Chapter 10 Purpura Haemorrhagica

Question 1

What is purpura hemorrhagica (PH)?

Answer 1

An acute, non-contagious, aseptic necrotizing vasculitis characterized by edema and petechial or ecchymotic hemorrhage of the mucosa and subcutaneous tissue.

Question 2

What causes vasculitis in purpura hemorrhagica?

Answer 2

Deposition of antigen-antibody immune complexes on blood vessel walls.

Question 3

What infections are commonly associated with purpura hemorrhagica?

Answer 3

Streptococcus equi subsp. equi, equine influenza, equine viral arteritis, equine herpesvirus type 1, Streptococcus equi subsp. zooepidemicus, Rhodococcus equi, and Corynebacterium pseudotuberculosis.

Question 4

What are the typical clinical signs of purpura hemorrhagica?

Answer 4

Urticaria, pitting edema of the distal limbs, head and ventrum, petechial/ecchymoses of mucosal membranes, anorexia, lethargy, weight loss, depression, fever, tachycardia, tachypnea, stiffness, and reluctance to move.

Question 5

What are the severe complications of purpura hemorrhagica?

Answer 5

Severe pneumonia, cardiac arrhythmias, renal failure, gastrointestinal complications, or severe muscle infarctions.

Question 6

What is the role of IgA in purpura hemorrhagica?

Answer 6

High IgA titers have been reported in horses with PH, suggesting its involvement in the disease pathophysiology.

Question 7

What are the proposed hypotheses for high IgA and low IgG levels in PH?

Answer 7

Uncontrolled B cell expansion, liver failure to remove IgA, delayed IgG production, defective or suppressed IgG production, and neutralization or excess utilization of IgG.

Question 8

What histological findings are characteristic of leukocytoclastic vasculitis in PH?

Answer 8

Presence of an inflammatory infiltrate of neutrophils, nuclear fragmentation, extravasation of erythrocytes, and necrosis of vessel walls.

Question 9

What are the key features of leukocytoclastic vasculitis?

Answer 9

Small-vessel inflammatory disease mediated by deposition of antibody-antigen immune-complexes, characteristic of hypersensitivity type III.

Question 10

What diagnostic methods are used for purpura hemorrhagica?

Answer 10

History of recent respiratory infection, clinical signs, skin biopsy, and exclusion of other causes of vasculitis.

Question 11

What are common blood work findings in horses with purpura hemorrhagica?

Answer 11

Mild to moderate anemia, leukocytosis, neutrophilia, hyperproteinemia, hyperglobulinemia, and hyperfibrinogenemia.

Question 12

What treatment protocol is recommended for purpura hemorrhagica?

Answer 12

Reducing inflammation with corticosteroids, removing the inciting cause, providing supportive care, and using antimicrobials like penicillin.

Question 13

What are the common drugs used for treating PH and their dosages?

Answer 13

Flunixin meglumine (1.1 mg/kg BID), phenylbutazone (2.2 mg/kg BID), dexamethasone (0.05–0.25 mg/kg BID or SID), and prednisolone (0.5–2 mg/kg BID or SID).

Question 14

What supportive care measures are important in managing PH?

Answer 14

Bandaging swollen legs, caring for wounds, cold hydrotherapy, intravenous fluids, and tracheotomy if needed.

Question 15

What is the prognosis for horses with purpura hemorrhagica?

Answer 15

Prognosis improves with early and aggressive treatment, with an estimated case fatality rate of 10% with appropriate treatment.

Question 16

What are the common histological features of leukocytoclastic vasculitis in PH?

Answer 16

Neutrophil perivascular infiltration with pyknosis and karyorrhexis, extravasation of erythrocytes, and vessel wall necrosis.

Question 17

What are the potential complications of prolonged immunosuppressive therapy in PH?

Answer 17

Increased risk of infections, laminitis, gastrointestinal issues, and delayed wound healing.

Question 18

What are the common clinical signs of systemic involvement in PH?

Answer 18

Colic, diarrhea, respiratory distress, and severe muscle infarctions.

Question 19

What are the typical clinical signs of severe head edema in PH?

Answer 19

Difficulty in breathing and eating, leading to anorexia, lethargy, and weight loss.

Question 20

What is the role of antimicrobial therapy in PH?

Answer 20

Treating underlying infections, especially with Streptococcus equi, using penicillin or other antimicrobials like trimethoprim-sulfamethoxazole and ceftiofur.

Question 21

What is the significance of elevated IgA titers in PH?

