An illness known as IMHA occurs when the body’s immune system obliterates its own red blood cells. This frequently results in severe anaemia and inadequate oxygenation of several organs, including the kidneys, liver, brain, etc. This illness affects both cats and dogs.
What percentage of dogs with IMHA survive?
One of the most frequent autoimmune diseases to affect dogs is immune-mediated hemolytic anaemia (IMHA), and several elements of its pathophysiology have been well studied.
2, 3 Although these findings are encouraging, the prognosis for dogs with IMHA is still uncertain, with published case fatality rates for canine primary IMHA ranging from 26% to 60%. 4, 5, 6 Various clinicopathologic anomalies have been related in the past with different outcomes in dogs with IMHA. However, few prognostic markers are constant throughout numerous studies, possibly as a result of variations in study populations or a lack of standardisation. It has been indicated that rapid validation and standardisation of diagnostic criteria for canines with IMHA is needed, and that stratification by mortality risk in upcoming interventional clinical studies would be advantageous. 7 Usually, sickness severity scores are used to determine the mortality risk for clinical trials. 8 A complicated scoring system may be necessary for accurate prognostication in the case of a disease process as complex as IMHA. The canine hemolytic anaemia objective score (CHAOS) and a score created in Japan (Tokyo) have both been suggested as such schemes, but neither has undergone an independent assessment to determine whether it is still possible to use them as prognostic indicators outside of the populations from which they were drawn.
The American Society of Anesthesiologists (ASA) health classification and the presence or absence of indicators of a systemic inflammatory response syndrome are alternatives to these disease-specific sickness severity scores that might be simpler to quantify (SIRS). The ASA classification is typically used to assess anaesthetic risk in patients10, but it has also been employed as a measure of disease severity in other canine groups since it is simple to administer. 11 Measurement of acute phase proteins or cytokine concentrations can be used to assess the inflammatory response related to IMHA in dogs. 13 While a SIRS score based on easily accessible clinical data is a more universal way to identify dogs with systemic inflammation, these measurements are not routinely accessible. 14
Recently, a number of studies from various UK hospitals have been published, but each documented only a small number of cases and focused on a different component of the illness. It is challenging to summarise the demographics, treatments, and results of the entire UK canine IMHA population presenting to referral centres, even with the advantage of these data. 15, 16, 17
By reviewing case presentations, management approaches, and treatment outcomes of dogs with IMHA who presented to several referral centres in the British Isles, we hoped to fill in these information gaps in this study. Additionally, we wanted to evaluate the prognostic value of two previously reported IMHA-specific disease severity ratings as well as the relationship between the illness severity indicators ASA and SIRS status and outcome. Using a multivariate analysis methodology, we also sought to isolate independent prognostic markers from our own dataset with the hypothesis that a multivariable scoring system would be more accurate in predicting survival than a single variable alone.
Is IMHA fatal in canines?
6 August 2020
Wiley was a hardy, joyful, and cheeky beagle. Despite having Addison’s illness, hypothyroidism, and a seizure issue, Wiley lived an active life with the support of her loving owners Brenda and Keith. Brenda, on the other hand, was unaware that Wiley was about to start a fight that neither of them could win when she discovered him lying outdoors one night.
Brenda and Keith took Wiley to the vet early the following morning. Wiley was identified as having immune-mediated hemolytic anaemia following a few tests (IMHA). The condition was unknown to Brenda and Keith, and the prognosis was not good. Brenda and Keith had to make the painful decision to say goodbye to Wiley as treatment started to fail and his condition continued to worsen.
“Brenda stated, “It feels like someone smacked you in the gut with a baseball bat.” “You have to move so swiftly with IMHA. There isn’t a lot of information available on the illness.
When the body suddenly interprets red blood cells as alien intruders, immune-mediated hemolytic anaemia develops. Similar to if the red blood cells were a virus or bacteria, the immune system targets and eliminates the red cells. Many dogs only show symptoms for one or two days at most due to the rapid onset of the disease. A sudden collapse like the one Wiley experienced is not uncommon.
The story of Wiley and Brenda is all too typical for canines that have this illness. All physiological systems are adversely impacted by a concurrent lack of oxygen, which is transported by red blood cells, when their numbers drop to dangerously low levels. Blood clots can form in any organ in dogs with IMHA and lodge there. Tragically, organ failure and death can occur when blood clots and low red blood cell counts are present simultaneously.
