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2. Environmental impacts and protective measures
2.1 Disease control
2.1.1 Diagnosis and treatment
2.1.2 Prophylaxis
Immunoprophylaxis
Chemoprophylaxis
Preventive management measures
2.1.3 Vector control
2.1.4 Epizootic-disease control
2.1.5 Zoonosis control
2.2 Laboratory activities
2.2.1 Laboratory diagnostics
2.2.2 Vaccine production
2.2.3 Residue analysis
2.3 Artificial insemination and embryo transfer
2.4 Food inspection
2.4.1 Meat inspection
2.4.2 Food hygiene
3. Notes on the analysis and evaluation of environmental impacts
4. Interaction with other sectors
5. Summary assessment of environmental relevance
Veterinary services are of even more immediate relevance to the environment than is the case for sectors such as plant or animal production. Their principal purpose is to preserve or restore animal health and their environmental impacts are thus essentially positive. However, the possibility of negative impacts - generally of an indirect nature - cannot be precluded. The veterinary sector primarily performs a service function for livestock farming and fisheries, as well as playing an important role in food inspection.
Activities in the veterinary sector cover the following areas:
- diagnosis and control of diseases, involving treatment, prophylaxis, vector control and epizootic-disease control
- artificial insemination and embryo transfer
- laboratory activities, comprising laboratory diagnostics, vaccine production and residue analysis
- food inspection, above all meat inspection in slaughterhouses and food hygiene.
In the fields of disease diagnosis, treatment and vector control, a distinction can be made between "modern" measures carried out by formally trained veterinary surgeons and traditional practices employed by the animal owners themselves or by healers.
In the agro-industry sector (meat and milk processing, fodder hygiene), veterinary services perform a monitoring function. Veterinary medicine is also closely linked with the pharmaceutical industry by virtue of its need for drugs and vaccines.
2. Environmental impacts and protective measures
Veterinary services perform a vital function through their key tasks of combating animal diseases and ensuring that foods of animal origin comply with the necessary hygiene regulations. Measures to protect health and the natural environment are necessary above all wherever veterinary drugs and pesticides are liable to have side-effects, leave residues or be used incorrectly or negligently, as well as in laboratory work and vaccine production. Disposal of wastes and of possibly infected carcasses (or parts thereof) unfit for human consumption is discussed in the environmental brief Slaughterhouses and Meat Processing.
- For drugs, the following principles should be applied: strict controls on sale and use; monitoring of production if necessary; livestock owners to be advised on potential side-effects; greater emphasis on use of traditional remedies. Although traditional remedies derived from plants may not be totally free of environmental hazards, they are in general likely to have less environmental impact than "modern" pharmaceuticals. Changes in livestock husbandry systems can also help to reduce the need for drugs.
- In prophylaxis and vector control, the following measures are essential: refrainment from use of products which are broken down in the environment only very slowly or not at all (e.g. DDT); greater emphasis on epidemiological aspects and promotion of forms of livestock husbandry likely to reduce parasite infestation.
Veterinary measures may interfere with established social structures, with adverse effects on the producers' rights and income. Women are particularly liable to be affected, since in many societies they play an important role as traditional healers, as livestock owners and in the processing and marketing of animal products.
2.1 Disease control
2.1.1 Diagnosis and treatment
Clinical diagnosis and treatment are carried out on the one hand by the animal owners themselves or by traditional healers, and on the other hand by formally trained veterinary surgeons. Clinical diagnosis has little direct impact on the environment (see environmental brief Analysis, Diagnosis, Testing).
Traditional methods of treatment often involve user-prepared plant extracts, although modern drugs are also used on a growing scale. Use of plant extracts (generally in aqueous form) can have undesirable effects on the diversity of species within the flora if medicinal plants are gathered in such large quantities that their existence as a whole is jeopardised. It can be assumed that "natural" remedies leave few residues.
Improper storage of modern drugs (chemotherapy) can have harmful effects on the environment. Certain drugs such as potent antibiotics are used too frequently or in incorrect doses; this can cause pathogens to become resistant to the antibiotic used and necessitate administration of a number of different antibiotics in rapid succession.
There is also a danger that drugs or drug residues may accumulate in products destined for human consumption - thereby giving rise to health risks - if the prescribed waiting periods are not observed before animals are slaughtered or used for other purposes (e.g. to obtain milk).
Practices such as using waste oil to treat dermatophiliasis can bring animals short-term relief but may cause contamination of water and soil.
