Immune mediated disease Pt. 2 Flashcards
(34 cards)
Feline IMHA: Clinical Presentation - what animals? what type is more common?
- Often young cats
- Secondary IMHA more common than primary
> Underlying infections:
> Mycoplasma hemofelis
> Feline leukemia virus
Feline IMHA hematocrit compared to dogs?
Compared to dogs, usually present with lower hematocrit
Feline IMHA diagnosis - hematocrit, spherocytes, coombs… what type of hemolysis is most common?
Compared to dogs, usually present with lower hematocrit
* Average of 0.12 L/L (normal 0.29-0.45)
* Can be non-regenerative
Spherocytes typically cannot be detected
* Due to feline RBC morphology
Coombs test positive in many cases
Extravascular hemolysis most common
Feline IMHA & FELV - what is the link?
- FeLV is a potential cause of secondary IMHA
- BUT - cats with IMHA can have positive FeLV snap test
> Often a false positive early in disease - If your feline IMHA has a positive FeLV snap, Confirm with another test (often FeLV PCR)
Feline IMHA: Complications
- Overall low rate of complications
- Unlike in dogs, thromboembolic complications rare
Feline IMHA: Treatment
Immunosuppressive treatment:
* Some cats respond to single agent
glucocorticoid
* Adjuvant options: cyclosporine most common
Investigate for underlying disease and treat if possible
* E.g., doxycycline mainstay of treatment if Mycoplasma hemofelis
* Corticosteroid often not required if Mycoplasma
Feline IMHA: Outcome - how long to respond to treatment? long term approach? relapse rate?
- Can take months to respond if non-regenerative anemia
- Long-term approach is similar to dogs
- Gradual tapering of immunosuppressive
therapy - Relapse rate similar to dogs (~15-30%)
Epistaxis, petechiation, ecchymoses lead us to suspect…
- Suspect primary hemostatic defect
Melena points to…
- GI blood loss (primary or secondary)
Pale MM’s most likely cause
- Anemia most likely
can we show the immune mediated response against platelets in IMT? how do we diagnose?
- Unlike IMHA:
> No clinically relevant methods to show immune mediated response against platelets - Diagnosis of exclusion
> Rule out other causes of thrombocytopenia
IMT: Establishing the Diagnosis
- how common? what platelet count we expect? what types are there?
- IMT = most common cause of marked thrombocytopenia in dogs
- Platelet count usually <50,000/uL
* Spontaneous bleeding usually <20,000 - IMT can be primary or secondary
* Similar to IMHA causes
Other Causes of Thrombocytopenia aside from IMT
- Sample error***
> Clot in tube, platelet clumps on blood smear - Bone marrow disease (e.g., neoplasia)
> Lack of production - Infection
> Ehrlichia canis, Anaplasma platys
> Disseminated intravascular coagulation
Breed Associated IMT? what do we see in these cases? what do the cells look like, and numbers?
- Congenital macrothrombocytopenia
- Platelet numbers often 50-100,000
- Circulating platelets larger than normal
- Autosomal trait in CKCS (30-50% in US are affected)
- E.g., Norfolk & Cairn Terriers, many others
IMT: Establishing the Diagnosis
- what must we do first? first tests?
Rule out secondary IMT, other causes of thrombocytopenia
* Testing for tick-borne disease as appropriate for region/travel history
* Examine for systemic disease
> Biochemical profile, UA
> Imaging – thoracic radiographs, abdominal ultrasound
IMT: Treatment
Immunosuppressive therapy
* Corticosteroids
* Majority of dogs: platelets improve to 50-100,000/μL in 1 week
Adjuvant immunosuppressives
* May be indicated if low response to therapy
IMT: Adjunctive treatment with vincristine? what is the mechanism?
- Vinca alkaloid, with action of releasing platelets from bone marrow
- Stimulate platelet production?
- More rapid increase in platelets in one study of IMT when used with prednisone
IMT: Adjunctive treatment with vincristine?
- adverse effects
- Potential for adverse effects
- GI, immunosuppression, soft tissue necrosis if injected outside of vein
IMT: Adjunctive treatment with vincristine?
- what cases is this for?
- Often reserved for more severe cases
- 1 dose given early in therapy while waiting for immunosuppression to work
IMT: Transfusion Therapy
- when would we do this? is it common?
- Replace RBCs if indicated
> Acute blood loss, severe anemia - Platelet transfusions uncommon
> Survival of transfused platelets <1 day
> Indications: uncontrolled or life-threatening hemorrhage
IMT: Other Therapies/Management aside from immunosuppressives, vincristine, transfusion…
- Melatonin?
> Potential immune modulation in people with ITP
> Sometimes used in refractory cases
> Unknown benefit - GI hemorrhage common
> Sucralfate, omeprazole? - Restrict activities
IMT: Prognosis
- how many dogs respond to treatment and how fast? mortality? recurrence rates?
- > 70% dogs will respond within 1 week
Single agent corticosteroid
Combination therapy - Recent studies suggest low (10-15%) mortality
- Reported recurrence rates 9-40%
Diagnosing IMPA (immune mediated polyarthritis)
Nonseptic joint cytology
* Usually non-degenerative neutrophils
* 2 or more joints
* No organisms on cyto/culture negative
Ruling out other causes
Antinuclear antibody titer (ANA)
* If other immune-mediated diseases are present
* Systemic lupus erythematosus
IMPA most common form? what forms are there?
- Non-infectious, non-erosive is most common form
- Primary or secondary
> Primary (idiopathic) common
> Secondary to: - Drugs
- Chronic infections (e.g., endocarditis)
- Neoplasia
- Tick-borne disease
