Visit: www.vets4wildlife.co.za

 

 

Wildlife Publications:  Click here to order:

 

Capture, Care and Management of Threatened Mammals

(click here to view Table of Contents)

Cheetahs as Game Ranch Animals

(click here to view Table of Contents)

Game Ranch Planning and Management

(click here to view Table of Contents)

Relocation of Large African Mammals

(click here to view Table of Contents)

Rhinos as Game Ranch Animals

(click here to view Table of Contents)

Sable Antelope as Game Ranch Animals

(click here to view Table of Contents)

The African Elephant as a Game Ranch Animal

(click here to view Table of Contents)

The Future Role of Conservancies in Africa

(click here to view Table of Contents)

The SASOL Symposium on Wildlife Rehabilitation

(click here to view Table of Contents)

Update on Diseases of Southern African Wildlife

(click here to view Table of Contents)

 

 

Healthcare of Wildlife


Dr J A Pretorius (BVSc, MMedVet (Fer))
Extracts from postgraduate degree seminars

 

 


This is a very broad subject and can roughly be divided in two parts: healthcare of individual animals and healthcare of populations, whether on a farm or a country’s population as a whole.

 

Healthcare of individual animals
The care of orphaned or injured wildlife is very specialized and should not be attempted by any layperson. Hand-reared wildlife often become very aggressive and several people have been injured or killed by “pet” wildlife. There is also legislation against keeping wildlife as pets in South Africa and a permit must be issued by Nature Conservation of the relevant province. They are however very strict on this and animals should rather be referred to registered rehabilitation facilities for wildlife. The aim of these facilities is to reintroduce these animals back into the wild if possible. If a game farm owner however have the relevant permits and wish to continue the treatment or rearing of an animal, it is advised to consult with a veterinarian with wildlife experience as each species has very specific needs.

 

Treating wild animals often is problematic especially in the case of ungulates. Keeping them in holding facilities is very stressful and often the animals die rather of the associated stress than the original problem, injury or disease.  Animals in holding facilities for quarantine purposes or before an auction, need special attention and again it is advised to have an experienced veterinarian involved with the whole process. Before animals are off-loaded into the pens, they need to be treated for internal and external parasites, as well as long-acting antibiotics and tranquillisers. Without these treatments animals will lose condition and easily become ill. Pneumonia is often a problem in dusty pens.

 

Healthcare of populations
Wildlife is often reservoir hosts of diseases that can affect domestic animals. The disease can be fatal or have serious economic effects for the farmer and the country as a whole. This resulted that several diseases carried by wildlife has been classed as either controlled or notifiable diseases in South Africa. Certain diseases can spread from domestic animals to wildlife and also need to be controlled.

 

An example is buffalo that before they can be moved from a farm or reserve, they need to be tested for foot-and-mouth disease (FMD), corridor disease, brucellosis and tuberculosis. Buffalo are reservoir hosts for FMD and corridor disease, whereas they can be infected with brucellosis and tuberculosis, transmitted from cattle. Warthogs are the reservoir hosts for African swine fever (ASF) and this is also a controlled disease which prevents the movement of any warthog or warthog product without veterinary permits and not at all from ASF areas to the ASF-free areas.

 

Zebra, for example, can carry African horse sickness (AHS) virus and cannot be moved to the Western Cape during the warmer months of the year. This is a controlled AHS-free area. AHS is a controlled disease in South Africa and if a horse dies of AHS the owner or the veterinarian involved must notify the relevant state veterinarian. Rift valley fever can affect buffalo the same as cattle and buffalo can during an outbreak be vaccinated with the killed vaccine.

 

Other diseases that are not economically as important, or don’t have zoonotic potential, are classified as notifiable diseases. Black and blue wildebeest are the reservoir hosts for malignant catarrhal fever virus that causes malignant catarrhal fever (MCF) in cattle. It is also known in Afrikaans as “Snotsiekte”. This disease is fatal in cattle and the disease has just become a notifiable disease in South Africa. Sheep is the reservoir host of a similar virus that causes the same disease in cattle. This makes control of the disease very problematic.

 

More information on the controlled and notifiable disease can be found on the website: http://www.daff.gov.za/

 

Heartwater is a tick-borne disease of mainly livestock, but also of some wild ruminants caused by the rickettsia Ehrlichia ruminantium (previously known as Cowdria ruminantium). E. ruminantium is transmitted by ticks of the genus Amblyomma. Mainly species historically from areas outside the Amblyomma distribution, and thus from areas outside the heartwater area, seem to be affected when introduced into an endemic area. In southern Africa antelope species such as the springbok (Antidorcas marsupialis), eland (Taurotragus oryx), black wildebeest (Connochaetus gnou), sitatunga (Tragelaphus spekei) and lechwe (Kobus leche kafuensis) are reported to have developed clinical disease. In blesbok (Damaliscus dorcas phillipsi) clinical disease has been reported but is very rarely seen under natural conditions. The black wildebeest, blesbok and eland as well as giraffe (Giraffa camelopardalis) can be affected sub-clinically.

