Immune Mediated Thrombocytopenia

Pet Tales
by Barry B. Burtis D.V.M.

Immune-mediated Thrombocytopenia

Her name was Asta and she certainly deserves a few words of remembrance, on her passing. According to her breed's description in Dogs Annual in Canada, "pep and personality are two key words in describing the wire fox terrier". Anyone who knew Asta would agree, she was the embodiment of those two traits.

We first met Asta at our animal hospital ten years ago, when she was just six years old. In routine blood tests performed on that visit, it was found that she had a slightly lower number of platelets than normal, in her circulation. Platelets are small circular or oval discs found in the blood of all mammals. Their major function is to help form blood clots to stop bleeding. When this finding was reported to Asta's owner, we learned a similar problem had been noted and treated two years earlier. Although, with medication, she recovered uneventfully from both these early episodes of trouble, it was to foreshadow what was to become a recurring and at times critical and life-threatening problem for this fine little dog.

Asta was a victim of the disease known as immune-mediated thrombocytopenia (ITP). It is one of these diseases, not yet completely understood, where our body's immune system fails us. Instead of giving protection against an invader or something different to which our body is exposed, the immune system begins to attack parts of our own body. With ITP, the immune system begins to remove platelets. Destruction of large numbers of platelets can lead to pinpoint bleeding in the skin or gums or may appear as nosebleeds. Occasionally, blood can be seen in the stool or urine. Severe anemia can result from excessive bleeding. Any breed of dog may be affected but cocker spaniels, poodles and Old English sheepdogs seem to have increased risk of developing the disease. Females are affected twice as frequently as males. ITP occurs only rarely in cats.

After those first two bouts with ITP, Asta had no recurrences of the disease for over two years. However, she did have problems with a recurring, shifting leg lameness. Veterinary specialists, consulted at that time, suspected an immune-mediated polyarthritis was responsible. She also suffered frequent periods when her skin was extremely itchy and uncomfortable. Both these problems pointed to an immune system that was not working properly.

After that brief two year respite from ITP, in each of the following two years, Asta had recurrences of ITP that required medical treatment.  Then, in the fall of 1999, Asta experienced a much more severe attack. Associated with that occurrence of trouble, she developed a severe anemia secondary to gastro-intestinal blood loss. When treatment with the usual drugs failed to halt the platelet destruction and blood transfusions failed to resolve the anemia, she was referred to the intensive care unit (ICU) at the Teaching Hospital of the Ontario Veterinary College. Here over a period of five days, with the help of more blood transfusions and a new regimen of medicines, including the use of certain immuno-suppressive drugs, considered experimental at that time, Asta rallied
and made a successful recovery. Unfortunately, it was not to be the last time she would require the medical expertise and support of the Guelph veterinary team.

ITP can be either primary - in which case no underlying cause of the immune destruction can be found - or secondary, where the immune attack is directed against an underlying condition such as cancer, infection, a drug or toxin exposure. Hence from the very beginning of Asta's battle with the disease, in addition to all her trips for medicines and treatment, she underwent a multitude of diagnostic tests. There were repeated blood tests to monitor her disorder, blood tests to rule out other immune diseases, such as lupus, urine tests, chest x-rays, chest and abdominal ultrasound examinations. All these Asta handled with never a whimper, a whine or other complaint. Asta, we learned, had primary ITP.

With advancing age and other health issues, some influenced by her need for constant medication to try and suppress her faulty immune system, Asta continued to be susceptible to ITP. In the last four years of her life, she was admitted to the ICU in Guelph another four times for life-saving therapy. On one of these admissions she was diagnosed with Evan's syndrome, a condition that causes a dog's immune system to destroy both their red blood cells and their platelets. On each of three of those occasions, though, Asta showed her resilience, her strength and her indomitable spirit and again recovered. Sadly, her most recent visit to the ICU, was to have another outcome. Though initially she appeared to be improving, after several days in a relapse of ITP, she fell into a coma and passed away.

Now on reading her story, some will despair and think only how sad that Asta was afflicted with such a disease. I, also, wish she had not had such health problems, yet, when I think of Asta, I smile and I marvel. She was such a wonderful little dog, in her sixteenth year, when she died. She would not be defeated by her illness, she overcame it. I do not remember her, in her illness, instead, I remember a friendly, happy, outgoing little dynamo. She was blessed with dedicated, loving owners, now grieving her loss. They were willing and able to pay back to her, with years of attention, commitment and caring, the joy, happiness and love that Asta gave them. Asta's bravery, her stoicism, her gentle nature, her outlook on life never wavered. Her trail of admirers - family, friends, veterinarians, veterinary technicians, in fact, just about anybody she ever crossed paths with - is a long one. Was that not a life worth living? Is that not a most honourable legacy?