Feline plasma cell neoplasia in a cat presenting with severe acute haematuria

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feline plasma cell neoplasia
Oscar, the patient

Advances in mobile, at-home veterinary care have been aided by the accessibility of high-quality technology and equipment, including portable tools such as microscopes, ultrasound units, and hand-held blood analysers. In this case study, we discuss how complex diseases, such as feline multiple myeloma, can be diagnosed and treated effectively under the care of a skilled home visiting veterinarian with the right tools and resources.

Oscar is a 15-year-old male desexed domestic shorthair cat who presented to our mobile emergency veterinary practice with an acute onset of severe haematuria and stranguria starting about four hours prior to evaluation. Oscar’s medical history included subtle but progressive changes to his mobility and willingness to jump on furniture in the preceding six weeks. On clinical examination four months prior, he had cardiothoracic auscultation and blood testing performed, which revealed a normal biochemistry and haematology panel, including normal renal parameters and electrolytes.

On examination for his acute urinary tract signs, Oscar was found to have a new grade IV/VI parasternal systolic heart murmur, mild tachycardia (HR 236bpm), mild tachypnoea (44rpm), and was continuing to frequently pass small volumes of dark red urine with moderate discomfort. Buprenorphine analgesia was administered (0.02mg/kg IM, with an ongoing Rx of 0.02mg/kg OTM q8-12h PRN). Venous blood samples and sterile cystocentesis urine samples (obtained with ultrasound guidance) were obtained at his home for submission to a local diagnostic laboratory. His clinical signs dissipated over the following 12 hours with analgesia alone by which time laboratory results became available.

Oscar’s testing revealed several abnormalities: a mild non-regenerative, borderline microcytic and hypochromic anaemia (HCT 22%; RBC 6.05 x 10^12/L, suspicious for iron deficiency); marginal thrombocytopaenia (PLT 234 x 10^9/L); mild hyponatraemia (Na+ 143mmol/L); hypokalaemia (K+ 3.4mmol/L); a moderate azotaemia (Creatinine 224umol/L, Urea 13.4mmol/L); and most notably, a severe hyperglobulinaemia (Globulins 114g/L). 

A pathologist review of his blood smear revealed several large lymphocytes, evidence of potential lymphoid neoplasia. The overall diagnostic and clinical picture pointed toward an immunoglobulin secreting neoplasm, such as B-cell lymphoma or multiple myeloma/plasma cell neoplasia. Oscar was admitted to hospital for overnight intravenous fluid diuresis and supportive care. 

feline plasma cell neoplasia
Dr Cunningham and Nic Saunders 

After ~24 hours of IV fluid therapy, Oscar’s Creatinine value improved to 185umol/L, and he did not develop recurrent lower urinary tract signs. He also had a significant improvement in demeanour and appetite. Urinalysis results became available, revealing near-isosthenuria (USG 1.014) in the face of azotaemia; pH 7.0; protein 1+; significant haematuria (RCC 650 x 10^6/L) and pyuria (WCC 110 x 10^6/L); no visible bacteria and occasional amorphous phosphate crystals. 

Urine culture was requested at time of submission, and a urine electrophoresis test was added to the diagnostic investigation. End-organ damage secondary to hyperviscosity syndrome was the primary concern regarding his azotaemia. Faecal output had notably decreased in the days leading up to illness, so lactulose therapy at 1-2mL PO q8-12h was instituted which improved his faecal consistency over the coming 12-24 hours. Fluid diuresis was continued for an additional 24 hours thereafter with a plan to pursue further investigation the following day.

By then, Oscar’s appetite, bowel movements and demeanour had improved with ongoing fluid support. A recheck of his bloods revealed a further decrease in Creatinine (176umol/L). However, his hyperglobulinaemia and anaemia worsened (HCT 19%; Globulin 135mmol/L). Neurologic examination did not reveal deficits, and fundic examination did not reveal evidence of haemorrhages or significant changes.

