Immune-mediated haemolytic anaemia in 110 dogs in Victoria, Australia

Objective   Evaluate the survival and prognostic indicators (i.e. breed predilection, season, blood transfusion, and the prevalence of autoagglutination) of dogs with immune-mediated haemolytic anaemia (IMHA) in Victoria, Australia.
Design   Retrospective study of 110 diagnosed with primary IMHA at the University of Melbourne Veterinary Clinic and Hospital.
Results   In total, 80 of the dogs (72.7%) were discharged from hospital and 48 of 65 (73.8%) dogs available for follow-up were known to be alive at 1 year, giving an overall 1-year survival of 48 (50.5%) of 95 dogs for which survival data were available. Regarding breed, 80 (18.2%) of the 110 dogs were Maltese-breed dogs compared with 81 (7.4%) of 1100 control dogs (P < 0.001). Springer Spaniels (P = 0.02), Hungarian Vizslas (P = 0.02) and Airedale Terriers (P < 0.001) were also over-represented compared with the control sample. There was no evidence of an association between the occurrence of IMHA in dogs and season in this study. Receiving one or more blood transfusions did not affect survival to the time of discharge from hospital. On initial blood smear examination, 57 (51.8%) of the 110 dogs had spontaneous autoagglutination and its presence was associated with decreased survival to discharge from hospital (P = 0.03). Packed cell volume, white cell count, platelet count and serum total bilirubin on admission had no effect on survival to the time of discharge from hospital or 1 year later.
Conclusion   Dogs with IMHA have a guarded prognosis as only half are still alive 1 year after the acute event.     

The use of the rapid osmotic fragility test as an additional test to diagnose canine immune-mediated haemolytic anaemia

Background

Diagnosing canine immune-mediated haemolytic anaemia (IMHA) is often challenging because all currently available tests have their limitations. Dogs with IMHA often have an increased erythrocyte osmotic fragility (OF), a characteristic that is sometimes used in the diagnosis of IMHA. Since the classic osmotic fragility test (COFT) is time-consuming and requires specialized equipment, an easy and less labour-intensive rapid osmotic fragility test (ROFT) has been used in some countries, but its diagnostic value has not yet been investigated.This study aimed to evaluate erythrocyte osmotic fragility in dogs with and without IMHA, to compare results of the classic (COFT) and rapid (ROFT) test and to assess the value of the ROFT as diagnostic test for canine IMHA.Nineteen dogs with IMHA (group 1a), 21 anaemic dogs without IMHA (group 1b), 8 dogs with microcytosis (group 2), 13 hyperlipemic dogs (group 3), 10 dogs with lymphoma (group 4), 8 dogs with an infection (group 5) and 13 healthy dogs (group 6) were included.In all dogs, blood smear examination, in-saline auto-agglutination test, Coombs’ test, COFT and ROFT were performed. In the COFT, OF5, OF50 and OF90 were defined as the NaCl concentrations at which respectively 5, 50 and 90% of erythrocytes were haemolysed.

Results

Compared with healthy dogs, OF5 and OF50 were significantly higher in group 1a (P < 0.001) and OF5 was significantly higher in group 3 (P = 0.0266). The ROFT was positive in 17 dogs with IMHA, 10 hyperlipemic dogs, one anaemic dog without IMHA and one healthy dog.

Conclusions

Osmotic fragility was increased in the majority of dogs with IMHA and in dogs with hyperlipidemia, but not in dogs with microcytosis, lymphoma or an infection. Although more detailed information was obtained about the osmotic fragility by using the COFT, the COFT and ROFT gave similar results. The ROFT does not require specialized equipment, is rapid and easy to perform and can be used easily in daily practice. Although, the ROFT cannot replace other diagnostic tests, it may be a valuable additional tool to diagnose canine IMHA.     

Staphyloccocus aureus-associated infarctive purpura haemorrhagica,immune-mediated haemolytic anaemia and myocarditis in a Quarter Horse mare

A 7-year-old Quarter Horse mare was presented for severe left hindlimb oedema and nonweightbearing lameness that was progressive over approximately 48 h. The mare subsequently developed marked and worsening oedema, immune-mediated haemolytic anaemia (IMHA), myositis and myocarditis. The marked oedema, degree of pain and severity of myositis were consistent with infarctive purpura haemorrhagica. Fine needle aspiration of affected tissue resulted in positive bacterial culture of Staphylococcus aureus. Purpura haemorrhagica and associated complications are typically associated with Streptococcal sp. infection or exposure, and have not been previously reported in association with Staphylococcus aureus in the horse. The mare responded favourably to long-term, high-dose corticosteroid therapy, antimicrobials and supportive care.     

