Demographic Characteristics, Survival and Prognostic Factors for Mortality in Cats with Primary Immune-Mediated Hemolytic Anemia

Fulminant Pneumonia Due to Reactivation of Latent Toxoplasmosis in a Cat-A Case Report

Toxoplasma (T.) gondii is an obligate intracellular parasite with felids, including domestic cats, as definitive hosts. In immunocompetent individuals, T. gondii infection is usually asymptomatic. However, under immunosuppression, it may have severe pathological impacts, which often result from the reactivation of a chronic infection. In this case study, a 21-month-old female domestic shorthair cat-diagnosed with primary immune-mediated hemolytic anemia three months prior and treated with cyclosporine and prednisolone-presented with acute tachypnea, dyspnea, diarrhea, and anorexia. Thoracic radiography suggested severe pneumonia. Testing for Mycoplasma spp., Anaplasma spp., Ehrlichia spp., and lungworm infection was negative. Serology for T. gondii revealed seroconversion of IgG, but not of IgM, indicating previous exposure to T. gondii. The cat remained stable but tachypneic for three days, followed by an acute onset of dyspnea and clinical deterioration, after which euthanasia was elected. Numerous protozoa were present in a postmortem transtracheal bronchoalveolar lavage and fine-needle aspiration of the lung. Microsatellite typing classified the extracted DNA as T. gondii type II variant TgM-A. This case demonstrates that T. gondii reactivation, leading to fulminant pneumonia, can be a sequela of immunosuppressive treatment in cats and should, therefore, be considered as a differential diagnosis in immunosuppressed cats with acute-onset respiratory signs. Rapid diagnosis may prevent fatal consequences.

Clinical findings, treatment and outcome in cats diagnosed with precursor-targeted immune-mediated anaemia in a referral hospital in the UK: 30 cases (2010-2021)

Aims

This retrospective study aimed to report clinical findings, treatment response and survival in cats diagnosed with precursor-targeted immune-mediated anaemia (PIMA) in a referral hospital in the UK.

Methods

Feline cases diagnosed with presumed PIMA between January 2010 and February 2021 were retrospectively recruited. Signalment, clinical signs, diagnostic tests, treatment and outcome were recorded. Descriptive analytics were performed. Outcomes were documented according to survival to discharge, 30-day survival, total survival time, response to immunosuppressive treatment and frequency of relapses.

Results

Thirty cats met the inclusion criteria. A higher prevalence of females (19/30) was identified (p = 0.001). Most cats (25/30) presented with haematocrit below 0.15 L/L. Concurrent cytopenias occurred in 18 of 30 cats. Bone marrow diagnosis was erythroid hyperplasia in 24 of 30 cases. Survival to discharge was documented in 26 of 30 cats, of which 23 survived more than 30 days since diagnosis. Initial treatment included blood products (26/30) and prednisolone (26/30) or prednisolone with ciclosporin (3/30); 18 of 30 cats responded to treatment, with a normal haematocrit at a mean of 28 days. The initial haematocrit and the presence of concurrent cytopenia were not statistically different between responders and non-responders. The median survival time was 140 days (range 1-3930 days).

Conclusions and relevance

The treatment response rate of feline PIMA was high (60%), with a mortality rate of 23% over the 30 days following diagnosis. Relapses occur frequently (77%) but the response rate after treatment modification was high (76%) and therefore ongoing treatment may be justified at that point. Long survival times (up to 3930 days) can be achieved.

