A female dog who has not been desexed will experience her first heat period when she reaches sexual maturity. The age at which this happens and the frequency of further heat periods will vary depending on the breed (largely related to the size) of your dog. Certain additional considerations must be taken when your dog is experiencing a heat period. Does this mean she cannot be groomed?
Approximate Heat Period Cycle
It's a good idea to ask your vet about the approximate heat period cycle for your dog. Although she will only experience it a few times each year, it's a good idea to know the rough timeframe so that you can best care for her. Dog grooming does not have to be entirely ruled out, but there are times when it might not be appropriate.
One of the hallmarks of a dog's heat period is an increased level of agitation, which can even present as aggression. Your dog will simply want to be left alone and will not appreciate excessive handling. Cleaning will still need to take place, and you need to pay particular attention to her genitals so that any vaginal discharge can be cleaned before it has a chance to dry on her fur. Your dog might take to licking her own genitals to clean herself, but she will often need assistance. Wiping the area with a damp, clean flannel will often suffice, or you can get some specialist dog wipes from your pet shop.
The level of agitation will vary considerably, and much of it is dependent on your dog's own personality. Some dogs might be absolutely fine with being taken to the groomers during their heat period, but you need to be cautious about other dogs. When a dog is in the estrous cycle of her heat period, she is most receptive to breeding. She is essentially emitting pheromones to signal other dogs that she's fertile. This means other dogs might be rather assertive in their efforts to mount her. Consider booking the last available grooming appointment for the day so that you're less likely to encounter other dogs. Alternatively, think about booking a mobile groomer to come to you.
If there is any doubt whatsoever about your dog's suitability for grooming during her heat period cycle, it can be best to delay grooming until you're sure that her heat period is over, while being sure to spot-clean as necessary during the cycle. Speak to a dog grooming professional to learn more.