can assess her hydration, check her signs of any sinister lumps/bumps or internal issues. They can also cover her with antibiotics, anti-nausea/vomiting medication by injection and even appetite stimulating drugs if necessary. Depending on the findings, the vet will be able pinpoint the trigger for this and treat to get her back on track before she develops further issues due to her anorexia.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,