Oscar’s family elected for him to be discharged home for ongoing monitoring and supportive care with the ultimate decision to forego the more aggressive diagnostic option of a bone marrow aspirate under general anaesthetic. A home visit by the mobile emergency veterinary service was initiated to pursue an abdominal ultrasound with organ aspirates as a next diagnostic step. 

feline plasma cell neoplasia
Splenic cytology

Point-of-care ultrasound was performed with a wireless handheld ultrasound probe and iPad set-up at Oscar’s home. Ultrasound revealed evidence of mild splenomegaly with mild heterogeneity and a hypoechoic liver with otherwise normal architecture. No evidence of lymphadenopathy was observed. Fine needle aspirates of both the liver and spleen were obtained without complication for submission to a clinical pathologist. A cursory review of the slides by the attending emergency vet revealed a large population of plasma cells in both organ samples, with the plasma cells displaying criteria of malignancy 

The next day, urine culture results revealed heavy growth of partially antimicrobial sensitive Pasteurella sp., thus Enrofloxacin 5mg/kg was initiated IV for treatment of bacterial urinary tract infection with consideration of potential pyelonephritis. Cytology review of the liver and splenic aspirates obtained confirmed suspicions of plasma cell neoplasia, with marked anisocytosis, anisokaryosis, variable N:C ratios, and frequent binucleation and multinucleation. 

Urine protein electrophoresis confirmed a monocloncal gammopathy with evidence of Bence-Jones proteinuria. A veterinary oncologist was engaged to discuss Oscar’s case, and the decision was made to initiate immunosuppressive prednisolone (2mg/kg/day PO) followed by the addition of melphalan chemotherapy once ordered into a local human chemist. 

We chose to use a more recently studied pulse dose protocol for melphalan (7 mg/m 2 q 24 hrs for 5 consecutive days every 3 weeks) on advice from an oncologist, as this meant Oscar, a pill-intolerant cat, would only require tableting periodically rather than every single day. His ongoing chemotherapeutic regimen will be adjusted based on periodic physical examination and serial blood test monitoring to evaluate his globulin levels and degree of potential immunosuppression/leukopaenia.

Multiple myeloma is a rare cancer of cats, representing only 0.9% of all feline malignancies. It is most often reported in geriatric domestic shorthair cats (median age 12-14 years). There are several negative prognostic factors that if present at time of diagnosis carry a worse prognosis (such as azotaemia, hypercalcaemia, evidence of immunosuppression or concomitant infections, and evidence of hyperviscosity syndrome). 

While multiple myeloma has a worse overall prognosis in cats than dogs, there are a number of affordable metronomic chemotherapeutic options available to treat these patients.

Oscar’s diagnosis was primarily achieved in the comfort of his living room under the care of our two-person vet and vet nurse team. We hope that all veterinarians, but especially those in mobile or home visit practices, are reminded that the scope of capability does not need to be limited by the size of your clinical team or your facilities.


Dr Paul Cunningham DVM MANZCVS (Emergency & Critical Care)

feline plasma cell neoplasia

Co-founder and chief veterinarian, Ready Vet Go 

Dr Paul Cunningham started his career in his home country, the United States. He obtained his DVM at Oklahoma State University and followed this with a rotating medicine and surgery internship at Michigan State University. He practised in the Detroit, Michigan metropolitan area for several years in a multi-speciality 24-hour hospital group before moving to Melbourne in 2021 during the COVID pandemic. 

Dr Cunningham quickly took up study to become a member of the Australian and New Zealand College of Veterinary Scientists (ANZCVS) in Emergency & Critical Care in 2023. 

Just prior to that, he launched Ready Vet Go. The service was founded with his partner Nic Saunders, a human nurse with a paramedic background. The ethos of the service is grounded in providing compassionate care to help bridge the gap between home and hospital. 

Ready Vet Go’s success lies in the evidence-based approach adapted from the human ambulance sector that ensures improved patient outcomes by providing pre-hospital and inter-hospital emergency and critical care support. 

The service sets itself apart by having a two-person veterinarian and veterinary nurse team on board to provide oxygen and ventilatory support, on-scene shock and polytrauma stabilisation, and an array of basic and advanced life support options. 

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