Pattern of Coombs' test reactivity has diagnostic significance in dogs with immune-mediated haemolytic anaemia

OBJECTIVES: To investigate the clinical significance of the pattern of Coombs' test reactivity in dogs with immune-mediated haemolytic anaemia. METHODS: Sixty-five anaemic dogs with a positive Coombs' test were included. Coombs' testing was performed at 4 and 37 degrees C with polyvalent canine Coombs' reagent and antisera specific for each of canine immunoglobulin G, immunoglobulin M and complement factor C3. The impact of performing testing with only polyvalent antiserum at 37 degrees C was assessed. Chi-squared tests were used to compare Coombs' test reactivity in dogs with primary immune-mediated haemolytic anaemia (group A) and in dogs with concurrent/underlying disease (group B). Following Bonferroni correction, significance was set at P < or = 0.003. RESULTS: Eleven dogs would have been regarded as Coombs' negative had they been tested with polyvalent antiserum at 37 degrees C alone. Group A dogs were significantly more likely to be positive with polyvalent antiserum and/or anti-dog immunoglobulin G at 4 and/or 37 degrees C (P < or = 0.001) and tended to be less likely to be positive with anti-dog immunoglobulin M at 4 degrees C (P=0.040). CLINICAL SIGNIFICANCE: Testing of anaemic dogs with polyvalent Coombs' reagent at 37 degrees C was less sensitive than testing with monovalent reagents at 4 and 37 degrees C. The pattern of Coombs' test reactivity differed significantly between dogs with primary immune-mediated haemolytic anaemia and those with concurrent/underlying disease.     

Concurrent immune-mediated haemolytic anaemia and severe thrombocytopenia in 21 dogs

The medical records of 21 dogs with concurrent immune-mediated haemolytic anaemia (imha) and severe thrombocytopenia (defined as an automated platelet count of less than 50x10(9)/l, confirmed by the examination of a blood smear) were reviewed. Their mean (sd) age was 5.8 (2.5) years. When compared with the 24,759 dogs in the hospital population for the same period Airedale terriers and dobermanns appeared to be over-represented with odds ratios of 22.5 (95 per cent confidence interval [ci] 5.2 to 97.9) and 7.6 (95 per cent ci 1.8 to 32.7) respectively. The median duration of the dogs' clinical signs was seven days, with a range from one to 17 days. Eleven of the dogs had a history of a tendency to bleed, and 15 had evidence of bleeding when examined. Twenty of the 21 dogs had been treated with glucocorticoids, nine with vincristine, and seven with azathioprine. Their median stay in hospital was four days, with a range from one to 17 days. The median period for which they survived after admission to hospital was five days, with a range from one to 558 days, and 16 of the 21 dogs had died or been euthanased within 30 days of their admission.     

Serum cardiac troponin I in dogs with primary immune-mediated haemolytic anaemia

Objectives : The assessment of serum cardiac troponin I concentrations in dogs with a range of nonprimary cardiac illnesses has revealed that cardiac myocyte damage is commonplace in many canine diseases. Whilst it is well established that dogs with fatal immune‐mediated haemolytic anaemia frequently have cardiac pathology based on post‐mortem examinations, there is limited information on the incidence of cardiac myocyte damage in this population of dogs. Methods : Serum cardiac troponin I concentrations were measured in 11 healthy dogs, 27 dogs with primary haemolytic anaemia and 49 hospitalised dogs without primary cardiac or haematological disorders. Results : Dogs with primary haemolytic anaemia have higher serum concentrations of cardiac troponin I than hospitalised ill dogs (P<0.005) and healthy dogs (P<0.01). Using a cut‐off of less than 0.1 ng/mL, 20 of 27 dogs with primary haemolytic anaemia had increased serum cardiac troponin I concentrations, which was a significantly higher proportion compared to the hospitalised ill dogs (P<0.001, 16 out of 49 dogs) and healthy dogs (P<0.05, 3 out of 11 dogs). Clinical Significance : Dogs with primary haemolytic anaemia have a higher incidence of subclinical myocyte damage than healthy dogs or dogs with non‐haematological or primary cardiac illnesses. The prognostic significance of increased serum cardiac troponin I concentrations in dogs with primary haemolytic anaemia merits further investigation.     

Clostridial myonecrosis,haemolytic anaemia,hepatopathy, osteitis and transient hypertrophic cardiomyopathy after intramuscular injection in a Thoroughbred gelding

A 9‐year‐old Thoroughbred gelding was presented for swelling over the left neck and inappetence. There was recent history of intramuscular administration of flunixin meglumine into the left neck. On examination, there was evidence of focal myositis, anaemia, haemolysis and pigmenturia. Culture of aspirated fluid from the left side of the neck produced a heavy growth of a Clostridium species. Complications of infection included haemolytic anaemia, hepatopathy, osteitis and transient hypertrophic cardiomyopathy. Treatment included intravenous fluid therapy, antibiotics, anti‐inflammatory drugs, blood transfusion and surgical debridement. There was complete resolution of clinical, haematological, biochemical and echocardiographic abnormalities, and the horse returned to ridden work. This report highlights the complications that can arise from clostridial myonecrosis, including the effect on the myocardium.     

