Purpura haemorrhagica

DR WAQAS NAWAZ
PMAS Arid Agriculture University, Rawalpindi
Pakistan

1. Purpura Haemorrhagica Fiaz Hussain 11-Arid-932 Fatima Zahra Naqvi 11-Arid-934

2. Rare complication of equine  strangles  and is caused by bleeding from  capillaries  which results in red spots on the skin and  mucous membranes together with  oedema  (swelling) of the limbs and the head .

3. It is more common in younger animals and is often fatal . Traditionally, cases of purpura hemorrhagica are associated with previous bouts of strangles. Unlike strangles, purpura is not infective; horses cannot catch purpura from other horses .  

4. T he immune system damages vessel walls, causing them to become leaky. Blood components leak into the tissues, resulting in swelling. The head, legs and underbelly of the horse are most often affected. Hemorrhage into the tissues may occur and may be visible as areas of red spotting on the gums and other mucous membranes .

5. Hemorrhage into the tissues may occur and may be visible as areas of red spotting on the gums and other mucous membranes. Serum may begin to seep from the skin and, in severe cases, the skin may die and slough off, exposing the tissues beneath. Purpura is not limited to the skin .

6. The effects extend to wherever blood vessels run, including the lungs, muscles and the kidneys. This body wide involvement can lead to other clinical signs such as lameness, laminitis, colic, weight loss, and neurologic signs.

7. Cause:  Hypersensitivity to streptococcal antigen; secondary to respiratory tract bacterial or viral  infection , e.g  Streptococcus equi  (  S. equi var equi  ).  equine influenza   ,   wound  infection or idiopathic .

8. Signs  : V ariable severity; edematous plaques 2-10 cm diameter over neck, chest, thigh   →   edema of distal limbs, head, ventral mid line   →   serous exudation, fissures, necrosis and  cellulitis     ; +/-pyrexia; petechial/ecchymotic hemorrhages on mucous membranes

9. Stiff, painful limbs, reluctance to move. Ventral edema Edema sometimes associated with the intestinal tract   →   acute abdominal crisis epidsodes Serosanguinous nasal discharge.

10. Full thickness tissue necrosis or  cellulitis      of dermal structures and pressure sites, eg lower limbs, under rugs. Colic   [Abdomen: pain - adult]   and diarrhea, due to intestinal edema

11. Diagnosis  : H ematology, Blood biochemistry, H istopathology .

12. Treatment  : R esolve underlying infection by antibiotics, C orticosteroids(dexamethasone), D iuresis .

13. Reasons for treatment failure Sloughing and necrosis of severely affected areas. Secondary complications, e.g   pneumonia , suppurating lesions, myositis,  renal failure and   laminitis   .    

14. Prognosis  : F air to poor depending on severity; complications may   →   death. Guarded to poor - if mild, but may be protracted course. Grave - if severe (high mortality), if diarrhea or respiratory distress present; if refractory to initial treatment.

15. Note: It is difficult to predict and prevent.  If a horse has experienced a reaction to the strangles vaccine, a veterinarian may recommend the horse not be administered that vaccine again, at least without further testing. Research has found that horses that have high serum levels of antibodies to Streptococcus equi  may be at increased risk of developing purpura hemorrhagica. 

16. Outcomes of purpura hemorrhagic vary wildly . Many times the disease is mild and horses recover well. Other times, horses are severely affected and may die or are euthanized .