P e rsp e ctive s

A Newsletter for Fanciers From The Cornell Feline Health Center

Summer 1988

New Feline Virus Threatens Health of

Margaret Barr, D.V.M.

Feline immunodeficiency virus (FIV), formerly associated disease even when repeated tests for called feline T-lymphotropic lentivirus (FTLV), the virus were negative. Now that a test for is a recently recognized feline virus belonging FIV is available, it is apparent that about 20 to the family Retroviridae. Although FIV is in percent of these FeLV-negative, immunosup- the same family of viruses as feline leukemia pressed cats are infected with the feline lenti­ virus (FeLV), it is not classified in the oncor­ virus. navirus subfamily. Instead, the morphology and biochemistry of FIV closely resemble the FIV or FeLV? characteristics of the retroviruses that are associated with non-malignant disease processes. Feline immunodeficiency virus and feline leuke­ These viruses, the lentiviruses, include the mia virus are similar in certain disease manifes­ causative agents of progressive pneumonia of tations. However, there are major differences sheep, infectious anemia of horses, arthritis- indicating that FIV is not just a slightly differ­ encephalitis of goats, and acquired immunodefi­ ent strain of FeLV. One difference between ciency syndrome (AIDS) of humans. FIV and FeLV is the morphology (shape) of the viral particle. Infected cells can be examined Clinically, the disease caused by FIV may by electron microscopy, a technique which al­ have been recognized for years. However, the lows visualization of very tiny particles by immunodeficiency-like syndrome with its multi­ magnifying them tens-of-thousands of times. tude of secondary infections, anemia, and low Viruses can be seen budding from the outer white-blood-cell counts, is indistinguishable surface of the cell into the surrounding envi­ from the non-neoplastic syndromes associated ronment. Both FIV and FeLV have a char­ with FeLV infection. Prior to the isolation of acteristic outer envelope, comprised of a por­ FIV, many cats were diagnosed as having FeLV- tion of the host cell’s membrane and some viral proteins, which is formed around the virus as it exits the cell. However, the internal structure of the FIV particle is elongated or cone- Inside this Issue . . . shaped while that of FeLV is more circular.

New Feline Virus Threatens page 1 The genome (genetic material) of FIV, as Health of Cats with other retroviruses, consists of single­ stranded ribonucleic acid (RNA). The produc­ The Mighty page 3 tion of a double-stranded deoxyribonucleic acid (DNA) copy of the viral genome is an essential Honor Roll page 7 step in the replication of this virus within the host cell. This step requires the activity of an Student Receives Summer Fellowship page 8 enzyme, reverse transcriptase, which is carried into the cell as one of the viral proteins. All retroviruses must have their own reverse trans­ criptase since it is an enzyme which is not generally used by host cells. FIV can be dis­ Perspectives 2 O n C a t s

