Following the infectious disease, animals may end up with other related conditions such as Endrometitis and Pyometra.
All these result in lost income to the farmer as the animals may be unable to give birth again. Brucellosis and Q-fever are also highly contagious, and may transfer to people causing agonizing pain and sickness and very expensive medication, so paying close attention to the reproductive health of your animals is highly recommended.
Non-infectious conditions and other abnormalities include:
- Silent heat
- White heifer disease
When a herd of cows or sheep tend to have reduced number of calves, longer time before the female becomes pregnant, as well as when frequent abortions are observered or suspected, it is likely that a genital disease could be the problem. Farmers would in such cases be advised to invite a veterinarian to investigate the herd and take samples for analysis that can determine the cause of the problem. Reduced fertility in a herd means less profit and slower build up of herds.
Genital infections are spread through sexual contact between male and female animals. Unsually infected males do not show signs, but they can spread the disease to the female.
The incidence of retained placenta in healthy dairy cows is 5 - 15%, while the incidence in beef cows is lower.
Usually there is no systemic illness. When there is, it is it is related to toxaemia (blood poisoning). Symptoms may include fever, lack of appetite, depression, a reduction in milk yield, straining, a foul smelling vaginal discharge and diarrhoea. These symptoms are more likely to occur in cases where retention follows extensive interference as in a difficult calving.
Anoestrus is a condition where some cows do not show heat signs for a long time after calving. In this case, no ovulation takes place. The condition can be caused by an infection or inflammation of the uterus and underfeeding of the cow, especially with minerals.
Rectal examination by qualified vet to determine the cause.
Proper feeding and mineral supplementation of dairy cows including:
- Adequate quantity and good quality roughage.
- Adlibitum mineral supplementation.
Treat the underlying cause. See Endometritis below.
|Local Names:||Embu: kuyuna / Luo: tuo bwogo / Kikuyu: muhono, kihuna / Maasai: Aibiriu, olik, ibiroto / Samburu: ikiboroto /Swahili: homa ya kutupa mamba / Turkana: akiyech / Maragoli: Iuhusidza / Luyugusu: livure / Nandi: sutonik|
|Common Names:||Contageous abortion, Bang's disease|
|Scientific name:||Brucella abortus, Brucella melitensis, Brucella canis, Brucella suis|
|Description:||Reproductive problem and Zoonotic disease|
Brucellosis is a bacterial infection, caused by organisms belonging to the genus Brucella. The disease is prevalent in most countries of the world. It primarily affects cattle, buffalo, pigs, sheep, goats, camels and dogs, and occasionally horses.
The disease in humans, sometimes called Undulant Fever, is a serious public health problem, especially when caused by Brucella Melitensis.
Brucellosis in cattle is caused almost exclusively by Brucella abortus, although occasionally Brucella melitensis or Brucella suis may be implicated. Melitensis occurs primarily in sheep and goats, suis in pigs, Brucella canis is confined to dogs.
Cattle of all ages and sex can be infected with B.abortus, but it is primarily a disease of sexually mature femal cattle, with bulls and immature animals showing little or no clinical disease.
Mode of Spread
- Natural transmission occurs by ingesting the bacteria, which are present in large numbers in aborted foetuses, foetal membranes and uterine discharges. Cattle may ingest contaminated feed or water, or lick contaminated genitals of other animals.
- Venereal transmission by infected bulls to susceptible cows appears to be rare, Brucella may enter the body through mucous membranes, the conjunctiva, wounds or intact skin.
- The disease is spread when aborting animals discharge B. abortus bacteria in the placenta, foetus and vaginal discharges to the ground, where they can survive for several weeks. Excertion of the bacteria may occur several days before abortion and for some time after. Cattle become infected when they ingest or inhale contaminated material.
- A cow's tail, heavily contaminated with infected ulterine discharges, may spread infection if it comes in contact with the conjunctiva or intact skin of other animals. The placenta, placental fluids, and foetus from an aborting animal contain organisms which contaminate the vulva, tail and legs of the animal and the surrounding environment.
- In in-calf females, the bacteria invade and cause abortion in the 7th month. The incubation period is about 6 weeks. It is only when a placenta exists i.e. in the second half of pregnancy, that the uterus is invaded and abortion occurs.
- Shedding from the vagina largely disappears with the decrease in fluids following calving. Some cows that previously aborted shed Brucella from the uterus following normal calvings.
