L35: common immune-mediated diseases in primary care

what are the common clinical signs of immune-mediated diseases?

1. fever

2. lethargy

3. neutrophilia with bands

4. anorexia

which dog breed has an increased chance of IMHA?

cockerspaniels

what emergency tests do you do if you suspect IMHA?

1. physical exam (MM/CRT and HR)

2. PCV

3. Blood smear

MCQ: A 7-year-old dog is presented with a severe regenerative anemia and babesia organisms are identified on the blood smear. What form of immune mediated disease is this?

secondary

primary / non-associative

there is no trigger to the immune system (“autoimmune”)

how do you diagnose an immune mediated disease as primary?

exclude all secondary triggers

secondary / associative

something triggered the immune system to attack

what are common triggers in all immune mediated diseases?

1. infectious

2. inflammatory

3. drug/toxin

4. neoplasia

what is the common target for IMHA?

red blood cells

what is the common target for IMT?

platelets

what is Evan’s syndrome?

combination of IMHA and IMT

what is the target for immune mediated polyarthopathy (IMPA)?

synovium

what are the steps to diagnosing immune mediated disorders?

1. diagnose the disease

2. look for triggers

what tests would you do if you think that something inflammatory is triggering IMD?

1. abdominal ultrasound

2. if find mass → FNAs and biopsies

what tests would you do if you think that neoplasia is triggering IMD?

1. thoracic radiographs

2. abdominal ultrasound

how do we treat IMD if the patient is stable?

treat the trigger or etiology

what do we do for treatment of an IMD if the patient is not stable?

immunosuppression

what will you give in hospital to an unstable patient who has an IMD?

IV dexmethasone until patient is eating

what will you give at home to an unstable patient who has an IMD?

prednisone/prednisolone for 4-6 month (wean 25% every 2-4 weeks)

why can you not suddenly stop an immunosuppressive dose?

drug creates a negative feedback on ACTH → adrenal glands shrink over time → body cannot revert the adrenal glands quick enough to baseline function after abrupt stop

what is the physiologic dose of prednisone?

0.1-0.25 mg/kg/day

what is the anti-inflammatory dose of prednisone?

0.5-1 mg/kg/day

what is the immunosuppressive dose of prednisone?

2-4 mg/kg/day

what is the first drug used for immunosuppression?

prednisone/prednisolone

when can most animals be weaned off pred?

within 6 months

how can we prevent a relapse of IMD?

1. strict tick control

2. careful selection of drugs

what are the expected side effects of prednisone?

1. PU/PD

2. polyphagia

3. muscle wasting

4. iatrogenic Cushing’s

what are the side effects of prednisone that the owner should call the vet about?

1. early signs of infection

2. increased PU/PD

3. increased weight loss

what are the side effects of prednisone that the owner should take their pet to the ER?

1. melena

2. lethargy

3. pale mucous membranes

4. not eating or drinking

what tests do we use for diagnosing IMHA?

1. spherocytes

2. Coombs

3. autoagglutination

4. Tbili elevation

5. Flow cytometry

what is the gold standard for IMHA diagnosis?

flow cytometry

how many positive tests do we need for an IMHA diagnosis?

2 out of the 5

what infectious agents are linked with IMHA?

1. babesia

2. mycoplasma

what is the biggest complication in treating IMHA?

thromboembolic disease

what do we use to treat tick borne disese?

doxycycline

what anti-platelet drugs can we use to prevent thromboembolic disease in the treatment of IMHA?

1. clopidogrel

2. aspirin

what anti-coagulant drugs can we use to prevent thromboembolic disease in the treatment of IMHA?

1. heparin

2. rivaroxaban

what are the main triggers of immune mediated thrombocytopenia in cats?

1. neoplasia

2. drugs/toxins

3. inflammatory

what clinical sign is commonly associated with tapeworm infections?

shifting leg lameness

what are the categories for immune mediated neutropenia?

1. increased tissue demand

2. decreased production

3. increased destruction

what are the causes for decreased production of neutrophils?

1. drugs

2. genetics

3. bone marrow diseases

what infectious agents can affect bone marrow and lead to immune mediated neutropenia?

1. Erlichia

2. Parvovirus

3. Panleukopenia

4. FeLV