Immune-Mediated Hemolytic Anemia and Clinically Suspected Acute Pancreatitis in Dogs, a Pilot Study

Acute pancreatitis can be a complication of massive hemolysis, above all when intravascular in nature. Therefore, the aim of this study was to investigate the association between canine immune mediated hemolytic anemia (IMHA) and clinically suspected acute pancreatitis (CSAP) and the role of calculated free plasma hemoglobin (Hbfp) in CSAP occurrence/development. In this cohort study the records of 95 dogs with IMHA and 95 sick dogs with pathologies other than IMHA were compared for CSAP occurrence/development. At presentation, 12/95 dogs with IMHA met criteria for CSAP, while only 3/95 sick control dogs met these criteria (χ2 =1.58, P = .008). Within 7 days of hospitalization 9 additional dogs with IMHA had developed CSAP. The Hbfp was calculated and compared for dogs with IMHA that had/developed CSAP and for those without CSAP. In dogs with IMHA, a calculated Hbfp concentration ≥ 0.08 g/dL resulted in an increased relative risk (RR) of having/developing CSAP (RR = 2.54, 95% CI, 1.51-4.29; P = .003). No significant effect on short-term prognosis in dogs with IMHA was found between those having/developing CSAP and those without CSAP. This study showed that dogs with IMHA have an increased risk of having CSAP and Hbfp concentration may be involved in the pathogenesis of acute pancreatitis.

Disseminated T-cell lymphoma with non-epitheliotropic cutaneous involvement in a cat with erythematous patches and regenerative anemia

A 14-y-old, castrated male, diabetic, domestic longhaired cat was presented for investigation of anemia. General examination revealed widespread cutaneous erythematous macules and patches. Hematology and bone marrow aspiration revealed severe regenerative anemia and marked erythroid hyperplasia, respectively. Low numbers of intermediate-to-large, atypical lymphocytes were observed in the blood smear and bone marrow aspirates. Various imaging modalities demonstrated a diffuse pulmonary bronchial pattern, multifocal mural thickening of the urinary bladder, splenomegaly, and mild tri-cavitary effusion. Skin biopsies and cytologic examination of the pleural effusion demonstrated round-cell neoplasia consistent with lymphoma. Autopsy confirmed disseminated T-cell lymphoma, mostly affecting the urinary bladder, stomach, lymph nodes, and interscapular subcutis and muscles. Angiocentrism and nerve infiltration were present. The cutaneous erythematous patches, characterized by perivascular neoplastic lymphocytic infiltrates and angiodestruction, were a manifestation of the disseminated lymphoma in this cat, similar to the lesions reported in humans affected by angioimmunoblastic T-cell lymphoma.

Pulmonary thromboembolism due to immune-mediated hemolytic anemia in a cat: A serial study of hematology and echocardiographic findings

Pulmonary thromboembolism (PTE) secondary to immune-mediated hemolytic anemia (IMHA) is rarely diagnosed in cats. In this report, a 3-year-old cat was referred to our private hospital with dyspnea, anorexia, and anemia. On the thoracic radiography, cardiac enlargement and pulmonary edema were noted. Echocardiography revealed right ventricular and right atrium enlargement with mild tricuspid regurgitation (tricuspid regurgitation velocity 3.28 m/s). A thrombus was recognized in the main pulmonary artery on the right parasternal short-axis view. Blood examination suggested regenerative anemia and autoagglutination. The findings suggested immune-mediated hemolytic anemia and PTE. Antithrombotic therapy (dalteparin) and immunosuppressive therapy (prednisolone) were administered under oxygen supplementation in the ICU cage. After treatment, regenerative anemia and right-heart failure were improved. During follow-up, the cat remained hemodynamically stable, and the owner reported no cardiac-related clinical signs. Further blood examination confirmed the anemia was improved. Prednisolone was discontinued on Day 56, and the cat continues in good health, administered only mycophenolate mofetil. The clinical outcome of PTE secondary to the IMHA throughout 100 days of periodical observation was reported.

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 1- Defining populations at risk

OBJECTIVES

To expand the number of conditions and interventions explored for their associations with thrombosis in the veterinary literature and to provide the basis for prescribing recommendations.

