Immune-mediated hemolytic anemia: understanding the nemesis

Clinical presentation, outcome and prognostic factors in dogs with immune-mediated haemolytic anaemia: a retrospective single-centre study of 104 cases in Ireland (2002-2020)

BACKGROUND

Immune-mediated haemolytic anaemia (IMHA) has a high mortality rate within the first weeks to months of diagnosis. Identifying dogs at increased risk of death may help guide decision-making for owners and veterinarians. Prior studies have identified several but inconsistent prognostic factors. The objectives of the study were to describe the clinical presentation and outcome of canine immune-mediated haemolytic anaemia in Ireland and to assess for independent factors associated with survival including long-term survival. Medical records from a single centre were reviewed between 2002 and 2020 to identify dogs with immune-mediated haemolytic anaemia using the American College of Veterinary Internal Medicine (ACVIM) consensus statement algorithm. Survival analysis was performed using univariable Cox proportional hazards regression models with Breslow method for ties to identify prognostic factors.

RESULTS

One hundred and four cases were included. The diagnosis of immune-mediated haemolytic anaemia was classified as definitive, supportive and suspicious in 42 (40%), 50 (48%), and 12 dogs (12%) respectively. Twenty-two dogs (21%) were diagnosed with associative IMHA and 82 dogs were diagnosed with non-associative IMHA (79%). 65% of the cases received more than one immunosuppressive medication during the course of treatment. The mortality rate at one and three months was 16% (95% confidence interval [CI] 9-26) and 31% (95% CI 21-43) respectively. Excluding dogs that died within three months, the median survival time was 2664 days. The relapse rate during the follow-up period was 7%. Survival did not improve over the course of the study period. Thrombocytopenia and hyperbilirubinaemia were identified as negative prognostic indicators (Hazard ratio 2.2 and 2.5, 95% CI 1.1-4.1 and 1.1-5.6, respectively).

CONCLUSIONS

Excluding dogs that died within three months, the outcome was good in dogs with non-associative immune-mediated haemolytic anaemia in Ireland. The relapse rate was low regardless of the presence of associative causes. Thrombocytopenia and hyperbilirubinaemia were the only independent negative prognostic factors. The one-month and three-month mortality rates were similar compared to prior studies and survival did not improve over time during the study period: the mortality rate of canine immune-mediated haemolytic anaemia remains high in the acute phase.

Immune-mediated hematological disease in dogs is associated with alterations of the fecal microbiota: a pilot study

BACKGROUND

The dog is the most popular companion animal and is a valuable large animal model for several human diseases. Canine immune-mediated hematological diseases, including immune-mediated hemolytic anemia (IMHA) and immune thrombocytopenia (ITP), share many features in common with autoimmune hematological diseases of humans. The gut microbiome has been linked to systemic illness, but few studies have evaluated its association with immune-mediated hematological disease. To address this knowledge gap, 16S rRNA gene sequencing was used to profile the fecal microbiota of dogs with spontaneous IMHA and ITP at presentation and following successful treatment. In total, 21 affected and 13 healthy control dogs were included in the study.

RESULTS

IMHA/ITP is associated with remodeling of fecal microbiota, marked by decreased relative abundance of the spirochete Treponema spp., increased relative abundance of the pathobionts Clostridium septicum and Escherichia coli, and increased overall microbial diversity. Logistic regression analysis demonstrated that Treponema spp. were associated with decreased risk of IMHA/ITP (odds ratio [OR] 0.24-0.34), while Ruminococcaceae UCG-009 and Christensenellaceae R-7 group were associated with increased risk of disease (OR = 6.84 [95% CI 2-32.74] and 8.36 [95% CI 1.85-71.88] respectively).

CONCLUSIONS

This study demonstrates an association of immune-mediated hematological diseases in dogs with fecal dysbiosis, and points to specific bacterial genera as biomarkers of disease. Microbes identified as positive or negative risk factors for IMHA/ITP represent an area for future research as potential targets for new diagnostic assays and/or therapeutic applications.

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.

Diagnostic imaging findings in a referral population of dogs diagnosed with immune-mediated haemolytic anaemia: 50 cases (2015-2018)

OBJECTIVES

To describe and characterise changes documented on thoracic and abdominal imaging of dogs with confirmed immune-mediated haemolytic anaemia.

MATERIALS AND METHODS

Medical records from a referral hospital were searched from 2015 to 2018 for all dogs diagnosed with immune-mediated haemolytic anaemia that underwent thoracic and abdominal imaging by radiography, ultrasound or computed tomography.

