Uncovering a Mysterious Anemia: Paxton’s Not Off the Hook

Overview

As a young puppy, Paxton was treated successfully for a steroid-responsive meningitis, but he re-presented at the animal hospital for routine vaccines looking white as a ghost. Concerned about what might be causing the apparent anemia, his healthcare team methodically stepped through differentials and diagnostics to pin down a surprising diagnosis.

Case Details and History:

Paxton had previously been to the animal hospital as a puppy, referred by his regular veterinarian because he had developed neurologic signs of inappropriate mentation and demonstrative neck pain. Through CSF analysis, Paxton was diagnosed with meningitis that responded well to immunosuppressive doses of steroids. The hospital was seeing him monthly during his treatment and recovery. Paxton had been doing well and had tapered off steroids. He was now back at the animal hospital to catch up on his routine vaccinations that had been postponed with his illness.

Physical Exam

Paxton presented at the hospital happy and energetic with the owner reporting no problems or concerns at home. During the routine pre-vaccination physical exam, however, the clinician noticed that Paxton’s gums were very white. Concerned about an apparent anemia, the clinician ordered blood work, suspecting either IMHA (immune-mediated hemolytic anemia) given that Paxton had already had one immune-mediated condition and was now off all medications, or possibly occult internal bleeding. As soon as his blood work was submitted to the lab, Paxton was transferred to the ultrasound table.

Diagnostic Process

• Paxton’s ultrasound showed no internal bleeding — no hemoabdomen, hemothorax, or hemopericardium.
• Paxton’s CBC revealed a hematocrit of 11%. If he’d had a fast drop in hematocrit, Paxton would be clinical for anemia. But mom hadn’t seen any problems at home, and the 50-pound Paxton was bouncing happily around at the hospital, so the team now needed to tie together what they knew about Paxton’s history, the physical exam, and the lab work to understand that 11% hematocrit.
• When reviewing the CBC for a patient with anemia, the red blood cell indices help describe the anemia, including reporting of the RBC size (MCV, mean cell volume) and the hemoglobin concentration (MCHC, mean corpuscular hemoglobin concentration).
  • Finding: Paxton’s MCV was very low, termed microcytosis. The MCHC was also low, referred to as hypochromia (“low color” because of the decreased pink color attributed to hemoglobin).
  • Paxton’s pattern of a microcytic, hypochromic anemia was consistent with iron deficiency anemia.
  • Blood Film: Review of Paxton’s blood film revealed additional important diagnostic information.
    • Finding: In Paxton’s case, his red blood cells had a significantly expanded central pallor (hypochromia) with most cells staining very pale with only a thin rim of pink-staining hemoglobin. Since hemoglobin is bound to iron within RBCs, less visible hemoglobin in the cells indicates iron deficiency.
    • Assessing whether cells are microcytic can be challenging without a reference point. In Paxton’s case, it was noted that many of his red cells were the same size as his platelets, which are generally very small (much smaller than red blood cells in healthy dogs.

Differentials for iron deficiency anemia include causes for chronic occult blood loss. More rapid blood loss from hemoabdomen or traumatic hemorrhage are likely to result in clinical signs of hypoxia and hypovolemia and a much different clinical presentation. Iron deficiency is more commonly associated with focal GI tumors in older dogs with slow intestinal bleeding and GI parasitism in younger dogs, which was the greater concern for Paxton.

Diagnostics Round Two

• Looking for GI parasites, Paxton’s team performed a fecal flotation that identified numerous hookworm (Ancylostoma caninum) ova in Paxton’s stool sample.
• As parasitologists have become increasingly aware of multidrug resistance in hookworms, specifically, Paxton’s team additionally requested Antech’s KeyScreen™ GI Parasite PCR testing that includes markers for the genes that confer this resistance.
  • Performed at the Reference Lab, KeyScreen is a molecular diagnostic test that screens for 20 intestinal parasites, additionally identifying treatment-resistant hookworm strains and the zoonotic potential of Giardia.

Diagnosis and Treatment

Paxton’s fecal results confirmed the presence of hookworm ova, and KeyScreen confirmed that these hookworms were not drug resistant. Paxton was then treated with a routine deworming protocol as well as a multivitamin containing iron to help replenish his stores.

Paxton was rechecked at ten days (his owner had been advised to come in sooner if he wasn’t doing well) and he had turned the corner. His hematocrit had risen 10% and continued to slowly recover over the following months without incident.

Case Impact

Sometimes when a pet comes to the hospital with a disease that needs urgent care and intense treatment, routine care can become deprioritized. Every member of the patient’s care team—doctors, technicians, and assistants—must remain vigilant about preventive care, all double checking to ensure that the very basics are monitored and completed, and that owners are educated about the importance.

The CAPC (Companion Animal Parasite Council) recommends repeated fecal examinations and deworming during a puppy’s first year of life. In Paxton’s case, his routine puppy care had stopped when he was referred for meningitis. Not only was he not receiving repeated fecal testing and deworming, but he was also additionally immunosuppressed over the course of months, allowing the hookworm infection to grow unchecked. Routine fecal testing with KeyScreen could have identified the presence of parasites earlier — and more sensitively than fecal flotation alone —resulting in earlier treatment and avoiding this pale patient panic.

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