Cats are more influenced by changes in ambient light than changes in seasonal temperatures with respect to shedding fur.
Cats who spend all their time indoors are exposed to constant indoor light (and some window daylight). Consequently they may shed fur lightly and grow a new coat throughout the year rather than at the onset of a lighter season. It depends upon the specific arrangements at the home (e.g. is there a large well-lit catio).
This is in contrast to cats who spend most of the time outdoors who are exposed to more light (natural sunlight) in late spring causing shedding, which can last for weeks.
Indoor/outdoor cats who go out into natural light for part of the day normally shed at the beginning of summer and grow a new coat then.
There is no difference between intact and sterilised cats.
Note: I can’t guarantee that the video below will remain in place because it’s existence is controlled by others.
Carol Erickson talks about dogs shedding. She also refers to cats. She says that living indoors makes it harder for cats and dogs to recognise seasonal changes. They shed ‘lightly and regularly’. This concurs with the information I have provided above, the source for which comes from personal experience and the Cat Owner’s Home Veterinary handbook Third Edition.
When a cat sheds her coat (the telogen phase – the resting phase – ‘the resting hair remains in the follicle until it is pushed out by the growth of a new anagen hair’1) young hair forces out the older hair. Cat hair normally grows at 8 mm (.33 inch) per month.
The environment has an affect on the thickness of the coat. Clearly cats living outdoors in cold conditions grow a heavier coat for insulation.
Illnesses can affect shedding. Cushing’s disease, thyroid disease, poor nutrition and stress can increase shedding. Thyroid disease impairs the growth of coat and also affects the condition. A vitamin deficiency or parasites can also affect the coat’s condition causing it to to become more brittle and thinner. A generally poor coat indicates a ‘systemic health problem’.
Non-shedding cat breeds?
P.S. Fur around the home can upset some cat owners or those who want to adopt a cat. They search for a non-shedding cat breed. There are claims made by breeders that their cats are non-shedding. In my opinion this is not true. But the Rex cats shed less fur because they have less fur on them. These breeds may appeal to people looking to minimise hair around the home.