RESULTS

Fifty dogs were included. Thoracic imaging revealed abnormalities in 10 dogs (20%) of which lymphadenopathy and cardiomegaly were documented in four dogs (8%) each, and pleural effusion and pleural thickening in one dog (2%) each. Abdominal imaging revealed abnormalities in 43 dogs (86%), in which hepatomegaly and peritoneal effusion were documented in 20 (40%) and 19 dogs (38%), gallbladder wall thickening and sludge in 16 (32%) and 14 dogs (28%) and splenic nodules and splenomegaly in 13 (26%) and seven dogs (14%), respectively. Hepatic and splenic abnormalities were further investigated via fine needle aspirates in 18 dogs and revealed extramedullary haematopoiesis in 12 hepatic (66.7%) and 14 splenic (77.8%) fine needle aspirate samples. Cholecystocentesis was performed in nine dogs with gallbladder abnormalities and revealed bactibilia in three samples (33.3%).

CLINICAL SIGNIFICANCE

In this population of dogs with immune-mediated haemolytic anaemia, thoracic imaging abnormalities were uncommon. Hepatomegaly, peritoneal effusion and gallbladder wall thickening were the most common abdominal imaging findings with bactibilia confirmed in one third of collected bile samples. Hepatosplenomegaly and abdominal lymphadenopathy were not associated with neoplasia in any of the dogs included in this study.

Comparison of a commercial immunochromatographic strip crossmatch kit and standard laboratory crossmatch methods for blood transfusion compatibility in dogs

OBJECTIVE

To evaluate agreement between 2 standard laboratory (SL) methods and an immunochromatographic strip (ICS) method to crossmatch dogs receiving RBC transfusions. A second objective was to evaluate uninterpretable SL crossmatch results as compared to ICS in the presence of autoagglutination.

DESIGN

Prospective observational study (September 2018 to October 2019).

SETTING

University teaching hospital.

ANIMALS

Forty anemic dogs receiving RBC transfusions.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

All dogs received DEA 1-negative packed RBCs. Three crossmatch methods were evaluated against the same unit transfused to each dog: SL method performed at institutional laboratory (SL-I), SL method sent to a commercial laboratory (SL-C), and a commercially available point-of-care ICS method. Major and minor crossmatches were incompatible for 2.5%/7.5% of ICS tests, 82.5%/52.5% of SL-I tests, and 52.5%/27.5% of SL-C tests. Agreement between ICS and SL-C major (κ = 0.05) and minor (κ = 0.02) crossmatches and between ICS and SL-I major (κ = 0.009) and minor (κ = 0.03) crossmatches was slight. Agreement between SL-C and SL-I major (κ = -0.06) and minor (κ = -0.12) crossmatches was poor. Results of major and minor crossmatches were uninterpretable due to autoagglutination in 38%/38% for SL-I and 29%/18% for SL-C crossmatches. ICS method was interpretable for 93% (major) and 98% (minor) crossmatches. After exclusion of uninterpretable SL pairings, agreement still remained poor to slight between all tests. Only 1 of 40 dogs (2.5%; 95% confidence interval: <1.0%-13.2%) had an immediate immunological transfusion reaction.

CONCLUSIONS

Lack of agreement between all methodologies was noted. The high level of incompatibility predicted by SL methods despite lack of clinically relevant reactions suggests a high false incompatibility rate as compared to the ICS test. ICS testing was also able to give results more frequently in the face of autoagglutination. Further work is needed to investigate the ICS method's ability to predict clinically significant transfusion reactions.

Profiling the Murine Acute Phase and Inflammatory Responses to African Snake Venom: An Approach to Inform Acute Snakebite Pathology

Snake envenoming causes rapid systemic and local effects that often result in fatal or long-term disability outcomes. It seems likely that acute phase and inflammatory responses contribute to these haemorrhagic, coagulopathic, neurotoxic, nephrotoxic and local tissue destructive pathologies. However, the contributory role of acute phase/inflammatory responses to envenoming is under-researched and poorly understood—particularly for envenoming by sub-Saharan African venomous snakes. To provide data to help guide future studies of human patients, and to explore the rationale for adjunct anti-inflammatory medication, here we used an in vivo murine model to systematically assess acute phase and inflammatory responses of mice to ten African snake venoms. In addition to investigating snake species-specific effects of venom on the cardiovascular system and other key organs and tissues, we examined the response to intravascular envenoming by acute phase reactants, including serum amyloid A, P-selectin and haptoglobin, and several cytokines. Venoms of the spitting (Naja nigricollis) and forest (N. melanoleuca) cobras resulted in higher acute phase and inflammatory responses than venoms from the other cobras, mambas and vipers tested. Naja nigricollis venom also stimulated a 100-fold increase in systemic interleukin 6. Thin blood films from venom-treated mice revealed species-specific changes in red blood cell morphology, indicative of membrane abnormalities and functional damage, lymphopenia and neutrophil leukocytosis. Our ex vivo assays with healthy human blood treated with these venoms identified that N. nigricollis venom induced marked levels of haemolysis and platelet aggregation. We conclude that African snake venoms stimulate very diverse responses in this mouse model of acute systemic envenoming, and that venoms of the African cobras N. nigricollis and N. melanoleuca, in particular, cause marked inflammatory and non-specific acute phase responses. We also report that several African snake venoms cause haemolytic changes. These findings emphasise the importance of understanding acute responses to envenoming, and that further research in this area may facilitate new diagnostic and treatment approaches, which in turn may lead to better clinical outcomes for snakebite patients.

