Hi, I have had 4 ACD dogs over the last 25yrs. None of my ACD have ever had urinary tract infections, or any other major illnesses. I had a female ACD "Skye" for 15yrs. She died 5 years ago. I had her desexed at 6mths. There was never any issues that the vet was concerned about ,or me to not go ahead and get her desexed. I was recommended to do it with all my dogs by vets. I live in Australia where we have alot of ACD dogs, and alot of my friends own ACD both male, and females. Generally here in Australia everyone is encouraged to have their dogs desexed no matter what breed they are due to health reasons for the dog later in life, cancer ect, and unwanted litter issues aswell. Unless or course you are a breeder, or want the litter from your dog. My female "Skye" ACDs mother was my friends ACD and had 3 litters accidently before being desexed. She would jump the fence at home to get out as soon as she went on heat before the owners knew it. One night we spent all night looking for her which was quite stressful worrying that she could have been hit by a car. She returned home in the morning herself. :-) The last litter she had was due to another neighbours ACD male that broke into her house through a large cat flap in the back door during the night, she was locked inside sleeping. My friend found them downstairs in her kitchen. Lol. My ACD female "Skye" never had any post operation problems, and had a healthy,happy life .At 15yrs old she got ill suddenly one day and i took her to the vet. She passed away early the next morning while still in the vets as she was staying there overnight. She died from old age organ shutdown.I would do the desexing the same if i bought another female as they can socialise with other dogs earlier, which they need to learn to do without risking pregnancy. I also did not want her to have a litter without i kept the puppies as then i would have worried about them having good owners that would give them as happy lives as she had. The desexing didnt seem to change her temperament after. She was always a happy, friendly and loving dog since i bought her at 8 weeks old. I have a male ACD "Cody" now he is in my profile pictures. I hope this helps with any anxiety about getting her desexed. This information is just my opinion from having ACD dogs and on advice that my vets gave to me over the years. The decision is always the owner of the dog. I hope you have many happy years with her as i did with "Skye".