Siberian Tiger Species Survival Plan
Doug Armstrong, DVM
Siberian Tiger Species Survival Plan
Henry Doorly Zoo
3701 S. 10th St.
Omaha, NE 68107
The veterinary advisor for the Siberian Tiger SSP recommends the following vaccination protocol for use in all tiger SSP managed animals:
1 ml. given intramuscularly of Purevax Ferret Distemper Vaccine, Merial, Inc.
1 ml. given intramuscularly of Fel-O-Vax LV-K, Fort Dodge Laboratories Inc.
Some institutions use 2 ml. doses due to the greater body weight of tigers
although there is no direct evidence that this is more effective, it also doesn’t
really do any harm.
1 ml. given intramuscularly of Purevax Feline Rabies Vaccine, Merial, Inc.
Rabvac 3 from Fort Dodge Laboratories and Imrab 3 from Merial should also be
equally safe to use in tigers.
Animals never before vaccinated should receive at least 2 and preferably 3 booster vaccinations approximately 3 weeks apart after 6 weeks of age.
Previously vaccinated animals should receive an annual booster.
These recommendations represent, in my opinion, the best steps we can take to protect the tigers against common infectious diseases that are known to pose significant threats to them. However it is important for you to recognize the following qualifiers:
There are no vaccines, including those listed above, that are legally approved for use in non-domestic felids. This is particularly relevant with rabies vaccines.
We do not know how protective these vaccines actually are or how statistically effective.
Modified live vaccines for diseases such as canine distemper have some significant risk of inducing the disease when used in species which the vaccine is not labeled for. None of the vaccines listed above is a modified live virus vaccine.
There are no vaccines approved for use in non-domestic felids. However the large cat species are known to be or are thought to be susceptible a number of domestic cat and dog viral diseases. Some attempt needs to be made to protect the cats against diseases. The domestic feline viral diseases that effect tigers include:
In addition it is known that most species of large felids are also susceptible to canine distemper virus.
As a general policy, most institutions and clinicians do not use modified live vaccines in species that have not been approved for the vaccine because of the risk that a modified live vaccine may actually cause the disease it is supposed to help protect against. This can occur when modified live vaccines are used in species in which they have never been tested. Consequently most vaccinations are done with killed vaccines.
It is also true that no statement can be made with regard to how well any of these vaccines work or how protective they are for the animal against the particular disease. This is because neither the animals nor the resources exist to allow clinical trials and live virus challenges in endangered or exotic species. However vaccinating with killed vaccine, even though we cannot know for certain how effective it is, constitutes a better approach to the problem of disease prevention than doing nothing at all.
The veterinary advisor for the Siberian tiger SSP recommends the vaccination of normal healthy tigers for Feline Rhinotracheitis, Calici Virus, Panleukopenia, Feline Leukemia,
Rabies and Canine Distemper with killed vaccine. Some examples of available products which could be used, and have been used with no known adverse reactions at the Henry Doorly Zoo and other institutions, include:
1. for Feline Leukemia, Feline Rhinotracheitis, Calici Virus, Panleukopenia and Chlamydia
Fel-O-Vax LV-K, Fort Dodge Laboratories Inc., Fort Dodge, IA 505501
2. for Rabies
Imrab 3, Merial Inc., Athens GA 30601
Rabvac 3, Fort Dodge Laboratories Inc., Fort Dodge, IA 505501
Other killed vaccine products may be available. There are not at present any killed vaccines for canine distemper.
Merial Inc. introduced two new vaccines recently, one for canine distemper and one for rabies virus, which are not killed virus vaccines but rather live canarypox virus vaccines which carry a portion of the genetic sequence for either rabies virus or canine distemper virus. Although the vaccines are live virus vaccines, they are incapable of causing the diseases of concern even when used in species outside of that for which they are labeled because they carry only a fragment of the genetic sequence for the disease causing viruses. Significantly as well, these two Merial vaccines do not contain adjuvants which have been associated in some cases with tumors and some other disease problems in other species of cats.
The canarypox vectored vaccine for canine distemper and for rabies have both been used in large cats and it is the advisors recommendation that the canine distemper virus vaccine should be given to all SSP Siberian tigers. The Merial rabies vaccine provides another alternative for rabies vaccines in large cats.
1. for Canine Distemper
1 ml. given intramuscularly of Purevax Ferret Distemper Vaccine, Merial, Inc.
2. for Rabies
1 ml. given intramuscularly of Purevax Feline Rabies Vaccine, Merial, Inc., Athens
Unfortunately no claim can be made that any of the vaccines are effective in protecting the animals nor can any claim be made that they are absolutely safe. That information will probably not ever exist. However they do represent the best that we can do in protecting the animals and the vaccines cited above have all been used in a clinical setting with no significant adverse reactions observed.
A more comprehensive review of the disease issues of concern continues below. Canine distemper is particularly addressed due to the pervasive nature of the virus, the significant pathology it has produced in isolated cases to date and the fact that no vaccine that seemed to be safe to use in big cats was readily available until recently. Additional information concerning the Merial vaccines is available from Dr. Montali on the American Association of Zoo Veterinarians website www.aazv.org in the Medical Information Center.