 

A review of the advantages and disadvantages of the different types of vaccines used in wild animals:

 

1. Introduction

The vaccination of wildlife has become a very common procedure in South Africa, especially in privately owned herds where the farmer has paid a lot of money to acquire these animals. In high-risk areas where anthrax and botulism is a problem farmers will vaccinate endangered and expensive species annually. Breeders of the wild carnivores keep these animals in small camps and vaccinating these animals has become routine.

 

2. All Species

• Anthrax (Bacillus anthracis):

Sterne 34F2 spore vaccines are recommended for use in wildlife. These vaccines contain the uncapsulated avirulent strain of Bacillus anthracis. Onderstepoort Biological Products produces the vaccine “Anthrax”. Intervet produces “Anthravax” for protection against anthrax only; “Blanthrax” for protection against anthrax and blackquarter (Clostridium chavoei) and “Supavax” for protection against anthrax, blackquarter and botulism (Clostridium botulinum). “Supavax” is probably the most widely used in free-ranging animals and most commonly administered through the use of dropout darts. These vaccines are contra-indicated for use in pregnant animals but this is very difficult to determine in wild animals without immobilising them. The risk of fatal disease outweighs the risk of abortion in pregnant animals, especially in endangered or very expensive species. The vaccine is normally administered during the winter or early spring. Animals being translocated from areas where no anthrax has been reported to high-risk areas should be vaccinated at least 3 weeks prior to release. This is however not practical and seeing that most of the wildlife are captured and translocated during the winter period, vaccination at the time of capture is absolutely necessary. A booster vaccination four to six weeks later is ideal but not always practical but in very rare and expensive animals it should be considered. No antibiotics should be used in conjunction with live vaccines as this will interfere with the development of immunity.

 

• Rabies

Only two inactivated rabies vaccines are registered for use in wildlife. “Rabisin” (Merial) as well as “Imrab 3” (Phizer). Only inactivated vaccines should ever be used. The vaccine should be given subcutaneously or intramuscularly. The animals could be restrained in a crush cage, e.g. cheetahs in captivity or the animals might need to be immobilized, e.g. lions. Dropout darts could be used in carnivores but there is a risk that the animals might ingest the dart. If there is an outbreak of rabies or a high incidence in an area, it might be considered to vaccinate some of the more expensive or endangered herbivores by use of dropout darts.

A recombinant vaccine, making use of the rabies glycoprotein (VRG) has been used as an oral vaccine with great success in many species. When administered orally (directly or in bait) to young and adult animals, VRG elicits high titres of virus-neutralizing antibodies and produces protection against severe rabies challenge. No abortifacient, teratogenic, or oncogenic side effects have been noted. Other modified live rabies vaccines for oral administration are available (SAD B19 and SAG-1). The safety of these vaccines in non-target species is however questionable as reversion to virulence in especially immunologically compromised individuals is possible.

 

• Tuberculosis

The bacille Calmette-Guérin (BCG) is the basis of the vaccine most widely used in humans and domestic livestock. It is a Mycobacterium bovis isolate of low pathogenicity. It has shown variable results over the world but this is probably due to differences in dose and route of administration. Low-dose administration seems to result in better “immune-locking”, resulting in improved responses of the appropriate T lymphocyte population and in turn, better protection in cattle and deer. The administration of BCG to cattle, and in some cases of possums, via the oral, intranasal and intratracheal route, gave equal or superior protection in comparison with the subcutaneous route.

Other vaccine candidates include M. vaccae that was given to badgers orally and showed promising results, as well as M. microti, the vole bacillus, which yielded results similar to the BCG vaccine. 

Tuberculosis is a controlled disease in South Africa and a test and slaughter program is in place. However in wildlife it has become a huge problem for example in Kruger National Park and Hluhluwe-Umfulozi Nature Reserve where there is a high incidence of the disease in the buffalo, kudu, lion and other populations. A test and slaughter program is not really feasible; therefore a lot of research is aimed at the moment at finding an effective vaccine.

3. Carnivores

  • Felidae

The diseases felids should be vaccinated against are feline rhinotracheitis, calicivirus, panleucopenia and rabies. Young animals and animals never vaccinated previously should only receive dead vaccines. Adult animals previously vaccinated can receive modified live panleucopenia, rhinotracheitis and calici vaccines but the use of live vaccines is always questionable if it is not registered for that particular species.