- The disease can be transmitted to the unborn calf through the placenta by the infected dam. This disease can have serious negative economic consequences to stockmen in both modern intensive dairy systems and pastoral production enterprises.
- Organisms are shed in the milk for a variable period of time in most previously infected cattle for life.
- Housing or confining cattle increases the likelihood of transmission. Under range conditions the disease is of lower prevalence.
Spread to Man
- Man becomes infected when in direct contact with cows at abortion, calving or in the post calving period.
- Vets and stockhandlers are particularly at risk from the splashing of infected droplets into the eye.
- Infection occurs in people drinking unpasteurised milk or milk products.
- Symptoms include recurrent bouts of fever, headache, muscle and joint pains and general weakness. Brucellosis is often confused with malaria and influenza.
Signs of Brucellosis
- Abortion is the most obvious manifestation. Animals abort from the 7th month onwards.
- Infections may also cause still births or weak calves, retained placentas, and reduced milk yield. Usually general health is not affected in uncomplicated abortions.
- In less accute infections, cattle may give birth to a full term but weak calf, or merely show a retained placenta. Cows may become infertile due to chronic uterine infection.
- After abortion, the afterbirth doesn't come out (retained placenta). This can further develop to metritis (infection of the uterus), which often causes infertility.
- In bulls, no symptoms may be seen but if they are, they may include inflammation of the testes, lack of sexual activity and possibly infertility.
- Subcutaneous swellings containing infected fluid may appear on the legs of infected cattle and the placenta often has a thickened leathery appearance with necrosis of the cotyledons.
- Calves infected before puberty usually lose the infection once removed from the source of contamination.
- Mature non-pregnant animals, or animals in early pregnancy, when exposed to infection, are more likely to develop immunity than to show overt symptoms of disease.
This is based on the history, serology and bacteriology. Abortions occurring after 6 months of pregnancy are suggestive. However, blood samples should be taken for detailed laboratory analysis to confirm the disease.
- Serum samples should be taken for agglutination testing.
- When abortion occurs, aborted foetuses should be taken intact in a sealed container to the laboratory for detailed examinations. The organisms can be found in the placenta but more conveniently in pure culture in the stomach and lungs of an aborted foetus. All foetuses should be handled carefully with gloves to avoid human infection.
Diseases with Similar Symptoms
Abortion: See Vibriosis, Leptospirosis, Rift Valley Fever.
Prevention and Control
- The disease can be controlled through effective sanitary measures in the cattle environment. Pregnant animals must be closely observed and any which show signs of aborting must be immediately isolated.
- Any animal which has aborted must be kept isolated until all uterine discharges have stopped. If there is any suspicion of infection, any animal about to calve should also be isolated.
- Under cool conditions the organism may survive for up to 2 months. Exposure to direct sunlight kills the organisms within a few hours.
- The use of plastic gloves and thorough disinfection of the vulva and tail of the cattle helps greatly to reduce the risk of infection when examining pregnant animals.
- Pasteurisation of milk and milk products renders them safe.
- Because of the danger of human infection, infected foetuses, placenta and cows should be handled with great care. Proper hygienic precautions should be taken when handling abortions and where infection is known to occur in certain herds of cattle. Handlers of such material should always wear gloves for protection. They should also ensure that they keep their hands away from the mouth, nose and eyes until after the hands are thoroughly disinfected.
- Burn and bury all contaminated materials such as foetuses and foetal membranes.
- Clean and disinfect all cattle premises which may be contaminated with foetuses and foetal membranes.
- Drinking of raw milk and unpasteurized milk products is dangerous.
- Calves between three and eight months should be vaccinated with live vaccine (S.19) to prevent infection. Such vaccinations can provide lifelong immunity against all but the heaviest challenge.
- The live vaccine should be used with care in adult animals because it can cause abortion in in-calf females and inflammation of the testes in adult males. It also results in persistent antibody titres if used in adults, making differentiation between atibody levels due to natural infection and vaccination very difficult. Adult cattle should therefore be vaccinated annually with dead B. abortus vaccine (45/20), or with a reduced dose - one twentieth - of S19 vaccine.
- S19 vaccine should be handled with care. It is a live vaccine and can infect humans.
- Vaccination will reduce the number of infected animals in a herd by over 90% if carried out over a period of 5 years. Vaccination cannot eradicate Brucellosis but it can lay the groundwork for future eradication.