The use of high-dose immunoglobulin M-enriched human immunoglobulin in dogs with immune-mediated hemolytic anemia

BACKGROUND

The IV use of human immunoglobulin (hIVIG) in dogs with primary immune-mediated hemolytic anemia (IMHA) has been described previously, but herein we describe the use of high-dose IgM-enriched hIVIG (Pentaglobin).

HYPOTHESIS/OBJECTIVES

Dogs treated with high-dose Pentaglobin will experience shorter time to remission and hospital discharge and have decreased transfusion requirements compared to dogs receiving standard treatment alone.

ANIMALS

Fourteen client-owned dogs diagnosed with primary IMHA at specialist referral hospitals in the United Kingdom.

METHODS

All prospectively enrolled dogs received prednisolone, dexamethasone or both along with clopidogrel. Patients were randomized to receive Pentaglobin at 1 g/kg on up to 2 occasions, or to serve as controls. No additional immunosuppressive drugs were allowed within the first 7 days of treatment. Remission was defined as stable PCV for 24 hours followed by an increase in PCV.

RESULTS

Ten of 11 dogs from the treatment group and 2 of 3 dogs from the control group achieved remission and survived until hospital discharge. Survival and time to remission were not significantly different between groups. The volume of packed red blood cells transfused, normalized for body weight, was not significantly different between groups. Potential adverse reactions to Pentaglobin occurred in 2 dogs, but their clinical signs may have been related to the underlying disease.

CONCLUSIONS AND CLINICAL IMPORTANCE

Treatment with high-dose Pentaglobin was well tolerated by dogs with primary IMHA but no significant advantage was found in this small study. Additional studies examining larger groups and subpopulations of dogs with primary IMHA associated with a poorer prognosis are warranted.

Usefulness of peripheral venous blood gas analyses in cats with arterial thromboembolism

Feline arterial thromboembolism (ATE) is a condition with a high mortality rate. Acid-base abnormalities may be beneficial to the prognosis of cats with ATE. Venous blood gas and electrolytes data on the first day of ATE presentation of 47 cats with ATE were retrospectively reviewed and analysed. The Cox and logistic regression were analysed to evaluate the relationship between acid-base parameters and death. The most common venous acid-base disorder was simple metabolic acidosis. Age, body weight, and partial venous pressure of carbon dioxide (PvCO2) differed between the dead and alive groups within 7 days of the onset of ATE presentation (p < 0.05). Cox-regression showed that increasing age (HR=1.175 [95% CI: 1.027-1.343], p = 0.019), increasing PvCO2 (HR=1.066 [95% CI: 1.010-1.125], p = 0.021) and PvCO2 more than 34 mmHg (HR=7.878 [95% CI: 1.036- 59.915], p = 0.046) were associated with increased hazard of death. Multivariable logistic regression showed that age > 5 years (OR=9.030, 95% CI: 1.258- 64.823; p=0.029), and PvCO2 > 34 mmHg (OR=21.764, 95% CI: 1.747-271.141; p=0.017) were associated with an increased risk of death, while concomitant administration of enoxaparin with clopidogrel (OR=0.111, 95% CI: 0.015-0.795; p=0.029) were associated with a decreased risk of death within 7 days of the onset of ATE presentation. This study demonstrated the power of venous blood gas analysis which may be used as prognostic indicators for cats with ATE.

RNA sequencing of whole blood in dogs with primary immune-mediated hemolytic anemia (IMHA) reveals novel insights into disease pathogenesis

Immune-mediated hemolytic anemia (IMHA) is a life-threatening autoimmune disorder characterized by a self-mediated attack on circulating red blood cells. The disease occurs naturally in both dogs and humans, but is significantly more prevalent in dogs. Because of its shared features across species, dogs offer a naturally occurring model for studying IMHA in people. In this study, we used RNA sequencing of whole blood from treatment-naïve dogs to study transcriptome-wide changes in gene expression in newly diagnosed animals compared to healthy controls. We found many overexpressed genes in pathways related to neutrophil function, coagulation, and hematopoiesis. In particular, the most highly overexpressed gene in cases was a phospholipase scramblase, which mediates the externalization of phosphatidylserine from the inner to the outer leaflet of cell membranes. This family of genes has been shown to be critically important for programmed cell death of erythrocytes as well as the initiation of the clotting cascade. Unexpectedly, we found marked underexpression of many genes related to lymphocyte function. We also identified groups of genes that are highly associated with the inflammatory response and red blood cell regeneration in affected dogs. We did not find any genes that distinguished dogs that lived vs. those that died at 30 days following diagnosis, nor did we find any relevant genomic signatures of microbial organisms in the blood of affected animals. Future studies are warranted to validate these findings and assess their implication in developing novel therapeutic approaches for dogs and humans with IMHA.