High intravascular tissue factor expression in dogs with idiopathic immune-mediated haemolytic anaemia

A high mortality occurs in dogs with idiopathic immune-mediated haemolytic anaemia (IMHA) during the first 2 weeks after the diagnosis. The aim of this study was to investigate the inflammatory response and coagulation abnormalities in dogs with IMHA in relation to the prognosis and to establish the contribution of whole blood tissue factor (TF) and IL-8 gene expressions. Gene expressions in dogs with IMHA were compared to healthy dogs, dogs with DIC, dogs with sepsis, and in two groups of dogs that underwent intensive care treatment but had no evidence for either DIC or sepsis. The whole blood TF and IL-8 expressions were up regulated in all non-IMHA groups. Similarly, the TF expression in IMHA dogs was high, but the intravascular IL-8 expression was not increased. The dogs with IMHA had a pronounced inflammatory response that included a high WBC, left shift and monocytosis in comparison to the other disease groups. Coagulation factor activities in IMHA dogs were decreased fitting consumptive coagulopathy and the acute phase proteins FVIII and fibrinogen were increased. The platelet parameters suggested platelet activation and high platelet turnover in IMHA dogs. The model that best explained mortality contained monocytosis, increased activated partial thromboplastin time and elevated creatinine. Whole blood TF gene expression is up regulated and may contribute to consumptive coagulopathy in dogs with IMHA. Increased TF expression by activated platelets is an alternative explanation and should be investigated.     

Haemolytic anaemia in cattle in NSW associated with Theileria infections

Several outbreaks of anaemia, jaundice, abortion and mortality in cattle in New South Wales were attributed to the intracellular parasite, Theileria buffeli . Disease occurred predominantly in periparturient animals that had been moved from inland to coastal areas. Diagnosis was made via exclusion of other causes of haemolytic anaemia and observation of the parasite in blood smears. Treatments included both registered and non-registered products. There is a possibility of a new strain of Theileria sp. in Australia and the possible vectors encountered in NSW are discussed.     

Septic funiculitis caused by Streptococcus equi subspecies equi infection with associated immune‐mediated haemolytic anaemia

A 2‐year‐old Quarter Horse gelding presented for anaemia, icterus, depression and intermittent colic 2 weeks after routine castration. Bilateral septic funiculitis with Streptoccocus equi ssp. equi with secondary immune‐mediated haemolytic anaemia were diagnosed. A blood transfusion was required to facilitate general anaesthesia for surgical excision of the septic funiculitis. Antibiotic therapy was provided initially with chloramphenicol and later enrofloxacin. Immunosuppressive therapy was provided with dexamethasone and later azathioprine. The horse responded well to treatment and was discharged 8 weeks after presentation. Streptococcus equi ssp. equi should be considered in cases with septic funiculitis and the potential for a secondary immune‐mediated haemolytic anaemia exists with this bacterial species.     

Serial assessment of the coagulation status of dogs with immune-mediated haemolytic anaemia using thromboelastography

This study investigated the coagulation status of dogs with immune-mediated haemolytic anaemia (IMHA) over time. Thirty animals with primary IMHA were blood sampled on three occasions over a 5 day period and assays performed included prothrombin time, activated partial thromboplastin time, D-dimer and fibrinogen concentration, antithrombin activity and recalcified unactivated thromboelastography (TEG). Based on TEG, dogs with IMHA were significantly hypercoagulable vs. controls (P<0.001) and over the 5 day period, 3/4 of the TEG parameters reflected increased clotting kinetics (P ≤ 0.02). The 30 day survival of these patients was 80% and, at hospital admission, the TEG maximum amplitude (MA) was significantly higher in survivors than non-survivors (P=0.015). Each unit increase in MA was associated with an increased odds of 30 day survival of 1.13 (95%; CI 1.02-1.25). Based on TEG, most dogs with IMHA were hypercoagulable on admission and their clotting kinetics increased with time. Relative hypocoagulability identified by TEG at initial assessment was found to be a negative prognostic indicator.     

