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DanaDVM, Cat Answer Team
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Sudden Death in a cat

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I would prefer that this question be answered by a veterinarian or a veterinary pathologist.

What would cause sudden death in my 7 year old kitty?

Okay, here's some background and information.. I came home from work around 9pm Friday, March 25 to find my kitty, Birdie, dead on the couch. This is a place where she would often times sleep. She was on her right side, her body looked pretty natural (as if she was sleeping), no real distress other than: the hairs on her tail were somewhat puffed out (as when cats get scared), but her tail was down near her legs; a couple of her toes were splayed out as if she had stretched her toes; and there was bloody mucus seeping from her nose. I then took her body to an emergency vet where they did a quick necropsy. The e-vet did not find anything out of the ordinary. She said Birdie's heart looked a little enlarged and the tip of her tongue looked red. She thought that maybe Birdie had been electrocuted by biting a wire. I find this very hard to believe because Birdie was not at all the type to bite electric wires. The vet recommended that her body be taken to Texas A&M veterinary school for a more thorough examination. They iced her body down, and I drove her body to Tx A&M that Friday night/Saturday morning. Based on the information I provided, the emergency intake vet at A&M thought Birdie had suffered from hypertrophic cardiomyopathy. She examined Birdie's tongue before the body was sent back to the pathology department and said it looked as though Birdie had bitten down on her tongue. I then had to wait over a week for the necropsy results from Texas A&M.

Since Birdie had recently been to her regular vet to get her teeth cleaned one week before she passed, I contacted this regular vet while I was waiting for the necropsy results. I always elect for blood work before teeth cleanings. The regular vet said Birdie's blood work was all normal and that the pulse oxymeter showed her heart rate at 200 (I guess right before the procedure) and 146 during the dental procedure. And there was no detected heart murmur. (Both Birdie and her daughter had their dental cleaning done on the same day, and her daughter is just fine.)

Well, the necropsy results came back and the cause of death was undetermined. The intake vet at A&M faxed me the necropsy report after she interpreted it to me. Her heart was within normal limits; lungs okay; urinary tract fine except for slight "interstitial nephritis" on kidneys; nervous system and all other organs had "no significant lesions observed". Also, they did a limited microscopic examination. They couldn't do a complete one because some of the tissues had too much post mortem changes.

My regular vet, who got a copy of the necropsy report, spoke with the Texas A&M pathologist, then she called me. My vet tells me that the pathologist thinks that a thrumbus, blood clot or stroke didn't cause Birdie's death and there was no apparent indication of toxic poisoning. She said the pathologist thinks that it was an "acute hypoxic event" maybe that she choked on something. (I kind of find this hard to believe. She was laying on her side on the couch as if she was sleeping. If she had choked on something, I think she would have jumped down off the couch or would have been in a different position when I found her. Also, the two necropsies did not report finding anything in her throat, but I don't know how thoroughly they look.) My vet thinks her death was due to heartworms. (Again, I find this hard to believe. During the necropsy, wouldn't heartworms be found?)

Birdie was an indoor only spayed kitty weighing in at 13 pounds. She lived with three other cats, two of which are her daughters. There are no plants in the house. All my medications are in their container up in a cabinet. The only medication/supplement that I can remotely think of that she might have got would be an iron capsule that I'm taking. It smells like liver. I had set my evening supplements on the coffee table near the couch that Thursday evening prior to her death. (I take my supplements while I eat my evening meal in the living room.) I'm most certain (but not positive) I took all my supplements (only three) that evening. The iron capsule was a number '0' size capsule. Certainly, if she did eat that capsule, she would have swallowed it fine, right? Or if that choked her, then the pathologist would have found it in her throat, right? (The intake vet at A&M said the pathologist does a pretty thorough job. However, I'm wonder just how thorough..) Could a No. '0' capsule choke a kitty?