tinguished from FeLV by a difference in envi­ count. This decrease in white cells is primarily ronmental conditions necessary for optimal due to a lack of neutrophils, cells which are activity of this enzyme. involved in protecting the cat against bacterial infections. A low red-blood-cell count (ane­ Also, FIV and FeLV are only distantly re­ mia) frequently develops. The cause of this lated since they are antigenically different. sometimes precipitous drop in blood cells is Antibodies produced in cats infected with FIV unknown, although it is likely due to a loss of do not recognize FeLV antigens (viral proteins), precursor cells in the bone marrow. and antibodies to FeLV do not bind to FIV particles. Furthermore, FIV is not antigenically Once the white-blood-cell count decreases, cross-reactive with human immunodeficiency the cat’s ability to protect itself against infec­ virus (HIV), the lentivirus responsible for AIDS tion is compromised. Bacteria, viruses, and in people. fungi, which are common in the cat’s everyday environment and generally are innocuous to a Pathogenesis of FIV Infection healthy cat, can cause severe illness in the immunosuppressed individual. It is these secon­ Very little is known about the sequence of dary infections which are responsible for most events which occurs following initial infection of the clinical signs associated with FIV. with the virus. The actual method of infection, or mode of transmission, is also unknown. Signs of FIV Infection Transmission through bite wounds is the most likely method of viral spread since free-roaming The clinical signs associated with the disease male cats are most frequently infected. Other are diverse because numerous secondary infec- types of salivary contact, such as the use of contaminated food and water bowls and social grooming practices, may also play a role in transmission. However, casual, nonaggressive contact such as this does not appear to be an Perspectives efficient route of infection. Transmission from A Newsletter for Cat Fanciers an infected queen to her kittens does occur, On Cats From The Cornell Feline Health Center but it is unknown whether this happens in utero (during gestation) or when the newborn The ultimate purpose of the Cornell Feline Health Center is to kittens ingest infected milk. A fairly high improve the health of cats everywhere, by developing methods to prevent or cure feline diseases, and by providing continuing percentage of infected cats are neutered, there­ education to veterinarians and cat owners. All contributions are fore sexual transmission probably is not a pri­ tax-deductible. mary method of initiating infection. Director: Fredric W. Scott, D.V.M., Ph.D. Editor: June E. Tuttle Secretaries: Sheryl A. Thomas, Gwen Frost, Following the initial contact of the cat with Karen Havekost FIV, the virus appears to be carried to regional Special Consultant: Leo A. Wuori, D.V.M. lymph nodes, where it may replicate in a sub­ This publication is made possible, in part, by population of white blood cells known as T- a grant from 9-Lives Cat Foods. We grate­ fully acknowledge this interest and support lymphocytes. These cells are suspected of being in the furthering of feline health. This the primary target of FIV since laboratory acknowledgement of our gratitude is not an endorsement of any particular company or culture techniques require the use of feline T- product. cells in order to grow the virus. The virus ®1988 by Cornell University on behalf of the then spreads to lymph nodes throughout the Cornell Feline Health Center, College of body, resulting in a general lymphadenopathy Veterinary Medicine, Ithaca, NY 14853. All rights reserved. Permission to reprint se­ (enlarged, lymph nodes). This stage of the lected portions must be obtained in writing. disease generally goes unnoticed by the cat’s Cornell University is an equal opportunity, owner unless the nodes are greatly enlarged. affirmative action educator and employer. Some time later, perhaps days but possibly weeks to months, the cat may develop a fever accompanied by a drop in the white-blood-cell 3

The Mighty Mite

Dwight D. Bowman, B.A., M.S., Ph.D.

Although are small external parasites, Ear mites are transmitted from cat to cat they can be detrimental to a cat’s health. during contact, and kittens will often become Mites are in the same family () as infected from their mother. These mites cause spiders and ticks. Their common characteristics the cat to have intense itching of the ears and include having eight legs as adults and a hard also cause the production of a characteristically external shell (exoskeleton). However, mites dark-brown ear wax. During severe infestations, are considerably smaller and usually can be a cat may tilt its head to one side or shake its identified only by microscopic examination. head. Usually, both ears will be infested. Mites usually remain on the same host through­ Secondary bacterial infections can also develop out the entire course of their development. in the ear canal. In a multiple cat household, Thus, several generations can easily occur on all of the cats may be infested, and will require the same . The mites of this type that treatment. Ear mites can be a persistent prob­ are of interest to the cat owner include Oto- lem, especially if the cat has access to the dectes cynotis, Notoed res cati, Sarcoptes scabei, outdoors. blakei and Demodex cati. Larval trombiculid mites, commonly called chiggers, Diagnosis is based on the microscopic exam­ have feeding habits that are more like those of ination of ear wax. Treatment consists of a tick; they only attach to their host long applying ear mite medications as per the veter­ enough to feed. inarian’s instructions. Before applying the medication it is usually necessary to remove the Otodectes cynotis (ear mites) excess ear wax and debris from the outer ear canal. The adult mites derive their sustenance from their feline host by piercing the skin of the outer ear canal. The hatching larvae feed on Notoedres cati the ear wax. Ear mites mature within 3 to 5 days and begin reproducing. This is a very small mite that burrows along underneath the superficial layers of the skin, causing a condition called notoedric mange (feline scabies). These mites are most com­ monly found on the top of the head or the forehead of the infested cat. Usually, the first sign will be a bald patch in one of these two areas caused by constant scratching by the cat. The bald patch may extend down the back of the head or across the bridge of the nose onto the cheeks. Prolonged infestations result in a grayish crust forming over the affected skin. Diagnosis will require that the veterinarian take skin scrapings or perhaps even biopsies from the affected areas to be examined microscopi­ cally. Treatment is relatively straightforward because all the various life cycle stages are on the same animal. Because of the ability of this parasite to spread from cat to cat by contact, it will again probably be necessary to treat all the cats in the household. Perspectives O n C a t s 4

