Erythrophagocytic multiple myeloma in a cat

A 7-year-old neutered male domestic shorthair cat was presented to the Veterinary Medical Teaching Hospital at the University of Georgia for further evaluation of a suspected osteolytic lesion of the left 10th rib. Results of a CBC and biochemistry profile revealed mild nonregenerative anemia, hyperproteinemia, hyperglobulinemia, and hypercalcemia. Serum protein electrophoresis was consistent with a monoclonal gammopathy. Marked proteinuria with an increased urine protein to creatinine ratio was found. Cytologic examination of the liver, spleen, and bone marrow revealed numerous plasma cells, many of which were erythrophagocytic. Within the bone marrow, the plasma cells contained phagocytosed metarubricytes in addition to phagocytosed erythrocytes. A diagnosis of erythrophagocytic multiple myeloma was made and treatment with prednisone and melphalan was begun. Four weeks after presentation, the cat was euthanized due to clinical deterioration. A complete necropsy was performed. The distal one-third of the left 10th rib was completely absent. Histologically, there was no evidence for osteolysis or neoplastic cells in the remaining portion of the rib. However, large sheets of plasma cells were found infiltrating the spleen and bone marrow. Moderate erythrophagocytosis by the plasma cells was observed in both organs. The plasma cells, including the erythrophagocytic cells, were positive for CD79alpha by immunohistochemical staining. Erythrophagocytosis by plasma cells as a cause of anemia is uncommon in people with multiple myeloma and is rare in animals. To our knowledge, this is the first report of erythrophagocytic plasma cells in a cat with multiple myeloma.     

Detection of biclonal gammopathy by capillary zone electrophoresis in a cat and a dog with plasma cell neoplasia

Gammopathies associated with plasma cell neoplasms in a 15-year-old female spayed domestic shorthaired cat and a 9-year-old female spayed Rottweiler dog were evaluated by serum protein electrophoresis. In the cat, the plasma cell neoplasm was found in the liver and spleen, and an evaluable sample of bone marrow was not obtained. Some of the plasma cells had the morphologic appearance of flame cells. The paraprotein was confirmed as IgG based on agar gel immunodiffusion precipitation and both immunocytochemical and immunohistochemical staining. The dog had multiple myeloma with production of IgG and IgA paraproteins. In both cases, serum proteins were evaluated by 2 methods of protein electrophoresis: cellulose acetate electrophoresis (CAE) and capillary zone electrophoresis (CZE). In the cat and the dog, CAE showed a single large oligoclonal-like peak, which occurred in the γ-region in the cat and the β-γ-region in the dog, whereas CZE showed a biclonal gammopathy with 2 very close narrow spikes in the γ- and β-γ-regions in the cat and dog, respectively. In selected cases, CZE may be more effective than routine CAE in distinguishing oligoclonal from monoclonal or biclonal paraproteinemia.     

Caecal duplication in a 13‐year‐old Thoroughbred

A 13‐year‐old Thoroughbred gelding was presented for evaluation of recurrent colic of 4 weeks duration. These colic episodes were mild and responsive to medical therapy. Episodes of colic became more frequent and more painful. Exploratory laparotomy revealed a large intestine duplication with a cystic structure located at the caecocolic junction that was unable to be exteriorized and therefore not amenable to surgical correction. Thirty‐six hours following surgery, the horse became acutely painful, sweaty, and febrile suggesting gastrointestinal rupture. Post mortem examination showed a 0.6 × 1 m duplication and a 0.5 × 0.6 m cystic dilation that was probably associated with the caecum. There was a 10 × 30 cm area of rupture located within the duplication. Histological evaluation confirmed the presence of a true duplication.     

B‐cell intestinal lymphoma with Mott cell differentiation in a 1‐year‐old miniature Dachshund