Evaluation of platelet activation in canine immune-mediated haemolytic anaemia

Objectives : To establish whether heightened platelet activation is a common feature of canine immune-mediated haemolytic anaemia, and to evaluate the hypothesis that platelet activation plays a role in the pathogenesis of thromboembolism. Methods : Using whole-blood flow-cytometric analysis, the proportion of activated platelets and platelet-leucocyte aggregates in blood samples from 14 dogs with immune-mediated haemolytic anaemia and 14 healthy dogs was calculated. General linear models with binomial errors were used to compare groups. Results from the immune-mediated haemolytic anaemia-affected dogs were then correlated with established risk factors for thromboembolism in canine immune-mediated haemolytic anaemia, D-dimer concentration and antithrombin activity. Results : There was a strong correlation between platelet activation and severe thrombocytopenia, with heightened platelet activation being observed predominantly in severely thrombocytopenic dogs. Clinical Significance : Dogs with immune-mediated haemolytic anaemia, particularly those with concurrent severe thrombocytopenia, are likely to have heightened platelet activation, which may play a role in the pathogenesis of thromboembolism.     

Hemosiderin in leukocytes of dogs with immune-mediated hemolytic anemia

Hemosiderin granules were identified in blood neutrophils and monocytes of three dogs. The brownish granules were 1 to 4 microns in diameter and stained positively for iron with Prussian blue stain. All three dogs had evidence of immune-mediated hemolytic anemia and received whole blood transfusions prior to observation of hemosiderin. The mechanism of hemosiderin accumulation by blood leukocytes from these dogs was undetermined. Iron overload produced by administration of whole blood transfusions during immune-mediated hemolytic anemia was implicated as a causative factor.     

Multiple extra-pulmonary disorders associated with Rhodococcus equi infection in a 2-month-old foal

A 2-month-old Thoroughbred filly was referred to Hagyard Equine Medical Institute for further evaluation of acute pyrexia and a suspected intra-abdominal abscess based on abdominal ultrasonography performed in the field. Initial examination revealed bilateral uveitis, polysynovitis, a large internal abdominal abscess and pneumonia. A transtracheal wash confirmed the presence of a multi-sensitive strain of Rhodococcus equi. Anaemia and thrombocytopenia were noted during hospitalisation. Results of a Coombs test were consistent with an immune-mediated haemolytic process. Recurrent pyrexia, abdominal discomfort and severe respiratory distress unresponsive to intensive medical support motivated euthanasia followed by necropsy after 30 days of treatment. Overall, six extra-pulmonary disorders were simultaneously diagnosed despite the lack of pulmonary pyogranulomas.     

Application of vincristine-loaded platelet therapy in three dogs with refractory immune-mediated thrombocytopenia

Three dogs presented with refractory immune-mediated thrombocytopenia (IMT). All patients failed to respond to prednisone, which is considered a mainstay of immunosuppressive therapy. Vincristine-loaded platelets (VLPs), which act selectively on mononuclear phagocytes,were introduced. After the VLPs were transfused, two dogs responded quickly withimproved clinical signs while the third dogwith recurrent IMT was euthanized due to its deteriorating condition. This case report describesthe efficacy of VLP therapy in refractory IMT patients.     

Evaluation of immunosuppressive regimens for immune-mediated haemolytic anaemia: a retrospective study of 42 dogs

Objectives : Immune‐mediated haemolytic anaemia (IMHA) is a severe disease for which evidence is lacking to make informed choices regarding immunosuppressive regimen. The aims of the current study were to determine the effect of different treatment regimens on outcome in affected animals and to identify parameters that may be used as prognostic factors for the disease. Methods : The records of dogs presenting to a veterinary hospital in the period 2002 to 2010 for treatment of IMHA were examined and follow‐up data were obtained. Statistical tests were performed to establish whether treatment regimen affected outcome and to identify prognostic factors for outcome. Results : Treatment regimen had a significant effect on the outcome (measured as survival of hospitalisation) but there were insufficient subjects to determine the cause of the difference. Serum bilirubin and urea concentrations were found to be significant negative prognostic factors for the outcome of IMHA cases and the concentrations of these parameters were significantly different between animals that survived or died while hospitalised. Clinical Significance : This study presents the first report of a significant difference in outcome comparing animals treated with immunosuppressive drugs which are in widespread clinical usage. Although possible confounding factors should be considered, these findings could have major consequences for the treatment of IMHA.     

Haemolytic anaemia in a pony associated with a perivascular abscess caused by Clostridium perfringens

A 5‐year‐old Welsh Pony mare presented with a history of dullness and inappetence and a large swelling on the left side of the neck extending to the pectoral region. Flunixin meglumine had been administered intravenously 10 days previously for treatment of laminitis. The pony was anaemic at presentation. Clostridium perfringens was isolated from an abscess overlying the left external jugular vein. Treatment consisted of supportive treatment, drainage of the abscess and administration of sodium benzyl penicillin G intravenously. A marked improvement in the mare's demeanour and a gradual increase in packed cell volume over a period of one month were observed. The historical, clinical and clinicopathological findings were consistent with immune‐mediated haemolysis associated with C. perfringens infection.