The short answer to this question is four to six months. However, it depends on why your Persian doesn’t have his full coat, to begin with. There are several factors that have an affect on your cat and the time it takes for their fur to grow back in.

Reasons Your Persian Would Need To Grow Fur Back

There are several reasons your cat would need to grow his fur back. 

1. If your Persian has tangles or mats that are impossible to brush or comb out, you may have to cut it out. Use blunt-edged scissors or pet clippers. If you can, slide a comb between the mat and your kitty’s skin that way, you avoid any accidents. A tip for Persian or any long-haired cat owners is to keep the hair around your cat’s anal and genital area trimmed, that way you can avoid fecal material getting caught in the long hair at their rear end. 
2. If for some reason you’ve had to have your Persian shaved. There is some information on why you shouldn’t just have your cat’s fur cut, especially long-haired breeds. Their coat provides thermal insulation that protects them from both hot and cold temperatures as well as protecting them from sunburn. Long, thick layers also help protect them from injuries, and if their fur is thick enough from bug infestation. Your cat also uses their hair to communicate. If you’ve ever seen a cat bristle, you’ll see what I mean. They do this to scare attackers. Their sense of touch through their coats help them understand their surroundings, sense danger, and it even affects their activity. 
3. Surgery or lab work. Your cat may be at the vets for blood work or surgery. A vet tech will have to shave an area on your cat to find a vein to draw blood from, start an IV, or if your cat is having surgery, that area of their body will be shaved. 
4. Stress can make your cat’s fur fall out if the stress is hard enough on your cat’s system. I remember when we help my Grandparents moved from the ranch my grandpa worked for forty years, their Siamese cat had lived his entire life there, and suddenly after nine or ten years of his life, we loaded him into the car and drove him twenty or thirty miles to their new home in town. Grandma, my cousin, and I were covered in stress released fur from this Siamese.

How Your Cat’s Coat Grows 

There are several stages of growth. They are the Anagen phase, this the time the hair grows the quickest, the catagen phase, where the hair stops growing, and then the telogen phase when the hair falls out. We know it as shedding. If the telogen phase is interrupted, it’s called telogen effluvium and is caused by high amounts of stress. This can lead to what is called generalized alopecia, which is the loss of hair. This requires no treatment except to be patient and wait for your furry pal to regrow their coat. The normal cycle of phases will allow your cat’s fur to grow in thick and healthy all over without you noticing, except for some extra hair on your furniture or clothes. 

Conclusion

Different factors affect the rate at how long it will take your cat’s fur to grow back. Their coat can take weeks to months to grow back. A healthy cat should have its fur back in four to six weeks. However, if they were ill, it will more than likely take longer. You’ll have to figure in the time it takes your cat to get well before you can factor in their fur growth. If their diet is lacking, it will also affect the growth rate. 

One thing I’ve learned from writing this is that it’s not necessary to have your Persian shaved to keep them cool. Their coat is equipped to keep them cool in the summer and warm in the winter.