Abstract: A 1‐year‐old intact female miniature Dachshund was presented with hematochezia, vomiting, and diarrhea of more than 1‐week duration. An abdominal mass was palpated, which at exploratory surgery was found to be a 7‐cm‐long thickened section of ileum. The thickened ileum was resected. Impression smears revealed numerous small‐ to medium‐sized lymphocytes, with a smaller number of cells resembling Mott cells. The Mott‐like cells contained multiple pale vacuoles that were positive for periodic acid‐Schiff (PAS) in wet‐fixed smears, consistent with Russell bodies. Histologic evaluation of the surgically excised ileum revealed 2 populations of neoplastic lymphoid cells. The majority were uniform medium‐sized lymphocytes with hyperchromatic oval or round nuclei and inconspicuous nucleoli. The remaining cells resembled Mott cells, which contained several PAS‐positive eosinophilic globules in the cytoplasm, occasionally compressing the nucleus. The majority of neoplastic cells stained positively for vimentin, CD20, CD79a, and Pax‐5, but were negative for CD3 and lysozyme; 43.5% of cells stained positively for Ki‐67. The Mott cells were strongly positive for immunoglobulin but were negative for Pax‐5. Using electron microscopy, a homogenous substance of intermediate electron density was observed frequently in the cisternae of rough endoplasmic reticulum in the cytoplasm of the Mott cells, and rarely in the perinuclear cisternae of the lymphoid cells, corresponding to the site of immunoglobulin staining. Monoclonal rearrangement of immunoglobulin heavy‐chain (IgH) gene was observed by PCR testing for lymphocyte–antigen receptor rearrangement. The morphologic features, immunophenotype, and IgH gene rearrangement verified the lymphoid cells were neoplastic (mature cell type) and had a B‐cell phenotype, with evidence of immunoglobulin production and differentiation into Mott cells. This case was unusual because of the age of the dog and because most intestinal lymphomas are T‐cell phenotype. The Mott cell morphology also differed from typical mature B‐cell lymphoma types and may be a unique B‐cell lymphoma variant.     

Mandibular squamous cell carcinoma in a 5‐year‐old Tennessee Walking Horse

Squamous cell carcinoma (SCC) is the second most common neoplasm reported in the horse, but occurs rarely in the oral cavity. Clinical signs may be insidious in onset and mimic other non‐neoplastic processes, thus delaying appropriate treatment. Timely evaluation and advanced diagnostic imaging may offer the opportunity to initiate definitive treatment. This report describes a young gelding with mandibular SCC that was evaluated for mandibular swelling failing to respond to symptomatic therapy.     

Splenic mast cell tumour and mastocytaemia in a cat: case study and literature review

Case: An 11-year-old female domestic shorthaired cat presenting with clinical signs of depression, anorexia, weight loss, fever, anaemia and a mid-abdominal mass was referred for abdominal ultrasound examination.

Clinical findings: Ultrasonography of the abdomen identified a markedly enlarged spleen. Ultrasound-guided fine- needle aspiration biopsy of the spleen revealed a uniform population of mast cells, 11% of which were observed to have phagocytosed erythrocytes. It is speculated that this may have been a contributing factor in the development of anaemia in this case. Mast cells were detected in a peripheral-blood smear and a diagnosis of systemic mastocytosis (splenic mast cell tumour together with mastocytaemia) was made. This diagnosis was subsequently confirmed by histopathology of the spleen.

Conclusion: Splenectomy and treatment with corticosteroids appears to have resulted in remission of clinical signs and anaemia. A reduction in the concentration of mast cells in the peripheral blood had not occurred 6 weeks post- splenectomy, but was evident by 10 months post-splenectomy.     

Transitional cell carcinoma of the urinary bladder in a 12‐year‐old Belgian Warmblood gelding

A 12‐year‐old Belgian Warmblood gelding was examined for haematuria and dysuria of 24 h duration. Cystoscopy revealed an intraluminal multinodular soft tissue mass originating from the dorsal bladder neck. Histopathological examination of biopsies identified transitional cell carcinoma. The bladder mass was surgically debulked via a temporary perineal urethrotomy. The horse commenced treatment with oral piroxicam. Follow‐up examination 18 months post operatively revealed no evidence of tumour recurrence. Neoplasia of the equine bladder is uncommon and this case describes the successful short‐term outcome of treatment of a transitional cell carcinoma by surgical debulking and oral piroxicam.     

X‐linked CD40 ligand deficiency in a 1‐year‐old male Shih Tzu with secondary Pneumocystis pneumonia

An approximately 1‐year‐old male intact Shih Tzu dog was referred to a tertiary facility with a history of progressive tachypnea, increased respiratory effort, and weight loss over a 3‐month period that failed to improve with empirical antimicrobial treatment. Upon completion of a comprehensive respiratory evaluation, the dog was diagnosed with severe Pneumocystis pneumonia and secondary pulmonary hypertension. Clinical signs resolved and disease resolution was confirmed after completion of an 8‐week course of trimethoprim‐sulfonamide, 4‐week tapering dose of prednisone to decrease an inflammatory response secondary to acute die‐off of organisms, a 2‐week course of clopidogrel to prevent clot formation, and a 2‐week course of a phosphodiesterase‐5 inhibitor to treat pulmonary hypertension. Immunodiagnostic testing and genetic sequencing were performed to evaluate for potential immunodeficiency as an underlying cause for the development Pneumocystis pneumonia, and identified an X‐linked CD40 ligand deficiency.     