DESIGN

A population exposure comparison outcome format was used to represent patient, exposure, comparison, and outcome. Population Exposure Comparison Outcome questions were distributed to worksheet authors who performed comprehensive searches, summarized the evidence, and created guideline recommendations that were reviewed by domain chairs. The revised guidelines then underwent the Delphi survey process to reach consensus on the final guidelines. Diseases evaluated in this iteration included heartworm disease (dogs and cats), immune-mediated hemolytic anemia (cats), protein-losing nephropathy (cats), protein-losing enteropathy (dogs and cats), sepsis (cats), hyperadrenocorticism (cats), liver disease (dogs), congenital portosystemic shunts (dogs and cats) and the following interventions: IV catheters (dogs and cats), arterial catheters (dogs and cats), vascular access ports (dogs and cats), extracorporeal circuits (dogs and cats) and transvenous pacemakers (dogs and cats).

RESULTS

Of the diseases evaluated in this iteration, a high risk for thrombosis was defined as heartworm disease or protein-losing enteropathy. Low risk for thrombosis was defined as dogs with liver disease, cats with immune-mediated hemolytic anemia, protein-losing nephropathy, sepsis, or hyperadrenocorticism.

CONCLUSIONS

Associations with thrombosis are outlined for various conditions and interventions and provide the basis for management recommendations. Numerous knowledge gaps were identified that represent opportunities for future studies.

Evaluation of the role of Babesia species and Cytauxzoon felis in feline anemia cases in Colorado, USA

Objectives

The aim of this study was to evaluate the blood of cats in Colorado, USA, with suspected infectious causes of anemia for the presence of Babesia species and Cytauxzoon felis DNA. Results of PCR testing for other common vector-borne diseases potentially associated with anemia are also reported.

Methods

Samples from 101 cats were tested using a PCR assay that coamplified the DNA of C felis and Babesia species mitochondrial DNA. PCR testing for DNA of hemoplasmas, Bartonella species, Ehrlichia species, Anaplasma species, Neorickettsia risticii and Wolbachia genera was also performed if not carried out previously.

Results

Twenty-two cats (21.8%) were positive for DNA of an infectious agent. DNA from hemoplasma species were amplified from 14 cats (13.9%). Bartonella species DNA was amplified from four cats (4%) and Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum and Wolbachia genera DNA were amplified from one cat each. Babesia species and C felis mitochondrial DNA were not amplified from any sample.

Conclusions and relevance

Based on the results of this study, it does not appear that Babesia species or C felis are clinically relevant in anemic cats in Colorado, USA. For C felis, this suggests that the vector Amblyomma americanum is still uncommon in this geographic area.

Precursor-targeted immune-mediated anemia in a dog with a stage IV mast cell tumor and bone marrow infiltration

A 12-year-old spayed female Shiba Inu dog was referred to our hospital for a suspected mast cell tumor (MCT) of the bone marrow (BM). Laboratory abnormalities included severe nonregenerative anemia (packed cell volume or PCV: 12.5%; reference interval (RI): 37.3-61.7%; reticulocytes: 35.1 × 10³ /µL; RI: 10-110 × 10³ /µL), and a few mast cells were visualized in the blood smear examination. The BM was hypercellular with hematopoietic cells, a decreased myeloid:erythroid (M:E) ratio (0.77; RI, 0.9-1.8), and no dysplastic hematopoietic cells. Mast cells accounted for 11.5% of the total nucleated BM cells. Neoplastic mast cells and histiocytes phagocytizing erythroid progenitor cells were occasionally noted. The dog was diagnosed with precursor-targeted immune-mediated anemia (PIMA) concurrent and a stage IV MCT infiltrating the BM. Multimodal treatment included toceranib, imatinib, vinblastine, lomustine (CCNU), prednisolone, cyclosporine, mycophenolate mofetil, and a blood transfusion. The dog died due to MCT progression lasting 139 days after the initial BM examination. To the best of our knowledge, this is the first report of a dog presenting with PIMA and a stage IV MCT infiltrating the BM.

