first congratulations, 18 years old is great for a Yorkshire terrier! I am sorry to hear about her problem during this holiday.
To better assist you, can you answer some questions for me?
1- Is your dog on any medications/supplements?
2- What tests were done for the enlarged heart?
3- any blood test/urine test done lately?
4- How is her dental health?
5- how is her water consumption?
6- How is her urine production?
7- Have you noticed any change in her mentation, interaction in the last few months?
Let me know, looking forward to assist you.
it is hard to say if this is related to the heart or not. She may have had a short time where she lacked oxygen to the brain. This could have been due to a heart arrhythmia (abnormal heart rate). You may want to place your hand on her chest and check what is her heart rate. Feel what it is normally, so if she has another crisis, you may be able to detect an abnormal heart rate. Also at the same time, check for the femoral pulse.
Here is a link about valvular disease, the most common heart disease found in older dogs:
I am giving you a link about checking your dog. A the bottom, they give you hints about how to get their femoral pulse:
If you still have trouble finding it, ask your veterinarian to show you.
I would have her checked again by your veterinarian, sometimes when they are on enacard and furosemide, they may get some electrolytes imbalances, or their kidney does not respond very well, and the dose may have to be reevaluated.
Dental disease: they may have an impact on her heart health. If you cannot do dentistry, you may discuss with your primary veterinarian about pulse antibiotic therapy. Some tooth can abscess into the sinuses, and the brain is not far.
She may have had some neck pain from a slipped disk in her neck, or other cause of spinal compression. usually some brain infarct (stroke) symptoms would last longer.
Brain disease is a possibility.
Liver/kidney disease process.
So, a lot of different possibilities. I think since she has more quiet in the last few days, it is letting us know something is not right with her, and a visit to your primary care veterinarian would be recommended. If you can, you may even want to get to the ER to be on the safe side.
Let me know if you need additional information.
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to know what to do with those attacks, you need to know what is causing them.
What can be done will depend of the cause.
Like already mentioned, I would recheck the blood values.
if arrhythmias are a possibility, which you may be able to detect yourself with taking her heart rate and the femoral pulse, this might be controlled with medication.
If she is painful, analgesic could be given.
Some dogs that are suspected to have arrhythmias, can have a holter (do not know if they have one small enough for Yorkshire), and make 24 hours recording of his heart rate.