Getting rid of disposable cannulas and containers made of plastic and other synthetic materials can give rise to problems. Incineration pollutes the air (e.g. with dioxins), while incineration residues may contaminate water and soil.
Successful treatment of sick livestock can lead to an increase in the number of animals; this in turn may result in over-use of fodder resources, giving rise to a greater risk of erosion and general degradation of fodder bushes, fodder trees and pastureland.
Where malnutrition is a contributory factor in disease, control measures should be combined with improved feeding.
2.1.2 Prophylaxis
· Immunoprophylaxis
Isolated immunoprophylaxis for infectious diseases (vaccination) can result in an increase in the number of livestock, leading to overgrazing. A shortage of fodder can in turn weaken the animals and eventually lead to their death.
The disposable equipment used (syringes, cannulas, vaccine containers) has direct impacts on the environment. Improper disposal creates a risk of injury for human beings and animals (cannulas), while disposal on landfill sites can contaminate water and soil. Waste incineration causes air pollution and incineration residues may accumulate in soil and water.
· Chemoprophylaxis
Chemoprophylaxis involves preventive treatment such as daily subtherapeutic doses of a vermifuge or prophylactic administration of trypanocides. Such treatment can also help animals adapt to new surroundings, for example new pastures, by enabling them to develop premunity. Chemoprophylaxis enables particular species or breeds to use pastureland on which they could not be kept previously, e.g. by making it possible for zebu to graze in areas infested with the tsetse fly.
However, chemoprophylaxis can cause pathogens to become resistant to the drugs used. It may also adversely influence the development of immunity or premunition, with the result that mortality will rise after chemoprophylaxis is discontinued until the animals have developed immunity of their own.
To prevent tensions from developing between population groups, veterinary measures must pay equal attention to the needs and interests of all groups concerned.
· Preventive management measures
Preventive livestock management measures that can reduce the animals' risk of infection include the following:
- appropriate herd distribution: depending on the varying spread of diseases specific to particular types of animal, certain areas are used only by cattle and small ruminants, or only by camels.
- avoidance of specific pastures (at particular times of the day or year, or throughout the year): if pastureland is not used in the early morning when the grass is wet, invasion by infectious larvae of gastro-intestinal parasites will be reduced. Areas with a large population of mosquitos and biting flies during the rainy season are only used for grazing during the dry season or not at all. Areas infested with worm eggs and larvae or ticks in various stages of development (e.g. abandoned paddocks) are avoided for a number of months.
- keeping livestock away from moist pastureland: this prevents worm infestation (liver fluke) and reduces the risk of such parasites being transmitted to man.
- during migratory herding, areas infested with parasites (worm larvae, tsetse flies, ticks) are avoided at the times of year when the parasite population is at its largest (Sutherst 1987, Sykes 1987).
These preventive practices have long been employed by ethnic groups engaged in traditional animal husbandry. They have extensive beneficial effects on biodiversity and pasture resources, as they ensure that pastureland is not over-used.
Drainage of land for the purpose of creating specific forms of landscape and vegetation can lead to the loss of wet biotopes. Both biodiversity and the landscape will benefit if wet areas are fenced off and not used for grazing.
A changeover from pasture farming to confined livestock raising in the interests of animal health (see environmental brief Livestock Farming) will increase the livestock owners' workload. At the same time, however, the fact that grazing is replaced by growing and cutting of roughage may help to reduce the risk of erosion.
The resistance of productive livestock can be enhanced by improved feeding, in particular by giving the animals high-energy and protein-rich feedstuffs along with minerals. The environmental impacts of pasture farming with supplementary feeding are treated in the environmental brief Livestock Farming.
2.1.3 Vector control
Vector control involves attempting to change the balance of species so as to hinder the transmission of diseases by intermediate hosts and vectors or interrupt the cycle of transmission to man and livestock.
Chemical control of vectors includes measures such as use of insecticides in dips and the like to combat ticks, large-scale or targeted spraying of insecticides to control flies and mosquitoes, and application of molluscicides to kill snails. Long-term use of such methods can cause resistant strains of parasite to multiply, with the result that in tick control, for example, the agents used (acaricides) must be changed at frequent intervals. There is also a danger that other arthropod species may be affected as well. Pesticides may contaminate soil and water and, if the specified waiting periods are not observed, leave residues in milk and meat. The acute and chronic toxicity of the insecticides used thus creates direct risks for both man and animal. Large-scale vector control measures, such as aerial spraying of insecticide to combat the tsetse fly, involve an additional problem, namely disposal of the insecticide containers. Such containers must be treated as hazardous waste and must not be used for storing or processing food.
