What can cause fatal seizure in 2 different dogs in a short time?

Last week, my 3.5 years old dog died after 3 days of seizures that started unexpectedly and visibily caused him damage, because he wasn't himself anymore between them. His seizure was more like gran mal, collapsing on one side, paddling and foaming at the mouth, that's why the local vet thought it was epilepsy. 2 days ago, I noticed that his mother (don't know exactly her age, but we got her from the streets 5 years ago as an adult, so she might have been 7-8 or older) was panting hard at night, losing her balance like she was trying not to collapse on one side and her head was shaking and tilting. This episode was very short and she acted normally afterwards. The next day she didn't want to eat anymore and she seemed pretty lethargic, like she wasn't even barking anymore. Yesterday she was ok in the morning, but when the heat started she began to excessively pant, drool, the seizures I mentioned she had that night started again, but more violent like she was about to get into a wall and urinated involuntarily (the urine was looking normal tho). I thought it was a heat stroke, splashed water on her, put a wet towel under, gave her an antispasmodic shot and she got better for a while, but then she refused to drink water, became restless running around, the seizures got worse with nystagmus and she finally crossed the rainbow bridge as well, exactly one week after her son... Please don't judge me, but here where I live in the countryside I don't have access to ER services for pets, a big clinic where to do tests and we don't even own a car. I wished I could have had the resource to do more. I'm terribly in shock... What do you think it could have been? Could it be distemper? Could it be heat related since it's started since the temperatures went very high (they are outdoor dogs, but are sheltered in a shadowed place and we change their water many times a day). I'm starting to worry for the other ones... 🥺

Hi - With regards to Distemper, what country are you in?   -  this is a UK site and Distemper is rare here but it is not the same everywhere.  Secondly, heat stroke and fits can look very similar and it is less about what they look like, than the circumstances in which they happened.  Taking the temperature of fitting dogs is a mug's game (I know you haven't suggested this) because as well as being dangerous, they are almost always hot because of the muscle contractions anyway (therefore still difficult to know whether the fitting happened because of a high ambient temperature in the first place, or not).  Again, are you living somewhere / were circumstances such that this seems likely?  Could you leave a thermometer in the hottest and shadiest places there?  (Obviously if there are a lot of dogs and limited shade, territory disputes could mean that some dogs don't get to lie in the shade, even if there ought to be space).   If you are even considering heat stroke as an option, be sure to do everything you can in terms of shade or indoor options for the other dogs.  Other causes of fitting include head injuries, clotting problems, brain tumours, very high blood pretture for various reasons, but it seems quite a coincidence for this to happen in two dogs at the same time.  Heat would be likely to affect some dogs not others.  Toxicity (poisening), affecting the liver or kidneys, could also be on the list of cause.  So could genetic conditions.  I hope that this hasn't muddied the water further - I hear that resources are limited, but the best way to understand what the local vet has on their differentials list (possible causes  that can't be ruled out) is always to ask.  Let me know if you need information about distemper.

Finally - and I was so interested in the question than I haven't said this - I wanted to let you know how sorry I am to hear about these circumstances.

I'm living in Bulgaria and I've heard about some cases of distemper in childhood, but not so much recently, so idk. I would like to know more information tho, please. And I was also thinking about one thing. Many times my dogs go to play in the field behind my yard and there's a spot where people throw away garbage and especially dead birds like chickens, ducks etc. Sometimes they ate them, even in a rotting disgusting state, but nothing happened to them. One week before the first dog getting sick, my parents found some feathers in the backyard. Is it there a possibility for the consuming of rotting birds to cause such consequences in dogs?

hi. i am not a vet and have zero science aptitude and am unsure if it's ok for me to even comment. please forgive me/let me know if this is a no no. I live in small city south america, with a dog who was once diagnosed with placenta passed distemper in a very different situation but one, like yours i imagine, in which the phases that typically accompany that diagnosis were not reflected. Just here to comment that what you describe is also what has happened to a cat and a dog of different friends and speculated to be toxin related. did they happen to do blood tests? I wouldn't know anything specific , but my friend sent me the highly abnormal blood tests of her dog, who passed a away a couple days after similar symptoms.  In these situations i believe it's thought that the toxins were intentionally put/left where the animals could/would consume them.  There are many strays where we live, and sometimes toxins are intentional- but it doesn't seem that is suspected and you're out in the country- but things like pesticide treatments (which may not be a thing- i am not farmy) maybe? I don't think i have anything specifically helpful to suggest other than i would probably try to keep the other animals away from that area of garbage and dead animals for sure. Did/could your vet share if this is happening more frequently/is typical for your area?  And sorry if this is insensitive suggest- but if possible for your vet to do any testing that could determine bacterial/fungal/parasitic/toxic on any samples-  i wonder if they could learn anything that could be helpful re: the other animals.  My dog's specific past re: environment re: bugs, ticks, non-drinkable water, naturey stuff, jungly stuff have = a complext past and i have googled a lot, and have no knowledge, but understand terrible mysterious symptoms and living in places where there may be similar circumstances- and i am so so sorry to hear about your losses (i apologize for commenting if that is not ok).

and sorry, as this may be icky of me to suggest and unsure if possible- but i have tried and failed a few times to preserve the ticks and then a mystery insect- and know a dead bird/duck is much more of a situation- but vets have expressed how helpful it would have been had been able to have those things tested (and i would 100% have zero idea how one would approach, safely, picking up/transporting  one of those ducks/ birds- ideally though a town agency who has a person trained to do that with whatever total protective everything on them.. or who could test them- but if you live near any university towns, that's a possibility (i had planned to spend couple months between Plovdiv, Burgas, and Sofia but, covid- i hear it's beautiful).- It's possible that a vet school/academic team would be interested in trying to to identify anything in the dead birds/ducks (soonish). sorry. I am out of practice with social cues but I am always an advocate of contacting universities. I hope this wasn't inapproriate to suggest. sorry