Fortunately, this parasite is very rare these transmitted by direct and indirect contact. days. However, it should also be noted that Cheyletiella mites have been found on fleas, lice Notoedres cati has some zoonotic potential. and flies, thus implying that these larger para­ That is, this parasite is capable of infesting the sites may be a form of transportation for mites. cat owner. For this reason, care should be taken in handling the infested . Cheyletiella blakei has a tendency to crawl off the cat and bite the owner. Therefore, Sarcoptes scabei often it is the owner who first notices some­ thing is wrong when he or she is being bitten This parasite was recently reported from the with something that they cannot see. Searches domestic cat. Previously, it had been found of the cat’s fur may then reveal the presence only on wild cats. Sarcoptes scabei is very of these mites or their eggs. similar to Notoedres cati both in its habits and its physical characteristics. The tunnels made Demodex cati by this parasite tend to be deeper in the skin than those of Notoedres and these mites tend This is an elongate mite that is designed to to be less often confined to the head. The live within a hair follicle, causing a condition resulting condition is called sarcoptic mange. known as demodicosis. Related species live in the hair follicles of humans, dogs, and other Diagnosis from skin scrapings will require animals. Usually on humans and cats there is some care and expertise on the part of the no pathology associated with these parasites, veterinarian to differentiate these two mites. although the species on the dog can cause However, the treatment of both is very similar severe dermatitis. Occasionally, cats may show and should be successful since all the mites’ symptoms of infection, a mild dermatitis on the life stages are found on the cat. head or perhaps in the ear canals, but usually

Sarcoptes scabei may be passed from cat to cat. Other strains tend to prefer other hosts; thus, there are canine strains and human strains. When Sarcoptes scabei is found on a cat, it may indicate that the source of the infection is some other member or species in the household. It should be remembered that the cat may not be guilty of having brought this mite into the house.

Cheyletiella blakei

This mite is slightly larger than Notoedres and Sarcoptes, and it crawls about on the sur­ face of the cat. It has specially designed claws for clasping onto hairs, and will also glue its eggs onto the shafts of individual hairs. These mites can be seen moving about on the surface of the cat, if one examines a cat carefully. Often their is no apparent sign of their pres­ ence or the only sign will be flaky skin (dand­ ruff).

A diagnosis is made from the physical ap­ pearance of the mite. Once a diagnosis is made, this is a relatively easy disease to treat Demodex cati with medicated shampoos. These mites are 5

neither the cat nor the owner will know that Summary these mites are present. There have also been rare reports of generalized demodicosis occur­ Feline disease due to mites is a rare occurrence ring in cats. However, it is believed that with in the United States. When cases or outbreaks most of these cases, the demodicosis may be a do occur, they tend to be very disturbing to secondary symptom of another disease, such as both the owner and cat. Treatments are ap­ feline leukemia or diabetes. In generalized plied topically and often repeatedly, thus re­ demodicosis, the hair loss is more noticeable quiring a strong commitment by the owner for and may be associated with skin lesions and their cat’s improved health. In those very rare crusts. instances where both the owner and the cat are infested with the same mite species, it will be The mites are identified by microscopic necessary to seek the aid of both human and examination of skin scrapings. Treatment in­ feline doctors. In both cases, the services of a cludes the application of topical ointments to professional who can make a proper identifica­ the affected areas. Generalized demodicosis is tion is necessary to treat and control the pos­ treated with weekly parasiticidal dips or sham­ sible spread of the infestation. ■ poos. In some cases, the condition will regress spontaneously without treatment. Dwight D. Bowman, B.A., M.S., and Ph.D. is assistant professor of parasitology at the Col­ Larval Trombiculid Mites (chiggers) lege of Veterinary Medicine at Cornell University.

