OPHTHALMOLOGY

Maxitrol ® should be used with caution in cats ! Maxidex ® should rather be utilized . The reason for this is there have been cases of acute anaphylaxis reported with the use of Maxitrol ® in cats . Hume-Smith et al ., 2011 subsequently did a retrospective study and Polymixin-B was present in all cases , which is a component of Maxitrol .

Tear substitutes are commonly used in practice , however are often not used when they should be . KCS [ Dry eye ] is common in patients other than bulldogs ! Endocrine diseases also commonly causes dry eye and a simple Schirmer Tear Test [ STT ] will confirm your suspicion . Excellent tear replacers on the mar-ket include Admyrin ®, Systane Ultra ® and Optive Plus ®.

• Topical prednisolone and dexamethasone corticosteroid preparations are able to penetrate through the cornea due to the their amphoteric properties

• When presented with a uveitis case an oral corticosteroid , in addition to a topical corticosteroid , is hugely beneficial as there is a breakdown of the blood ocular barrier

• Anecdotal evidence suggests that topical prednisolone is superior to topical dexamethasone in pannus cases . This must be used in addition to topical Tacrolimus ® though .

• Do not use topical corticosteroids in cats which you suspect have Feline Herpes Virus ([ FHV ] ocular pa-thology . These have a local immunosuppressive effect and once stopped the virus reactivates and often causes flare ups of clinical signs .

Use antibiotics when indicated .

• For simple corneal ulcers , start treatment with a third generation fluoroquinolone , such as ofloxa-cin ( e . g . Exocin ®, Octin ®). Fluoroquinolones are a good choice as they are bactericidal against a wide variety of both gram positive and negative organisms .

• Try reserve moxifloxacin ( e . g . Vigamox ®), a fourth generation fluoroquinolone , for the more seri-ous corneal ulcers , such as desmetocoeles and melting ulcers .

The use of the anti-glaucoma medication , Cosopt ® ( Dorzolamide-Timolol combination ), is to be used with caution in small and cardiac patients . There has been anecdotal evidence of patients decompen-sating post administration . This would be expected from the beta-blocker effect of Timolol . Trusopt ® ( Dorzolamide alone ) should rather be utilized in such patients . The additional benefit of the combina-tion drug is minimal ( Plummer et al ., 2006 )

The use of topical atropine drops in glaucoma cases is not advised , as the iris gathers at the irido-corneal angle further hampering the outflow of aqueous humour .

New on the South African market is Cidofovir ® for FHV , and it is one drop BID . Happy cat ! Happy own-er !

In exceptionally painful eyes , one can utilize morphine ( 10mg / ml ) topically . Apply 1 drop every few hours onto the corneal surface . No need to dilute .

References

1 . Hume-Smith , K . M ., Groth , A . D ., Rishniw , M ., Walter-Grimm , L . A ., Plunkett , S . J . & Maggs , D ., 2011 , ‘ An-aphylactic events observed within 4 h of ocular application of an antibiotic-containing ophthalmic preparation : 61 cats ( 1993 – 2010 )’, Journal of Feline Medicine and Surgery , 13 ( 10 ), 744-751 .

2 . Ford , M . M ., Dubielzig , R . R ., Giuliano , E . A ., Moore , C . P . & Narfström , K . L ., 2007 , ‘ Ocular and systemic manifestations after oral administration of a high dose of enrofloxacin in cats ’, American Journal of Veterinary Research , 68 ( 2 ), 190-202 .

3 . Gelatt , K . N ., Van der Woedt , A ., Ketring , K . L ., Andrew , S . E ., Brooks , D . E ., Biros , D . J ., Denis , H . M . & Cut-ler , T . J ., 2001 , ‘ Enrofloxacin associated retinal degeneration in cats ’, Veterinary Ophthalmology 4 ( 2 ), 99-106 .

4 . Plummer , C . E ., MacKay , E . O . & Gelatt . K . N ., 2006 , ‘ Comparison of the effects of topical administration of a fixed combination of dorzolamide – timolol to monotherapy with timolol or dorzolamide on IOP , pupil size , and heart rate in glaucomatous dogs ’, Veterinary Ophthalmology 9 ( 4 ), 245-249 .

Issue 05 | OCTOBER 2017 | 31