Infection of abrasions may cause ulcer. Age. House dogs. Puppies on vegetable food. Exhaustion. Starvation. Improper, insufficient diet. Specific microbes and toxins. Symptoms: Ulcer with peripheral zone of opacity. Photophobia. In marasmus little other local trouble. Diagnosis by oblique focal illumination or fluorescin. Granulation of Descemete’s membrane. Escape of aqueous. Keratitis. Panophthalmia. Staphyloma. Prognosis in debilitated, vigorous. Treatment: tonics, fresh air, good food, sunshine, exercise, silver nitrate, mercuric chloride, iodoform, alcohol, chlorine water, boric acid, cocaine, eserine, atropine, warm antiseptic compress, juice of fresh cassava.
Causes. Wounds of the cornea making an infection entrance for pus microbes, are liable to lead to ulceration, and a corresponding destruction of the epithelium and superficial layers by inflammation, may start a similar ulcerative process. Apart from these conditions, ulceration is especially liable to occur in very old dogs, in closely confined house dogs, in puppies raised on an exclusive diet of vegetable food, and in animals worn out by disease, exhaustion, starvation, or improper and insufficient diet. Majendie’s dogs fed on sugar, starch and other imperfect diet, suffered in this way. Finally, the local action of certain specific disease poisons, enzootic purulent ophthalmia, canine distemper, dogpox (Trasbot), equine influenza (Schindelka), sheep pox, and blennorrhœa (Möller), leads to ulceration.
Symptoms. In keratitis there is usually a marked local opacity in the centre of which the breach of the surface may be found. The attendant photophobia with closure of the lids and pupil is strongly suggestive of ulcer. In the specific diseases, the local inflammation, the rapid progress of the lesion and the coexistence of the particular infective disease are characteristic. In cases due to debility and marasmus the disease may appear with little indication of attendant irritation, lachrymation, tenderness, photophobia, or even opacity. At one circumscribed point only is there a grayish cloud, perhaps no more than a thirtieth of an inch in diameter, and slightly projecting. This becomes soft and gelatinous and finally drops off, leaving a shallow excavation or abrasion, surrounded by a narrow grayish zone. This necrobiosis may extend inward and even penetrate the membrane, before the lesion has enlarged to more than a hemp seed in diameter. In other cases lateral extension occurs.
It is always important to recognize the ulcer at an early stage, and this may be done by oblique focal illumination and the use of a magnifying lens. In case of doubt a drop of solution of fluorescin placed on the cornea and at once washed out, will promptly reveal the lesion by the high color given to the tissues which have been denuded.
When perforation has taken place the membrane of Descemet may bulge out of the orifice and undergo granulation, or it may open and allow the escape of the aqueous humor. Active keratitis and even panophthalmia are liable to follow perforation. Again, the escape of aqueous humor tends to the approximation or contact of the iris with the cornea, where it may become adherent and staphyloma may ensue.
Prognosis is unfavorable in debilitated subjects, and when the lesion is extensive and in the line of vision. In slight recent cases in good constitutions it is favorable.
Treatment. Debility must be met by tonics and rich diet, fresh air, sunshine and exercise. Specific diseases must be met according to their nature.
Locally the daily application of silver nitrate lotion (1 ∶ 200) is often very effective, proving an excellent antiseptic, checking the microbian proliferation, and coagulating the albumen in the wound so as to form an antiseptic barrier to further invasion. A mercuric chloride solution (1 ∶ 5000) is an excellent substitute. Iodoform powder though less antiseptic, is especially valuable in favoring the healing process. It is dusted over the cornea, and the upper lid immediately drawn down and held over the cornea for several minutes. If this is neglected the dry powder is removed by the flow of tears, and the movement of the lids and membrana nictitans. Trasbot recommends dilute alcohol (5 ∶ 100). Möller advises chlorine water reduced to one-third the standard strength, or boric acid solution (2 ∶ 100). Bouley found good results from a cocaine solution. Cadiot and Almy get the best results from creolin (.5 to 1 ∶ 1000) 5 or 6 times a day, with eserine.
In all cases great relief can be obtained from a strong atropia lotion (1 ∶ 100). Indolent cases may often be helped by warm antiseptic compresses, which seem to stimulate the circulation and nutrition of the part. The juice exuding from the scraped fresh cassava and concentrated to a syrupy consistency, is strongly antiseptic, and used with atropia or pilocarpin is the best agent known for senile ulcer (Risley).
In perforation use eserine, and antiseptic bandages and in case of prolapsus iris, excise as already advised.