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Differential diagnoses for the painful equine eye:
Differential diagnoses for the painful equine eye:
* Ulceration
* Uveitis
* Blepharitis
* Conjunctivitis
* Glaucoma
* Dachrocystitis
A full ocular exam should be performed on every painful eye you are presented with.
A full ocular exam should be performed on every painful eye you are presented with.
Medical therapy should be based upon the severity of disease initially, and then by the response to therapy – if it ain’t broke don’t fix it, but don’t flog the metaphorical dead horse! The aims of our initial therapy are:
Medical therapy should be based upon the severity of disease initially, and then by the response to therapy – if it ain’t broke don’t fix it, but don’t flog the metaphorical dead horse! The aims of our initial therapy are:
* Antibiosis
* Analgesia
* Anti-inflammatory
* Mydriatic
The initial choice of antibiotic depends upon personal choice, experience and availability, but could include chloramphenicol, chlortetracycline, bacitracin-neomycin-polymyxin (BNP), ciprofloxacin, ofloxacin and tobramycin. Topical gentamicin formulations are also available, but in the opinion of some, should be reserved for cases with stromal melting. Frequency of application can vary from q1h to q8h, depending on both the severity of the lesion, and the formulation used (ointment vs. drops).
The initial choice of antibiotic depends upon personal choice, experience and availability, but could include chloramphenicol, chlortetracycline, bacitracin-neomycin-polymyxin (BNP), ciprofloxacin, ofloxacin and tobramycin. Topical gentamicin formulations are also available, but in the opinion of some, should be reserved for cases with stromal melting. Frequency of application can vary from q1h to q8h, depending on both the severity of the lesion, and the formulation used (ointment vs. drops).
Melting ulcers reflect inappropriate collagenolysis of the corneal stroma, by matrix-metalloproteinases (MMPs). Bacterial pathogens (especially Pseudomonas and β-haemolytic Streptococcus) induce the corneal epithelial cells and resident leucocytes to upregulate pro-inflammatory, and MMP-activating cytokines (IL-1,-6 and -8). These bacteria can also produce their own proteinases. The combination of exogenous, and upregulated endogenous, proteinases leads to a rapid breakdown of collagen, with the characteristic melting appearance. Untreated this can lead to perforation within 12 hours (so act hard and fast!). There are several therapeutic options for inhibiting MMPs:
Melting ulcers reflect inappropriate collagenolysis of the corneal stroma, by matrix-metalloproteinases (MMPs). Bacterial pathogens (especially Pseudomonas and β-haemolytic Streptococcus) induce the corneal epithelial cells and resident leucocytes to upregulate pro-inflammatory, and MMP-activating cytokines (IL-1,-6 and -8). These bacteria can also produce their own proteinases. The combination of exogenous, and upregulated endogenous, proteinases leads to a rapid breakdown of collagen, with the characteristic melting appearance. Untreated this can lead to perforation within 12 hours (so act hard and fast!). There are several therapeutic options for inhibiting MMPs:
* Autogenous serum – administer topically as often as possible. Keep refrigerated and change every 8 days.
* EDTA - 0.05% q1h
* Acetylcysteine – 5-10% q1h
* Tetracyclines – Doxycycline especially has been shown to have anti-MMP effects
* Tetanus antitoxin – can be delivered sub-conjunctivally. Contains macroglobulins with anti-collagenase effects.
A combination of the above may be necessary early in the disease course. Effective antibiosis is also paramount, and gentamicin is a good empirical choice (although there are some reports of gentamicin-resistant Pseudomonas species). Obviously, treating an eye this frequently in practice will be difficult, so referral is probably the best option.
A combination of the above may be necessary early in the disease course. Effective antibiosis is also paramount, and gentamicin is a good empirical choice (although there are some reports of gentamicin-resistant Pseudomonas species). Obviously, treating an eye this frequently in practice will be difficult, so referral is probably the best option.