A further disadvantage of chemical vector control is that indigenous animal populations may lose their natural resistance or premunity with respect to numerous diseases. If the continuity of chemical vector control is not guaranteed, man and animal frequently have an increased risk of contracting the disease transmitted by the vector.
Unlike large-scale chemical control measures, use of attractants and insecticide-impregnated traps - for example in tsetse control - admittedly does not lead to eradication of the vector but at the same time ensures an almost total absence of insecticide residues. There is also virtually no danger that livestock will lose their premunity. Biological control methods such as use of sterilised flies to combat the tsetse fly and screw-worm fly generally do not entail any risks apart from those attaching to the necessary radiation treatment in the laboratory.
Targeted attempts to eradicate wild animals serving as a "reservoir" for pathogens causing particular epizootic diseases destroy the diversity and balance of species within the wild fauna. By reducing opportunities for hunting, they can moreover jeopardise the income and food supply of specific population groups.
Land clearance has far more complex impacts. By destroying the habitat of tsetse flies and other insect pests it reduces the infection risk for both man and livestock. The balance of species will change, with grasses and herbaceous plants becoming dominant; at the same time there is a risk of increased soil erosion and a reduction in the soil's water retention capacity. Local clearance techniques which - like those used in West Africa - leave 30 to 50 trees standing per hectare and allow the topsoil to remain largely intact have considerably less environmental impact than technically sophisticated methods. The pastureland created through clearance is highly susceptible to erosion if overgrazed. However, land clearance can also help to alleviate the pressure on overgrazed areas, thereby reducing their erosion risk and enabling the vegetation to recover.
Bush fires are seldom started with the aim of improving animal health. A reduction in the presence of vectors such as ticks (West 1965) is merely a side-effect of such measures, which have complex impacts on flora and fauna. Fire can also help to keep a savannah open and thus ensure that the insect-pest population remains low. As a result of interference with the species composition, however, insect pests may penetrate into hitherto unaffected areas and subsequently multiply here.
Theoretically speaking, breeding of livestock with particularly high resistance to a disease or vector (e.g. ticks) makes it possible to introduce a particular species into areas where it could not be kept in the past (Sutherst 1987). Indigenous livestock, however, already possess a high degree of resistance. For example, West African zebu can acquire a certain "trypanotolerance" if they have lived in tsetse areas for a number of generations and are regularly exposed to the pathogen.
2.1.4 Epizootic-disease control
The purpose of epizootic-disease control measures is to prevent diseases from spreading. Such measures are necessary in connection with the export and import of animals and animal products. They comprise general control measures (e.g. export or import bans), compulsory vaccination, ring vaccination in the event of acute outbreaks of disease, quarantine measures, compulsory slaughtering of sick animals and directives governing disposal of the carcasses of animals that have died or been compulsorily slaughtered.
Compulsory vaccination is a means of keeping certain diseases effectively under control for a lengthy period of time.
Ring vaccination is often accompanied by quarantine measures. The resultant restriction of herd mobility may lead to overgrazing in some places, creating tensions between sedentary and nomadic livestock owners. To ensure their acceptance, government quarantine measures should also take account of traditional practices that help to curb the spread of epizootic diseases.
Compulsory slaughtering is the most radical control measure, but is seldom used. It gives rise to severe financial losses for the farms affected and may oblige them to change their livestock management practices. For example, pastoralists may be forced to become less mobile if their herds fall below the critical size necessary for migration and this can create an increased risk of local overgrazing.
Disposing of dead animals by burning the carcasses creates unpleasant odours and pollutes the air. If wood is used, it also increases fuelwood requirements and thus women's workload wherever women are responsible for procuring wood (see also environmental brief Meat Processing).
Compulsory slaughtering is an emergency measure which prevents the spread of epizootic diseases and has beneficial effects on the health of both man and animal.
2.1.5 Zoonosis control
Through treatment of sick animals, prophylaxis, vector control and epizootic-disease control, veterinary services help to reduce the incidence of zoonoses and thus improve human health. Epizootic-disease control measures such as banning the keeping of dogs to curb the spread of echinococcosis and reduce the risk of rabies can restrict herding or make it difficult for nomads to guard their camps and thus have far-reaching socio-cultural implications. They may necessitate changes in livestock management practices and, by reducing mobility, can lead to overgrazing in certain areas.
