Patchy fur is often demodetic mange caused by mites. It’s not contagious, but will require consistent medicated baths to clear up. Even if it’s not bad, you don’t want to let it progress. The vet should be able to prescribe you with a medicated shampoo. If not there are OTC shampoos available on Amazon, but please consult with your vet.

I’ve done bathing regimens with either vet prescribed or OTC shampoos. There are two OTC shampoos I have used effectively that I will link below. I first do the sulfur shampoo, than the benzoyl peroxide separately.

Bathing daily during the first/second week, every other day for the next two weeks. And then twice a week for the next 2/3 weeks. You may not need to treat as long, it just depends.

It’s important to let the shampoo sit on the skin for a the recommend time. This is what actually takes care of the mite overgrowth.

Hope this helps!

Veterinary Formula Clinical Care... https://www.amazon.com/dp/B0037Z6VK8?ref=ppx_pop_mob_ap_share

Davis Benzoyl Peroxide Medicated... https://www.amazon.com/dp/B0078LOTV0?ref=ppx_pop_mob_ap_share

Preservatives called "itchy Ms" can be a culprit - they are typically Methychloroisothiazolinone & Methylisothiazolinone, long names starting with M. Some good products without them are Shea Moisture, Cantu, Yes to Carrots, Not Your Mothers Naturals.

If it's really serious you might want to see a dermatologist. I did and was diagnosed with seborrheic dermatitis. I was given a medicated shampoo and it worked OK but through Amazon I found this dog shampoo and it is freaking amazing even if it smells like tar. Works better than everything I've ever tried.

I've switched over to the "curly girl" method so I use all sulfate/silicone free products, that dog shampoo works well with that routine but I don't have a lot of issues like I used to so I rarely need to use it.