Haemoabdomen and colitis following a colon displacement in a 9‐year‐old Thoroughbred mare

This report describes acute haemoabdomen following phenylephrine administration in a case treated for left dorsal displacement of the large colon. The horse also subsequently developed a severe colitis which was treated with aggressive medical therapy.     

Haemolytic anaemia and bilateral uveitis associated with leptospirosis in a 6‐year‐old Quarter Horse gelding

A 6‐year‐old Quarter Horse gelding was presented for bilateral uveitis resulting in vision loss as well as icterus. Anaemia with autoagglutination was consistent with a presumptive immune‐mediated haemolytic anaemia. Urinary PCR was positive for Leptospira spp. and microscopic agglutination test (MAT) titres were elevated to multiple serovars supportive of a diagnosis of leptospirosis. Treatments included broad spectrum antibiotics and aggressive anti‐inflammatory medications. While the horse was hospitalised, the development of bilateral corneal ulcers precluded the use of topical ophthalmic anti‐inflammatories for a number of days. The corneal ulceration resolved, vision returned in both eyes and the immune‐mediated haemolytic anaemia resolved. After 9 days of hospitalisation, oral minocycline was administered for 2 weeks at home as well as low dose oral flunixin meglumine and topical ophthalmic diclofenac and atropine. This case represents the first published case of haemolytic anaemia associated with leptospirosis in a horse.     

Diagnostic imaging,surgical treatment and histopathological findings of a vascular hamartoma in a 2‐year‐old horse

We describe a case of a 2‐year‐old mare that presented with a large firm swelling on the lateral aspect of the right tarsus. Diagnostic ultrasound demonstrated a fluid filled cavernous mass that was not clearly demarcated from the surrounding subcutaneous tissue. Contrast radiography with intralesional injection of contrast medium showed accumulation of the medium in the caverns of the mass and in the saphenous vein. Contrast enhanced computed tomography demonstrated 2 vascular meshes, one deep and one more superficially, closely associated with the mass. Surgical excision of the mass was performed and a vascular hamartoma was diagnosed based on histopathology. The horse showed no signs of recurrence 7 months after surgery.     

Ataxia and weakness as uncommon primary manifestations of hepatic encephalopathy in a 15‐year‐old trotter gelding

A 15‐year‐old trotter gelding was evaluated because of an acute onset of ataxia in all 4 limbs. There was no known history of trauma. The gelding showed grade 2/5 ataxia in all 4 limbs, which was localised after clinical neurological examination to the cervical vertebral spinal cord. Initial therapy consisted of oral anti‐inflammatory doses of prednisolone and antimicrobial treatment with potentiated sulphonamides. The ataxia progressed to grade 3/5 at Day 10 of hospitalisation. Additionally, the horse was slightly depressed and showed spontaneous yawning during examination. Facial sensation was blunted. Blood chemistry revealed a marked elevation of liver specific enzymes and blood ammonia levels. Transcutaneous abdominal ultrasonography revealed hepatomegaly. Due to a guarded prognosis, the horse was subjected to euthanasia. At necropsy the left lateral liver lobe was markedly enlarged and showed a firm texture, whereas the cranial part and the right and quadratic liver lobe displayed a severe and diffuse atrophy. Histopathologically, the left lateral liver lobe revealed a moderate to severe cirrhosis with a severe, diffuse hepatocellular iron‐accumulation. Increased numbers of Alzheimer type II astrocytes in the cerebral cortex and cerebral white matter vacuolisation were indicative for encephalopathy. These findings were interpreted as haemosiderosis and cirrhosis of the liver with consecutive hepatic encephalopathy. Aetiologically, haemosiderosis should be considered as a cause of liver cirrhosis with consecutive hepatic encephalopathy. Although hepatic encephalopathy in horses usually presents with predominating cerebral signs, it has to be taken into account as a differential diagnosis in cases of acute onset generalised ataxia.     

Diagnosis and treatment of biaxial keratomas in the left fore foot of a 15‐year‐old Clydesdale mare

A 15‐year‐old Clydesdale mare presented for further diagnostics and treatment of waxing and waning lameness and recurrent subsolar abscesses. Radiographs and computed tomography revealed biaxial masses extending from the hoof capsule, causing bone resorption of the distal phalanx. Surgery was performed to remove the masses and post operative care included regional limb perfusions, systemic antibiotics and therapeutic shoeing. Histopathology was consistent with the diagnosis of keratoma for each of the masses; this is the first case of confirmed biaxial keratomas. Two months after surgery the horse is sound at the walk and is expected to return to full function within the next year.     

