Canine autoimmune hemolytic anemia: management challenges

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.

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.

Increased risk of select glucocorticoid adverse events in dogs of higher body weight

There are limited data on glucocorticoid treatment in dogs. The purpose of this study was to investigate whether dogs of higher body weight experienced more adverse events when receiving glucocorticoid therapy. Data pertaining to glucocorticoid therapy was abstracted from the records of 61 dogs that were prescribed glucocorticoids for treatment of immune-mediated thrombocytopenia or hemolytic anemia from 2014 to 2019. The odds of developing muscle atrophy and polyphagia during therapy were increased by 30% for each 5 kg of additional body weight. Almost half of the dogs (44.3%) fluctuated > 15% from baseline weight during therapy. Dogs whose body condition scored as above ideal were at increased risk (odds ratio = 4.2) for being diagnosed with urinary tract infection. Our findings suggest that standard linear glucocorticoid dosing may place higher body weight dogs at increased risk of developing adverse events. Accelerated glucocorticoid tapering and/or alternative dosing schemes in dogs with higher body weights may be prudent in efforts to improve tolerance and client compliance.

Breed predispositions, clinical findings, and prognostic factors for death in dogs with nonregenerative immune-mediated anemia

BACKGROUND

Breed predispositions, survival, and prognostic factors have not been evaluated in dogs with nonregenerative immune-mediated anemia (nrIMA).

HYPOTHESIS/OBJECTIVES

To describe clinicopathologic variables, evaluate their associations with survival, and determine breed predispositions for dogs with nrIMA.

ANIMALS

Fifty-nine client-owned dogs with nrIMA.

METHODS

Referral hospital records were reviewed retrospectively for dogs with primary nrIMA (PCV ≤30%, corrected reticulocyte percentage (CR%) ≤1.0, bone marrow sampling with evidence of immune-mediated destruction, and underlying causes excluded). Breed predispositions were evaluated by calculation of odds ratios in a case control study; prognostic factors by logistic regression in a cohort study.

RESULTS

Fifty-nine dogs with nrIMA had a median PCV of 12% (interquartile range [IQR]: 10%-17%) and CR% 0.1 (0%-0.2%). At least ≥1 ACVIM IMHA diagnostic criteria were met by 35 dogs (59%). Whippets, Lurchers, and miniature Dachshunds were predisposed to nrIMA. Median survival time was 277 days (IQR: 37-1925), with 3- and 12-month survival rates 61% and 43%, respectively. Erythroid regeneration and remission were achieved by 88% and 62% of dogs, respectively. Corrected reticulocyte percentage >0.2 was associated with improved survival.

CONCLUSION AND CLINICAL IMPORTANCE

Although there is overlap of clinical features between dogs with IMHA and nrIMA, the prognosis for those with nrIMA depends predominantly on the severity of reticulocytopenia.

Wound healing in immunocompromised dogs: A comparison between the healing effects of moist exposed burn ointment and honey

Background and Aim:

Natural topical products have been used to enhance wound healing, especially in immunocompromised animals. The aims of this study were to evaluate and to compare the effects of moist exposed burn ointment (MEBO) and honey on the healing of full-thickness skin wounds in immunocompromised dogs.

Materials and Methods:

The study was conducted using 12 adults, apparently healthy mongrel dogs. Immunosuppression was induced in six dogs by oral administration of prednisone (2 mg/kg) and azathioprine (2 mg/kg), once a day for 21 days. On each dog, a total of 9, 1.5 cm in diameter full-thickness skin circular wounds were created aseptically in the thoracolumbar area under general anesthesia using customized skin punch biopsy kit. In a random fashion, three wounds in each dog were treatment using MEBO (contains b-sitosterol, baicalin, and berberine as active ingredients in a base of beeswax and sesame oil), honey or no treatment (control), once per day for 21 days. Wounds were grossly evaluated once a day for signs of inflammation or infection. In addition, biopsy specimens and digital imaging data of each wound were obtained on days 7, 14, and 21 for histopathological evaluation of the healing process.

Results:

Wounds in immunocompromised dogs appeared to heal significantly in a slower fashion than in non-immunocompromised counterparts. Digital analysis data showed that MEBO-treated wounds expressed better epithelialization area, faster contraction, and smaller wound area percentage when compared with honey-treated wounds. Histopathological analysis showed significantly higher angiogenesis scores in MEBO-treated wounds when compared with other treatments.

Conclusion:

Results of this study showed that MEBO resulted in significant enhancement of wound healing in both healthy and immunocompromised dogs. However, when compared to honey, the wound healing effect of MEBO was superior to that of honey.

Leptospirosis and immune-mediated hemolytic anemia: A lethal association

Immune-mediated hemolytic anemia (IMHA) is a common cause of anemia in dogs. The immune aggression towards erythrocytes can be triggered by many pathological conditions such as infection, inflammatory disease or neoplasia. Upon ruling out any eliciting conditions, a diagnosis of the primary immune-mediated disease can be made. In this particular case of severe anemia (tested positive for circulating antibodies against red blood cells with flow cytometry), vector-borne diseases (which are a common cause of immunopathology in Mediterranean countries) were excluded, leptospirosis was not. This resulted in an unsuccessful immunosuppressive therapy with prednisone, two whole blood transfusions and ultimately death of the patient. Leptospirosis (confirmed positive in two tests, micro-agglutination test for antibodies and PCR for microbial DNA in urine), can mimic a primary IMHA and must be considered in its differential list of causes. A liver involvement, that included elevated serum activity of liver enzymes and increased serum bile acid was observed at the admission and suggested an etiopathogenesis other than a primary IMHA.

MacNeill AL, Dandrieux J, Lubas G, Seelig D, Szladovits B. 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.