EQUINE VETERINARY EDUCATION / AE / OCTOBER 2014


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On Day 8, digital palpation of the nasal mass revealed a


soft area inside the nares, and a pocket of echogenic fluid was visualised via ultrasonography. Fine needle aspirate at this time yielded mucopurulent material that was submitted for culture. The mass was lanced and copious purulent material was drained. The following day fluorescein staining of the left eye indicated that the corneal ulcers had resolved. Topical therapy with Neo-Poly-Gramicidin solution was discontinued and replaced with Neomycin Polymyxin B Dexamethasone solution (Neo-Poly-Dex solution)8 t.i.d. Ultrasonographic examination of the ventral left eyelid revealed a pocket of echogenic fluid that was aspirated and submitted for culture and sensitivity. The abscess was then drained and lavaged, and a Penrose drain was placed. Preliminary culture of the purulent material from the nasal


and ventral palpebral abscess also grew E. coli with identical antimicrobial susceptiblility patterns to the E. coli in the CSF. Pulsed field gel electrophoresis performed on the 3 isolates revealed identical banding patterns. Further incubation and identification revealed growth of an alpha haemolytic Streptococcus and strict anaerobes from the nasal abscess and Bacteroides and Actinomyces from the palpebral abscess. Re-incubation of the CSF sample did not reveal any further bacterial growth. The horse remained stable with varying levels of dysphagia from Days 9–11. Softened, pelleted feed was offered and


a) 140.0


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b)


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enteral feeding with a powdered complete feed (Purina Well-Gel 11, 454 g with 5–6 l water, b.i.d.) was administered. Intravenous fluid therapy (lactated Ringer’s solution, 50 ml/kg bwt/day) was instituted. Compete blood count on Day 9 revealed an improved leucocytosis (12.32 ¥ 109 cells/l) with a mature neutrophilia (10.23 ¥ 109 cells/l). Fibrinogen had decreased from 8 g/l to 6 g/l. Serum samples were submitted for quantification of IgG (determined by nephelometry) and IgM levels (determined by radial immunodiffusion); both were within normal range. On Day 11, gentamicin and ceftiofur were discontinued, and replaced with enrofloxacin (Baytril4 7 mg/kg bwt, i.v. q. 24 h) for improved CNS penetration. Omeprazole (Gastrogard6 0.8 mg/kg bwt, per os s.i.d.) was added to the treatment at this time. Ophthalmic examination on Day 12 again revealed negative uptake of fluorescein stain, significantly decreased periocular swelling, and a normal fundic examination; therefore, the sub- palpebral lavage system was removed. Intravenous fluids were discontinued at this time. On Day 13, the horse’s ability to masticate and swallow improved rapidly and he was returned to normal feed. Periocular swelling gradually decreased until Day 15 when


it became possible to assess the horse’s vision thoroughly. Both globes were normal in appearance, with the exception of a mydriatic unresponsive left pupil. The right eye was fully functional, with an intact menace response and dazzle reflex.


c)


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Fig 2: Rod function was recorded in response to low intensity stimulus (0.01 cd.s/m2) and is demonstrated in a) (left eye) and b) (right eye). The waveform and implicit time (77.7 and 72.7 msec in the right eye and left eye, respectively) are comparable in both eyes; however, the b-wave amplitude of the left eye (144 mv) is lower than the right eye (216 mv). Combined rod-cone function was recorded in response to high intensity stimulus (3 cd.s/m2) and is demonstrated in d) (left eye) and c) (right eye). The waveform of both eyes is normal; however, the b-wave implicit time of the left eye is slightly delayed compared to the right eye (80.7 vs. 72.7 msec respectively) and the b-wave amplitude of the left eye was lower than the right eye (215 vs. 372 mv respectively). Note that a blink artefact is present in traces recorded from the right eye, this artefact is absent in traces recorded from the blind left eye.


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