- Bulls should not be vaccinated as the vaccine may result in the organism appearing in teh semen.
This is the inflammation of the endometrium (internal lining and mucus membrane of the uterus). It occurs as a result of an infection by microorganisms. Infection normally occurs during mating or around labour and delivery by such organisms as Campylobacter fetus (See Brucellosis) or Trichomonas fetus (See Leptospirosis) and other opportunistic bacteria like the Corynobacterium pyogenes, E. coli and Fusobacterium necrophorum. Endometritis often occurs following difficult or abnormal labour or delivery and/or retained placenta.
- Repeated heat after mating.
- History of repeated heat.
- Difficult calving.
- Retained placenta.
Routine and strict hygiene at calving:
- Cows should be kept clean at calving.
- Ensure that calving boxes are cleaned and disinfected.
Treat the underlying cause.
Epivag is a rare chronic venereal infection of cattle probably caused by a virus. It occurs in East and Southern Africa. In the 1930s the disease was rampant in Eastern and Southern Africa, prompting the creation of the world's first national AI service to control it in Kenya. It has now become sporadic and reports are unusual.
The infection is spread by coitus or contaminated obstetrical equipment.
Signs of Epivag
Affected bulls have enlarged and distorted testes. The lesions take 3-6 months to develop and sometimes longer. Enlargement of the head and tail of the epididymis occurs. Often both epididymses are affected. Bulls are at first infertile and then sterile. The semen is affected before clinical signs are apparent. The volume is reduced, the appearance is watery and floccules of mucus appear.
The incubation period in cows lasts only a few days but the infection persists for months. In cows, the clinical signs vary from slight reddening of the vagina with little or no discharge to severe inflammation of the inner lining of the vagina, cervix and uterus with profuse thick yellowish discharges. Infection usually persists for several months in cows with most of them recovering while a few may become permanently sterile.
Diagnosis is based on the herd history, the clinical signs, and the semen examiniation. Lesions in the female are difficult to assess in the absence of the disease in the male.
Diseases with Similar Symptoms
The clinical signs in the female are easily confused with those of Infectious Pustular Vulvovaginitis. Lesions in Epivag, however, persist for many weeks.
Prevention and Control
Use of artificial insemination with semen from clean bulls is an effective control measure. All affected bulls should be slaughtered.
Because the specific cause is uncertain, no attempt should be made to treat the bulls, but cows can be treated symptomatically by a veterinarian and then later inseminated.
The widespread use of artificial insemination using semen from clean bulls has brought the disease under control dramatically in Eastern and Southern Africa.
This is one of the most common reproductive abnormalities, mainly congenital, affecting female cattle. It occurs when both male and female conceptus are present in the same uterus. In cattle there is a tendency for the placenta of twin fetuses to merge, thereby causing the circulatory system of the twins to become interconnected. This often affects the development of the female sex organs of the female twin probably due to the androgens of the male blood circulation.
- History of twin male and female calves.
- Failure of estrus to occur.
Culling of freemartin heifers.
This condition is due to an accumulation of pus in the uterus and can occur after chronic endometritis or may result from the death of an embryo or fetus with subsequent infection by Corynobacterium pyogenes bacteria. The situation may persist undetected for some time and may be confused for pregnancy.
- Enlarged uterus.
- Discharge of pus when the cow lies down.
Treatment used by estrogens and oxytocin.
Q Fever was first identified in Queensland, Australia; hence its name.
This is a bacterial disease and an important zoonosis (an animal disease that can be transmitted to humans). Q Fever is caused by an organism called Coxiella burnetii. It is found all over the world, in every country where it has been sought.
Coxiella burnetii is an extremely difficult organism to eliminate. It is very tough, resisting most disinfectants, heat and drying, and surviving for years in dust.
Mode of Spread
There are two different cycles:
1. The bacterium cycles between small free-living ground mammals and ticks.
2. The bacterium cycles in domestic ruminants (cattle, sheep, goats), independent of the wild animal cycle.
Ticks can act as reservoirs of the organism. Tick-free cycles in domestic ruminants allow the organism to be concentrated in the genital tract and udder, from where large numbers are shed in milk, faeces or urine, or, from the genital tract at lambing or calving.
A wide variety of other animals and birds may also be affected and play a part in spreading Coxiella burnetti. These include dogs and several species of birds.
At-risk animals, and man, become infected by inhaling infected fluid discharges in the air or dust loaded with dried discharges.
