You can only speculate at what may be wrong without a physical exam. Dogs normally have a regularly irregular heartbeat, but they can also have skipped beats due to heart disease. The shallow breathing is subjective and may be normal for her. If you are using an inhaler, you need to know what medication you are giving and why. Some medications are fine for humans but can be poison to dogs. NEVER give a human medication to your dog unless you check with a veterinarian. For inhalers to be effective in dogs, a specer and face mask are needed. If you have not used this, you are just wasting the medication.
Have a veterinarian check her out. She may be normal or she may have a problem that could be corrected or controlled.