C1 inhibitor in canine intravascular hemolysis (C1INCH): study protocol for a randomized controlled trial

BACKGROUND

Immune-mediated hemolytic anemia (IMHA) is a common disease that affects all breeds of dogs and is associated with significant morbidity and mortality. Intravascular hemolysis of erythrocytes in IMHA is caused by complement activation and is often fatal. No current treatments target complement activation in canine IMHA. Human C₁ esterase (C₁-INH) reduces canine complement-mediated hemolysis in vitro, and a recent pharmacokinetic analysis of an FDA licensed formulation of C₁-INH in dogs confirmed that a 50 IU/kg dose of C₁-INH is safe to administer to dogs, and effectively inhibits canine complement mediated hemolysis ex-vivo. The C₁INCH randomized controlled trial will evaluate the efficacy of this drug in dogs with intravascular hemolysis.

METHODS

We will conduct a multicenter, placebo-controlled double-blind randomized clinical trial of C₁-INH in dogs with intravascular hemolysis due to IMHA. We will randomize 18 dogs to receive three doses of intravenous C₁-INH or saline in 24 h. Immunosuppressive and antithrombotic therapies will be standardized. Primary outcome measures will be changes in plasma free hemoglobin, serum concentrations of LDH, bilirubin, and haptoglobin. Using patient samples, we will evaluate complement activation in canine IMHA using a novel C5b-9 ELISA assay, flow cytometric detection of C3b on RBC, and by measurement of residual plasma complement activity. Secondary outcome measures will be survival to hospital discharge, duration of hospitalization, number and volume of red blood cell transfusions, and rescue therapy requirements. We will monitor dogs for adverse drug reactions. Sample size was estimated from pilot data on LDH and hemolysis index (HI) in dogs with IMHA. To detect 2-way differences between the upper and lower 50% of the LDH and HI values of equivalent size with 80% power at P < 0.05 will require 9 dogs in each arm.

DISCUSSION

We anticipate that IV administration of C1-INH will significantly inhibit complement mediated hemolysis in dogs with intravascular IMHA, as determined by blood biomarker measurements (decreased plasma hemoglobin, LDH and bilirubin, increased haptoglobin). We expect this will translate into significant reductions in transfusion requirements and duration of hospitalization.

TRIAL REGISTRATION

This trial has been prospectively registered with the AVMA registry (AAHSD005025).

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.

Randomised controlled trial of fractionated and unfractionated prednisolone regimens for dogs with immune-mediated haemolytic anaemia

METHODS

A randomised non-blinded non-inferiority trial was conducted to determine whether treatment with an unfractionated regimen of oral prednisolone was inferior to a fractionated regimen for dogs with primary immune-mediated haemolytic anaemia. Dogs received the same total daily dose of prednisolone as unfractionated (group 1, starting at 4 mg/kg orally once daily) or fractionated (group 2, starting at 2 mg/kg orally twice daily) doses. Questionnaires were administered to owners to assess adverse effects and quality of life (QoL). End points included survival to eight weeks, and changes in QoL and clinicopathological parameters over time.

RESULTS

Thirty-nine dogs were enrolled in the study, of which 5 were withdrawn and 17 were assigned to each group. The number of cases recruited was insufficient to determine whether unfractionated treatment was inferior to fractionated. Total serum bilirubin decreased more rapidly in dogs in group 2, whereas polydipsia improved more rapidly in group 1. Blood pressure and score for polyuria were higher in dogs in group 2 over time, whereas lymphocyte concentration was lower.

CONCLUSION

Administration of the same total daily dose of prednisolone as an unfractionated dose resulted in fewer adverse effects but the effect on survival could not be assessed in this study.

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.

Phenylephrine use for blood sparing during splenectomy in a dog

A dog with immune-mediated haemolytic anaemia was presented for splenectomy. Phenylephrine administration immediately before the removal of the spleen induced splenic contraction and significantly elevated packed cell volume. This technique conserved red blood cells and may be beneficial in euvolaemic animals to reduce the likelihood of a transfusion being required in the event of surgical haemorrhage.