The disease is highly infectious. Animal handlers are particularly at risk from infection, especially at lambing or calving, from inhalation, ingestion or direct contact with birth fluids or afterbirth.
However the main route of most human infections is by inhalation of contaminated air droplets or dust originating in infected ruminants or other animals e.g. cats.
Spread can occur up to 10 kilometers from the source of infection by wind dispersal of dried reproductive products, such as afterbirth, genital discharges, etc from infected sheep, cattle and goats, depending on wind condition.
Symptoms of Q Fever
Infection in ruminants is usually symptom-free, but it can cause late abortions, inflammation of the uterus and mastitis in sheep and goats, together with loss of appetite, and offspring of carrier animals can often appear weak, showing low vitality. Large numbers of organisms are shed in the milk, urine, faeces, saliva and especially through the afterbirth and uterine discharges. These are the main sources of infection for man.
Cows may shed the organism in milk for years.
- Symptoms of Q Fever in man can easily be mistaken for those of flu: fever, headache, chills, muscle pains, lack of appetite and nausea. The incubation period is about 2 to 3 weeks, and the disease lasts for 1-2 weeks.
- In severe and chronic cases, pneumonia, hepatitis and endocarditis may occur and in some cases the infection causes death, as has happened in the recent outbreak in north-west Europe.
- The infection of pregnant women can result in abortion or premature delivery.
- The main route of infection is by inhalation of infected dust or aerosol droplets. Drinking contaminated raw milk products is unlikely to cause any symptoms of disease.
There are no clinical signs in domesticated animals. The sudden appearance of an influenza-like disease in man following an association with cattle, sheep or goats, or with their carcases, hides, tissues, or following an autopsy, should be regarded as evidence of infection.
But neither the history nor the clinical picture is enough to prove the presence of Q Fever. A definite diagnosis can be established only by lab tests to identify the bacteria that causes the disease in teh blood or sputum of a patient.
Other causes of abortion in ruminants should be considered when reaching a diagnosis.
Prevention - Control - Treatment
Recovered animals remain infected and infective for many years and sometimes for life. It is therefore necessary to take the steps to limited the spread of infection by adopting hygienic precautions at the time of lambing, kidding and calving. In particular afterbirths should be destroyed. In known infected flocks or herds pregnant animals should be separated from others indoors.
Vaccines are available and are being developed in Europe and when giving to uninfected animals have prevented infection. When given to previously infected animals the vaccines have improved fertility and reduced the shedding of organisms.
This disease is probably much more common than is realized, due to under reporting and lack of facilities in reaching a diagnosis.
In animals this is seldom attempted. Oral tetracyclines are reported to have a beneficial effect, but their use carries risks in ruminating animals such as cows, and is therefore not recommended.
Silent heat is the term used when a cow which has already shown heat signs shows them again after 6 weeks or later. The regular heat period at 3 weeks is often referred to as the silent heat. The heat signs might have been weak and therefore not observed. If the cow has been inseminated before, she might have had an early abortion so that she shows heat signs again 6-9 weeks after the last insemination.
- Small vulva.
- Long tuft of hair at the ventral end of the vulva.
- Clitoris is prominent when you open the vulva.
- Complete anoestrus.
Proper feeding and mineral supplementation of dairy cows including:
- Adequate quantity and good quality roughage.
- Adlibitum mineral supplementation.
- Timely and regular heat detection.
Use of hormones.
Trichomoniasis is a venereal protozoal infection of cattle caused by Titrichomonas foetus. It occurs without fever and is contagious. Trichomoniasis is confined to the reproductive tract of the cow and the preputial sac of the bull. The disease occurs worldwide.
Mode of Spread
T.foetus infection is confined to the reproductive tract where it can invade most parts. Infection normally lasts about 3 months. There is usually a mild inflammation of the vagina shortly after infection but significant changes do not normally take place until 50-60 days after infection when vaginitis, cervicitis, endometritis, pyometra and early abortion may take place.
Abortions are often undetected and the main feature observed is often a failure of cows to hold to service.
Infection in the male is usually confined to the surface of the prepuce and penis and is usually so mild it is not clinically apparent.
Signs of Trichomoniasis
- Cows may have a profuse watery vaginal discharge about 2 weeks after coital infection.
- Abortion may occur in early or late in pregnancy.
- There is irregular oestrus which may cease altogether.
