Pets, like people, don't magically maintain an optimum body weight.
Calculating calories in is a no problem as there are many charts available, both in print and on the internet, to help with conversions. Any reasonable comercial pet food should list the caloric value per kg, or gm, of food on the product information label.
Calories out is more difficult to calculate as it varies with the life stage, activity and health of your pet. Fortunately there are some formulas that help to give us guidelines to follow.
The Resting Energy Requirement (RER) in Kcal/day is the starting point
RER = 30x(wt in kg) + 70 or RER= 30x(wt in lbs/2.205) + 70 as wt in lbs/2.205 = wt in kg
EXAMPLE: RER for a 10kg dog 30x10+70=370 or 30(22.05/2.205)+70=370 Kcal/day
However this calculation does not account for age, activity, or health. To estimate for these factors standard multipliers are used for various scenarios as follows:
Multipliers for age, activity, and health:
Weight loss 0.8-1.0 x RER
Neutered adult normal activity 1.6 x RER
Intact adult normal activity 1.8 x RER
Light work 2.0 x RER
Moderate work 3.0 x RER
Heavy work 4-8 x RER
Pregnant (first 42 days) 1.8 x RER
Pregnant (last 21 days) 3.0 x RER
Lactating female 4-8 x RER
Juvenile - weaning to 4 months 3.0 x RER
Juvenile - 4 months to adult size 2.0 x RER
So if our 10kg dog is a neutered adult with normal casual activity RERx1.6=592 (the total kcal requirement/day). It is very important to remember that this is the TOTAL kcal requirement including all snacks, treats and scrounging! If you feed your pet snacks and treats the Kcal/treat or snack must be factored in.
Now that we know how many Kcal to feed, how much is that in pet food quantity?
To know this one must know the number of Kcal/cup or can of food. This value should be on the bag or can of food. If it is not you may want to consider another choice! If you home cook for your pet you will have to break down your recipe into ingredients and from that calculate the Kcal/recipe batch. The number of cups per batch, and from that, the Kcal/cup.
Once you know this value, calculating how much to feed your pet is straight forward. One divides the number of Kcal/day by the Kcal/cup of food.
So, for example, if the food has 425 kcal/cup, the math would look like this:
Kcal/day divided by kcal/cup = 592Kcal/425Kcal/cup= ~1.4 cups /day or 0.7 cups/meal
**One must remember that these are simply guidelines ... a starting point if you will. It is very important to weigh your pet regularly and if they are gaining, or losing, too much weight then the amount of food and/or activity should be adjusted accordingly. If you have adjusted your pet's food intake and/or exercise and they are continuing to increase or decrease weight a veterinarian should be consulted as many medical conditions can influence metabolism (weight gain or loss).**
Other questions you may ask:
- How long will a bag last?
- How much does it cost to feed my pet each day?
To calculate how a long a bag will last one divides the number of cups/bag by the number of cups fed each day. If the bag contains 50 cups and you feed 1.4 cups/day the bag will last 50/1.4=35.7 days.
Some bags do not list the number of cups within. If not, for many pet foods the gm per cup is listed or readily available online. If that is the case the weight of the bag in kg or gm per cup will give the number of cups/bag. So if a food was 110gm/cup and the bag weighed 2kg there will be (2x1000)/110=10.1 cups in the bag.
How much will it cost to feed my pet per day?
One divides the price of the bag by the number of days it will last.
Thus, if you know the Kcal/bag, cups/bag, price/cup and cups/day you can calculate what it costs to feed your pet for a day!
1. kcal/kg x kg/bag = kcal/bag 3570x13.6 = 48552kcal/bag
2. kcal/bag divided by kcal/cup = cups/bag 48552/407 = 119.29c/bag
3. cups/bag divided by price/bag = price/cup 119.29/49.49 = 2.41/cup
4. cups/day x price/cup = price/day 2.41x2.41 = $5.78/day
You may then ask .... is my pet a healthy weight?
For that one turns to body score indexes. Using a score of 1-5, it is optimal to have pets in the mid score range.
Viewing a body score index will help you determine if your pet would benefit from losing or gaining weight.
Once this goal is established one feeds for the desired weight, not the current weight.
Body Score Condition Index 1-5
1 = Emaciated
2 = Thin
3 = Moderate
Ribs palpable without excess fat covering. Abdomen tucked up when viewed from side.
4 = Stout
General fleshy appearance. Ribs palpable with difficulty. Noticeable fat deposits over lumbar spine and tail base. Abdominal tuck may be absent. Waist is no longer evident.
5 = Obese
At WBVC we take diet and nutrition seriously. As with people, pets are what they eat. One pet food is not suitable for all pets and not all pet foods are created equal. Even when ingredients are compared, similar diets may be far from equal in their make up. Not all ingredients are sourced similarly, and not all pet foods have solid clinical research behind them! "Holistic", "all natural", and "high quality" are marketing terms that do not speak to the nutritional value of the food for your pet.
Veterinary Prescription Diets are available only from your veterinarian. These diets are thoroughly researched and contain ingredients that are carefully sourced. Manufacturers of these health products fully understand that veterinarians can make educated decisions about the use of their diets and, as such, these diets can be appropriately prescribed to optimize health benefits for each individual pet.
At WBVC, the veterinarians have created a spread sheet for Veterinary Prescription Diets that aids them in making the best nutritional choices for your pet and lets you know how much a product costs per package, how many Kcal your pet requires per day, how much to feed your pet each day, and how much that will cost you on a daily basis. This can help bring you peace of mind and can save you lots of tedious calculations!
For a Wellness Examination & Consult including dietary recommendations please book an appointment by calling WBVC at 604-266-7421.