In vitro Inhibition of Canine Complement-Mediated Hemolysis

BACKGROUND

Immune-mediated hemolytic anemia (IMHA) is the most common hematologic immune-mediated disease in dogs. Complement fixation on erythrocytes causes hemolysis. Complement inhibition decreases hemolysis in people with the hemolytic disease and also may prove effective in treating IMHA in dogs.

HYPOTHESIS/OBJECTIVES

Evaluate the in vitro efficacy of 2 complement inhibitors used in humans against canine complement.

METHODS

The inhibitory activity of the C3-inhibitor compstatin and recombinant human C1-esterase inhibitor (C1-INH) was evaluated using an in vitro hemolytic assay and spectrophotometric measurement of released hemoglobin. Dose-response curves for each inhibitor were generated.

RESULTS

Compstatin decreased approximately 50% of canine complement-mediated hemolysis in initial experiments. This inhibition largely was lost when a new lot of drug was purchased. C1-INH showed a dose-dependent inhibition. The highest concentration of C1-INH tested (500 μg/mL) decreased >80% of canine complement-mediated hemolysis, and the lowest concentration tested (31.25 μg/mL) decreased hemolysis >60%.

CONCLUSIONS AND CLINICAL IMPORTANCE

Human C1-INH is a robust inhibitor of canine complement-mediated hemolysis, whereas compstatin was minimally and variably effective. Human C1-INH may substantially decrease complement-mediated hemolysis in dogs with IMHA and warrants further investigation.

Bisphosphonate-Functionalized Imaging Agents, Anti-Tumor Agents and Nanocarriers for Treatment of Bone Cancer

Bone metastases result from the invasion of primary tumors to bone. Current treatment modalities include local treatments such as surgery and radiotherapy, while systemic treatments include chemotherapy and (palliative) treatment of skeletal metastases. Nevertheless, once bone metastases have been established they remain incurable leading to morbidity and mortality. Bisphosphonates are a well-established class of drugs, which are increasingly applied in the treatment of bone cancers owing to their effective inhibition of tumor cells and suppression of bone metastases. The increased understanding of the mechanism of action of bisphosphonates on bone and tumor cells has prompted the development of novel bisphosphonate-functionalized imaging and therapeutic agents. This review provides an update on the preclinical efficacy of bisphosphonate-functionalized fluorophore, anti-tumor agents and nanocarriers for the treatment of bone metastases. After an overview of the general characteristics of bisphosphonates and their mechanisms of action, an outline is provided on the various conjugation strategies that have become available to functionalize imaging agents, anti-tumor agents and nanocarriers with bisphosphonates. Finally, the efficacy of these bisphosphonate-modified agents and carriers in preclinical studies is evaluated by reviewing their potential to target tumors and inhibit tumor growth in clinically relevant animal models for the treatment of bone cancer.

Characterisation of the Immunophenotype of Dogs with Primary Immune-Mediated Haemolytic Anaemia

Background

Immune-mediated haemolytic anaemia (IMHA) is reported to be the most common autoimmune disease of dogs, resulting in significant morbidity and mortality in affected animals. Haemolysis is caused by the action of autoantibodies, but the immunological changes that result in their production have not been elucidated.

Aims

To investigate the frequency of regulatory T cells (Tregs) and other lymphocyte subsets and to measure serum concentrations of cytokines and peripheral blood mononuclear cell expression of cytokine genes in dogs with IMHA, healthy dogs and dogs with inflammatory diseases.

Animals

19 dogs with primary IMHA, 22 dogs with inflammatory diseases and 32 healthy control dogs.

Methods

Residual EDTA-anti-coagulated blood samples were stained with fluorophore-conjugated monoclonal antibodies and analysed by flow cytometry to identify Tregs and other lymphocyte subsets. Total RNA was also extracted from peripheral blood mononuclear cells to investigate cytokine gene expression, and concentrations of serum cytokines (interleukins 2, 6 10, CXCL-8 and tumour necrosis factor α) were measured using enhanced chemiluminescent assays. Principal component analysis was used to investigate latent variables that might explain variability in the entire dataset.

Results

There was no difference in the frequency or absolute numbers of Tregs among groups, nor in the proportions of other lymphocyte subsets. The concentrations of pro-inflammatory cytokines were greater in dogs with IMHA compared to healthy controls, but the concentration of IL-10 and the expression of cytokine genes did not differ between groups. Principal component analysis identified four components that explained the majority of the variability in the dataset, which seemed to correspond to different aspects of the immune response.

Conclusions

The immunophenotype of dogs with IMHA differed from that of dogs with inflammatory diseases and from healthy control dogs; some of these changes could suggest abnormalities in peripheral tolerance that permit development of autoimmune disease. The frequency of Tregs did not differ between groups, suggesting that deficiency in the number of these cells is not responsible for development of IMHA.