Any dog can get IMHA, while some breeds are more susceptible to the condition than others. Breeds that are more susceptible are:
- Beagle
- Spaniel Cocker
- ih tzu
- Burger fries
- English sheepdog of old
- Collie
- Schnauzer in miniature
- Maltese
- Retrievers from Labrador
- Poodle
- Dachshund
- Springer Spaniel in English
- Terrier Jack Russell
IMHA mainly affects dogs in their middle to later years, although cases of the disease in puppies less a year old have been documented.
symptoms of IMHA Low red blood cell counts are the secondary cause of immune-mediated hemolytic anemia’s symptoms, which can include:
- White gums
- breathing heavily or panting
- gums and/or eye whites that are yellow
- sudden exhaustion or collapse
- Anorexia
These symptoms frequently appear quickly and dramatically. Most owners identify a problem right away and seek veterinarian care.
Usually, a diagnosis is easy to make. The defining characteristic is low red blood cell numbers, and additional red blood cell abnormalities are frequently seen.
The goal of treatment is to halt the immune system’s destruction of red blood cells. First-line therapies include immunosuppressive medications like steroids. Many dogs need blood transfusions in an effort to temporarily increase their red blood cell counts until the medication starts to calm the immune system.
Anticoagulant drugs, also referred to as blood thinners, are advised because dogs with IMHA are susceptible to the formation of aberrant blood clots.
Treatment is similar to walking a tightrope because almost all therapies have detrimental side effects. Unfortunately, even in dogs who receive quick medical attention, IMHA has a significant death rate, with 50% to 70% of affected dogs passing away within a few weeks of diagnosis. Additionally, there are claims that up to 20% of dogs with IMHA that recover will recur within the first year.
Improved survival and quality of life for dogs with IMHA are urgently needed, as are more effective medicines with fewer adverse effects.
Dogs are currently being enrolled in a clinical trial at Cornell University that is being supported by the Morris Animal Foundation and is looking at a novel treatment for IMHA. The team is employing a customised strategy for immune system suppression that avoids the crippling side effects of conventional medication. The Cornell team is concentrating on intravascular IMHA, a particularly lethal variant of IMHA. If effective, this therapy could be a game-changer for dogs with IMHA.
The Foundation is aware that this horrible disease requires better medical care. Because of this, we have spent more than $1 million over the past 20 years on 16 studies that looked at cutting-edge IMHA treatments.
Although our work has aided veterinarians in providing better care for dogs with IMHA, there is still much work to be done.
Canine IMHA be cured?
An key contributor to severe anaemia in dogs is immune-mediated hemolytic anaemia (IMHA), a prevalent immune-mediated condition. Extravascular hemolysis—the destruction of red blood cells by phagocytic cells in the liver and spleen (IMHA) or by complement proteins in blood vessels—occurs when autoantibodies are produced against red blood cells (intravascular hemolysis). As a result, a potentially fatal hemolytic anaemia develops quickly.
Although IMHA can affect any dog, a significant study found that 89% of all instances involved purebred dogs, with Cocker and Springer Spaniels having an overrepresentation.
1 Lethargy, inappetence, and weakness are a few of the non-specific clinical symptoms of IMHA. Owners might spot jaundice, especially on the gums, sclera, pinnae, or in parts of the body with sparse hair, like the ventral abdomen. Owners may observe urine colouring due to hemoglobinuria in cases of intravascular hemolysis. An enlarged spleen and liver may be seen during a physical examination; this condition can result from extravascular hemolysis as well as extramedullary hematopoiesis. Due to the high systemic inflammatory response, fever is typically present, and tachycardia and tachypnea are frequent compensatory reactions to anaemia.
Any dog with a sudden onset of anaemia and signs of hemolysis should have IMHA on the differential diagnosis list. Significant spherocytosis, a positive saline agglutination test, or a positive Coomb’s test all support an immune-mediated aetiology. Strong evidence for IMHA is regarded to be any of these elements along with signs of hemolysis, such as hyperbilirubinemia, ghost cells, hemoglobinemia, or hemoglobinuria. Approximately 30% of dogs with IMHA will not have signs of regeneration at the time of diagnosis, despite the fact that majority of them have a severely regenerative anaemia. 2 Most of these dogs have “pre-restorative” anaemia, which means the bone marrow has not had enough time to produce a regenerative response.