Canine Distemper Virus
Multiple cases of the morbillivirus, canine distemper, as a cause of morbidity and mortality in Panthera tigris and other felid species have now been documented. Historically the canine distemper virus as a cause of chronic encephalomyelitis in a Bengal tiger (Panthera tigris bengalensis) was reported in 1983.(3) Evidence of a paramyxo-like virus associated with encephalitis in a Siberian tiger (Panthera tigris altaica) was also reported in 1983.(6) Two adult snow leopards (Panthera uncia) died in 1988 with symptoms of weakness, hemorrhagic feces, seizures, head tilt, ataxia, nasal discharge and dyspnea.(5) Feline panleukopenia virus was confirmed by enzyme-linked immunosorbent assay ante-mortem in one of these leopards. In addition to lesions consistent with feline panleukopenia virus found on necropsy, evidence of interstitial pneumonia was found in both animals. Although virus isolation attempts were negative, canine distemper virus was confirmed in the affected lung of one animal by multiple fluorescent antibody tests. In addition, both snow leopards developed positive serum titers for canine distemper virus during the course of the disease.
During 1992, canine distemper outbreaks in Panthera species occurred at three geographically separate facilities in the United States. Two leopards (Panthera pardus) died in Illinois with symptoms of depression, anorexia, ataxia and seizures.(4) Two tigers at a California facility also developed central nervous system symptoms. One of these cats died and the other recovered with no chronic symptoms.(2) At a separate facility in California, enteric, respiratory and central nervous system symptoms developed in a large group of cats.(1) Seventeen animals died including one jaguar (Panthera onca), four leopards, five tigers, and seven lions (Panthera leo).
Canine distemper virus was isolated from at least one animal at each of the three locations. The isolated viruses were indistinguishable from the naturally occurring type of the virus isolated from dogs and other species. No evidence was found of other concurrent viral infections such as feline immunodeficiency virus which might have predisposed the cats to canine distemper infection.(2) Raccoons (Procyon lotor) were considered the source of the virus in two cases and dogs were the source in one case.
During 1993 a large group of privately owned tigers developed symptoms of enteritis, primarily severe diarrhea. This enteritis spread extremely rapidly through this group of cats. Circumstantial evidence indicates that this outbreak may have been due to a primary canine distemper virus infection or a concurrent infection, however canine distemper virus was not isolated.(7)
In 1994 a canine distemper outbreak occurred in the wild free-ranging lions in the Serengetti in Africa.(11) Similar CNS symptoms and significant mortality were reported. Canine distemper antibody titers have been confirmed in free ranging leopards in the Russian Far East, indicating exposure but no morbidity or mortality has been observed to date. (10)
In 1996 and 1997 at the Shanghai Zoo 14 tigers developed symptoms consistent with and tentatively diagnosed as enteric canine distemper virus including anorexia, vomiting, diarrhea and depression. No animals died.
In 2002 an outbreak of distemper took place in multiple large cat species including tigers and lions at a private rescue facility in the southern U.S.. The disease was confirmed immunohistochemically. The disease spread slowly through the population, not in a dramatic outbreak fashion, and primarily manifest as CNS symptoms. Limited information is available but at least 2 deaths had occurred as of 08-06-02. Another outbreak in North Carolina had run a 3 week course in a population 35 big cats in a private facility. 3 animals had died and no others were clinically ill as of 14-06-02. The disease was confirmed but no information regarding specific technique was available. A third outbreak has also occurred in a private facility in the U.S. but no information is available beyond that.
The canine distemper virus had historically been considered largely insignificant as a felid pathogen. However, recent cases identify canine distemper as a potentially significant pathogen in captive populations. At the present time no vaccine is available that is approved in a regulatory sense as effective and safe in Panthera species. No commercially produced killed vaccine is currently available. Modified live vaccines carry the risk of inducing the disease in species in which they have not been tested.(8) The protection of captive felid populations from direct contact with potential sources of infection such as dogs and free ranging wildlife capable of carrying the infection is an important method of prevention. If an outbreak of canine distemper occurs or the risk of exposure is very high, then in the past vaccination with highly attenuated avian-origin modified live vaccines such as FrommeD (Solvay Animal Health Inc., Mendota Heights, MN, USA) or FER VAC-D (United Vaccines, Inc., Madison, WI, USA) has been considered but does carry some risk of inducing the disease since no clinical trials have been conducted. Fromme-D is no longer available and Ferr-vac may carry greater risks than the new canary pox vaccine described below.
In 2001 the Merial Company introduced a live Canarypox vectored canine distemper vaccine (Purevax Ferret Distemper) vaccine. This vaccine does not carry live canine distemper virus however a portion of the canine distemper genome is carried in a live canarypox virus. The vaccine produces immunity to canine distemper virus in ferrets and is marketed for that species. This vaccine was used in large cats, including tigers, in a clinical trial in 1997. No adverse reactions were reported and cats did develop detectable antibody titers to canine distemper virus. No challenge studies could be done so no claims can be made that the antibodies are protective against the disease. However, it is likely that they are and no other option other than modified live canine distemper virus vaccines currently exists, therefore this vaccine represents the best option available to try to provide some protection against canine distemper virus.