Adult trombiculid mites feed as micropredators on other organisms found in the fields and grasslands where they live. The larvae, how­ ever, require a meal from a mammalian host, usually a small rodent, in order to complete W hat are you doing in September their development to adults. Again, as with for Cat Health Month? ticks, if a cat brushes past a waiting chigger, the chigger will attach to the cat. Often the larval mites will then crawl to the ears of the ★ affected cat, but some species tend to cause more disseminated bites. Show how much you care about cat health by giving a gift membership to a Some chiggers sit on the surface of the skin friend or relative who owns a cat. The and cause a large mound of reaction around recipient of your gift will receive one their mouthparts from which they feed. Others year’s subscription to Perspectives on cause such a great reaction, that they are ac­ Cats, a membership certificate and lapel tually engulfed by the swelling to become to­ pin. Order your gift membership by tally embedded in the skin. In any case, they completing the form below. Gift cause severe itching, and in a sensitized host, memberships are only $15. the lesions may become open sores. Diagnosis is often done solely on the basis of clinical signs, although the chiggers can occasionally be recovered. Treatment involves treating the Name______symptoms of itching and perhaps killing the Address ______chiggers by applying a topical parasiticide. The City ______only good thing about chiggers is that they State ______ZIP usually leave the host after several days to a week even without treatment; and the itching From: will resolve, although in some cases this may Name______take several weeks. City/State ______Perspectives 6 O n C a t s

(continued from page 3) tions may be contracted by the immunosup- However, these therapies are not directed at pressed cat. General unthriftiness and poor fighting FIV itself. Some research has been coat condition are frequently the only outward done using a drug called interferon to control sign of a problem. Fever of at least 103°F is the virus, but it is too early to know if the often present in the later stages of disease and results will be promising. The drug AZT, used may be much higher at times. A very common in therapy for AIDS patients, may be useful presenting complaint is a loss of appetite or against FIV, but its side effects are apparently evidence of pain when eating due to infections greater in cats than in humans. Drugs designed of the gums (gingivitis) and mouth (stomatitis). to enhance or modify the cat’s immune system These conditions can lead to inflammation may also prove to be valuable in treating FIV around the teeth (periodontitis) with eventual infections. loss of the teeth. Prevention of Infection with FIV Chronic, nonresponsive or recurrent infec­ tions of the skin, urinary bladder, and upper Presently, vaccination of cats against FIV is respiratory tract are commonly seen. Persistent not possible. Certain aspects of viral patho­ diarrhea due to intestinal tract infection is also genesis may make the production of a tradi­ a frequent problem. Abortion of kittens or tional type of vaccine difficult or impossible. other reproductive failures have been seen in Human immunodeficiency virus and equine infec­ infected queens. Some infected cats have ex­ tious anemia virus are known to undergo fre­ perienced seizures and other neurologic disor­ quent antigenic variation in the proteins found ders. on their envelopes. This means that the host’s immune response is constantly having to adapt It is suspected that some of the cats identi­ to these changed proteins in order to fight the fied as FIV-positive have been infected for viral infection. In addition, lentiviruses are several years. A few of these cats have histor­ able to avoid the immune response altogether by ies of recurrent illnesses with periods of rela­ spreading directly from cell to cell. Finally, tive health between episodes. In such cases, these viruses infect and replicate in some of leukopenia (low white blood cells) and anemia the cell types which are important in immunity appear to be cyclic, with episodes of low cell against most other viruses. All these mechan­ counts followed by near normal levels. How­ isms play a role in protecting the virus from ever, the general trend seems to be progressive the antibodies induced by traditional vaccination with cell counts dropping lower during each methods. New methods of inducing immunity to subsequent episode. Slow but progressive viruses such as FIV and HIV are being explored, weight loss also is common, with severe wasting but it may be many years before a breakthrough occurring late in the disease process. is achieved. Presently, pet owners can protect their cats only by preventing contact with Treatment of FIV-Associated Diseases potentially infected cats. Pets kept indoors and away from free-roaming cats are highly unlikely Treatment for illnesses caused by FIV is based to contract the disease. Catteries and multiple- on clinical signs. Antibiotic therapy for secon­ cat households should test all cats in the col­ dary bacterial and fungal infections is moder­ ony. Once a negative status is established, all ately successful but must be continued long­ new additions should be tested prior to intro­ term or reinstituted as new infections occur. duction to the household. Current testing pro­ Supportive treatments such as intravenous cedures look for the presence of antibody to fluids, blood transfusions, and feeding of high the virus in a serum sample. Kits for in office calorie dietary supplements are frequently re­ veterinary testing are now available, making quired. The use of corticosteroids and other detection of infected cats no more difficult anti-inflammatory drugs may be indicated in than FeLV testing. some cases to control gingivitis and stomatitis. Anabolic steroids may help to combat weight (continued on page 8) loss and wasting. 7

