Sudden stop of wet food diet is causing my cat to vomit

Question

I went to the vet on Saturday for my cats yearly checkup. They are 2 years old now. The male cat (Joe) weights around 8kg (or 17.7 pounds), and the female cat (Moe) weights around 6kg (or 13.2 pounds). Joe's height standing up is 2.3'. Little Moe is about half his size. Their meal consists of dry food available 24/7, "satiety balance" (which is the brand that the vet told me to give them) and 200g of wet food.

The vet said they are fat. He advised me that should only feed them wet food once a week. Since Saturday I have been feeding them only dry food. Every time I get home at around 7pm, I see vomit on the floor consisting of dry food. It's as if Joe is swallowing them.

I have decided to get back on feeding them the previous diet, but with only wet food once a day. At the moment I'm feeding them Wild Freedom brand wet food. Do you think it's ok to get back on feeding them wet food once a week? Are they fat?

---

Wild Freedom is a complete wet food for adult cats
Cold River: 55% chicken (meat, liver, stock), 43% pollock, fish stock, 2% minerals
Wide Country 98% chicken (meat, liver, gizzards, stock), 2% minerals
Green Lands: 53% chicken (meat, liver, stock), 45% lamb( meat, kidneys, liver, stock), 2% minerals
Golden Valley: 53% chicken (meat, liver, stock), 45% rabbit (meat, heart, kidneys, liver, stock), 2% minerals
Deep Forest: 53% chicken (meat, liver, stock), 45% game (venison/deer meat), game stock, 2% minerals
Farmlands: 62% chicken (meat, liver, stock), 36% beef (lung, meat, stock), 2% minerals

Additives:
Nutritional additives per kg:
Vitamin D₃ 200 IU, vitamin E (alpha-tocopherol acetate) 25mg, taurine 1000mg, zinc [zinc sulphate, monohydrate], 15mg, manganese [manganese (II) sulphate, monohydrate] 3mg, iodine [potassium iodide] 0.5mg.
Energy / 100 g:
Wide Country, Cold River, Golden Valley: ME (FEDIAF, 2014): 399 kJ / 95 kcal
Green Lands: ME (FEDIAF, 2014): 416 kJ / 99 kcal
Deep Forest: ME (FEDIAF, 2014): 425 kJ / 102 kcal

protein 10.5 %
fat 6.0 %
fibre 0.3 %
ash 1.7 %
calcium 0.27 %
phosphorus 0.2 %
moisture 81.0 %

Answer 1

Firstly, free feeding dry food is the fastest way to turn any cat into an overweight cat. Your vet's advice is wildly wrong in this case. Hill's (a respected pet food company) has this to say:

Free feeding cats can lead to overeating and obesity. It can also be difficult to tell if your cat's appetite has changed, for the better or worse. It's also difficult to tell, if you have multiple cats, how much each one is eating.

(source: Meal Feeding vs. Free Feeding Cats: What's Best?, emphasis mine)

The idea that wet food is "unhealthy," "a treat," or otherwise bad for cats is an older belief that more vets are beginning to leave behind, but some older vets still hold on to that belief. Free feeding kibble is the old, and honestly lazy, way of caring for a cat, and has led to large numbers of overweight pet cats. From Global Pet Foods:

Free feeding makes it easy for indoor cats to consume more calories than they are expending, leading to weight gain and possible obesity.

(Source: Is free feeding your cat the best option?)

Secondly, simply looking at weight isn't a good way for anyone to determine the body condition of your cat. Please reference my answer on "How can I measure the weight of my cat?" for the appropriate way to determine if your cat does in fact need to lose weight, as well as an explanation of why pure weight isn't a sufficient metric to use.

Thirdly, simply looking at the quantity of food being offered isn't a way to determine if your cat is getting the right amount; each brand and flavor will have a different calorie (kCal) content, and just like in humans, calories are what's important for weight gain, loss, and maintenance. According to All Feline Hospital:

The average indoor cat should have 20 calories per pound to maintain weight. The average outdoor only cat should have 35 calories per pound to maintain weight. Indoor/outdoor cats are somewhere in between.

(Source: Getting Your Cat to Lose Weight)

You also can't cut their food too drastically; from the same link above, "If your cat is overweight, you will want to feed for 2 pounds less, or 40 fewer calories a day, and readjust every time your cat loses a pound, until you hit a healthy weight, and then maintain." An extreme drop in calories, particularly with an overweight cat, can cause hepatic lipidosis, also known as "fatty liver disease," a fatal condition.

Cats will naturally eat a number of smaller meals, which is very similar to their wild behavior; cats have not been domesticated all that long in the grand scheme of the species, and still retain most of their wild traits, including frequent small meals and getting most of their water from food. Because of the water content, wet food is actually more filling than dry to them; this may be part of why your cat is vomiting, as well. He may be eating a similar physical quantity, but as the food absorbs moisture in his stomach, it swells and causes him to vomit.

I would advise the opinion of a second vet, as the advice to move "fat" cats to a feeding pattern that is well known to encourage feline obesity is not good. Check their condition yourself using the touch-test linked previously, and find a different vet for additional consultation about their body condition and caloric needs. I would also advise returning to their original diet and schedule for now.

Answer 2

Dry food expands on contact with liquids in the stomach, so if your cat can fill it’s entire stomach in one sitting, the expanding food has nowhere to go but back out the mouth.

The usual solution is free-feeding, but that doesn’t work with a cat that already has weight problems. For many cats, this is what causes their weight problems.

The only other solution is to feed smaller meals more often. If your cat can’t fill its entire stomach at once, then there will be room for the food to expand. Automatic (timed) feeders can help with this.

Answer 3

I disagree with your vet. Firstly I was always told that male neutered cats should only be fed wet food-they are at increased risk of urinary blockages and dry food is terrible for that. A water fountain also helps ensure the cats get plenty of fresh water-I can't recommend them enough.

One of my male cats is a big fatso and he has actually lost a fair amount of weight just by being fed a small can of wet food daily. Previously he was on dry only. That's literally all I've done-give him a small can every morning and eliminated free feeding of dry. I put one cup of dry out for 2 large males and they share the can of wet food. Maybe try this for a couple months and see if you get results.

This may sound silly but if possible be in the room when you feed the cats. My cats seem to like it when I'm nearby as they eat. My shy cat will eat a few bites and run away if I feed him and leave the room. I guess everyone likes company when they eat.

If you're uncomfortable with your vet definitely see a different one. Hopefully your cats will live a long life so you need to have a vet you trust and can work together with on the health of your cats. Good luck!