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Volume 39 | Issue 1 Article 6

1977 Pseudorabies in the Dog and Cat John D. Boucher Iowa State University

George Beran Iowa State University

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

Recommended Citation Boucher, John D. and Beran, George (1977) "Pseudorabies in the Dog and Cat," Iowa State University Veterinarian: Vol. 39 : Iss. 1 , Article 6. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol39/iss1/6

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]. Pseudorabies in the Dog and Cat

by John D. Boucher* and Dr. George Berant

Introduction with the disease in small animals may be an Pseudorabies, also called Aujesky's important aid in diagnosing pseudorabies Disease, Mad Itch, and Infectious Bulbar In sWIne. Paralysis, is a viral disease which primarily affects pigs. It occurs in, a wide variety of Clinical Case domestic and wild animals and birds, but On September 26, 1976, a veterinarian in not in apes, reptiles, or insects. The natural Gainesville, Missouri, referred a dog to the viral reservoir is swine, in which it produces Iowa State University Clinic. It was the high mortality in suckling pigs, relatively fourth dog he had examined for a farmer low mortality in older pigs, and may client during the past 48 hours. The first produce carriers showing few or no symp­ three had exhibited sudden profuse toms. salivation followed rapidly by death. The Pseudorabies has been reported fourth was now showing similar clinical throughout the world. References in the signs. literature indicate that the disease was The dog, an 18 month old female of present in the United States as early as mixed breeding, arrived at the ISU 1813. In 1962, severe outbreaks occurred on Veterinary Clinic in clonic spasms and several farms in Indiana; since that time, it unable to rise. Her pupils were constricted has been recognized in other areas of the and she was salivating profusely. She nation where swine are raised. Due to moved her jaws in a chomping motion, increased awareness on the part of snapped at hands held near her head, and veterinarians and swine producers or to an exhibited hysteria. Her temperature was 0 actual increased incidence, the disease is 107 ; the heart and respiratory rates were being reported with greater frequency elevated. While being examined, the dog throughout the United States. vomited blood and mucus. These clinical It is essential that large and small animal signs had become progressively worse. practitioners be cognizant of pseudorabies A preliminary diagnosis of in small animals. In a recent pseudorabies organophosphate toxicity was made and the outbreak in central Iowa, small animals dog was given fluids, bicabonate, Solu­ contracted the disease and died on 12 of the Delta-Cortef® , Valium® , and atropine, 16 farms involved. On 4 of these farms the and placed in a cold water bath. The bath small animal cases occurred before the succeeded in bringing the temperature disease was recognized in the swine. In down; the -atropine injection resulted in many instances, such as the clinical case dilated pupils and alleviated the excessive reported here, the death of a dog or cat on a salivation. The other symptoms, the farm has been the only indication that the spasms, chomping, and hysteria, continued virus was present. Therefore, familiarity and, four hours after initial treatment, 2 cc of Myothesia® were given. The dog died 10 minutes later and was sent to post *] . Boucher is a senior student in veterinary medicine, Iowa State University. mortem for necropsy. tDr. Beran is Professor of Microbiology, College of The following day, another dog and cat Veterinary Medicine, Iowa State University. from the same farm were sent for necropsy.

22 Iowa State University Veterinarian No significant gross lesions were found in Iowa State University, dogs were fed 2-3 any of the three animals. Liver, lung, grams each of liver from which spleen, and mesenteric lymph nodes from pseudorabies had been isolated, but failed all three animals were saved for bacterial to develop the disease. Another Iowa State culture. Stomach contents and brains were research project involved feeding a dog saved for organophophate, chlorinated increasingly larger amounts of infected hydrocarbon, rabies, and pseudorabies material but also failed to produce the tests. No significant pathogenic disease. When a suspension of the same microorganisms were cultured from the tissues was inocculated subcutaneously, bacteriological specimens, but the dog developed pseudorabies and died. pseudorabies virus was isolated from the In a case reported to the ISU Clinic, brain tissues. however, a dog belonging to a veterinarian In a telephone conversation with the was infected and died after licking at owner, it was learned that all five dogs were several blood spots following a post martem kept outdoors, but two were kept tied. He examination of an infected pig. also remarked that he had sprayed his Possible causes of such variable house two weeks previously with chlordane. susceptibility include age, varying Upon further questioning, he noted no virulence of the different strains of virus, problems in his swine herd. However, he acquired or maternal resistence, or other added that he had fed the dogs some dead unknown factors. These variables are pigs, indicating some health problems. The presently being researched. owner's veterinarian was asked to collect The possibility that infected dogs and blood samples from the pigs for testing at cats may shed the virus and be involved the Iowa State University Diagnostic in the transmission of the virus is also Laboratory. The swine tested were found to under investigation. There IS have high pseudorabies titers, indicating an epidemiological evidence to support this active infection was present in the swine hypothesis, but it has not yet been con­ herd. firmed by laboratory studies.

Etiology Pathogenesis The pseudorabies virus is a DNA virus of After gaining entry through a skin the Herpes group. It may survive in nature abrasion, the pseudorabies virus invades from 14 to 48 days or longer depending the local peripheral nerves and passes upon temperature and humidity. along them toward the central nervous Putrefaction will destroy the virus in ap­ system. It initially invades the spinal proximately 11 days and it is killed instantly ganglia, then passes into the spinal cord via by 1% sodium hydroxide (NaOH) or by the dorsal horns. The virus continues to heating to 100°C. move centrally to the medulla oblongata or, The virus will replicate and produce in some cases, more rostrally in the brain intranuclear inclusions in a wide variety of stem. In some animals, experimental mammalian cell cultures, providing a inoculation has been followed by transitory microscopic method for its detection. Cells viremia and secondary infection of other of swine, rabbit, or dog kidneys are most tissues. From each new location it also sensitive and the virus produces an easily moves centrally along the afferent nerves. recognizable cytopathic effect. An acute serous inflammation may develop at the point of inoculation but Transmission direct tissue reaction to the virus is The probable sources of pseudorabies to negligible. Self inflicted trauma does result dogs and cats are ingestion of dead and in severe inflammation and hemorrhagic infected pigs, cows, or rats, or being bitten necrosis. Lymphocytes collect along the or slashed by infected wild or domestic infected nerves and within the infected SWIne. ganglion; the neurons degenerate and The amount of infected material which necrose. A few of these neurons and some produces infection by the oral route seems mesenchymal cells develop intranuclear to vary. In an experiment performed at inclusion bodies. Foci of neuronal