Honor Roll

The following individuals have contributed $100 or more to support the Cornell Feline Health Center’s work on feline diseases. We are most grateful for their support and the support of many others who are not listed on the honor roll. Name Funds given for: Warwick Bonsai, South Carolina General Donation Fritz Castle, New York In memory of friend’s cat, DickyCarol Carol Cofey, Virginia In memory of Koshka Helen Dailey, Maryland In memory of Miss Kitty, Duchess, Mitzi, and F luffy Fowler-Milburn Foundation, Inc., New York General Donation Mr. and Mrs. E. James Honig, N ew York In memory o f Little Boy Loretta and Tim Kuehn, West Germany In memory of Little Rosie Adrienne Mason, New York In memory of Count Dracula Mary Charlotte Peters, Connecticut Camuti Fund Mr. and Mrs. John Rooker, N ew York General Donation Lois and Lorna Shade, California In memory of Siddhartha and Shadow Helen Shepard, New York Camuti Fund Mr. and Mrs. L.O. Weingart, N ew York In memory of Planty Pal and Boots Stephen B. Wuori, New York General Donation Cheryl Yeip, Michigan In memory of Tuna

Contributing Memberships

Joyce Compson, New York Ana R. and D. Ronald Daniel, New York Cozy Cat (Dr. and Mrs. Emil Perona), New Jersey Lois Jane Gibson, California Dr. Leslie S. Harrold, Ohio Eleanor D. Johnson, Pennsylvania Jake and Jetta Johnson, New York

Cat Club Support We also are very grateful for the support the following cat clubs have provided during the last three months.

Circle City Cat Club, Indiana Greater Lancaster Feline Fanciers, Pennsylvania Hi-Desert Cat Club, California Manasota Cat Fanciers, Florida Potomac Area Cat Enthusiasts, Virginia Perspectives 8 O n C a t s

Student Receives New Feline Virus Birmingham Feline Fanciers’ Summer Fellowship (continued from page 6)

Joyce Carnevale, a Cornell University veterinary Public Health Significance student, is this year’s recipient of the Birming­ ham Feline Fanciers’ Summer Fellowship. Dur­ Although FIV is closely related to the human ing the next several weeks she will be working immunodeficiency virus and causes a disease on determining parameters of fat metabolism similar to AIDS in the cat, it is highly species- and absorption in cats that are fed diets that specific. Only feline cells have been found to are low in taurine. Her advisor on the project support its replication. There is no antigenic is Dr. Harold Hintz, professor of animal nutri­ cross-reactivity between FIV and any of the tion. other lentiviruses, including HIV. In addition, initial studies of humans who have had close Carnevale received her B.S degree from contact with FIV-infected cats show absolutely Cornell University in 1984. She is concurrently no evidence of infection. Of course, careful working on obtaining her D.V.M. degree from research will continue to explore the relation­ Cornell University and her M.S. degree in ani­ ship of the animal lentiviruses to the human mal nutrition from Colorado State University. lentivirus in an effort to increase the under­ standing of the pathogenesis, epidemiology, and The Summer Fellowship Program was estab­ potential control methods of this very important lished by the Birmingham Feline Fanciers in group of viruses. ■ 1985 and is renewable on an annual basis. The purpose of the fellowship is to introduce veter­ M argaret Barr, D.V.M., is currently working on inary students to the specialties in feline medicine. obtaining her Ph.D. in veterinary virology. Her thesis project is the feline immunodeficiency virus.

Cornell Feline Health Center Cornell University College of Veterinary Medicine Ithaca, New York 14853

Flower Library Schurman Hall Feline Health Center