Left heart dimensions in anemic cats and dogs before and after blood transfusion

Background

Whether anemic cats and dogs with increased left heart dimensions are at higher risk of transfusion‐associated circulatory overload, and the effect of blood transfusion on left heart dimensions in naturally occurring anemia is unknown.

Hypothesis/objectives

To evaluate the effect of blood transfusion on left heart dimensions in clinically relevant anemia.

Animals

Twenty dogs and 20 cats presenting to a university veterinary teaching hospital.

Methods

In this prospective observational study, anemic dogs and cats requiring blood transfusion were included. Packed cell volume (PCV), total solids, and echocardiography were performed before and within 24 hours of blood transfusion. Signalment, bodyweight, disease process, transfusion duration and volume, and prior treatments were recorded. Nonparametric statistics were reported as median [range]. Post hoc Bonferroni correction set significance at P < .006.

Results

After transfusion, PCV increased in cats (12% [6–16] to 18% [10‐33], P = .001) and dogs (14% [7–24] to 25% [9‐37], P = .001), heart rate decreased in dogs (104 bpm [86‐166] to 87 bpm [56‐138], P < .001), and fractional shortening decreased in cats (57.1% [36.0‐84.7] to 41.0% [28.1‐69.6], P = .002) and dogs (33.79% [19.33‐62.79] to 31.89% [19.06‐51.47], P = .006). Left ventricular internal diameter in systole increased in cats (6.5 mm [2.7‐9.8] to 7.9 mm [5.3‐11.1], P = .001). Normalized left ventricular internal diameter in diastole (1.48 [1.25‐1.79] to 1.57 [1.33‐2.00], P = .001) and systole (0.87 [0.58‐1.19] to 1.00 [0.74‐1.36], P = .001) increased in dogs. Incidence of volume overload did not differ before (14/20 cats, 70%; 9/20 dogs, 45%) or after (12/20 cats, 60%; 11/20 dogs, 55%) transfusion (P = .64).

Conclusions and clinical importance

Blood transfusion is well tolerated when signs of volume overload are present before transfusion.

Presumptive precursor-targeted immune-mediated anemia concurrent with gastrointestinal lymphoma in a cat

A 10-year-old spayed female mixed-breed cat presented with progressive nonregenerative anemia. Clinicopathological abnormalities included severe nonregenerative anemia (packed cell volume [PCV]: 7%, aggregate reticulocytes: 1.12 × 10³/µl) and a hypoechogenic mass well-localized in the stomach. Bone marrow (BM) smears revealed increased particle hematopoietic cellularity with decreased myeloid:erythroid (M:E) ratios, no dysplasia of any lineage, and presence of erythroid precursors phagocytized by macrophages. The cat was diagnosed with presumptive precursor-targeted immune-mediated anemia (PIMA). The stomach mass was consistent with CD 20 positive T-cell lymphoma. The lymphoma was completely resected via surgery, and the PIMA was cured by immunosuppressive therapy. On day 410, both diseases have not recurred without medications. This is the first report of feline PIMA and concurrent gastrointestinal lymphoma.

Immunophenotypic characterization and clinical outcome in cats with lymphocytosis

Background

Lymphocytosis is relatively common in cats, but few studies describe lymphocyte populations or the clinical course associated with different immunophenotypic expansions.

Hypothesis/Objectives

We hypothesized that cats frequently develop non‐neoplastic lymphocytosis and that different neoplastic immunophenotypes have variable prognoses. We aimed to characterize the lymphocyte expansions in a large population of cats with lymphocytosis and to assess clinical presentation and outcome in a subset.

Animals

Three cohorts of cats older than 1 year with lymphocytosis (>6000/μL) were examined to define immunophenotypic categories (n = 146), evaluate outcome (n = 94), and determine prevalence of immunophenotypes (n = 350).

Methods

Retrospective study of cats with blood submitted for flow cytometry. Medical records (n = 94) were reviewed for clinical data, treatment, and survival information.