Issue No.1, 1977 23 degeneration and inflammation within the be confirmed by the subcutaneous brain and spinal cord, particularly in the inoculation of mice or a rabbit with a ganglia, elicit a severe itching sensation. suspension of tissues from the suspect Death is probably due to neuronal injury in animal. Neural tissue from the site of in­ the medulla resulting in respiratory failure. tense itching or sections of spinal cord The pathogenesis of pseudorabies nearest the affected site are the tissues of following exposure by ingestion has not choice. Positive material causes intense been clearly elucidated. In swine and local pruritis 4-6 days post inoculation, perhaps in other animals as well, the virus followed by death. In the laboratory several travels to the medulla and pons via the 1st methods are commonly used for con­ (olfactory), 5th (trigeminal) and 9th firmation of pseudorabies. One of the most (glossopharyngeal) cranial nerves. Many important is histological examination of the dogs have been reported to display pruritis brain and spinal cord for typical lesions and of the area of the head after oral ingestion. the presence of intranuclear inclusion bodies. Other means of identification are Clinical Signs virus isolation in cell cultures and typing by The incubation period for pseudorabies fluorescent antibody or virus neutralization in both the dog and cat is 72-96 hours. tests. The most characteristic clinical It is important to differentiate manifestations are intense localized pruritis pseudorabies from the furious form of with scratching or chewing to the point of rabies. The shorter course, lack of vicious self mutilation and sudden death. Of the attacks on other animals and man and the many cases reviewed in the literature, intolerable pruritis are important dif­ nearly all infected dogs and cats displayed ferential characteristics which indicate pruritis and self mutilation. However, in a pseudorabies infection. few cases, such as the clinical case reported here, pruritis was not observed; perhaps it did not occur or it occurred early in the Prevention and Treatment course of the disease, before the animal Although vaccines for pseudorabies have was professionally observed. This sign will been developed and are used for disease not always be seen and its absence should prevention in several foreign countries, not preclude consideration of pseudorabies none are yet available in the United States. in the differential diagnosis. Prevention must, therefore, be directed Other clinical signs include high tem­ toward avoiding contact with infected perature, unresponsiveness to owners, animals. Dogs and cats should not be refusal to eat or drink, profuse salivation, allowed to eat any dead pigs, nor should vomiting blood and mucus, clonic spasms, they have access to the live pigs. incoordination, convulsions, collapse, coma Symptomatic treatment of animals with and death. All or only some of these severe pruritis and pain, accompanied by symptoms may occur in any given case. convulsions is indicated, although death is The disease is considered to be nearly almost certain. General anesthesia is the 100% fatal in small animals. One case of treatment of choice. pseudorabies antibodies in a clinically normal cat has been reported. In any case REFERENCES of sudden death in a farm dog or cat, pseudorabies should be included in the Baskerville, A., et al-(1973), Aujesekys Disease In differential diagnosis. Pigs, Veterinary Bulletin, Vol. 43, No.9, pp. 465­ 475. Blood, D. C., Henderson, ]. A., (1974) Veterinary Medicine, Williams & Wilkins Co., Baltimore, pp. Diagnosis 536-538. A presumptive diagnosis of pseudorabies Chastain, C. B., Andrews, ]. ]., Rekemeyer, R. R. can be made whenever the classical clinical (1973), Suspected Pseudorabies In Two Dqgs, signs of pruritis, salivation, and sudden ]AVMA, Vol. 163, No.1, p. 77. Dow, C., (1963), Aujeszrys Disease In The Dog And death occur, especially in a farm dog or one The Cat, Veterinary Record, Vol, 75, No.4, pp. exposed to farm animals. The diagnosis can 1099-1101.

24 Iowa State University Veterinarian Gustafson, D. P. (1970), Pseudorabies, Diseases Of Diseases Of Feedlot Cattle, Lea & Febiger, Swine, Ed. By H. W. Dunn, Iowa State University Philadelphia, pp. 13-17. Press, Ames, Iowa pp. 337-353. Merchant, I. A., Packer, R. A., (1971), Veterinary Harris, A. L., (1968), Aujeszkys Disease In A Dog, Bacteriology And Virology, Iowa State University JAVMA, Vol. 152, No.1, p. 54. Press, Ames, Iowa, p. 622. Hobson, H. P., Ellett, E. W., (1975), Canine Shen, D. T., Gorhan, J. R., (1974), Pseudorabies In Medicine, American Veterinary Publications Inc., The Dog And Cat, Current Veterinary Therapy V, Wheaton, Ill., p. 145. Ed. By R. W. Kirk, W. B. Saunders Co., Hutchcroft, T., Beran, G., Pseudorabies In Cattle, Philadelphia. Iowa State University Veterinarian, Vol. 37, No.3, Smith, A. S., Jones, T. C., Hunt, R. D., (1972), p. 83. Veterinary Pathology, Lea & Febiger, Jenson, R., Mackey, (1974), Aujeszkys Disease, Philadelphia, pp. 369-373.

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Issue No.1, 1977 25