Volume 3 | Issue 2 Article 7

1941 Keratitis Herman Farley Kansas State College

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Recommended Citation Farley, Herman (1941) "Keratitis," Iowa State University Veterinarian: Vol. 3 : Iss. 2 , Article 7. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol3/iss2/7

This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Keratitis The virulence, transmissibility and course of bovine "pinkeye"

Herman Farley, D.V.M., M.S.*

ERATITIS or "pinkeye" in cattle is calves in Kansas during April or May, K an infectious disease which infects and continues to be prevalent among cattle cattle of all ages and breeds. It has a wide of feeder and dairy class until freezing distribution and has been reported in Hol­ weather. This fact has caused those inter­ land, South Africa, India, England and in ested in the disease to suspect flies or parts of Canada. This disease has been other insects as possible vectors in the recognized as a serious cattle disease in transmission of the infection. A vitamin­ almost every part of the United States. osis is probably not a primary factor in Keratitis is not a new disease. It was the production of keratitis as observed in recognized in Nebraska more than 70 these studies. years ago. Although the mortality is rela­ tively low, the economic factor is great. Symptoms Veterincrians and livestock owners read­ Marked lacrimation, photophobia, ily recognize the importance of keratitis clouding of the cornea and congestion of to the cattle industry. blood vessels of the cornea and conjunc­ The disease is more prevalent among tiva are observed in all cases with the cattle in the Middle West. Although cattle onset of the disease. During the first three of all ages and breeds are affected, it is or four days the eye secretions are of a primarily a disease of young cattle. It has watery consistency, but later develop into been found in field and laboratory studies the mucous type and continue in this at this station that adult cattle show a manner throughout the course of the dis­ greater resistance to keratitis than do ease. young calves. The period of incubation in this disease following artificial expos­ Course ure under laboratory conditions has Field and laboratory studies conducted varied from three days to three weeks. at this station have shown that the diseas2 Keratitis is more prevalent during sum­ appears in three forms-the mild, acute mer and early fall. However, it has been and chronic types. observed among cattle during winter Mild type. Affected animals show a months when the infection became more slight cloudiness of the cornea with con­ extensive and involved a large number of gestion of blood vessels of the cornea and feeder calves. In these cases the animals conjunctiva. Watery secretions flow con­ were crowded into sheds and barns. tinuously from one or both eyes, depend­ Keratitis of cattle is apparently specific ing upon whether the infection is uni­ for the species since sheep, swine, rabbits lateral or bilateral. and guinea pigs could not be infected un­ Acute type. Apparently this is the most der laboratory conditions. This disease common type of infection observed in cat­ usually makes its appearance among tle. Photophobia, marked lacrimation, extensive clouding of the cornea and con­ • Division of Veterinary Medicine, Kansas State Col­ lege, MDnhattan, Kan. junctivitis which occurs synonymously 74 The Veterinary Student with clouding the cornea. The circum­ Exposures were made by dropping the corneal blood vessels and those of the virulent eye secretions on the cornea of conjunctiva are congested in every case. susceptible calves. It has not been neces­ Clouding of the cornea is due to the ac­ sary to scarify the cornea or conjunctiva cumulation of leucocytes. A yellowish in order to cause transmission in these discoloration of the cornea may be ob­ cases. Occasionally animals were found served and a slight protrusion of the cor­ to be resistant to infection induced in this nea may be noticed at a point just below manner even though composite eye secre­ the center of the eye. If the cornea ulcer­ tions collected from numerous animals ates it usually occurs at this area and the were used in the attempt. Calves recov­ infection becomes more extensive. ered from mild infection can be reinfected Chronic type. The chronic type of in­ by artificial exposure. Those animals re­ fection may develop when the cornea ul­ covered from acute or chronic types of the cerates and pyogenic infection becomes a infection cannot be reinfected under lab­ secondary factor, causing extensive in­ oratory conditions. Calves recovered from volvement of the cornea, iris, membrana acute infections have not retained the in­ nictitans and the anterior eye chamber. fection in eye secretions longer than three In these cases the animal becomes perma­ months. On the other hand, a calf in­ nently blind. A thick pus may accumu­ fected with the chronic type of infection late in the anterior eye chamber and con­ during early fall was proven a source of tinue to escape through the break in the keratitis infection in the spring when an­ cornea. Enucleation of the eye is some­ other calf developed acute keratitis after times resorted to in these cases. This type ten exposures with eye secretions from the of infection is often observed among cattle first animal. Eschericia coli, Coryne­ that are continually exposed to sunlight, bacterium pyogenes, StTeptococci, Sta,­ wind, dust, flies, etc. It has been found phyloccocci and Pasteurella boviseptica, that if calves affected with the mild or were isolated from eye secretions in one acute type of "pinkeye" or keratitis are calf affected with the chronic type of removed from the herds and placed in keratitis. This is an indication that pyo­ darkened flyproof stalls the disease may genic infection as observed in chronie be prevented from developing into the types of the disease cannot be depended chronic type. upon to destroy the causative infection by bacteriolysis. It is not known to what Transmission extent calves recovered from chronic in­ It is difficult to determine the mode of fection would be a source of infection in transmission in natural outbreaks of kera­ herds of cattle, but it is a factor. Escher­ titis because the causative factor has not ichia coli, CorynebucteTium pyogenes, been determined. The incubation period Streptococci and Stuyhylococci have been of infection following artificial exposure isolated from calves actively infected with with virulent eye secretions has varied the disease in the field and in the labora­ from three days to three weeks. In a nat­ tory. Pusteurellu bovisepticu was isolated ural outbreak it might be that a number from eye secretions of one calf affected of calves were exposed at the same time, with chronic keratitis. The above orgc>u­ but a difference in the period of incuba­ isms have not reproduced the disease in tion would indicate that the infection was calves held under laboratory conditions. spreading rapidly through the herd. Ap­ Virulent eye secretions were obtained parently there is no correlation between from numerous cattle in ten herds during the severity of the disease and the incu­ three years of study and filtrates of this bation period as observed in these studies. material were used to expose susceptible With few exceptions the type of disease calves. The filtration studies have been produced under laboratory conditions has repeated in thirty-eight calves and four been the acute type. This can probably cows since the experiment was com­ be attributed to the use of semi-darkened, menced without reproduction of the dis­ flyproof stalls in housing these animals. ease. Approximately 70 percent of these

