How to tell if a rat is underweight
Weight is not everything. Some minor weight loss/gain is normal, and keeping track of the weight of small animals is ideal, but it is vital that we also consider body condition just as much. Here is a video as to what I am speaking of.
While it is normal for rats to gain a bit during the growth stages, and lose a very small amount of weight/mass as they age, it is vital we know the signs of serious underweight, and when we need to step in and assist them in weight gain. If they drop too much, their immune system can be easily compromised. They are at risk when they are underweight, as they are not in ideal physical health. Of course vet examination is important unless there’s clear genetic issues at play, as underlying conditions can go unnoticed. See a vet when you notice unknown weight loss.
You may notice weight loss when you record their weights, but the largest indicator is body condition. You might feel their bones, see the definition of their spines. A rat should be a ‘tube’ shape, the same thickness down their whole torso. They should not widen at the middle, or sink inward. *This can be hard to explain in writing, please refer to the video above for a more in depth explanation as well as visuals.
Here is a photo example of what I mean by ‘tube shape’.
Weighing your rats
Wether they’re sick or young, youthful or old, weight should be monitored. It is advised one does a weigh in once a month at minimum, this is vital for small animals like rats. Fluctuation in weight can be a sign of a health issue. A food scale can be extremely useful, I bought one for less than $20 from Walmart.
The best way to weigh rats is to place a carrier or box on top of the scale first. ‘Zero it out’, in which you would have the weight of the carrier starting as zero.
For instance, if the weight of my carrier is 100 grams, and I place my rat inside the carrier and the scale then reads 250 grams, just subtract. 250 (the weight of my rat in the carrier)-100 (the weight of my box or carrier)=150, therefore the weight of my rat is 150 grams.
How to help them gain weight
Senior rats, sick rats, and rats being fed/who were fed a poor/improper diet are at risk of severe under weight. I increase the protein intake for old rats when they begin losing weight (If they begin to rapidly gain during protein increase, they don’t need the extra help, so stop if you notice significant weight gain). Treats are given more often, but not to an extreme amount, to ensure they do not gain unhealthy weight.
Sick rats are monitored, and unless old or dropping in weight, I do not add anything to their diet other than offering vitamins and caffeine free teas with tissue healing properties. When a rat starts losing weight, you want to get on it as soon as possible (unless of course weight loss is the goal!). They are already very small, being underweight can have serious affects.
Foods to give an underweight rat
There are many rat safe foods you can give your rats when they are losing weight. Things high in protein or high in healthy fats can help them gain weight, the healthy kind of weight. Things like eggs, nuts (Almonds, Cashews, Walnuts, etc. Always unsalted!), Ensure, full fat greek yogurt, cheese (no moldy cheeses!), oatmeal, avocado (no pit or skin!), watered down potatoes (Water down, as it’s a choking hazard. I often water down with things like almond milk, makes it more fun!) cooked unseasoned chicken, cooked unseasoned fish (like tuna or salmon), and cooked unseasoned chicken bones. You can even use things like high quality dry or wet dog food (not as a main diet). I often provide protein like scrambled eggs alongside other fresh foods, my girls seem to ignore protein alone haha!
*Do not give calcium rich foods with Tetracyclines or Fluoroquinolones. Doxycycline can be an exception, refer to Rat Guide‘s health section to find medications and their specific contradictions.
*Leave things like dairy in very small quantities, as rats technically do not have the means to digest lactose and upset can easily happen. If you notice reaction, do not feed it again.
Critical care formulas (Omnivore!)
Oxbow Critical Care is a brand of powdered food, this is made for carnivores, herbivores, and omnivores. Critical care formula is *not* designed for use in animals losing weight. It is simply a powder form of their diet, there is no additional protein than what is already necessary for a healthy animal within their regular diet. Unless your rat cannot or will not eat their regular dry feed, do not use Critical Care formulas. Unless you were to mix with baby food/other proteins, it’s just a waste for when you do really need it. In the event that your pet is truly in critical condition (hence the name), you will want to have this on hand in a first aid kit. Again, this is not affective within weight gain in healthy rats.