I've also been worried that her death might have been a result of the dental cleaning she had about 6½ days before. The vet and the pathologist didn't think that the anesthesia (I believe it was isoflurane gas) had anything to do with her death. But I'm wondering if maybe the IV fluid drip or the injections of Ketamine, Diazepam or Ampicillin might have played a part in her death.? If there was any air in those syringes, could that cause her death almost a week later?

That Thursday evening she did act a bit out of character. She let her daughter, Elsie Belle, groom her (which wasn't too unusual, but the length of time for tolerating Belle grooming her was). And what was unusual that evening was when Birdie got on the back of the couch (I was sitting on the couch) and she laid on the back, placed her paws on my shoulders and nuzzled and loved on my hair for about 5-10 minutes. She had never done this before! She's only loved on my hair when it was wet, and when I would get down to her level. Other than that she seemed normal.

Also, I'm not certain, but I think maybe she wasn't eating as much the last couple of days - the food bowls she and her two daughters ate/eat out of had some food left over in them when I refilled them. Unfortunately, I had been busy with my executor duties, and I didn't get to keep a very close eye on her, nor my other kitties that week. This is something I greatly regret.

Sorry this is long. But I figure the more info the better. If you need more info, I'll see if I have the answer. So, what do you think could have caused my pretty girl's death?

 First let me say I am truly sorry for the loss of your friend. It is evident from your post and care of your cat...that you were a wonderful friend and owner to her.

This is my second time responding..the first time just disappeared due to the I am going to break it up alittle...please be patient.


 I think your assumptions are correct. I do not think your cat choked. Lets just assume that two vets missed a pill or something lodged in the throat....the lungs look different if the cat can not breath and dies.  For one, there is no air in the lungs...and it is obvious. So please don't worry anymore about the pills.  And no, Iron ingested wouldn't do this either.

Next, electrocution is not likely. If it was acute, the cat would be dead by the cord. If it was secondary...there would be pulmonary edema...again something seen in the lungs...and the mouth and fur would be burnt.



Heartworms. It is possible. Cats only have one or two in an infection...unlike dogs who have a heart full of them.  The other thing I have found, is many times (since cats are dead end hosts) the one or two adult worm is not even sitting in the heart but in the pulmonary artery.  Since heartworms are transferred via mosquitos..we both know they come inside and there is a chance.  So, if during the first necropsy the lungs/heart were handled enough...the one or two heartworm could have been missed.


DanaDVM, Cat Answer Team
Category: Cat
Satisfied Customers: 998
Experience: Cat Expert
DanaDVM and 2 other Cat Specialists are ready to help you

 The tongue, I think it is incidental at the time of death.

The dental... I don't think it was from the drugs or anesthesia...or acutal dental procedure.  You have to remember that while under anesthesia...the body is in an "altered state"  and a pulse oximeter ( if that was the only monitoring equipment) does not tell us too much about the entire body. Blood pressures change, and ECG arrythmias and so forth.

For example, what if the heart developed a "misbeat".  It wouldn't show up other than just subtle changes of behavior...and maybe slight fatigue. And after a  few days could get out of a maintainable rhythm until the heart stops acutely.  This can happen but have no changes in the actual "look" of the heart.  These arrythmias are not common, but do happen.

If you need further explanation let me know, if I didn't address a question, let me know.



Customer: replied 11 years ago.
Your third post about heartworms just vanished... I wish I could get the information back... Thank you for the information, though. The necropsy from Texas A&M talks about the first necropsy. It says that "the diaphragm was incised and the pericardium is opened (previous abbreviated necropsy)". But it doesn't say anything about the lungs. Can I assume that if the necropsy doesn't mention something, then the organ is fine?

No you can not assume it is normal...unless that pathologist is contacted and that is the standard for them.  Failure to mention normal pathology suggest no exam at all OR tissue was damaged beyond interpretation...which should be mentioned. I don't know how they can suggest hypoxia..which is abscence of oxygen without commenting on the lungs.

Re-try to view that post, now that you reopened the question you should have access to.