- Cows eventually clear themselves of infection and the uterus is usually normal 2-6 months after infection.
- Bulls show no symptoms but once infected tend to remain permanent carriers.
Trichomoniasis can be suspected in any breeding cattle if there is a history of reproductive failure characterized by repeated returns to service a lower than expected pregnancy rate a wide range of gestational ages and cases of early abortion and pyometra.
Laboratory diagnosis is possible and can be made from a foetus, placental fluids, uterine contents, or via mucus taken from the vagina or from the prepuce of a bull.
Diseases with Similar Symptoms
- The simplest control method involves ceasing to breed cows for at least 3 months, by which time they will have eliminated the infection, and to carry out examination of the cervical mucus using the vaginal mucus agglutination.
- Use of a clean bull either for natural mating or artificial insemination is also a control method.
In bulls treatment using various imidazoles has been used but none is both safe and effective. Ipronidazole is probably the most effective but can cause sterile abscesses at the injection site. In addition bulls are probably susceptible to re-infection after successful treatment.
Resistance to iponidazole may be a concern. The biggest problem, however, is that the success of treatment is measured by repeat sampling which may mean that the individual bull can never be definitely said to be negative. Therefore it is better to cull bulls and replace them with virgin bulls or to test and cull positive bulls.
Re-infection is prevented by exposing only uninfected (clean) bulls to uninfected (clean) cows. Clean cows are assumed to be those with calves at foot and virgin heifers.
|Scientific Name:||Campylobacter fetus venerealis and Campylobacter fetus fetus|
|Common Names:||Bovine campylobacteriosis, Genital vibriosis|
Vibriosis is a bacterial venereal disease of cattle and sheep characterized primarily by early embryonic death, infertility, a protracted calving season and occasionally by abortion. It occurs worldwide.
It is caused by bacteria called Campylobacter fetus, Venerealis and Campylobacter fetus fetus. C. fetus fetus was thought for many years to be primarily an intestinal organism but it has been found to be a significant cause of the classic infertility syndrome usually attributed to C. fetus venerealis.
Vibriosis in sheep is evidenced by abortions in late pregnancy and still births.
Mode of Spread
In cattle the disease is transmitted venereally by coitus. It is also trasmitted by contaminated instruments, bedding or by artificial insemination using contaminated semen. Individual bulls vary in their susceptibility to infection. Some become permanent carriers, while others appear to be resistent to infection. In young bulls, less than 3-4 years of age, infection tends to be temporary with transmission apparently relying on sexual contact with a non-infected cow within minutes to days of breeding with an infected cow. Spontaneous clearance in these younger bulls does not seem to be related to any immunte response and so re-infection can readily occur. Bulls older than 3-4 years are more likely to suffer chronic infections.
Some cows clear the infection rapidly, others carry it for up to or longer than 2 years. Although most of the genital tract may be free of infection, when a cow eventually conceives the vagina may remain chronically infected throughout pregnancy.
Some infected females can maintain pregnancy but abort usually around the fifth month of pregnancy or sometimes earlier. This means that the presence of the disease can go un-noticed without proper herd fertility records. Breeding females eventually eliminate the infection six months after being infected at service and recover completely. They are then immune and can breed normally.
Vibriosis affects both breeding males and females but clinical signs of temporary infertility are confirmed to females. Clincal signs, other than reproductive failure or abortion, are minimal or absent. The infection of females at conception results in infection in teh anterior vagina which subsequently spread to teh uterus and fallopian tubes. The infection persists for months and causes the developing foetus to die. The embryonic death initiates cyclical activity in the ovary but these cycles are often irregular with prolonged intervals. Observed abortions are uncommon.
Clinical signs in herds for which good records are maintained are soon evident shortly after the introduction of an infected bull. Animals which have been presumed to have been in calf have irregular returns to heat. In more extensive systems using natural service infection may not be suspected until the calving pattern indicates a delay in conception and a reduced calf crop.
Where the disease has been present for some time indications that C. fetus is present may be much less dramatic, with only heifers, calved heifers and a few susceptible cows being affected, as older animals have acquired natural immunity.
Bulls show no symptoms and produce normal semen. In other words they are fertile, generally virile, and provided they do not have to serve too many returning females, active. The females they server conceive, but they have been infected. Subsequently the foetus dies and they return to service.