Answer 21

Elevated IgA titers to Streptococcus equi are suggestive of PH and may indicate an immune response to the infection.

Question 22

What is the role of anti-thrombotic agents in PH treatment?

Answer 22

Preventing thromboembolic complications using agents like pentoxifylline, low molecular weight heparin, and acetylsalicylic acid.

Question 23

What are the differential diagnoses for vasculitis in horses?

Answer 23

Drug or vaccine response, pastern and cannon leukocytoclastic vasculitis, photo-activated vasculitis, equine viral arteritis, equine infectious anemia, and others.

Question 24

What is the significance of early diagnosis and treatment in PH?

Answer 24

Improves prognosis, reduces complications, and prevents severe outcomes.

Question 25

What are the potential long-term outcomes for horses that recover from PH?

Answer 25

Generally good with appropriate treatment, but monitoring for recurrence and managing long-term complications is necessary.

Question 26

What is the importance of avoiding vaccination in horses with high SeM antibody titers?

Answer 26

To prevent triggering purpura hemorrhagica in horses with elevated antibody levels to Streptococcus equi.

Question 27

What are the common side effects of corticosteroid therapy in PH?

Answer 27

Laminitis, immunosuppression, and gastrointestinal issues.

Question 28

What are the clinical signs of purpura hemorrhagica?

Answer 28

Edema, petechial hemorrhage, anorexia, lethargy, weight loss, depression, fever, tachycardia, tachypnea, stiffness, and reluctance to move.

Question 29

What are the common histological findings in a skin biopsy of a horse with PH?

Answer 29

Leukocytoclastic vasculitis, neutrophil infiltration, nuclear fragmentation, extravasation of erythrocytes, and vessel wall necrosis.

Question 30

What are the typical blood work findings in horses with PH?

Answer 30

Mild to moderate anemia, leukocytosis, neutrophilia, hyperproteinemia, hyperglobulinemia, and hyperfibrinogenemia.

Question 31

What is the treatment protocol for PH?

Answer 31

Reducing inflammation with corticosteroids, providing supportive care, and using antimicrobials to treat underlying infections.

Question 32

What are the common drugs used for treating PH?

Answer 32

Flunixin meglumine, phenylbutazone, dexamethasone, and prednisolone.

Question 33

What is the prognosis for horses with PH?

Answer 33

Prognosis improves with early and aggressive treatment, with an estimated case fatality rate of 10% with appropriate treatment.

Question 34

What supportive care measures are important in managing PH?

Answer 34

Bandaging swollen legs, caring for wounds, cold hydrotherapy, and intravenous fluids.

Question 35

What is the role of anti-thrombotic agents in PH treatment?

Answer 35

Preventing thromboembolic complications using agents like pentoxifylline, low molecular weight heparin, and acetylsalicylic acid.

Question 36

What is the significance of elevated IgA titers in PH?

Answer 36

Elevated IgA titers to Streptococcus equi are suggestive of PH and may indicate an immune response to the infection.

Question 37

What are the differential diagnoses for vasculitis in horses?

Answer 37

Drug or vaccine response, pastern and cannon leukocytoclastic vasculitis, photo-activated vasculitis, equine viral arteritis, equine infectious anemia, and others.

Question 38

What is the importance of avoiding vaccination in horses with high SeM antibody titers?

Answer 38

To prevent triggering purpura hemorrhagica in horses with elevated antibody levels to Streptococcus equi.

Question 39

What are the potential complications of prolonged immunosuppressive therapy in PH?

Answer 39

Increased risk of infections, laminitis, gastrointestinal issues, and delayed wound healing.

Question 40

What are the clinical signs of systemic involvement in PH?

Answer 40

Colic, diarrhea, respiratory distress, and severe muscle infarctions.

Question 41

What is the role of antimicrobial therapy in PH?

Answer 41

Treating underlying infections, especially with Streptococcus equi, using penicillin or other antimicrobials like trimethoprim-sulfamethoxazole and ceftiofur.

Question 42

What are the common clinical signs of severe head edema in PH?

Answer 42

Difficulty in breathing and eating, leading to anorexia, lethargy, and weight loss.

Question 43

What are the potential long-term outcomes for horses that recover from PH?

Answer 43

Generally good with appropriate treatment, but monitoring for recurrence and managing long-term complications is necessary.

Question 44

What are the clinical signs of purpura hemorrhagica?

Answer 44

Edema, petechial hemorrhage, anorexia, lethargy, weight loss, depression, fever, tachycardia, tachypnea, stiffness, and reluctance to move.