Customer: replied 11 years ago.
Reply to Dr. Vamvakias's Post: Why is the tongue incidental at death? If the tongue was bitten, would this just show that she had some pain in the last few moments?

Birdie was a pretty energetic kitty. She often times zipped through the house.. I guess my question is, are you saying that Birdie also could have had an arrythmia?If so, since I have two of her daughters, and I know the people who have her other offspring (Birdie had 5 kittens in my closet after I adopted her. Long story, but all kittens went to good homes..), should we be on the lookout for any health concerns with these kitties?
Customer: replied 11 years ago.
Reply to Dr. Vamvakias's Post:   The only thing that the necropsy mentions about the respiratory system is the bloody mucus around both nostrils "inspissated epistaxis, presumed". Actually, it doesn't really mention anything about the lungs other than where it talks about the histopathology. It mentions the lung (singular) and says "no significant findings". The intake vet at Tx A&M was the one who verbally told me the interpretation of the necropsy and she said the lungs were okay... And it was my vet who said the pathologist said/thought Birdie's death was hypoxia. The gross necropsy does not mention the lungs, so I don't know where the pathologist was getting his assumption...

I wish the necropsy was more thorough. The sudden death of my pretty girl is too much for me to take .. I was at least hoping the necropsy could give me some closure .. Dr. V. is it possible for me to fax you the necropsy report (2 pages) and you give me your interpretation?

 No it doesn't mean pain at all.  To have pain is to suggest consciousness and I don't think that is the case. The mouth closed down during death and the tongue was relaxed and got bit... not bit in pain. Does that make since?

I am not suggesting there was a pre-existing arrythmia. I think you had a healthy seven year old cat ( cant rule out the HW)...but as a result of anesthesia...not the drugs but the overall experience, an arrythmia developed....I don't know...a response to the drugs can do really is hard to pinpoint...or the two vets you have seen would have given you a absolute answer.

I am just one vet who never saw your cat. This is just my opinion pulled from my experience.


 I am sorry, I feel like receiving a fax oversteps the boundaries I have as an online specialist. 

What you can do is speak with your vet and request not only the pathology reports but the histopath slides be sent for a second pathological evaluation.  I am not a there may be something further they can expand on that I can't.

Now the other thing to by reporting all the normal results they ruled out tons of underlying disease and toxin there were some answers...just not the final cause of death.



Customer: replied 11 years ago.
Reply to Dr. Vamvakias's Post: Dr. V. thank you so much for your replies!!  I do have some more questions for you,

In regards XXXXX XXXXX heartworm theory...  This past summer and fall mosquitos were very
bad here.  What is the time frame from
being bit by an infected mosquito ‘til the time the heartworm develops and can
kill the cat?   If she did have heartworms, do you think she
felt them and knew something was wrong (ie: that Thursday evening when she
acted out of character a bit)?

Also, I had a question in my original post that I’m not
quite sure you addressed.  If there was
air in one of those surgines, would that kill her six and a half days later?

I just read where diazepam if injected too quickly
intravenously might cause a blood clot or cardiotoxicity.  How does the pathologist know she didn’t have
blood clots?  What would be the
indications pathologically for a blood clot?

And on your point regarding her developing an arrhythmia
post dental procedure, that sounds quite plausible.  Birdie, like most cats, absolutely hated being
in a carrier.  However, she would get
much more stressed than any of my other cats.  She would try her darnedest to claw her way
out of the plastic carrier.  (I hated to
stress her, but she did have tarter build up (Grade I), besides, she has had
two previous dentals that went fine.) 
So, were you meaning that the overall experience (car trip to vet, being
at vet, anesthesia, drugs, dental cleaning, etc) could have caused an

Also, if she did develop this arrhythmia, she would probable
feel it and that would explain her loving on me that Thursday evening (her
knowing something wasn’t right with her body). 
She also, tried to get my attention when I was on the computer earlier
that evening…  hindsight is 20/20, but I
regret not paying more attention to her that evening/week…  



So sorry for the delay.

