Scotty Smith, a 10.5-year-old, FS Labrador mixed breed was presented for further evaluation of non-regenerative anemia.  Signs had started about one month prior to presentation and initially started as loss of appetite.  She was also reported to have vomited a black tar-like substance prior to signs starting but did not have ongoing vomiting and had normal stools.

She was initially seen by another emergency facility where blood work revealed severe non-regenerative anemia with a hematocrit of 14%, mild thrombocytopenia or artifact with 147k platelets, and 7,000 reticulocytes confirming the anemia is not regenerative.

 

Abdominal imaging revealed a nodule or mass-effect in the left adrenal gland that did not appear to have vascular invasion on ultrasound.  A 4DX was negative and chest radiographs were unremarkable.

Her only other pertinent history was a history of mast cell tumor removed surgically in 2018.  She is current on vaccines and up to date on Trifexis. 

She was started on immune-suppressive prednisone therapy at 2 mg/kg/day along with ondansetron as needed for any nausea and chronically takes diphenhydramine for skin allergy issues.

It was recommended for her to have a left-sided adrenalectomy along with bone marrow cytology.  Prior to scheduling these procedures, the owner wished to have another opinion so was presented to the internal medicine department at HOTVSC.

On presentation, she had a soft heart murmur grade 2/6 but otherwise a fairly unremarkable exam.  Rectal exam was normal, and her gums were pale.  She was reported to still be picky at home and had not regained her appetite though some improvement was seen on the prednisone.

Further evaluation of the red cell indexes on the previous CBC revealed a low MCV and a new CBC pathologist review did not reveal any current evidence of spherocytosis, ghost cells, or agglutination.  This was performed knowing the caveat that she had been on immune-suppressive prednisone for almost one month.  However, the PCV remained low at 14%, so it was determined that either the diagnosis was not correct or adjustment in immune-suppression therapy was needed.  Serum gastrin levels were also obtained prior to starting antacid therapy and returned in a normal range.  Gastrinomas are uncommon but can cause severe gastric ulceration in older dogs.

These cases can be tricky at times because we know bone marrow level auto-immune anemias can take months to respond to treatment.  Trying to decide whether to add immune suppression or to reconsider the diagnosis is always done on a case-by-case basis for me.  The other differential that is often forgotten especially in larger dogs is chronic blood loss anemia.  These anemias are regenerative early on and become non-regenerative later when iron stores become depleted.  The MCV does not always need to be low, but often can be when iron stores are depleted.  The overall lack of other evidence of immune destruction along with the low MCV and history of vomiting black tarry mucus material (suspect for blood) prompted me to change treatment to an aggressive antacid treatment plan with iron supplementation.  It is also very rare to see gross melena if the anemia occurs slowly enough.

Interpreting serum iron levels can be tricky especially in more chronic cases and in cases where dogs are on high doses of steroids.  Bone marrow sampling is a good way to look at iron stores but is a relatively expensive and mildly invasive test.  Often if there is enough evidence, I will treat with a single iron dextran injection of 10-15 mg/kg IM and start the patient on sucralfate q8h and omeprazole at 1 mg/kg q12h.  For this patient, I also decreased prednisone to physiologic dosing to hopefully better allow any possible ulcers to heal. 

Traditional or video capsule endoscopy and be performed to look for ulcers.  Because there are few downsides to antacid trials, I often will treat and look at response to therapy rather than pursue an anesthesia procedure.  I also always confirm monthly parasite prevention because I have also diagnosed this problem in adult dogs with hookworms if not on routine preventatives.  I find most of these patients will rapidly improve within 1-2 weeks of being on appropriate therapy.  If response is not seen, bone marrow sampling and moving forward with endoscopy are indicated.

If response to therapy is seen, antacid therapy is slowly tapered over several weeks or months.  Depending on the age of the patient, I may leave them on some level of antacid medication chronically.  It is rare in my experience for dogs to require more than one iron injection. 

Through the years I have found that many more dogs with non-regenerative anemias appear to have subclinical gastrointestinal ulcers rather than primary bone marrow disease.  In this patient, the low MCV, black tarry vomit, lack of improvement on immune suppression, and mild thrombocytopenia all fit clinically better with a diagnosis of iron deficiency anemia than with a primary bone marrow level anemia.  However, each case is different and sh

Crystal Hoh DVM, MS, DACVIM

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