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Top 5 undiagnosed eye conditions in cats and dogs

5th February 2021

James Histed, Specialist in Veterinary Ophthalmology, shares what he believes to be the 5 most commonly undiagnosed eye conditions in cats and dogs.

There are several ‘common misconceptions’ vets can make in diagnosing and evaluating clinical signs and response to therapy. These can be critical to the patient and involve all aspects of ophthalmology from conjunctivitis, corneal ulcers, glaucoma, and blindness.

Here are my ‘Top Five’. Each is illustrated using an actual referral that I have received, with links to the Highcroft Referrals website for more discussion should you wish. Please do not hesitate to contact me via email directly (james.histed@cvsvets.com), or call Highcroft Referrals and ask to speak to me if you would like to talk about the management of your ophthalmology cases.

Number five – Indolent ulcers in young dogs

A referral for surgery to correct a suspected indolent ulcer in a 3 year old Poodle, Fifi.

In fact, three year old dogs do not get indolent ulcers. This is a disease process that effects a median age of 8-9 year old dogs and older. If the ulcer is axial, it is most likely due to a decrease in tear production. If it is in the superior 1/3rd of the cornea, you can start looking for the ectopic cilia. This is common in the Poodle, Shih Tzu, and in Golden Retrievers, less than a year of age.

A & B: typical appearance of a spontaneous chronic corneal epithelial defect (SCCED/indolent/refractory/Boxer ulcer) in dogs. Note the loose epithelial edges, edema limited to the ulcer bed, and neovascularization (not a finding always present in SCCEDs)

A: depiction of a diamond burr debridement being performed in a conscious patient. This is one of the most commonly used treatment methods currently for the treatment of SCCEDs with a very high success rate, and often performed with just topical anesthetic applied. B: other commonly used instruments in the treatment of SCCEDs. Top of the image is a 30 gauge needle used for anterior stromal puncture/keratotomy procedures. Middle is a special anterior stromal puncture needle with a depth limited tip for multiple punctate keratotomy procedures. Lowest is a 64 microsurgical blade also used for performing a keratotomy procedure in the treatment of SCCEDs.

 

Number four – Allergies and conjunctivitis

Referral for a deep ulcer following conjunctivitis, from suspected allergies in a 4 year old Shih Tzu, Gizmo.

In my opinion dogs do not have allergies that cause only conjunctivitis. However, many breeds have a predisposition to keratconjunctiviits sicca (KCS) resulting in recurring conjunctivitis that may vary based on circumstances i.e. outside more in summer and spring.

Mild affected cases (STT greater than 10mm/min) will improve with almost any topical solution or ointment that supplies moisture to the cornea. Central corneal ulcers are caused by KCS and/or lagophthalmos.

In addition, all these one eyed pugs didn’t get poked in the eye. The pug is a great example of KCS with an associated lagophthalmos. As a side note, Pugs and many other brachycephalics are predisposed to so-called brachycelphalic ocular syndrome, for which many preventative measures are available. Finally, note that the Schirmer tear test is one of the must underutilized diagnostic tests when assessing canine ophthalmic concerns.

A. Depiction of an obvious case of a dog with severe KCS. Not the crusted discharge on the eyelids, the thick muocoid-mucopurulent discharge across the globe surface, the diffuse conjunctival hypermia, the altered camera flash reflections on the corneal surface, and the general lack lustre appearance to the globe. B. Note the axial deep ulcer (descemetococle) and the ring of corneal neovascularaiztion that is typical of dogs with KCS.

A. An eye with chronic, non-responsive KCS. B. Same eye 24 hours following parotid duct transposition surgery as a salvage procedure to treat the non-responsive dry eye.

Number three – Treatment of cataracts in diabetic dogs

Referral to discuss the benefits of starting treatment for cataracts whilst diabetes is unstable vs waiting for it to be under control first, particularly with development of clinical symptoms.

Every diabetic dog deserves a thorough ocular examination immediately or at least at the first sign of cataracts. All diabetic cataracts result in some degree of phacolytic uveitis. Untreated, this develops into a severe anterior uveitis and secondary glaucoma.

The glaucoma is usually refractory to medication and require enucleation, just to make the patient comfortable. In many diabetics, relatively urgent cataract surgery, even on an emergency basis in some cases, is often recommended in order to prevent the development of glaucoma and enucleation.

A. Diabetic cataract in a dog. Note the finding of lens induced uveitis depicted by dyscoria, posterior synechiae ventrally. The cloudy appearance in the medial anterior chamber is the result of uveitis and fibrin accumulation. The uveitis resulted from the acute onset cataract with secondary lens capsule rupture. Any diabetic dog, especially if cataracts are present, should be assessed by an ophthalmologist at the earliest possible time. This dog required emergency cataract surgery to control the uveitis, reduce the risk of secondary glaucoma, and to restore vision.

Number two – Cyst or tumour?

Referral for possible enucleation in a 5 year old Golden Retriever, Shannon, with suspected ocular tumour.

Golden retrievers, Labrador retrievers, and Boston terriers have a high incidence of iris and ciliary body cysts. These appear as free floating translucent pigmented spheres in the anterior chamber or pupil margin, and could be mistaken for tumours. These cysts rupture and pigment may be deposited in the iris, lens, or cornea. The diagnosis is based on knowing the breed incidence and being able to trans-illuminate the pigmented cyst.

A & B: typical appearance of anterior uveal cysts in dogs. Note in image B, you can see the brown colouration of the iris visible through the wall of the cyst medially, thus helping confirm that this is a cyst and not a tumour. C: with the slit beam on the cornea, light can be shown to shine through the cyst, again confirming its presence and ruling out a solid intraocular tumour. D: ciliary body cyst in a cat. Yes, cats get uveal cysts as well, but can be harder to diagnose than in dogs. An ocular ultrasound would help on this front, and has been shown useful to avoid unnecessary enucleations, especially in cats.

 

Number one – Preventative treatment for glaucoma

Referral of an 8 year old Cocker Spaniel, Betsy, with suspected blindness from glaucoma in remaining eye, other eye enucleated one year previously.

The list of dog breeds with primary glaucoma grows yearly. The cocker spaniel is probably the number one in incidence. I recommend any dog with primary glaucoma in one eye should be under the care of an ophthalmologist and on prophylactic treatment in the ‘normal’ eye. Enucleating the blind, painful first eye is correct, but it is just as important to perform histopathology on the enucleated eye and concentrate all efforts on trying to preserve the remaining one.

Blind dogs that are comfortable do great! If vision can’t be returned in the second eye (poor prognosis by this time), it too should be enucleated or an intraocular prosthesis placed. An intravitreal gentocin injection is also an option to discuss the pros and cons of. Veterinarian and clients do not relate the inactivity in uncontrolled glaucoma dogs to the chronic pain they suffer. After over 11 years, I am still impressed with how well blind dogs function.

A: common appearance of canine glaucoma. Note the diffuse corneal edema and dilated pupil. Not appreciable in the image is the presence of buphthalmos. B: an eye with chronic glaucoma. The pressure in this buphthalmic eye was now normal, but the eye is blind. The visible cross hatch lines present represent Haabs striae (ruptures in decemets membrane), another finding helping to diagnose glaucoma in some cases (but not always present). Important point to remember: cats often times do not present with the classical signs of glaucoma displayed in the majority of canine patients.

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