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Dr. Karing
Dr. Karing, Veterinarian
Category: Dog Veterinary
Satisfied Customers: 286
Experience:  General veterinarian with a special interest in internal medicine and emphasis on individualized care.
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My dog was recently (2 weeks ago) diagnosed with arvc (boxer

Customer Question

My dog was recently (2 weeks ago) diagnosed with arvc (boxer cardiomyopathy) after suffering 3 seizures from being excited/nervous (they lasted 2-3 minutes each, with 2 of these being cluster seizures) we first thought it was a brain tumor so we wanted to make sure her heart was healthy enough for anesthesia for the mri. her vet dx her with arvc after going into ventricular tachycardia during the echo and ekg. The vet believes her heart is causing the seizures which makes since. She was put on sotalol and zonisamide. It makes 2 weeks that she has been on the medications. Saturday she collapsed and what looked to me as a seizure after chasing after a bird. After calling my vet he believes it was a collapse and not a seizure. I'm not sure since her neck did pull to the side and her jaw was locked as it was in the first seizures. She also was drooling and very sleepy afterwards (which I thought was the postictal phase) Now four days later, she still seems very off. She looks to be wobbly and off balance. To be honest, it may just me being nervous but I feel like she'll fall over at any moment. Also, this may be just coincidental but her legs seem to slightly dragging more, increase in sniffing, and always looking up like she'd see someone above her. Overall you can tell she doesn't feel right. She still has the same amount of activity and it has been a challenge to stop her from running. Do you have any thoughts on this?
We are bringing her back to the vet in a week to do another Holter test. I'm also very nervous to bring her since she gets so nervous at the vet, and im scared she would go back into v tach or pass out. Do you think I could ask for a sedative or maybe benadryl to give to her before going? Would this decrease her heart rate or change the results of the Holter test? Any advice is GREATLY appreciated!
Submitted: 1 year ago.
Category: Dog Veterinary
Expert:  Dr. Karing replied 1 year ago.

Hi there,

I'm Dr. Karing and I would be glad to help with your questions about Roxy. Her case does sound very complicated. Is she seeing a cariologist? I would recommend that she does. An event monitor (i.e. Holter test that runs only during an episode) would discern between seizure events and syncope (i.e. fainting/collapse) so that is worth considering.

I do wonder if the Zonisamide could be causing her some sedation as part of what you are noticing now: I would like to know Roxy's dose. I would also suggest you try to check Roxy's heart rate (i.e. beats per minute) which you can probably feel easily by cupping your hand over her chest or you may be able to take her pulse by placing your fingers on the inside of her thigh area at a back leg. You will get different opinions about what is "normal" but I would suggest if the value is consistently 160 beats per minute even when appearing calm or less than 40 at any time, then you should notify your vet as this may be the reason for the odd behavior. Of course, the concern for a brain tumor causing the odd behavior is present as well but obviously you have to deal with Roxy's heart issue before pursuing an MRI. I would not recommend a sedative prior to the visit for Holter: it could change the results. I would rely on your veterinarian to recognize if the stress is too great and give Roxy a break if necessary.

I hope that the information I provided has beenhelpful. Please remember to select REPLY TO EXPERT if you have more questions orwould like additional information. It ismy goal to provide you with the most complete information possible prior to youleaving a feedback rating. If youreceived all the information you needed, then kindly submit a rating.

Sincerely,

Dr. Karing

Customer: replied 1 year ago.
Roxy is seeing a cardiologist. The Holter test is definitely the next step. Sometimes she's full of energy then today she isn't. She looks very tired and almost like she's about to pass out, but she isn't even panting or out of breath. Her heart rate is about 72-80 at rest. It's very hard to hear her heart rate even with a stethescope when she's excited or walking outside because of her loud panting. When we take walks outside I'm constantly checking her gums and they are light pink. Not dark pink like they normally are. Is it normal to feel side effects of the zonisamide after two weeks?
Customer: replied 1 year ago.
Also her doses are zonisamide 100 mg and sotalol 80 mg bid. I give them at 9 and 9.
Also do you think it is necessary to do an mri with her age. Yes I want to do whatever I can to extend her life, but I also don't want to put her through any unnecessary anxiety and stress. If it is a brain tumor, how fatal could this be if her seizures are controlled? Everything was completely normal for her 2 weeks ago before her first seizure after "crying for attention." The second cluster seizure was after hearing loud noises. Also how common is sudden cardiac death after collapsing or seizing? I feel like I'm watching every single move to prevent this from happening. Should I continue to stop her from running in the mean time?
Thank you for all of your help!
Expert:  Dr. Karing replied 1 year ago.

A resting heart rate of 72-80 per minute is good. I would discourage excitement for now: especially since she just collapsed Saturday and we don't know for sure if that was a heart related event. It is difficult to know what her prognosis for ARVC until after you have the repeat Holter performed and see if the arrhythmia is controlled. Again, an event monitor is different than the typical 24 hour Holter and I think that is the only way you are going to know if these episodes are cardiac or seizure related in nature. If they are cardiac related events that occur despite Sotalol use, then that is very concerning (i.e. dogs that have cardiac related syncope are at significant risk for sudden death) and the cardiologist may recommend other therapies.