The association of 2‐year‐old training milestones with career length and racing success in a sample of Thoroughbred horses in New Zealand

Reasons for performing study: There is increasing evidence that exercise early in life has a positive effect on musculoskeletal health. At present, there is little whole population research investigating the effect of racing as 2‐year‐olds on future racing career. Objectives: To investigate the association between attaining training milestones as 2‐year‐olds with length of career and racing success in Thoroughbred horses in New Zealand. Methods: Retrospective data were obtained of the 2001/02‐born Thoroughbred foal crop. The 3 training milestones were: registered with a trainer, trialled and raced. The association of the training milestones with career length was measured using the outcomes: number of race starts and number of years raced, in a Cox regression model. Logistic regression models analysed the association of the training milestones with the outcomes: won or placed in a race. Linear regression was performed to assess the association of training milestones with total career earnings. Results: Of 4683 horses in the population; 3152 horses were registered with a trainer, 2661 horses trialled and 2109 horses raced. Horses that raced as 2‐year‐olds had significantly (P<0.001) more race starts than those first raced as 3‐year‐olds or older, this was also true when the 2‐year‐old year data were omitted. Horses that raced as 2‐year‐olds had significantly (P<0.001) more years racing. Horses registered with a trainer, trialled or raced as 2‐year‐olds were more likely to have won or been placed in a race than those that achieved the milestones as 3‐year‐olds or older. Horses that first trialled and raced as 2‐year‐olds had greater total earnings than those that first trialled or raced at a later age. Conclusions and potential relevance: Two‐year‐old training milestones had a strong association with positive racing career outcomes. Horses in training or racing as 2‐year‐olds may have better musculoskeletal health throughout life than horses that are first in training or racing at a later age.     

Treatment of sustained monomorphic narrow‐complex ventricular tachycardia in a 16‐year‐old Arab mare with a constant rate of infusion of lidocaine and oral propranolol

A 16‐year‐old Arab mare was referred for treatment of a tachydysrhythmia detected on electrocardiogram by the referring veterinarian. Monomorphic, narrow‐complex ventricular tachycardia (VT) was confirmed by electro‐cardiogram in a normal base‐apex configuration. Subsequent diagnostic testing, including echocardiography and measurement of plasma cardiac troponin concentration, did not reveal a definitive cause for the dysrhythmia. Conversion of VT to ventricular bigeminy occurred following treatment with magnesium sulfate and lidocaine hydrochloride, administered intravenously. Treatment with orally administered propranolol subsequently led to conversion to sinus rhythm with intermittent ventricular premature complexes (VPCs). Oral prednisolone treatment was also initiated to address the possibility that VT resulted from underlying myocarditis. The mare was discharged with oral propranolol, a tapering course of prednisolone, and exercise restriction. Follow‐up cardiac examination 6 weeks later revealed persistent, intermittent VPCs and reversion to VT occurred during exercise. Sinus rhythm with intermittent VPCs was re‐established following the administration of lidocaine. The mare was again discharged with oral propranolol therapy, which was subsequently replaced with oral sotalol. Sudden death occurred 4 weeks later but a post mortem examination was not performed.     

Prospective evaluation of flow cytometric characteristics,histopathologic diagnosis and clinical outcome in dogs with naïve B‐cell lymphoma treated with a 19‐week CHOP protocol

Canine B‐cell lymphoma is a clinically heterogenous disease; however, it is generally treated as a single disease entity. The purpose of this clinical trial was to prospectively evaluate naïve canine B‐cell lymphoma patients using histopathology, flow cytometry (FC) and a standardized chemotherapy protocol to better define subsets of this disease that may respond differently to treatment. Sixty‐four dogs with naïve multicentric B‐cell lymphoma were treated with a standardized 19‐week CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy protocol. Most of the dogs (84.3%) were diagnosed with diffuse large B‐cell lymphoma (DLBCL), followed by nodal marginal zone (7.8%), small B‐cell (4.7%), Burkitt‐like (1.6%) and follicular lymphoma (1.6%). FC confirmed the diagnosis of B‐cell lymphoma in all cases. There were no clear phenotyping differences between the subtypes of B‐cell lymphoma detectable by our FC panel. The histologic subtypes in this study exhibited a range of forward scatter values on flow cytometry, but all of the DLBCL cases were higher than a value of 469, while the only cases with a lower forward scatter value were follicular lymphoma and diffuse small B‐cell lymphoma. Dogs with DLBCL had a significantly better objective response rate to the CHOP protocol (96.3%) than the non‐DLBCL subtypes (70%, P = .024). The median progression‐free survival time for patients with DLBCL (233 days) was significantly longer than that of all other histopathologic subgroups combined (163 days, P = .0005).