The disease in sheep manifests with abortions in late pregnancy and still births. Ewes may develop metritis (inflammation of the uterus) after expelling the foetus, which is usually rotten, with 40% having orange-yellow spots in the liver. The disease in sheep is acquired by mouth, not via the ram.
This would be based on the history of late abortions and return to heat after successful mating.
Laboratory diagnosis is based on the vaginal mucus agglutination test. Samples are taken from at least 10% of the herd, concentrating on those females most recently exposed to infection by service, open cows or those returning to their third or fourth service. Tampons are placed in the anterior vagina and sheath washings are taken from suspected bulls.
- Use of Artificial insemination with semen from non-infected bulls should eliminate the infection from an infected herd by the end of two pregnancies.
- Care must be taken when buying breeding bulls. A veterinary certificate stating that they are free of Vibriosis (and Trichomoniasis) should be insisted upon.
- Where AI is not feasible, all animals in a herd should be tested and the infected and non-infected animals managed separately. This approach requires a high level of management and careful veterinary supervision.
- Vaccination is practiced where the vaccine is available
- In sheep strict hygiene and regular vaccination, where the vaccine is available, should be practiced.
In sheep the use of tetracyclines may help to prevent exposed ewes from aborting.
White Heifer Disease
This condition has been estimated to account for about 5% of infertility in heifers. The condition is an abnormality when the reproductive tract of white heifers gets blocked during development. Unlike freemartins, the cow's ovaries are well developed and functional and therefore heat and ovulation takes place normally. However, fertilization may not take place depending on the site of the reproductive tract that is obstructed.
1. William Ayako, KARI Naivasha. Aug - Dec 2009.
2. Hugh Cran, Practicing Veterinarian Nakuru. March - Oct 2010.
3. Review workshop team. Nov 2 - 5, 2010.
- For Infonet: Anne, Dr Hugh Cran
- For KARI: Dr Mario Younan KARI/KASAL, William Ayako - Animal scientist, KARI Naivasha
- For DVS: Dr Josphat Muema - Dvo Isiolo, Dr Charity Nguyo - Kabete Extention Division, Mr Patrick Muthui - Senior Livestock Health Assistant Isiolo, Ms Emmah Njeri Njoroge - Senior Livestock Health Assistant Machakos
- Pastoralists: Dr Ezra Saitoti Kotonto - Private practioner, Abdi Gollo H.O.D. Segera Ranch
- Farmers: Benson Chege Kuria and Francis Maina Gilgil and John Mutisya Machakos
- Language and format: Carol Gachiengo
Information Sources Links
- Barber, J., Wood, D.J. (1976) Livestock management for East Africa: Edwar Arnold (Publishers) Ltd 25 Hill Street London WIX 8LL. ISBN: 071310063X
- Blood DC, Henderson JA, Radostits OM (1983): Veterinary medicine: A textbook of the diseases of cattle, sheep, pigs & horses. 6th Edition. Bailliere and Tindall, 24-28 Oval Road, London NW1 7DX, UK. ISBN NO: 0-7020-0988-1.
- Force, B. (1999). Where there is no Vet. CTA. Wageningen. The Netherlands. ISBN 978-0333-58899-4.
- Handbook on Animal Diseases in the Tropics 4th Edition Sewell & Brocklesby
- Henning MW (1956): Animal Diseases in South Africa, 3rd Edition. Onderstepoort Veterinary Institute, Central News Agency Ltd., Pretoria, South Africa
- Hunter, A. (1996). Animal health: General principles. Volume 1 (Tropical Agriculturalist) - Macmillan Education Press. ISBN: 0333612027
- Khan CM and Line S (2005): The Merck Veterinary Manual, 9th Edition, Merk & Co Inc Whitehouse Station NJ USA. ISBN 0-7020-1502-4
- Merck Veterinary Manual 9th Edition 2005 ISBN Number : 0-911910-50-6
- Q Fever booklet, CEVA Sante Animal, France
- Veterinary Medicine A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses Blood, Radostits & Henderson 6th Edition 1983 Bailiere Tindall 1 St Anne's Road, Eastbourne England BN21 3UN ISBN 0 7020 0988 1
- Veterinary Reproduction and Obstetrics 5th Edition 1986 Arthur, Noakes & Pearson Bailliere Tindall 33 The Avenue Eastbourne, East Sussex, England BN21 3UN
- lowey, R.W. (1986). A Veterinary book for dairy farmers: Farming press limited Wharfedale road, Ipswich, Suffolk IPI 4LG