Why Are My Young Kittens Losing Weight?

By: Chewy EditorialPublished:

Why Are My Young Kittens Losing Weight?


I raise Sphynx cats and have had issues with kittens. Currently, I have two 5-week-old kittens who were doing great, looked healthy and happy and then went downhill healthwise. They lost weight at a shocking rate (female weighed 14 ¼ ozs. and in two days was at 10 ½ ozs.). Luckily these kittens are a little older this time (this has happened with younger kittens and I usually lose them). These two kittens may be coming around, especially the male. I am feeding formula, Nutrical and Pedialyte and giving them some Clavamox.

Another breeder said it might be because the mother came into heat and the milk got bacteria in it. I also have heard that if the mother and father have different blood types and the kittens do not match the mothers that the red blood cells are destroyed by the different blood types (this is usually said of the less than 2-week-old kittens).


Any weight loss in kittens is a cause for concern; healthy kittens should never lose weight. The weight loss you describe is indeed dramatic. It sounds like you’ve intervened aggressively and hopefully these kittens will pull through. I’d be careful with the Clavamox; this is an antibiotic and should only be used if infection is proven, or strongly suspected. It is a penicillin and sometimes causes diarrhea, which would be disastrous in kittens that are already losing weight.

Mastitis (infection of the mammary gland) occasionally occurs in lactating queens as a result of nipple damage that can occur from constant sucking from kittens or from abrasions from sharp kitten claws and teeth, allowing bacteria to enter the gland. Mastitis can affect one or multiple glands. If only one gland is affected, kittens can safely nurse from the other glands. If more than one gland is affected, kittens should not nurse at all. Check the queen’s mammary glands to make sure there is no sign of infection. Mastitis and subsequent ingestion of infected milk, however, is an unlikely cause for your kitten’s decline.

The other condition you mention, which occurs when the parents have different blood types, is called “neonatal isoerythrolysis” (NI), and is a common cause of “fading kitten syndrome” in purebred cats. The term can be loosely translated to “exploding red blood cells.”

When a queen with type B blood mates with a tom with type A blood. Some of the kittens in the litter may end up being type A. When these type A kittens nurse, the milk they drink contains antibodies from the mother. Type B queens have a high level of antibodies directed against type A red blood cells. These antibodies will be in the milk. These anti-A antibodies will attack the kittens’ type A red blood cells, causing the kittens to become very sick.

Nearly all domestic shorthair, domestic longhair, and Siamese cats are type A, but purebred cats have a higher likelihood of being type B. Seventeen percent of Sphynx cats are type B. It is certainly possible that NI affected your previous kittens. Usually, the effects are seen in very young kittens. It is unlikely that NI is the culprit in your 5 week old kittens; they’re too old.

I do not know why your kittens experienced a sudden drop in weight like they did, but if they do come around and start gaining again, I would have them carefully evaluated by your veterinarian (or a more urban veterinarian) to make sure they’re OK once their condition stabilizes.

By: Arnold Plotnick, DVM

Featured Image: Shutterstock/Family Way


By: Chewy EditorialPublished: