Volume 37 | Issue 2 Article 1

1975 And Detached as Post- Distemper Lesions in the Canine Barb Milke Iowa State University

R. W. Carithers Iowa State University

Follow this and additional works at: https://lib.dr.iastate.edu/iowastate_veterinarian Part of the Commons, and the Small or Companion Animal Medicine Commons

Recommended Citation Milke, Barb and Carithers, R. W. (1975) "Chorioretinitis And Detached Retina as Post-Distemper Lesions in the Canine," Iowa State University Veterinarian: Vol. 37 : Iss. 2 , Article 1. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol37/iss2/1

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]. Chorioretinitis And Detached Retina As Post-Distemper Lesions in the Canine

by Barb Milke* R. W. Carithers D.V.M., M.S., Ph.D.t

Summary Case Report #6J017 In the canine species there are many On December 2, 1974 a 3 year old male causes of choriorentinitis and detachment Blue Coonhound was admitted to the of the retina. Among these are: fungal Stange Memorial Clinic. The dog exhibited Infections such as Blastomycosis and Coc­ an ataxia with the toes spread wide in cidiodomycosis; invasion by Toxoplasma splay fashion as he walked. He also ap­ organisms; trauma to structures of the eye peared weak and was showing some dys­ with subsequent hemorrhage, infection or metria of the front legs. The first signs of rupture of the vitreous; tumors of the cho­ front leg lameness had appeared ten days roid or retina; parasitic larval migrans following hunting for coons thus a Coon­ such as Toxacara canis; progressive hered­ dog paralysis was suspected. The dog had itary diseases; post-systemic diseases such been given butazolidine tablets at that as distemper; and those of unknown eti­ time. Upon close examination it was noted ology.! The ophthalmoscopic lesions of that the were dilated and by oph­ the case presented were those of a bi­ thalmoscopic exam a severe was lateral, chronic chorioretinitis with a uni­ discovered in both eyes. The right eye lateral detachment of the retina suspected showed chronic scarring lesions and the of being due to a delayed post-distemper left eye had a detached retina. At this virus infection reaction. stage chorioretinitis and detached retina were diagnosed with a possible ceJ:ebellar Introduction lesion as a cause of the dysmetria. Since Due to the juxtaposition of the retina to the dog was not vaccinated for canine dis­ the , both structures usually are in­ temper a post-distemper demyelination volved in an inflammatory process. Chori­ was also suspected. Further examination oretinitis by definition means primary in­ revealed with the left di­ flammation of the choroid with subsequent lated more than the right one. The left spread of the inflammatory process to the eye was not responding to light with direct retina. The retina is attached to the cho­ or consensual pupillary response from the roid only at the optic disk and at the ora left to the right eye. Direct and consens­ serrata. It is held against the choroid due ual pupillary response from the right to to the pressure of the vitreous.9 Thus the the left eye was normal. retina can be easily detached due to loss of Differential diagnosis for the dysmetria vitreous pressure, presence of inflamn1a­ of the forelimbs included a space occupy­ tory exudates, or hemorrhage between the ing lesion of the cerebellum, Coondog pa­ choroid and the retina. Consequently, cho­ ralysis, distemper, tick paralysis and ra­ rioretinitis often leads to a partial or com­ bies. The dilatation of the left pupil with plete detachment of the retina with re­ no light response could have been due to sultant i~pairment or complete loss of a lesion in the area of cranial nerves II vision. and/or III. Some of the differentials con­ sidered as possible causes of the eye le­ ~ Miss Milke is a fourth year student in the College of Veterinary Medicine, Iowa State University. sions were distemper, , pro­ t Dr. Carithers is an Assistant Professor of Veterinary Clinical Sciences at Iowa State University. gressive retinal atrophy, or detached retina

40 !07.1J'a State University Veterinarian due to trauma or some unknown etiology. and prognosis for vision of the animal. Blood taken for clinical pathology analy­ Ophthalmoscopically, chorioretinitis Ie.. sis on Dec. 3rd revealed no abnornlalities. sions have been divided into two forms: Serum for the toxoplasmosis titer was (1) active chorioretinitis and (2) inactive iound to be negative. On Dec. 5th a cere­ or chronic chorioretinitis, which is the brospinal fluid tap was taken and the re­ form most recognized by clinicians due to sults are as follows: the fact that active inflamnlation often Pandy test-negative obscures good observation of the retina. Glucose-72 Active chorioretinitis can be characterized Blood glucose-113 ophthalmoscopically by cellular infiltra­ Cells-O tion, which appears as dull grey areas Culture-negative with indistinct borders in the tapetal re­ A complete ophthalmoscopic exam of gion and white or grey areas in the non­ the left eye revealed several superficial tapetal region, usually accompanied by lines across the , forma­ retinal exudates, edema and perivascular tion on both the anterior and posterior cuffing. Bullous can capsules of the and a detached retina. occur and appear as well delineated cystic The right eye showed multifocal areas of spaces between the retina and the pigment chorioretinitis suspected of being old dis­ epithelium.1 Inactive or chronic' chorioret­ temper lesions. initis, on the other hand, is characterized The dog was released on Dec 13, 1974 by retinal atrophy and scarring either after close observation and no treatment. focal or diffuse. This appears as bright. His condition appeared to be getting bet­ hyperreflective areas in the tapetal region ter. He was less ataxic now and his toes and pale areas in the non-tapetal regioll were less splayed than when admitted. where the pigment epithelium has atro­ The damage to the retina was thought to phied. In addition, pigment epithelial pro­ be permanent, although the dog had some liferation can also occur in which the le­ vision in the right eye, he was completely sions themselves are invaded by focaL blind in the left eye. multifocal or diffuse pigmentation. The decreased caliber of the retinal vessels in­ Discussion dicate thinning of the retina. In many cases chorioretinitis progresses Canine distenlper is the most common causing a partial or complete separation cause of chorioretinitis in the dog. 3 Ac­ of the retina from the overlying pigment cording to experimental research reported epithelium. Ophthalmoscopically, retinal by Parry12 in 1953, twenty-five dogs were detachment appears as if the retina has proven to have canine distenlper by viral been folded over maybe even obscuring inclusion body isolation from the renal the optic disk. The retina is a silver grey pelvis, urinary bladder, bronchial epithe­ color and it undulates with movenlent of lium or the brain. All but two of these the eye as if it were floating free in the dogs showed degeneration of the retinal vitreous. The retinal vessels are tortuous ganglion cells upon histopathological ex­ and appear elevated whereas the choroid amination, although these dogs did not vessels are hard to envision. A sharp line necessarily exhibit signs of blindness. appears at the junction of the attached These lesions were thought to be due to and unattached portions and the detach­ primary localization of the virus in retinal ment uS'tl:ally continues to spread to the tissues or due to secondary extension of rest of the retina resulting in complete viral infection from the brain through the loss of vision. to the retina. Thus it is im­ The histological lesions caused by infec­ portant to perform an ophthalmoscopic tion with canine distemper virus with re­ exam on any animal suspected of having spect to the eye are as follows: necrosis canine distemper in order to determine and degeneration of retinal ganglion cells the extent of choriorentinal involvement with accompanying edema and perivascu-

Issue No.2, 1975 41 lar cuffing, swelling and proliferation of the overlying the retinal detach· retinal pigment epithelial cells, inclusion ment in a triangular pattern 6 mm. from bodies found in the retinal and optic nerve the limbus to 1 mm. from the optic nerve. glial cells, local and diffuse atrophy of the The muscle and are closed rods and cones, sometimes with a loss of separately with #OOOO'catgut and the can­ retinal layer organization, and eNS in­ thotomy incision closed with #0000 silk. flammation and demyelination of the optic Post-operative treatment includes atropine nerve and its tracts.lO to maintain dilation of the eye and 2.5 mg. prednisolone given subconjunctivally. Treatment Dexamethasone drops 0.1 % are given q.i.d. for six days and 5 mg. prednisolone The treatment of chorioretinitis medi­ orally for three days. Benzathil1e penicil­ cally has had questionable results due to lin, 400,000 units, has also been given at the fact that many of the cases are not the conclusion of the surgery. This pro­ recognized until they have reached the cedure caused destruction and retil1al chronic stages and retinal detachment atrophy in the area burned but prevented with permanent scarring has already oc­ the rest of the retina from detaching thus curred resulting in clinical syrnptoms of resulting in only a partial loss of vision, blindness. If diagnosed early, however, medical treatment of the inflammatory, Conclusion exudative type of chorioretinitis with reti­ nal detachment has had some good re­ In conclusion, the canine distemper sults. The therapeutic regimen of steroids, virus can often lead to chorioretinitis and Diurila , and chloramphenicol when indi­ more serious retinal detachment with re­ cated has resulted in absorption of sub­ sultant loss of vision. This can occur retinal fluid with reattachment of the ret­ either during acute infection with the ina and return of vision.!l Possible use of virus even a few years post-infection. systen1ic enzymes such as Kymarb may be Thus, it is important to perform an oph­ helpful. This treatment is recommended thalmoscopic exam on dogs -suspected of for at least two weeks before a hopeless having canine distemper in order to de­ prognosis is given.11 It should be noted, termine the extent of ocular lesions and to however, that the condition must be recog­ initiate therapy early. History of an un­ nized in its very early stages and therapy vaccinated dog, past systemic disease with initiated immediately in order to obtain or without accompanying nervous signs, any response to medical treatments. and sudden onset of blindness can help In man there are various techniques differentiate this consequence of distem­ used to correct a detached retina such as per from progressive retinal atrophy or perforating diathermy, electrolysis, scleral other causes of chorioretinal lesions and resection, surface coagulation, photocau­ detached retina. terization, cryo freezing techniquel1 and the laser beam method. Few of these Bibliography methods have been used in the canine spe­ 1. Aguirre, Gustavo V.M.D. The Retina, AAHA Contin­ cies. however a surgical technique has uing Education Series. 1974. been used by Rubin. 13.14 In this method 2. Aguirre, Gustavo V.M.D. "", Kirk's Current Veterinary Therapy V, Philadelphia: '\T. B. a lateral canthotomy is performed and the Saunders Co., 1974, pp. 501-5. 3. Albert, R. A, "Lesions of the ocular fundu~ al\Sf\c1­ conjunctiva is incised 6 mm. from the ated with systemic disease", JAVMA Vol. ]57 No.l1, Dev. 1, 1970. pp. 163./)-9. limbus in an 80° arc laterally. A stay 4. Appel, M. J ..G., ,"Distemper pathogenesis in dogs" suture is placed in the lateral rectus mus­ .TAVMA Vol. 156. June IS, 1970, PP. 1681-3. .:J. Barnett, K. C. Variations of the Normal Ocular Fun­ cle, it is transected and freed laterally. A dus of the Dog. AAHA publication lQ7? 6. Bistner, Stephen I. "Examination of the eye", Kirk's 1.5 mm. electrode needle is used to burn Current Veterinary Therapy V, Philadelphia: W. B. Saunders Co., 1974, pp. 467-8. a series of holes 1.5 to 2.0 mm. apart in i. Bistner, Stephen I. "Ocular manifest.ation of systemic disease", Vet. Clinics of N.A. Vol. 3 No.3. Sept., 1973. R. Fischer, C. A. "Retinal and retinochoroidal lesions in :I, Diuril. ch]orothiatide. "\ferck. Sharpe & Dohme. early neuI'opathic canine distemper", .TAVMA Vol. 158, h. }\.\I11;\I. CIl\lllotrypsin, ArmClur. 1971, p. 740.