2.2 Laboratory activities
2.2.1 Laboratory diagnostics
Preparation, transportation and handling of infected specimens in connection with laboratory work can give rise to environmental hazards. Improper handling and disposal of infectious specimens can endanger human health and contribute to the spread of disease.
In addition to the problems involved in disposing of non-reusable materials, there is also a risk that air, water and soil may be contaminated during transportation, storage and disposal of chemicals and reagents. Incineration of specimens no longer needed likewise causes air pollution.
To protect the environment, it is essential that safety regulations be strictly observed and that glass and plastic containers, reagents, chemicals and the specimens examined be collected, recycled where appropriate and properly disposed of (see OECD 1983). Use of toxic chemicals can sometimes be reduced by selecting appropriate analytical methods.
2.2.2 Vaccine production
Apart from the usual environmental risks attaching to laboratory work, vaccine production also involves all the hazards that can arise when live pathogens are being handled.
The most essential environmental protection measures are strict compliance with safety regulations, improvement of safety facilities where necessary and appropriate disposal precautions.
2.2.3 Residue analysis
By bringing to light undesirable environmental impacts, residue analysis also helps to safeguard human health and can thus be seen as a form of environmental protection. Detailed residue analyses can often be conducted only in specially equipped laboratories (see also environmental brief Analysis, Diagnosis, Testing).
2.3 Artificial insemination and embryo transfer
Artificial insemination (AI) and embryo transfer (ET) are modern techniques for importing high-performance breeds (primarily cattle) into tropical and subtropical countries. Animals produced in this way and born in the importing country are better adapted to the environmental conditions there than those imported live. Artificial insemination is also a means of controlling the spread of venereal diseases.
AI and ET do not have any direct environmental impacts. By curbing the spread of venereal diseases they may contribute indirectly to improving livestock fertility and may thus lead to higher productivity and an increase in livestock numbers. The resultant effects on the environment depend on the prevailing husbandry system.
Importing of high-performance livestock calls for strict control of vectors and ectoparasites; it may also be necessary to step up chemoprophylactic measures (see Section 2.1 above). There is a danger that the contribution of AI and ET to raising animal production may be overestimated and existing production systems consequently neglected.
2.4 Food inspection
Veterinary control and inspection of foods of animal origin is intended to prevent human health being endangered by tainted or infected foods.
2.4.1 Meat inspection
Meat inspection has hitherto often been confined to large modern slaughterhouses. It is a prerequisite for the export of animal carcasses and thus contributes to improving the income of livestock dealers and producers.
Attempts to introduce and apply meat inspection regulations from other countries without creating the necessary infrastructure (monitoring services, analysis facilities) can lead to a loss of income. The activities of small village slaughterhouses may be considerably restricted if they too are required to comply with such regulations and this can have an adverse effect on the rural population's meat supply. As women in some countries play an important role in slaughtering and meat marketing (particularly where small livestock are involved), such a development would have particularly serious consequences for the women's income and economic status.
However, meat inspection and proper disposal of products seized by the authorities prevent the spread of epizootic diseases and zoonoses. Hides contaminated with anthrax pathogens, for example, can be a highly dangerous source of infection for tanners.
2.4.2 Food hygiene
Milk hygiene plays a particularly important role in this field. Bacteriological monitoring is intended to prevent the spread of diseases such as tuberculosis and brucellosis, while analysis of milk composition helps to ensure high product quality. Milk testing and sales bans imposed as a result can have far-reaching social consequences if they extend to smallholdings which generally process only a few litres of milk a day and on which there is little danger that large quantities of milk may be contaminated. Direct marketing of milk and other dairy produce is often a major source of income for women. Sour-milk products have the advantage that the souring process kills pathogenic germs. Boiling the milk to kill germs increases energy requirements.
Legislation on milk hygiene could conceivably be misused to force small-scale processing and marketing operations out of the milk production sector.
The possibility of health risks can be counteracted by advising and informing women about hygiene precautions to be taken during processing of dairy produce.
3. Notes on the analysis and evaluation of environmental impacts
The environmental impacts of traditional veterinary medicine have not yet been the subject of any summarising assessment. Use of traditional practices is generally confined to specific groups. Relevant references are contained in a number of annotated bibliographies (e.g. Mathias-Mundy and McCorkle 1989).
