Thank you for your prompt reply.
First off, I am sorry to hear of your loss. I can onle speak by stating statistics....sudden unexpected death for a 15 yr old dog is usually from cardiac arrest. Being a shepherd chow cross, a tumor on the spleen called a hemangiosarcoma is also likely.
Rarely do 15yr old dogs pass away from anything infectious but to be safe I would still have your other dog checked out by your vet.
Sorry again
Dr
Redford
I understand how difficult that must have been for you. I lost my first pet I had as an adult in a similar manner. He was a 14 year old rescue greyhound and was amazing. It is difficult of course to say what happened but statistically speaking, sudden death in a senior dog is most commonly a heart attack. In your case however, the symptoms you are describing, and with your dog being part shepherd I worry about a tumor on the spleen known as a hemangiosarcoma. These tumors can develop and not show any signs for months and then one day they rupture and internal bleeding occurs. Often the dog then passes away from internal blood loss within 12 hours. I wish I could tell you more info with more certainty, I can reassure you though and say likely the sibling is not at risk of an infectious agent. To be sure have the veterinarian examine him/her in the next week or two.