42 Iowa State University Veteritlarial1 9. Jenson, H. E. Stereoscopic Atlas of Clinical ophthal· 13. Paton, H. J. et al. Atlas of Eye Surgery 2nd ed. New mology of Domestic Animals, St. Louis: C. V. Mosby York: McGraw-Hili Book Co., 1962, pp. 162-5 Co., 1971. '14. Rubin, L. F. Atlas of Veterinary aphthamology, Phila· 10. Jubb, K. V., Saunders, L. Z. and Coates, H. V., "Tbe delphia: Lea and l'ebiger, 1973. Intraocular lesions of Canine distemper", J. Compo 15. Rubin, L. F. "Correction of retinal detachment in a Path'" Therap. Vol. 67, 1957, pp. 21-9. dog", JAVMA Vol. 157, Aug. 15, 1970, pp. 461-6. II. Magrane, Wm. G., Canine aphthamology, Philadel· 16. Vainisi, S. J. The Canine and Feline Ocular Fundus phia: Lea and Febiger, 1971. AAHA publication, 1965. 12. Parry, H. Brit. Journal aphtha/. Vol. 37, 1953 p. 37, Vo1.38, p. 295.

Our symbols can complement yours Aesculapian Staff. The What is a nitrofuran? A man-made chemical disease-fighting nitrofurans. compound that kills disease-producing And the Eaton name. organisms by interfering with their Together they symbolize [I] metabolic processes. For complete our joint effort toward specifications, on any Eaton nitrofuran improving and maintaining animal health. product, write Eaton Veterinary This is true in thousands of veterinary Laboratories, Norwich, New York 13815. practices today. One reason, we believe, is Eaton Veterinary Laboratories' continued support of the educational aspects of veterinary medicine. More important, though, our nitrofuran products have earned a position of trust through consistent effectiveness and proven quality. For proof, just ask around. Will the Real Feline Respiratory Disease Please Stand Up?

by Char Slindee*

Feline respiratory diseases are a serious erinarian must be aware of the organisms and' frustrating problem to cat owners and most commonly encountered in order to veterinarians alike. They are highly con­ gain the· most value from a preventative tagious and difficult to treat. In recent program of vaccination. years, a number of agents have been rec­ In the past, "pneumonitis" was thought ognized as causing or contnbuting to dif­ to be almos,t synonymous with feline res­ ferent forms of respiratory disease. Com­ piratory disease. Recent extensive research plicating the problem, the clinical signs of indicates this disease, caused by a chlamy­ each are very similar, requiring laboratory dia, actually plays a much l~ss significant facilities for specific diagnosis. The vet- role. Numerous agents producing indis­ • Miss Slindee is a third year student in the College of Veterinary Medicine, Iowa State University, tinguishable clinical signs have been rec-

Issue No.2, 1975 43