The OECD guidelines on sound laboratory practice provide pointers concerning the environmental impacts of laboratory testing and analysis. Information on this subject will also be found in the environmental brief Analysis, Diagnosis, Testing.
The environmental impacts of residue analysis are discussed in the relevant literature (e.g. Barke et al. 1983, DSA 1984, Rico 1986, Großklaus 1989).
4. Interaction with other sectors
Through treatment of disease, epizootic-disease control and vector control, the environmental impacts of veterinary measures are linked to those of animal production and fisheries. By monitoring hygiene in food production and processing, veterinary services contribute to environmental protection in other sectors (e.g. agro-industry, slaughterhouses and meat processing). Veterinary medicine is dependent on the pharmaceutical industry for its supply of modern drugs. Wastewater and solid waste disposal is of relevance to laboratory activities, which also have links with the chemical industry by virtue of the need for reagents and chemicals.
5. Summary assessment of environmental relevance
The principal tasks in the veterinary sector are disease control and food inspection. However, disease control measures and laboratory work may have adverse effects on health and the natural environment, either directly or indirectly. Regulations governing epizootic-disease control and food hygiene can interfere with the social structures forming the basis of the livestock owners' existence.
The traditional remedies used by livestock owners are often based on plant extracts, which play an particularly important role in the treatment of small animals.
Therapeutic and prophylactic measures may cause pathogens to develop resistance and can give rise to residues in food.
While traditional forms of treatment have few negative impacts on the environment, this is not true of modern drugs, particularly if they are used improperly.
The activities of veterinary laboratories may give rise to water and air pollution; disposal of laboratory waste can cause contamination of air, water and soil.
Improved animal health is reflected in lower mortality and higher productivity, providing the producers with a more secure livelihood. However, consequent expansion of livestock husbandry can increase the danger of overgrazing if veterinary measures are not accompanied by improvements in the fodder supply and appropriate livestock management measures.
Epizootic-disease control, measures to curb the spread of zoonoses and monitoring of compliance with food hygiene regulations all have essentially positive effects on human health and the livestock owners' income. In some cases, however, incomes can be adversely affected. Imposition of excessively stringent standards for food hygiene can lead to the disappearance of small-scale slaughtering and milk-processing operations. Such a development could adversely affect the supply situation in rural areas and the income of those engaged in such activities, particularly women.
Barke, E. et al. 1983: Rückstände in Lebensmitteln tierischer Herkunft. Situation und Beurteilung. Verlag Chemie.
DSA 1984: Safety and quality in food. Proceedings of a DSA symposium "Wholesome food for all". Views of the animal health industries. Brussels 29/30.03.1984. Amsterdam: Elsevier.
Großklaus, G. 1989: Rückstände in von Tieren stammenden Lebensmitteln. Berlin: Parey Verlag.
Mathias-Mundy, E. & McCorkle, C. M. 1989: Ethnoveterinary medicine: an annotated bibliography. Bibliographies in Technology and Social Change No. 6. Ames: Technology and Social Change Program, Iowa State University.
OECD-Grundsätze zur guten Laborpraxis: Bekanntmachung im Bundesanzeiger (Federal Gazette) Nr. 42 dated 2. März 1983, pp. 1814 ff.
Putt, S.N.H., Shaw, A.P.M., Matthewman, R.W., Bourn, D.M., Underwood, M., James, A.D., Hallam, M.J. & Ellis, P.R. 1980: The social and economic implications of trypanosomiasis control: A study of its impact on livestock production and rural development in Northern Nigeria. Reading: Veterinary Epidemiology and Economics Research Unit, Study No. 25.
Rico, A.G. 1986: Drug residues in animals. London: Academic Press.
Sutherst, R. W. 1987: Ectoparasites and herbivore nutrition. In: Hacker, J.B. & Ternouth, J.H. (Eds.) The nutrition of herbivores. Sydney: Academic Press, pp. 191-209.
Sykes, A.R. 1987: Endoparasites and herbivore nutrition. In: Hacker, J.B. & Ternouth, J.H. (Eds.) The nutrition of herbivores. Sydney: Academic Press, pp. 211-232.
West, O. 1965: Fire in vegetation and its use in pasture management with special reference to tropical and subtropical Africa. Hurley: Commonwealth Agricultural Bureaux (CAB), mimeographed publications 1/1965.