Canine autoimmune hemolytic anemia: management challenges

Immune-mediated hemolytic anemia is one of the most common manifestations of canine immune-mediated disease, yet treatment regimens remain nonstandardized and, in some cases, controversial. The main reason for this, as for most diseases in veterinary medicine, is the lack of large-scale placebo-controlled trials so that the efficacy of one treatment over another can be established. Most of the evidence used for treatment comes from retrospective studies and from personal preference and experience, and because of this, treatment regimens tend to vary among institutions and individual clinicians. Management of immune-mediated hemolytic anemia includes immunosuppression, thromboprophylaxis, and supportive care measures to help prevent and treat concurrent conditions.

Evaluation of a DLA-79 allele associated with multiple immune-mediated diseases in dogs

Immune-mediated diseases are common and life-threatening disorders in dogs. Many canine immune-mediated diseases have strong breed predispositions and are believed to be inherited. However, the genetic mutations that cause these diseases are mostly unknown. As many immune-mediated diseases in humans share polymorphisms among a common set of genes, we conducted a candidate gene study of 15 of these genes across four immune-mediated diseases (immune-mediated hemolytic anemia, immune-mediated thrombocytopenia, immune-mediated polyarthritis (IMPA), and atopic dermatitis) in 195 affected and 206 unaffected dogs to assess whether causative or predictive polymorphisms might exist in similar genes in dogs. We demonstrate a strong association (Fisher's exact p = 0.0004 for allelic association, p = 0.0035 for genotypic association) between two polymorphic positions (10 bp apart) in exon 2 of one allele in DLA-79, DLA-79*001:02, and multiple immune-mediated diseases. The frequency of this allele was significantly higher in dogs with immune-mediated disease than in control dogs (0.21 vs. 0.12) and ranged from 0.28 in dogs with IMPA to 0.15 in dogs with atopic dermatitis. This allele has two non-synonymous substitutions (compared with the reference allele, DLA-79*001:01), resulting in F33L and N37D amino acid changes. These mutations occur in the peptide-binding pocket of the protein, and based upon our computational modeling studies, are likely to affect critical interactions with the peptide N-terminus. Further studies are warranted to confirm these findings more broadly and to determine the specific mechanism by which the identified variants alter canine immune system function.

Serum cardiac troponin I concentrations decrease following treatment of primary immune-mediated haemolytic anaemia

OBJECTIVES

The measurement of serum cardiac troponin I concentrations in dogs with a range of non-primary cardiac illnesses suggests that cardiac myocyte damage is commonplace. Dogs with primary immune-mediated haemolytic anaemia have increased serum cardiac troponin I concentrations at the time of diagnosis. However, it is unclear whether biochemical evidence of cardiac myocyte damage improves following successful treatment of anaemia.

METHODS

A haematology profile was performed and serum cardiac troponin I concentrations were measured in 19 dogs with primary immune-mediated haemolytic anaemia before and after treatment.

RESULTS

The haematocrit increased significantly (P = 0 · 0001) following treatment of primary IMHA (median pre: 0 · 13 L/L, median post: 0 · 33 L/L). The serum cardiac troponin I concentrations decreased significantly (P < 0 · 05) after treatment (median pre: 0 · 26 ng/mL, median post: 0 · 16 ng/mL).

CLINICAL SIGNIFICANCE

Serum cardiac troponin I concentration decreases following successful treatment of primary immune-mediated haemolytic anaemia. The clinical and prognostic significance of serum cardiac troponin I concentrations before and after treatment in dogs with primary immune-mediated haemolytic anaemia merits further investigation.

Evaluation of prognostic indicators for canine primary immune-mediated haemolytic anaemia and application of a scoring system for the determination of prognosis

OBJECTIVE

Apply a previously described scoring system retrospectively to cases of canine primary immune-mediated haemolytic anaemia (pIMHA) to determine its accuracy and reliability for the determination of prognosis in Victoria, Australia.

METHODS

Retrospective cohort study of 41 dogs diagnosed with pIMHA at the University of Melbourne Veterinary Hospital (UMVH) between August 2006 to December 2012.

RESULTS

Of the 41 dogs included, 70.7% were female while 29.3% were male. The overall mortality in this study was 43.9%. The previously described prognostic scoring system when applied to cases of pIMHA in Victoria, Australia, was not found to show statistical significance for prognostification. None of the five prognostic factors were found to be independently significant for prognostification.

CONCLUSION

Application of the previously described prognostic scoring system indicated that it may not be reliable for predicting prognoses of dogs with pIMHA in Victoria, Australia.