Some dogs with IMHA may develop the ailment due to another disease process, even though the majority of instances of IMHA are considered primary because there is no known underlying cause. Even though a large number of vector-borne illnesses have been linked to the emergence of IMHA, only babesosis has a clear causal link to IMHA in dogs. Leishmania, Bartonella, and heartworm are just a few vector-borne diseases that have been linked to Coomb’s positive anaemia. Patients with IMHA have also been found to have concomitant Anaplasma infection. Treatment of infectious comorbidities is still a crucial component of therapy even if there is no proof that these infectious agents cause IMHA. 2 Treatment with doxycycline while awaiting the results of tick testing is a common and sensible approach in regions like New England where tickborne diseases are frequent. Even though babesia is a relatively rare infection, testing ought to be seriously taken into consideration for any dog that has IMHA, especially in overrepresented breeds like pit bull terriers. Due to anecdotal evidence linking IMHA to a number of cancer types, imaging tests like abdominal ultrasounds and thoracic radiography are frequently carried out on IMHA patients. Another crucial diagnostic method is an abdominal radiograph to rule out zinc foreign bodies like coins that could cause hemolysis. Contrary to immune-mediated thrombocytopenia (ITP), there isn’t much proof that drugs cause IMHA, yet drug-induced IMHA is still a possibility. Likewise, there is no proven connection between immunisation and IMHA. 2
Immunosuppressive drugs, anti-thrombotic drugs, and supportive care, such as blood transfusions, are used to treat IMHA. The patient frequently need many blood transfusions to stay stable while immunosuppressive drugs take effect. Prednisone beginning doses of 2 mg/kg/day or 40–60 mg/m2 for dogs above 25 kg are advised for IMHA patients. Steroids are the cornerstone of treatment for this condition. The use of secondary immunosuppressive drugs like cyclosporine and mycophenolate is widespread, although there is little proof that any of these treatments have any positive effects. Combining more than two immunosuppressive drugs is generally not advised due to the greatly elevated risk of infectious side effects. Cyclophosphamide is not advised due to evidence suggesting that it may impair results in IMHA patients. 3
More intensive therapies might be explored in cases of severe or refractory illness. Although a survival benefit has not been proven, human intravenous immunoglobulin (hIVIG) has been utilised as a salvage treatment for IMHA. In some trials, it has been demonstrated that splenectomy can lessen the need for medication and blood transfusions in patients with refractory IMHA. A more recent treatment for IMHA patients that removes autoantibodies from their systems is therapeutic plasma exchange, which has shown promise in stabilising more severe or refractory IMHA cases.
Since thrombosis is one of the main causes of death in people with IMHA, anti-thrombotic drugs are a crucial component of their treatment. Anti-coagulant drugs like heparin may be more effective than anti-platelet therapies like clopidogrel or aspirin since venous clots (especially pulmonary thromboembolism) are most frequent in IMHA patients. 3 This is not a practicable option for the majority of patients, though, as heparin should ideally be adjusted in each individual patient based on measurement of anti-factor Xa levels. A more recent oral factor Xa inhibitor called rivaroxaban is utilised in human medicine to prevent venous thrombosis without the need to check anti-Xa levels. Despite the fact that rivaroxaban has not yet received widespread use in canine IMHA patients, a small study did find that this patient population took medication well and there were no bleeding problems. 4 Many veterinarian patients cannot afford this medication right now, but if generic versions become available in the future, it might be a better option.
Most dogs with IMHA are given clopidogrel or aspirin to try to avoid thromboembolism due to the existing practical restrictions associated with anti-coagulant medicines in veterinary patients. Because of aspirin’s unexpected platelet inhibition at low doses and its increased risk of causing gastrointestinal bleeding, clopidogrel (1.1-4 mg/kg once daily) is preferable over aspirin. 3 A recent study found that using clopidogrel in combination to prednisone did not raise the risk of gastrointestinal bleeding in healthy dogs compared to using prednisone alone. 5 However, in healthy people, taking aspirin alone was linked to gastrointestinal haemorrhage. Additionally, after two weeks of treatment, dogs getting aspirin and prednisone combined showed more severe lesions on endoscopy than dogs receiving prednisone alone. 6 Most owners find generic clopidogrel to be straightforward to use because it is widely accessible and reasonably priced.
Patients with IMHA have a guarded prognosis; death rates of 50% and relapse rates of 6–13% are frequently recorded.
7 Patients are most vulnerable during the acute phase of treatment, when immunosuppressive drugs have not yet had time to take full effect and thromboembolic disease risk is highest. Patients who make it through this time, though, may have a longer survival with the right kind of ongoing care and surveillance. Prednisone dosage should typically be decreased every three weeks as long as the hematocrit stays steady above 30% and there is little indication of continued hemolysis (such as spherocytosis). Since using steroids is linked to an increased risk of thrombosis, anti-thrombotic medicine should be taken until prednisone has been stopped. Once patients have successfully weaned off of prednisone, secondary immunosuppressive medications like cyclosporine or mycophenolate may be decreased or stopped if necessary. Owners should be aware that patients will be taking immunosuppressive drugs for at least 3-6 months due to the lengthy taper suggested for IMHA. 3
Thromboembolic illness or severe anaemia frequently cause IMHA patients to pass away, making it a serious condition. Patients who are aggressively and effectively treated and survive the initial stage of hospitalisation, however, may experience longer survival and improved quality of life.