WinleY-I 94 I 75 animals were proven susceptible when ing summer and early fall, but it has been exposed with known virulent secretions. observed among cattle during winter Three attempts have been made to months. prove flies (Musca domestica and Stom­ 4. Keratitis is principally a disease of oxys calcitrans) transmitters of keratitis. young cattle but is found in adult cattle Diseased and susceptible calves were of the feeder class during every month of placed in an outdoor screened stall and the year. subjected to outdoor conditions. A solid 5. The disease can be transmitted with partition was placed between the dis­ fair consistency provided virulent eye eased and susceptible animals to prevent secretions are dropped on the surface of them from rubbing heads and possibly the cornea. It has not been necessary to transmitting the infection in this manner. scarify the eye tissues in order to assure Although flies were noticed feeding upon transmission in these studies. secretions around the margins of the eyes of the diseased and normal calves, the in­ 6. The incubation period of infection following artificial exposure has varied fection was not transmitted to the suscep­ from three days to three weeks. tible animals. Numerous attempts have been made to 7. Some calves are naturally resistant transmit keratitis from sheep to cattle to infection and cannot be caused to con­ and from cattle to sheep, but in all cases tract the disease, even though they are the infection proved specific for the species exposed repeatedly over a long period. of animal and could not be transmitted. 8. It is difficult to cause transmission of infection from diseased to healthy cattle Treatment even though they are compelled to eat Anti-serum was prepared from three and drink from the same receptacles. calves that had recovered from acute 9. Three types of the disease have keratitis. Two calves were given three been demonstrated in calves studied un­ injections of this serum at seven day in­ der laboratory conditions-the mild, acute tervals. Two weeks after the third injec­ and chronic types. tion both calves were exposed with viru­ 10. It has been impossible to re-infect lent eye secretions. Both calves developed those calves that have recovered from keratitis within ten days. Symptomatic treatment is usually re­ acute or chronic keratitis. sorted to in handling outbreaks of kera­ 11. Keratitis is probably a localized titis in herds of cattle. Argyrol, boric infection. acid solution, silver nitrate solution, and 12. Anti-serum prepared from calves re­ calomel, are some of the drugs used in covered from acute infection failed to treating diseased cattle. If the diseased protect calves from the disease as pro­ animals are detected during the early duced under laboratory conditions. stages of the disease and are placed in a 13. Calves recovered from chronic dark stall for several days, the progress of keratitis may prove a source of the infec­ the disease can be checked in some cases. tion for seven months or longer. Summary 14. Filtrates of virulent eye secretions failed to reproduce the disease. 1. Infectious bovine keratitis has a ----.!'+-,---- wide distribution. It has been diagnosed All wild animals suffer from disease among cattle of all ages and breeds in and sickness. These diseases are intensi­ practically every part of the United States. fied when the animals are used in captivi­ It was first reported upon scientifically ty because they have not built up the more than 70 years ago. immunity common in domestic stock. For 2. Keratitis spreads rapidly through instance, silver faxes raised in captivity herds of cattle under barnlot and pasture are susceptible not only to canine dis­ conditions. temper, but to paratyphoid and many 3. The disease is more prevalent dur- other ailments.

76 The Veterinary Student