Theileriosis in six dogs in South Africa and its potential clinical significance

Theileriosis is a tick-borne disease caused by a piroplasma of the genus Theileria that can causeanaemia and thrombocytopenia. Its clinical importance for dogs’ remains poorly understood,as only some develop clinical signs. In this study, physical and laboratory findings, treatment and outcomes of six client-owned diseased dogs presented at the Onderstepoort Veterinary Academic Hospital are described retrospectively. In the dogs, Theileria species (n = 4)and Theileria equi (n = 2) were detected by a polymerase chain reaction (PCR)-reverse blothybridisation assay in blood samples, whilst PCR for Babesia, Anaplasma and Ehrlichia were negative. The most common physical findings were pale mucous membranes (five out of six dogs), bleeding tendencies (five out of six dogs) and lethargy (three out of six dogs). All dogs were thrombocytopenic [median 59.5 x 109/L (range 13–199)] and five out of six dogs were anaemic [median haematocrit 18% (range 5–32)]. Bone marrow core biopsies performed in two dogs showed myelofibrosis. Theileriosis was treated with imidocarb dipropionate and the suspected secondary immune-mediated haematological disorders with prednisolone and azathioprine. Five dogs achieved clinical cure and post-treatment PCR performed in three out of five dogs confirmed absence of circulating parasitaemia. An immune-mediated response to Theileria species is thought to result in anaemia and/or thrombocytopenia in diseased dogs with theileriosis. A bleeding tendency, most likely secondary to thrombocytopenia and/or thrombocytopathy, was the most significant clinical finding in these cases. The link between thrombocytopenia, anaemia and myelofibrosis in theileriosis requires further investigation and theileriosis should be considered a differential diagnosis for dogs presenting with anaemia and/or thrombocytopenia in endemic tick-borne disease areas.

Bovine immune-mediated hemolytic anemia: 13 cases (November 2008-August 2009)

BACKGROUND

Immune-mediated hemolytic anemia (IMHA) occurs in cattle; however, there are few reported cases.

OBJECTIVE

The aim of this study was to investigate the prevalence of IMHA in cattle with anemia, describe the associated clinical and laboratory findings, including osmotic fragility, and identify potential causative infectious agents or drugs.

METHODS

This study included 42 anemic cattle (HCT < 27.5%) comprising 31 females and 11 bulls with a mean age of 3.5 years referred to the University of Tehran Veterinary Teaching Hospital during a 10-month period. CBCs, saline osmotic fragility tests, direct Coombs' tests, and biochemical profiles were performed, and blood smears were evaluated for spherocytosis, parasites, and microscopic agglutination. Five clinically healthy cattle were used as controls for testing osmotic fragility of RBCs.

RESULTS

The Coombs' test was positive in 13/42 (30%) cattle; 5 had no evidence of concurrent disease or history of drug administration, and 8 had underlying or concurrent diseases, positivity for BLV, or exposure to drugs. The HCT (mean ± SE) of Coombs'-positive cattle (16 ± 1.7%) was significantly lower than that of Coombs'-negative animals (21 ± 0.8%). Hematologic and biochemical findings in cattle with IMHA included anisocytosis (2), polychromasia (2), basophilic stippling (2), spherocytosis (2), hyperfibrinogenemia (5), left-shifted neutrophilia (3), and hyperbilirubinemia (8). RBCs from Coombs'-positive anemic cattle were more fragile than those from Coombs'-negative anemic cattle. Four osmotically different populations of RBCs were detected in cattle with IMHA, whereas RBC populations were homogeneous in the Coombs'-negative anemic cattle and in normal cattle.

CONCLUSION

IMHA was identified in a significant proportion of anemic cattle. Idiopathic IMHA and IMHA secondary to infectious diseases and administration of certain drugs occur in cattle.

Haemoplasma infection is not a common cause of canine immune-mediated haemolytic anaemia in the UK

OBJECTIVE

The aim of this study was to investigate whether the two canine haemoplasma species, Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum," are commonly associated with immune-mediated haemolytic anaemia (IMHA) in UK dogs.

METHODS

Three groups of dogs were recruited to the study: anaemic dogs with primary IMHA (n=37); anaemic dogs not meeting the inclusion criteria for primary IMHA (n=77) and non-anaemic dogs (n=113). DNA was extracted from 100 μl of blood and subjected to real-time quantitative polymerase chain reaction (qPCR) assays for both species of Mycoplasma. Each assay incorporated co-amplification of canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an endogenous internal control.

RESULTS

Canine GAPDH was successfully amplified by qPCR from all 227 canine blood samples but none contained M. haemocanis or "Candidatus M. haematoparvum" DNA.

CLINICAL SIGNIFICANCE

Haemoplasma infection is uncommon in dogs in the UK and no evidence was found that these organisms act as triggers for IMHA.

