Canine AutoImmune Thrombocytopenia
Shirley writes: Our dog died two days ago and the symptoms were those associated with ingesting rat poison. But we don’t have any poison in our house or in our yard. We don’t have rats. We adopted our dog four weeks ago (three years old about 55 pounds). We were with him when he was anywhere out of our house or yard. Could the poison have been in his food? Is it possible he ingested the poison before he came to live with us (four weeks prior to his death)? He was at a city shelter for several months, so it is unlikely he would have been around poison. I know I can’t change the outcome, we are very sad, he was so good for us, but I feel so awful and would like to know how long the poison can stay in a dog before he dies. He went for a long walk in the morning and a shorter one in the afternoon. He was fine. We went out to dinner, got home to find him limp. The ER doctor could not save him. Shirley, please accept our condolences on the loss of your beloved pet. We understand how hard it is to lose a pet, especially when the circumstances come so suddenly.While your pet has symptoms similar to anticoagulant rodenticide poisoning,
it is more likely that he suffered from a problem that kept him from clotting his blood as he should, most likely autoimmune thrombocytopenia or AITP, also known as Immune-Mediated Thrombocytopenia or IMTP.
AITP is an attack on the platelets of the body. Platelets are fragments of cells called thrombocytes and are very important in the clotting of blood. If platelet production is too low, or platelet destruction or usage is too high, normal clotting fails and bleeding ensues. In the case of autoimmune thrombocytopenia, platelets are diminished because of an attack by the immune system. For whatever reason, the immune system begins to think the thrombocytes and/or platelets are foreign objects in the body and need to be removed.
The trigger for this condition is almost never identified.
Autoimmune thrombocytopenia usually has a very rapid course. Onset is usually “sudden.” I put sudden in quotation marks because we rarely know when the actual beginning of an episode is, we only know it’s going on when we see evidence of bleeding.
Treatment usually begins with a transfusion of platelets. Platelets are rarely available anywhere but an emergency or referral center, so your pet’s doctor usually doesn’t have them sitting on his shelves. Whole blood transfusion doesn’t include enough platelets to suffice, although it is better than doing nothing and the loss of red blood cells and volume still needs to be accounted for.
Many of these patients die because the process has gone too far by the time treatment has begun, because of lack of platelet availability, or because the immune system’s attack cannot be stopped.
For completeness’ sake I will address your other questions.
While you don’t have rats, plural, it takes only one. Dogs eating a mouse or rat with active rodenticide in its gastrointestinal (GI) tract can easily become poisoned. A thorough necropsy of the entire GI tract might locate such an animal or its parts. Modern rat poisons are very effective in very small amounts, so the quantity a mouse might eat could easily poison a 55-pound dog.
Poison he might have been exposed to weeks ago would not take this long to cause problems. If rodenticide was his problem, he ate it very recently. The likelihood of rat poison being in his food from the manufacturer is close to zero.
All of our readers share in your sense of loss.
See you tomorrow, Dr. Randolph.