Increasing the life-saving capacity of animal shelters and communities through education, shelter outreach, and development of new knowledge

Seeking advice on how to feed an emaciated cat


Authors: Dr. Cynthia Karsten and Dr. Cristie Kamiya
Document Type: FAQs
Topics: Infectious Disease and Behavior and Enrichment
Species: Feline

Three UC Davis veterinary students offer general advice on strategies to help an emaciated, formerly free-roaming cat gain weight safely. First, have a local veterinarian examine the cat...


Summary: I found a stray male cat eating sunflower seeds in my yard and fed him for 3 days.  I trapped him in a live trap this past Friday and took him to the veterinarian.  He is 1-2 years old, only 6.5 lbs, and has a horrible ear infection.  He is FIV and FeLV negative.  I had him neutered, labs were okay, he received an antibiotic injection, was placed on eardrops for 10 days, and was de-wormed twice.  He is very skinny and has hair like straw.  He now lets me pet him at times and I have held him and he purrs.  This fella has stolen my heart.


I am rehabbing this fella in a spare bedroom.  I am feeding 2-3 cans of Fancy Feast with supplemental chicken broth, boiled chicken, some dry.  The veterinarian really did not give me an idea on calories, just said keep feeding what I had before I trapped him to not stress him.  If he will get along with my female cats, I want to try and keep him indoors.  He deserves someone who loves cats.


Any suggestions on caloric intake or food hints?  I have Wellness Core that one cat will eat but the vet said to leave him on what I have for now.  Just want to do the best for this unfortunate guy as he is so skinny.  Also do you have any ideas on how to help him adjust to house life and the other cats?  There are 3 females who think they are each princesses.  I would appreciate some professional advice.


[Please note that some editing has been done for publication purposes.]



Thank you for your questions and for caring for this underweight cat. He sure is a lucky fella. To answer your questions, we have enlisted the assistance of three aspiring shelter veterinarians, top-notch UC Davis veterinary students, Christina, Christina, and Claire. We hope that you find the following information helpful to getting this guy into good health and living cohesively with your resident cats.


First, we will tackle the issue of weight gain. Without meeting your cat in person, it is nearly impossible to make any real recommendations. So, we will make a few assumptions to go through this process of calculating caloric intake. However, you must see your veterinarian to make an accurate assessment of body condition and to determine the ideal target weight of this cat in order to create an effective and safe weight gain plan. It is also a good idea to have your veterinarian rule out any potential medical conditions that can cause a cat to be underweight.


For the sake of calculations, we will make an assumption that a 6.5 pounds skinny average size cat is underweight and that his ideal weight is around 8 to 10 pounds. The estimated caloric intake for an adult cat in good body condition that weighs between 8 to 10 pounds is 180-220 kcal/day to maintain this weight [Resting Energy Requirement (RER) = 30 x Body weight in kilograms + 70].


However, when a cat needs to gain weight, their caloric needs increase to 230-270 kcal/day [RER x 1.3 (weight gain factor)]. This translates into feeding the cat their current daily caloric needs (180-220 kcal/day) divided into 4 meals over the course of the day initially, then gradually increasing the amount fed by approximately 25% each day to reach the caloric needs for weight gain (230-270 kcal/day). If the cat had not been eating previously, up to a 50% reduction in the amount at the beginning of the feeding program may be needed.


We must remember that each individual cat has a different metabolism, and these calculations are only estimates and will likely have to be modified and adjusted as the cat gains (or loses) weight. What we want to avoid is the cat gaining too much weight.


Current weight and weight gain should be monitored at least weekly and we recommend seeing your veterinarian to monitor and modify the weight gain program. We also recommend monitoring the body condition score and activity level to adjust the caloric intake accordingly, once the ideal weight and body condition for the frame of the cat has been achieved. The entire process can take a few months and weight gain should be a slow and steady process. Purina provides a chart for a basic understanding of body condition scoring to help monitor the cat’s condition.


Now, back to our calculation example. The caloric content of one can of Fancy Feast ranges anywhere from 70 to 100 kcal/can. Thus, to achieve a daily caloric intake goal of 180-220 kcal/day, the cat must be fed 2-3 cans per day split over 4 meals. Feeding other foods in addition to the cans of Fancy Feast, for instance, dry kibble, chicken, or treats, will contribute to the total daily caloric content. Therefore, the amount of canned food fed must be decreased accordingly.


Different cats can have different food preferences, and if you choose to transition your cat to a different food, it should be done slowly over the course of at least a week to decrease the chances of GI upset. Once you know the caloric content of both the old and new foods, slowly decrease the amount of the old food by 10-20% as you increase the new food the same amount every day or two as it is tolerated. Also, if your cat is eating the kibble and the wet food well, and does not need to be enticed to eat, we recommend removing the chicken broth. Though it is sometimes helpful to increase the palatability of food, chicken broth does not provide any additional nutritional value and commercial products have a high sodium content.


The calorie content of most pet foods can be found on the label. Wellness Core dry food is very calorie dense at 536 kcal/cup and thus offering ¼ cup per day would allow you to feed 1-2 cans of wet food per day.


For more of the science behind refeeding, see Starvation and Re-Feeding Animals.


Now let us move onto addressing the second part of your question. Introducing your new friend to the household can be challenging and the key is a slow introduction and patience. Be sure to provide an adequate number of litter boxes (the number of cats plus 1), multiple feeding areas and plenty of enrichment for all of the cats. This should help you ensure that every cat has ready access to food, water and a litter box, and that they are able to seek places to hide if needed.


Formulating a specific introduction plan for your cats is beyond the scope of this FAQ, however, there are many useful resources available online that provide detailed explanations on how to effectively introduce new animals. Following are some links to these resources:

It is important to ensure that your resident cats are up to date on their vaccines prior to introduction of a new cat. Additional information on infectious diseases can be discussed with your veterinarian.


Thank you again for your question and a great learning opportunity for our students.




University of Wisconsin Shelter Medicine Program
Koret Shelter Medicine Program

CK2 (aka Drs. Kamiya and Karsten, shelter medicine residents)
Claire Jacobson, Class of 2013
Christina Riffle-Yokoi, Class of 2014
Christina Tam, Class of 2014