1. Appel, M.J.G., R.A. Yates, G.L. Foley, J.J. Bernstein, S. Santinelli, L.H. Spelman, L.D. Miller, L.H. Arp, M. Anderson, M. Barr, S. Pearce-Kelling and B.A. Summers. Canine distemper epizootic in lions, tigers and leopards in North America. 1994 J. of Vet. Diag. Invest. (In Press).
2. Appel, M. Personal communication.
3. Blythe, L.L., J.A. Schmitz, M. Roelke and S. Skinner. 1983. Chronic encephalomyelitis caused by canine distemper virus in a Bengal tiger. J. Am. Vet. Med. Assoc. 183: 1159-1162.
4. Dierks, R. Personal Communication.
5. Fix, A.S., D.P. Riordan, H.T. Hill, M.A. Gill and M.B. Evans. 1989. Feline panleukopenia virus and subsequent canine distemper virus infection in two snow leopards (Panthera uncia). J. Zoo Wildl. Med. 20(3): 273-281.
6. Gould, D.H., and W.R. Fenner. 1983. Paramyxovirus-like nucleocapsids associated with encephalitis in a captive Siberian tiger. J. Am. Vet. Med. Assoc. 183: 1319-1322.
7. Houck, R. Personal communication.
8. Montali, R.J., C.R. Bartz, J.A. Teare, et. al. 1983. Clinical trials with canine distemper vaccines in exotic carnivores. J. Am. Vet. Med. Assoc. 183:1163.
9. Montali, R.J. Unpublished data.
10. Quigley, K. S., D.L. Armstrong, D.G. Miquelle, J.M. Goodrich and H.B. Quigley. 2001. Health Evaluation of wild Siberian tigers (Panthera tigris altaica) and Amur leopards (Panthera pardus orientalis) in the Russian Far East. American Association of Zoo Veterinarians Annual Conference, Orlando, FL., Sept. 18-23, 2001. Pp 179-182
11. Roelke-Parker, M.E., L. Munson, C. Packer, et.al. A canine distemper virus epidemic in Serengeti lions (Panthera leo). Nature 379: 441-445, 1996
Feline Upper Respiratory Disease Complex
A combination of organisms produce this disease including a chlamydia, herpes virus and calici virus. It has been diagnosed in tigers, leopards, lions and cheetahs but is probably most significiant in clouded leopards and some other small cats.
The organisms are spread by saliva and respiratory secretions. The viruses remain stable for months in organic material. Following exposure there is a 2-4 day incubation period. The cat then develops nasal and ocular discharges. Sneezing, salivation and a rising fever accompany development of the disease. Generally the cats stop eating.
Primary viral pneumonia and death can occur. Secondary bacterial pneumonia and death is more common. The most common outcome is development of long term infections of the nasal turbinates and sinuses in clouded leopards. Some cases involving infection of the ethmoid plate have occurred.
Reported in snow leopards, lions, tigers, jaguars, jaguarundi, clouded leopards and cheetahs. Can be significant pathogen but killed vaccine is available and effective.
Feline Leukemia Virus
Reported in a number of species based on detectable titers. Probably not a significant pathogen. Vaccination with modified live vaccines is not recommended.
Feline Infectious Peritonitis
Reported in lions, cougars, leopards, jaguars, lynxes and other cat species but is rare in all species except cheetahs. It is a significant problem in cheetahs.
This cornoavirus infects a high percentage of cheetahs in North America (40-65% test positive) and has been found in wild populations. Both the enteric and systemic strains are found in cheetahs. Transmission is by ingestion or inhalation of the virus. Domestic cats are the probable primary source of the virus in most cases except in cheetahs which infect each other.
Primary symptoms are intermittent diarrhea, anorexia, weight loss, lethargy, abdominal distension and leukocytosis. Reproductive ability is reduced. Both wet and dry forms occur but normally there is a pleural effusion. Primarily very young and old cats are effected. Supportive care such as intravenous fluids and antibiotics will get animals through crises. On necropsy the serosa will be granulomatous, an effusion may be present and the intestines will be thickened and ropey.
The incidence in cheetahs may be related to reduced genetic diversity and reduced immunocompetence. The other cat population with a high incidence of FIP is Florida panthers. They are known to have a high level of inbreeding. FIP titer incidence in that population is 19%.
Feline Immunodeficiency Virus
A retrovirus producing chronic disease in domestic cats.
1 - acute - 1-4 months duration of lymphadenopathy, neutropenia and depression.
2 - asympomatic carrier - months to years duration. No symptoms.
3 - persistent generalized lymphadenopathy lasting 2-4 months.
4 - declining immune function and weight loss. Neoplasms, anemia, gingivitis and dermatitis.
Diagnosed in captive snow leopards, lions, jaguar, tiger and pallas cats as well as free ranging Florida panthers and bobcat (37% incidence in panthers).