Results

Five major immunophenotypic categories were identified: B cell, heterogeneous (≥2 lineages expanded), CD4+ T cell, CD4−CD8− (double negative [DN]) T cell, and CD5‐low‐expressing T cell. B‐cell and heterogeneous phenotypes were more consistent with a non‐neoplastic process, having polyclonal antigen receptor gene rearrangements, younger age at presentation, lower lymphocyte counts, and prolonged survival. The neoplastic phenotypes, CD4+ T cell, DN T cell, and CD5 low T cell, had different median survival times (752 days [n = 37], 271 days [n = 7], 27.5 days [n = 12], respectively). Among CD4+ T‐cell cases, cats with abdominal lymphadenopathy, intestinal involvement, or both and females had shorter survival. Among 350 cats with lymphocytosis, CD4+ T‐cell lymphocytosis was most common, followed by heterogeneous and B‐cell phenotypes.

Conclusions and Clinical Importance

Neoplastic CD4+ T‐cell lymphocytosis is common in cats and has a prolonged clinical course compared to aberrant T‐cell phenotypes. Cats with heterogeneous and B‐cell lymphocyte expansions commonly have non‐neoplastic disease.

The utility of diagnostic tests for immune-mediated hemolytic anemia

BACKGROUND

A definitive diagnosis of immune-mediated hemolytic anemia (IMHA) can be difficult to make. However, it is critical to differentiate IMHA from other causes of anemia due to the impact on prognosis and outcome for IMHA patients. Recently published American College of Veterinary Internal Medicine recommendations for the diagnosis of IMHA should be followed to concurrently confirm ongoing anemia, verify in vivo hemolysis, and detect anti-erythrocyte antibodies. The reliability of immunologic IMHA tests varies depending on which test is used and how it is performed.

OBJECTIVES

Our aims were to determine which tests are currently used in veterinary medicine to diagnose IMHA and review the utility of assays that have historically been used to diagnose IMHA.

METHODS

A short survey was designed to see which diagnostic tests for IMHA were currently being used by veterinary practices. The survey was distributed via list-serves to veterinarians and veterinary technologists. A literature review was performed to report the utility of diagnostic tests for the diagnosis of IMHA.

RESULTS

Survey respondents indicated a variability in test protocols used to diagnose IMHA. Most respondents perform saline agglutination or Coombs' tests to detect anti-erythrocyte antibodies. Additional tests that can be used to support a diagnosis of IMHA are discussed in this review.

CONCLUSIONS

A standardized diagnostic approach should be followed to differentiate IMHA from other causes of anemia. Test methodology can vary from one laboratory to another, and clinicians should be familiar with the procedures used by their laboratory.

Pharmacokinetics of mycophenolic acid and its effect on CD4+ and CD8+ T cells after oral administration of mycophenolate mofetil to healthy cats

Background

Mycophenolate mofetil (MMF) is an immunosuppressant used in human and veterinary medicine. Little pharmacokinetic and pharmacodynamic information on MMF is available in cats.

Objective

To evaluate the plasma disposition of mycophenolic acid (MPA) and assess its effect on total peripheral blood mononuclear cells and CD4⁺/CD8⁺ ratios after PO administration of MMF.

Animals

Healthy cats (n = 10).

Methods

Mycophenolate mofetil was administered at a dosage of 10 mg/kg q12h (n = 3), 15 mg/kg q12h (n = 3), and 15 mg/kg q8h (n = 4) for 7 days. Concentrations of MPA and derivatives were determined using ultra‐high‐performance liquid chromatography. Flow cytometry was used to assess CD4⁺/CD8⁺ T‐cell ratios.