The vaccine of choice is “Fel-O-Vax PCT” (Fort Dodge). This is an inactivated multivalent vaccine prepared from feline rhinotracheitis, calici and panleucopenia viruses which are grown on a feline kidney tissue cell line and inactivated. The vaccine can be administered intramuscularly or subcutaneously. Vaccination of pregnant females does not cause any deleterious effects.

A new recombinant modified live vaccine on the market “PureVax” (Merial) could possibly be used in nondomestic felids. The vaccine being recombinant and using only one or two isolated genes of the pathogen eliminates the risk of reversion to virulence.

Wild felids are also susceptible to feline leukaemia virus (FeLV) but this virus does not seem to be endemic in either free-range settings or zoo situations. It can cause clinical disease in these animals but intimate contact with an infected domestic cat is necessary for transmission. This however is rare.  The “Fel-O-Vax” (Fort Dodge) range of vaccines has a killed FeLV vaccine available which could be used if an animal is at high risk, for example animals hand-raised and kept with domestic cats.

Feline immunodeficiency virus (FIV) doesn’t seem to affect wild felids as it does the domestic cat and therefore vaccination is not necessary.

Cheetahs seem to be very susceptible to anthrax even though carnivores are normally seen as less vulnerable. The immunity seen in other free-ranging large carnivores might be due to these animals being exposed to anthrax carcasses when scavenging. Lions and hyenas tend to scavenge but cheetah only eat fresh meat and might therefore not be exposed to the antigens as the other species are. The vaccine tested in cheetah and seemed to be successful is the “Anthrax” spore vaccine (Onderstepoort Biological Products). This is a glycerine suspension of avirulent Bacillus anthracis 34F2 spores and has been registered for use in cattle, horses, mules, donkeys, sheep, goats, pigs and camels. No ill effects have been noticed with the use in cheetah. 

Toxoplasmosis in zoo situations has become a problem in species other than felids. Especially Australian marsupials and New World primates, as well as prosimians are very sensitive to Toxoplasma gondii infections and can die peracutely. A commercial vaccine registered for use in sheep and goats caused fatal toxoplasmosis in Tammar wallabies. Other vaccines are being developed for exotic species. Prevention is at the moment the best way to control the disease.

  • Felids of the genus Panthera seem to be susceptible to infection by canine distemper virus with the possibility of fatal disease, especially encephalitis developing. The use of modified live virus vaccines are contraindicated as the possibility of vaccine-induced distemper is too great. The killed vaccine provided only partial immunity to distemper in dogs and has therefore been withdrawn commercially. The best way to prevent the disease is to vaccinate or remove all domestic canines in the area. 

 

  • Canidae

    Canine distemper virus, canine adenovirus type 2 (canine infectious hepatitis), canine parvovirus and parainfluenza type 2 virus, as well as rabies are the main infectious diseases they should be vaccinated against. Only inactivated canine distemper virus vaccines should be used but it is not readily available in this country. Inactivated rabies vaccines should be used.

 

  • Viverridae

    This group of animals only need to be vaccinated in either a zoo situation or when they are kept as pets and in direct contact with domestic dogs and cats. They should be vaccinated with inactivated feline infectious enteritis, canine distemper, canine infectious hepatitis and rabies vaccines.

4. Herbivores

For most herbivores in areas with known problems, yearly vaccinations against botulism, anthrax and some of the clostridial diseases such as blackquarter are very important. Rabies vaccinations can become important with an outbreak of the disease where there are highly endangered and/or expensive species in the area.

• Clostridial diseases

This is a very important group of bacteria that is ubiquitous in nature. All animals are susceptible but the herbivores are more commonly affected. The main bacteria in this group causing disease include:

1. Clostridium botulinum (Botulism)
2. C. chavoei (Blackleg/Blackquarter)
3. C. sordellii (Gas gangrene)
4. C. novyi (Black disease)
5. C. perfringens type C and D (Enterotoxaemia)
6. C. septicum (Malignant oedema)
7. C. tetani (Tetanus)

