Osteomyelitis and sepsis

Question 1

Which of the following abnormalities is associated with an increased risk of SAPO (septic arthritis, physitis and osteomyelitis) in a 7-day old foal?
* Fetlock joint laxity
* Dysmaturity
* Omphalophlebitis
* Plasma IgG concentration of 800mg/dL
* Patent urachus

Answer 1

Omphalophlebitis

Question 2

Which of the following would be the most likely clinical presentation of a 3-day old foal with septic arthritis of the fetlock (metacarpophalangeal joint)?
* lameness, loss of suck, rectal temperature 39.9oC, unable to stand even with assistance
* effusion of the fetlock joint, resentment of joint flexion, rectal temperature 39.4oC diarrhoea
* lameness, effusion of the fetlock joint, reluctance to stand, rectal temperature 37.6oC
* lameness, reluctance to stand, cough, rectal temperature 37.6oC

Answer 2

• lameness, effusion of the fetlock joint, reluctance to stand, rectal temperature 37.6oC

The most common presenting signs are lameness and effusion of the affected joint. All of the above are possible, but diarrhoea and cough would indicate abnormalities of other body systems involvement as well, and A would suggest severe systemic disease which can be concurrent with SAPO.

Question 3

You are presented with 6-week-old foal with lameness and swelling over the right hock.
You obtain a sample of synovial fluid from the tibiotarsal joint. Which of the following would be the most likely clinicopathological data if the foal has type P septic physitis of the distal tibial physis?
* gross colour turbid yellow, total nucleated cell count 50x109/L, total protein 60g/L, cytology 98% neutrophils
* gross colour clear straw coloured, total nucleated cell count 0.3x109/L, cytology 50% neutrophils
* gross colour red, total nucleated cell count 3x109/L, total protein 25g/L cytology 50% neutrophils
* gross colour hazy yellow, total nucleated cell count 7x109/L, total protein 35g/L, cytology 80% neutrophils

Answer 3

• gross colour hazy yellow, total nucleated cell count 7x109/L, total protein 35g/L, cytology 80% neutrophils

Question 4

If the infection is within the physis then the synovial fluid is likely to have an inflammatory rather than a septic profile.
On further examination of the 6 week old foal you find that as well as distension of the tibiotarsal joint there is swelling and heat on the dorsolateral aspect of the limb just proximal to the joint. When you further investigate with radiography you wish to highlight the dorsolateral aspect of the physis.
Which would be the radiographic projection that will provide the best diagnostic image of this region?
* 45o dorsomedial-plantarolateral oblique
* latero-medial
* 45o dorsolateral-plantaromedial oblique
* plantaroproximal-plantarodistal with the limb in a flexed position
* dorso-plantar

Answer 4

• 45o dorsomedial-plantarolateral oblique

Question 5

Which would be the most appropriate therapeutic regime for management of septic physitis in addition to debridement under general anaesthesia?
* sodium penicillin and gentamycin IV, flunixin IV, clinical reassessment of lameness after 5 days of therapy
* ceftiofur IV, flunixin IV, repeat radiography after 14 days
* rifampin PO, meloxicam IV, measurement of serum amyloid A after 5 days of therapy
* clarithromycin PO, meloxicam IV, repeat arthroscopy under general anaesthesia after 5 days of therapy

Answer 5

• sodium penicillin and gentamycin IV, flunixin IV, clinical reassessment of lameness after 5 days of therapy

Ceftiofur and rifampin are inappropriate first line antimicrobial choices. Repeat arthroscopy is unnecessary if clinical and clinicopathological data is improving.