Results

All cats biotransformed MMF into MPA. Half of the cats (5/10) had adverse effects within 1 week of MMF administration. Area under the curve limit of quantification (AUC_0‐LOQh) of MPA ranged from 1.27 to 2.03 hours·μg/mL and from 1.77 to 8.54 hours·μg/mL after the first and last PO dose of 10 mg/kg. The AUC_0‐loqh of MPA ranged from 2.18 to 31 hours·μg/mL after the first dose of 15 mg/kg of MMF. Before the first dose of MMF, the average total number of PBMC ranged from 1.2 to 9.3 million/mL. At the last dose of MMF, the average total number of PBMC ranged from 3 to 5 million/mL.

Conclusion

Mycophenolic acid was detected in all cats. The dose 10 mg/kg given q12h for 1 week was tolerated (n = 3). The efficacy of MMF as an immunosuppressant and long‐term safety in cats of this dosage regimen is unknown.

Feline non-regenerative anemia: Diagnostic and treatment recommendations

PRACTICAL RELEVANCE

Non-regenerative anemia, or anemia with reticulocytopenia, is a daily diagnosis in feline practice.

CLINICAL CHALLENGES

The disease processes underlying non-regenerative anemia are many and diverse. A major diagnostic evaluation may be required to correctly diagnose and treat the underlying cause.

AUDIENCE

All veterinarians caring for cats will face the diagnostic and therapeutic challenge of non-regenerative anemia. Readers will benefit from the review of diagnostic testing and therapeutic options for non-regenerative anemia.

EVIDENCE BASE

This review summarizes the currently available literature informing diagnostic and treatment recommendations related to non-regenerative anemia. The evidence available to support the recommendations in this review is graded as low and includes predominantly expert opinion, case reports and cases series, on which the authors' interpretation/consensus is based.

Presumed immune-mediated haemolytic anaemia associated with pregnancy in a cat

Case summary

A 7-year-old female entire Birman presented with acute-onset haemorrhagic vulvar discharge. Moderate, normocytic, normochromic, non-/pre-regenerative anaemia, along with a moderate mature neutrophilia, were seen on haematology. Saline test for agglutination was positive. No haemotropic mycoplasmas were identified. Serum biochemistry revealed severe hyperbilirubinaemia. Retroviral testing was negative. Serology for toxoplasmosis revealed a titre of 1:512. Abdominal ultrasound identified a large uterus, containing at least three advanced-stage fetuses, two of which failed to exhibit independent motion or cardiac activity. Ovariohysterectomy was performed. Histology demonstrated mild, multifocal suppurative placentitis, with Gram staining revealing no evidence of bacteria. Complete resolution of the anaemia was seen within 1.5 months of ovariohysterectomy.

Relevance and novel information

Immune-mediated haemolytic anaemia (IMHA) in association with pregnancy has not been previously reported in cats. This case represents a potential novel cause for IMHA in cats, which resolved following ovariohysterectomy.

ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats

Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors.

Pharmacokinetics of Mycophenolic Acid after Intravenous Administration of Mycophenolate Mofetil to Healthy Cats

Background

Mycophenolate mofetil (MMF), the prodrug of mycophenolic acid (MPA), is becoming increasingly popular as an alternative immunosuppressant in feline medicine. Pharmacokinetic information is not available for cats.

Objective

The purpose of this study was to determine whether MMF is biotransformed into the active metabolite MPA and to evaluate the disposition of MPA after a 2‐hour constant rate intravenous (IV) infusion of MMF in healthy cats.

Animals

Healthy cats (n = 6).

Methods

This was a prospective pilot study. All cats were administered MMF at 20 mg/kg every 12 hours over a 2‐hour constant rate infusion for 1 day. The concentrations of MPA and its derivatives in blood were determined using a validated UHPLC–UV method.

Results

All cats biotransformed MMF into MPA. The mean AUC_0‐14 h ranged from 6 to 50 h*mg/L after IV dosing of MMF. Transient large bowel diarrhea was recorded in 2 of 6 cats after medication administration.

Conclusion and Clinical Importance

The disposition of MPA in plasma was highly variable, which could result in high interindividual variability in the safety and efficacy of treatment with MMF in cats.