The different syndromes are in most cases fatal if not treated early enough but animals are often found dead without any symptoms seen beforehand. The animals often die peracutely. The treatment of botulism is seldom successful even when the antitoxin is administered. In wildlife botulism is probably one of the more important clostridial diseases as wildlife are often not exposed to the predisposing factors associated with the other syndromes. Animals such as giraffe and sable is known to eat old bones during especially winter when their diet is phosphorus deficient. When wildlife however is captured and confined to a boma, they are more predisposed to the other clostridial diseases. Animals often fight in the bomas and blackquarter or malignant oedema can become a problem. The diet changes drastically and the animals can develop other problems, such as enterotoxaemia. Whenever wildlife is stressed and exposed to abnormal situations, they are as prone to diseases as any other domestic animal. It becomes then important to vaccinate animals against the possible diseases. It is however important but impractical to vaccinate animals two to three weeks before capture and confinement but in very rare or expensive animals it might be worth the input. A booster vaccination is advisable four to seven weeks after the initial vaccination. Animals captured and put into bomas are routinely given antibiotics to prevent problems such as pneumonia or abscesses developing but this is contra-indicated in the case of vaccinating animals with live vaccines. Most of the clostridial vaccine combinations however are inactivated and it is not contra-indicated in those cases.

 

Different vaccines exist on the market in different combinations. Onderstepoort Biological Products produces formalinised, inactivated “Black Quarter”, “Botulism”, “Clostridium septicum”, “Combined Botulism/Black quarter”, “Enterotoxaemia”, “Gas Gangrene Complex ”, “Lamb Dysentery”, “Swelled Head” and “Tetanus” vaccines. Intervet produces inactivated vaccines such as “Botuvax”, “Duovax”, “Multiclos”, “Multivax-P” (which includes Pasteurella haemolytica), “Pulpyvax”, “Sponsvax” and “Supavax” (which includes Bacillus anthracis). Cooper (Afrivet) produces “Covexin 10”,  “Ovivax 6” (which includes Levamisole, a dewormer) and “Tasvax PK Plus”. Phizer AH produces “One Shot Ultra 7” (which includes Pasteurella haemolytica) and “Ultrachoice 7”. Fort Dodge (Bayer AH) produces “Cydectin Eweguard” which includes moxidectin.

Perissodactyla 
Equidae, Rhinoceridae, Proboscidea
(As above)

Artiodactyla
Bovidae

• Brucellosis (Brucella abortus)

Different vaccines are on the market for use in cattle and other domestic stock, such as Brucella S19 (OBP) and RB51 (Schering-Plough) for cattle and Brucella Rev 1 (OBP) for goats and sheep. These are all live vaccines and the efficacy and safety of these vaccines have not been proven in any wildlife species. Brucella S19 has caused bison to abort and shed live virus while RB51 didn’t provide proper protection to bison with a few reported cases of abortions. The use of these vaccines needs to be properly tested in the different species for its safety and efficacy before widespread use is advocated. It is also a controlled disease in South Africa and any vaccine that might interfere with testing results are not allowed to be used. RB51 has been used in one or two small buffalo herds in South Africa but this was not part of any controlled vaccine trials.

 

• Foot and mouth disease

Vaccination of buffalo calves has proven to be unsuccessful and a different vaccine will need to be developed. An ideal vaccine wouldn’t need the animal to be captured for vaccination, e.g. a vaccine that could be administered orally or through expression of the antigens in microbial vectors would be ideal.

 

• Diseases in Zoo Animals

In a zoo situation animals might develop problems such as pasteurellosis (Pasteurella haemolytica, P. multocida): “Shipping fever” but this is not common in extensive situations. Corona and rotavirus infections can also become a problem in situations where high numbers of animals are kept in small areas. Different vaccines are on the market for these conditions in cattle but have not been tested in wildlife for their safety or efficacy.

5. Vaccine administration

Vaccination of animals in captivity is fairly easy as the animals can be handled with comparative ease and normally they are small numbers of animals. Vaccinating free-ranging wildlife will depend on the recommended route of administration. Various dropout darts and biobullets are available for long-range remote injection for large mammals but this is not always practical and is time-consuming and expensive. Animals can also be herded into a capture boma and into either a truck or narrow chute. The animals can then be vaccinated by using a pole-syringe. Vaccinating through darting or herding into a boma is expensive as a helicopter is used and it can be time consuming as well as very stressful for the animals. There will always be the risk of injury or death of an animal during these procedures. It would be more practical to administer the vaccine by means of baits, drinking water or aerosol sprays from a helicopter. It could also be spread by or as a self-replicating agent through the herd but this could only be contemplated if the environmental safety of the vaccine in the target and non-target species has been thoroughly investigated. 

• Animals in quarantine

Pre-release vaccination should be carefully considered and the decision whether or not to immunize the animals to be released should be made by the attending veterinarian after evaluating the immunological status of the animals held in quarantine as well as the likely challenge by enzootic and exotic disease agents upon release. Vaccination of wild ungulates against enzootic diseases of contiguous domestic livestock, such as foot and mouth disease, may be indicated, as may vaccination against diseases known to be present in the release environment, such as clostridial diseases and anthrax.