The Zonisamide could definitely be causing sedation at this time. Please tell me Roxy's weight: the dose seems right for a Boxer but I'd like to know for sure.

Many people choose not to have MRI performed because the odds of that information helping Roxy are unlikely. You probably don't want to pursue surgery (most are inoperable anyway). The MRI would just confirm that there is a tumor as the likely cause of the seizures. Sometimes the position or appearance on MRI will help to form a prognosis about what to expect with the tumor over time. The prognosis varies depending on how aggressive the tumor is. A small amount of growth can cause a substantial problem because of the limited room in the skull: sometimes other symptoms develop along with the seizures if the tumor changes (i.e. behavior change, circling, blindness, etc.). However, many times the tumors don't change much for years and the aim is just seizure control. Sudden death with seizures is rare BUT death with prolonged seizures that cannot be controlled with medication is not uncommon in dogs with severe seizure problems. Avoiding stress and monitoring for behavior change is about all you can do now except give the Zonisamide. Your vet can provide a dose of valium for rectal administration in the event of a seizure that occurs in your presence and lasts more than a minute or is very violent.

Customer: replied 1 year ago.
Her seizures are not violent at all. They told me not to administer the valium since we're not 100 % sure it's seizures and could worsen her cardiac problem if it's syncope. She weighs 51 pounds. I want to believe that it's just her heart causing these problems, but when she starts her sniffing and looking up (very unusual) it makes me think neuro. Also she shakes her head sometimes like her ears itch. And I just cleaned them and they were not dirty. Could an inner ear infection (no redness or drainage) cause these disturbances? How would they test for this if this was the case? Her wbc is normal. Also you said an event monitor is different from halter..how long does she wear this for? I'm praying there's no more episodes since they scare and upset all of us. Would halter monitor help get her heart under control?
Expert:  Dr. Karing replied 1 year ago.

I'm glad to hear the seizures are not violent, but I am a little confused: she had a cluster seizure but we're not sure that was a seizure? Generally a cluster seizure is a series of seizures occuring close together so it should be obvious what is going on.

Roxy's dose of Zonisamide is right in the middle of the dosage range so not on the high end. If this drug is causing her sedation, then she may adapt over time. It isn't very common to have marked sedation on this drug but it can happen. If it persists, then you may inquire about lowering the dose to 50mg every 12 hours instead but please don't do that on your own. The valium is nice to have on hand just in case you need it for an obvious proglonged seizure event.

Although an MRI or CT would be required to fully evaluate the inner ear, a problem there would not cause episodes like Roxy is having.

An event monitor is ar portable electrocardiographic recording device that records a 10-15 minute loop of ECG, continually over-writing previously acquired data. Unlike the traditional 24 hour Holter, an event monitor only records ECG information when the unit is triggered (manually because you observe an episode and press a button on the monitor), the ECG from the 5 minutes prior to the trigger, and 5 minutes after the trigger, is transferred from the buffer into memory, and can be subsequently downloaded and analyzed. If episodes are infrequent (i.e. not daily), then the event monitor is the best way to assess them. Roxy would wear the event monitor as long as needed to capture an episode: it is a little smaller than the Holter monitor. Please note that the 24 hour Holter monitoring is also helpful and necessary for Roxy to assess how well her arrhythmia is controlled. However, to get information about if an episode of collapse is cardiac or seizure related, the event monitor would be necessary.

Customer: replied 1 year ago.
The first three seizures were definitely seizures. Neck drawn, blank stare, defecation.. during the 2nd cluster seizure there was no heart beat heard or breathing. Her gums were pale. So this is what encouraged my vet to do an echo/ekg, also wanting to do mri. It had been 2 weeks since the seizure and meds (including sotalol). Then saturday she ran (fast as her body could) then collapsed. I felt like it was a seizure because her neck pulled but it was very short. I timed it and it was 15 sec. Her heart sounded normal after. After calling her vet, he said that was a collpase, not a seizure. Since then she's been very wobbly. Almost seeming a little drunk and out of it. And very tired. She'll take off running (after pottying) but I instantly make her stop. I believe she has abnormal rhythms and the arvc us causing the collapse/seizure. But I'm very nervous and scared about what's causing her drowsiness, dizziness, just off appearance now. It makes me feel like she will collapse at anytime. Thank you so much for your time also! Me and roxy truly appreciate it!
Expert:  Dr. Karing replied 1 year ago.

You're welcome. I hope All goes well with Roxy. Let me know any time if I can help further.

Expert:  Dr. Karing replied 1 year ago.
Hi,
I'm just following up on our conversation about Roxy. How is everything going?
Dr. Karing
Expert:  Dr. Karing replied 12 months ago.

Hi there,

I wondered how things are going with Roxy. Please let me know when you have a chance.

Thanks,

Dr. Karing