 <<If there was air in one of those surgines, would that kill her six and a half days later?>>

No, that is a myth from TV. It would take quite a bit air injected into the vessels to cause problems...a bubble or two won't do that.

<<How does the pathologist know she didn’t have blood clots?  What would be the indications pathologically for a blood clot?>>

The pathologist is usually able to see large clots that are blocking major vessels...depending on the type of necropsy. Smaller clots in the lesser vessels or brain, would not be found.

 <<I just read where diazepam if injected too quickly intravenously might cause a blood clot or cardiotoxicity.>>

The diazepam is usually mixed with some other drugs...and I have never seen a problem with it given.  They are usually such small amounts that I don't feel like "too quickly" would be a factor.

As far as the arrythmia. I don't think it developed because of stress, I think it can happen with anesthesia..the medications and sedation may cause or exacerbate an underlying problem that we wouldn't know is there for 6-8 months later.  I don't think the stress helped...but many times if the heart isn't given a drug to "readjust" it does get worse over the course of days to where it will go into a status where it is not pumping correctly and the paitent dies very quickly.

I do think if that is the case..she could "feel it"...but let me tell you that when people experience it , the complaint is lightheadedness..not pain.  Weakness as well. 

As far as the HW in cats...I need to look that up...I don't know the exact timeline in cats from larva stages to adult...I need to make sure it is the same timeline as dogs. Since cats are not the "host" they prefer...

I will let you know.

For now remember, you will need to go thru the normal stages of grief..and there are people that specialize in animal losses. If you feel this is becoming harder to handle...let me know or your vet so you will have someone to talk to.  Animal loss is a large stress...since they are in your every day life...and to many of us, furry little people.


Customer: replied 11 years ago.
 Dr. Vamvakias, thank you so much for your time. 
The information you have provided has put my mind at ease a bit. 
Her sudden death was bad enough, but not knowing or having a good idea
as to the cause really added insult to injury.

An arrythmia sounds lodgical and so does the heartworm(s).  From
now on, I'll be more vigilant when mosquitos are around to administer a
heartworm preventative to my kitties.

I just started seeing a counselor to help me with my grief (this loss
of Birdie is on top of loosing my mother several months ago). 
Birdie was a wonderful cat; she was also the alpha cat.  She often
times would play like a frisky kitten; she had a purr that could be
heard from across the room; and she would frequently show her love for
me by kneading the air in front of me or lightly touching me as she
kneaded.  She was my very pretty girl.

Two last quick questions if I may?...  Why do you think she had a
bloody nose ("inspissated epistaxis, presumed" from the
necropsy)?  And if you have found the timeline in cats from
heartworm larva stages to adult, that would be appreciated. (I did
treat her with Revolution in mid October and mid November last year,
but that was for earmites, so it was not a prolonged treatment.)

Thank you, Debbie

 Revolution is only effective at certain stages of the life cycle.

I do believe it is about 6 months from infection to an is  just that in cats they are harder to get infection...and they don't have circulating larva (dead end host) so they mosquito doesn't spread from a HW pos kitty. Then the adults only live a couple it isn't as long as an infection with dogs.

As far as the nose...the statement means thickend nose bleed...nothing more.

It can be from heavy breathing thru the nose at the end of life...or a lung lesion...but we don't put too much on it depending on the status of the cat.

I am glad you are talking with someone.  I am sorry for your mother.  Both my parents are battling cancer...and my Mom's breast cancer is winning. I lost my furry soulmate in Jan '04...and think of her often, loss is hard to grasp.  I sometimes wonder if God had my dog go emotionally prepare me for my parents. Either way, it is a struggle every day.

My thoughts are with you.


Customer: replied 11 years ago.
 Dr. Vamvakias, thank you so much for your replies.  I
greatly appreciate the quality and timeliness of your answers!  I
can tell by your professional yet personal manner that your clients at
your hospital have a wonderful doctor for their furry friends.

Thank you again. Take care.

 Thank you.


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