Treatment of Evans’ Syndrome With Human Intravenous Immunoglobulin and Leflunomide in a Diabetic Dog

An 11-year-old, spayed female miniature schnauzer with diabetes mellitus was presumptively diagnosed with Evans’ syndrome (ES). Because of the potential adverse effects of immunosuppressive doses of glucocorticoids in a diabetic dog, a single infusion of human intravenous immunoglobulin and oral leflunomide were used as first-line immunomodulatory therapy, after informed owner consent was received. This treatment resulted in complete remission of the ES, and leflunomide was discontinued after 10 months of therapy. Over a 19-month follow-up, the dog did not relapse and has remained a well-regulated diabetic.

Evaluation of liposomal clodronate in experimental spontaneous autoimmune hemolytic anemia in dogs

OBJECTIVES

Liposomal clodronate (dichloromethylene diphosphonate) has been used to deplete macrophages and block clearance of opsonized cells in mouse models of autoimmune disease. However, liposomal clodronate (LC) has not been previously evaluated in a large-animal spontaneous autoimmune disease model. Therefore, the safety and efficacy of LC treatment was assessed in normal dogs and in dogs with spontaneous autoimmune hemolytic anemia (AIHA).

METHODS

LC was administered intravenously first to healthy dogs and then to dogs with spontaneous, severe AIHA to determine if the treatment was safe and could block clearance of opsonized red blood cells (RBCs) in vivo. Studies were also conducted to assess the in vitro effects of LC on dog macrophages and dendritic cells.

RESULTS

Intravenous infusion of low doses of LC was well tolerated and blocked clearance of opsonized RBCs in normal dogs in vivo. LC was taken up by splenic macrophages and dendritic cells in vivo, and induced killing of macrophages and dendritic cells in vitro. Seven dogs with severe, spontaneous AIHA were treated with LC in a pilot study. Treatment was well tolerated, 2 of 7 LC-treated dogs with AIHA had a decrease in RBC clearance, and LC-treated dogs had significantly increased survival times compared to historical control dogs matched for disease severity.

CONCLUSIONS

These results indicate that LC can be safely administered intravenously to dogs and that even relatively low doses are capable of blocking RBC clearance and improving outcomes in a spontaneous large-animal model of AIHA. Therefore, additional studies of LC for treatment of autoantibody-mediated cytopenias in dogs and humans may be warranted.

Hemorrhagic disease in dogs infected with an unclassified intraendothelial piroplasm in southern Brazil

A hemorrhagic disease affecting dogs in Brazil, referred to popularly as "nambiuvú" (bloody ears) and believed to be transmitted by ticks, has been observed in animals infected with an organism described originally in 1910 as a piroplasm, and known locally as Rangelia vitalii. In this series of 10 cases, the disease was characterized by anaemia, jaundice, fever, spleno- and lymphadenomegaly, hemorrhage in the gastrointestinal tract, and persistent bleeding from the nose, oral cavity and tips, margins and outer surface of the pinnae. The ixodid ticks Rhipicephalus sanguineus and Amblyomma aureolatum infested affected dogs from suburban and rural areas, respectively. Laboratory findings included regenerative anaemia, spherocytosis, icteric plasma and bilirubinuria. Those intracellular organisms were found in bone marrow smears but not in blood smears. Microscopically, zoites were seen within the cytoplasm of blood capillary endothelial cells. Parasitized and non-parasitized endothelial cells were positive immunohistochemically for von Willebrand factor (vWF). Langhans-type multinucleate giant cells were observed in the lymph nodes and choroid plexus. There was prominent erythrophagocytosis by macrophages in the lymph node sinuses and infiltration of the medullary cords by numerous plasma cells. Ultrastructurally, this organism had an apical complex that included a polar ring and rhoptries but no conoid. This parasite was contained within a parasitophorous vacuole that had a trilaminar membrane with villar protrusions and was situated in the cytoplasm of capillary endothelial cells. This organism tested positive by immunohistochemistry for Babesia microti. This pathogen was also positive by in situ hybridization for B. microti. Tentative clinical diagnosis in these cases was based on the history, clinical picture, haemogram and favorable response to therapy, and confirmed through microscopic examination of smears from the bone marrow or histological sections of multiple tissues, especially lymph nodes where zoites were most frequently found. The disease was reproduced by intravenous inoculation of blood from a naturally infected dog into an experimental dog. The authors demonstrate in this study that this organism is a protozoa of the phylum Apicomplexa, order Piroplasmorida. This piroplasm seems to be different from Babesia since it has an intraendothelial stage. Molecular phylogenetic analysis is necessary to better characterize this parasite and clarify its taxonomic status.