Diseases of cattle cost both the farmers and their country a vast sum of money each year. However, vaccination, good management, tick control and careful inspection of cattle can prevent many of the worst diseases from occurring. If an animal appears to be sick, the following details should be noted so that the farmer can identify the disease or report any abnormal symptoms to his Veterinary Surgeon.
Figure 1: 2 year old Hereford bulls
The normal temperature for cattle is 38°C – 39°C. Any temperature above usually indicates that the animal is suffering from an infection.
This is the rate of the heartbeat of the animal and can be taken by listening to the heart at the chest just behind the left elbow. It can be taken also from the artery which runs over a bone in the middle of the underside of the tail about 100mm from the anus.
The normal pulse rate is 50 – 70 beats per minute.
VISIBLE MUCOUS MEMBRANE
These include the gums, inside of the eyelids and the lips of the vagina. They should be pink in colour and moist. Pale membranes indicate anaemia and yellow membranes indicate jaundice.
Should be examined for excessive fatness or leanness and for any swellings, wounds or discharge.
Should be soft and move freely when pushed. A dry tight skin can indicate dehydration and disease.
Healthy animals should eat normally and chew their cud. Dung should be examined for diarrhoea, constipation or blood or mucus.
Should be observed and the colour noted.
Rate should be 12 – 15 breaths a minute. Laboured breathing and coughing are signs that should be noted.
These are important in the diagnosis of some diseases. A small drop of blood taken by pricking the edge of the ear or the end of the tail is spread over a clean slide using the edge of a second slide as a spreader. The slide is wrapped in clean paper and given to the veterinary surgeon, or it can be sent to the nearest veterinary laboratory. The slide must be accompanied by the name, address, date, and any symptoms that have been observed in the animal.
The following table gives a list of the major diseases that affect cattle in Africa, together with brief details of symptoms. It is emphasised that cattle diseases cannot be recognised unless they have been seen in an animal, and if any doubt exists, the nearest veterinary surgeon should be contacted.
|Anaplasmosis (Gallsickness)||Anaplasma||Blue Tick||Dipping Vaccination||Tetracyclines||High fever; loss of appetite; anaemia and jaundice|
|Babesiosis (Redwater)||Protozoa||Blue Tick||Dipping Vaccination||Phenamidine or Berenil||High fever; loss of appetite; anaemia; jaundice; red urine|
|Heartwater||Rickettsia||Bont Tick||Dipping Vaccination||Tetracyclines||Fever; twitching of eyes and lips; high stepping gait|
|Theileriosis *||Protozoa||Brown Ear Tick||Dipping||Tetracyclines||High fever; loss of appetite; runny eyes; laboured breathing; 90% death rate|
|Nagana (Trypanosomiasis or Sleeping Sickness) *||Trypanosome||Tsetse Fly||None||Berenil||Loss of condition; enlarged lymph glands; anaemia|
|Anthrax *||Bacteria||Vaccination||None||Animal usually found dead|
|Botulism||Bacteria||Vaccination||None||Paralysis becoming progressively worse|
|Brucellosis (Contagious Abortion)||Bacteria||Infected water or food||Vaccination with S19||None||Abortion of foetus at 7th month of pregnancy|
|Quarter Evil (Black leg or Malignant Oedema)||Bacteria||Vaccination||Penicillin||Animal usually found dead. Swelling on affected quarter|
|Tetanus (lockjaw)||Bacteria||Vaccination||None||Fever; stiff muscles especially jaw muscles|
|Vibriosis||Bacteria||Infected bull||Vaccination||Irrigation||Cows fail to conceive or abort at 5 months|
|Ephemeral Fever (Three day Sickness)||Virus||Midges||Vaccination||None||Fever; stiff limbs|
|Foot and Mouth *||Virus||Vaccination||None||Fever; blisters on feet and in mouth; excessive salivation|
|Lumpy skin||Virus||Tick, Midges||Vaccination||None||Fever; small lumps on the skin|
|Rabies||Virus||Bite of affected animals||Vaccination||None||Animals become aggressive – difficulty in swallowing; paralysis followed by death|
|Rift Valley Fever||Virus||Mosquitoes||Vaccination||None||Fever; abortion in cows|
Diseases marked * are Notifiable Diseases and must be reported to the Veterinary Department at once.
FOOTROT (FOUL IN THE FOOT)
The animal is lame in one foot or more. A swelling often develops along the upper margin of the foot or between the claws, and this sometimes develops into an abscess. The lesion is evil smelling.
Foot rot is more common in damp conditions, especially muddy kraals. The germ penetrates the hoof through a small wound; soft, wet hooves are more susceptible.
Antibiotics such as tetracyclines or sulphadimadine can be administered by injection. Local treatment, cleaning of the lesion and application of an antibiotic spray are also helpful. Putting cattle through a foot-bath containing a solution of 10% copper sulphate or 5% formalin, two or three times a week, helps prevent further cases. This is not always practical with ranch cattle.
Lesion: a region in an organ or tissue which has suffered damage through injury or disease, such as a wound, ulcer, abscess, or tumour. Perpetuation: make (something) continue indefinitely. Necrosis: the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply. RINGWORM
Ringworm is a fungal infection which attacks young animals of many species. Calves are no exception. In calves, lesions occur mostly on the skin of the head and neck as round white hairless areas. Children may become infected by contact. Spontaneous recovery is usual after a few months.
TREATMENT: This is normally not necessary. In special cases, such as with show cattle, it may be desirable to treat the affected parts. Tincture of iodine, or one of the several commercial ringworm ointments on the market, must be applied daily. Treatment should be continued until the lesions develop a smooth shiny surface.
These are maggots of the fly chrysomyia bezziana, and develop only in wounds. For this reason it is extremely important to kill all the maggots when treating screw-worm cases.
TREATMENT: The common practice of first scratching the maggots out only ensures perpetuation of the life cycle of this parasite, and may well cause further injury. The recommended treatment is to apply the remedy gently over the whole surface and around the margin of the wound. It is very important to treat screw-worm cases at least twice a week until the wound is completely healed and dry. If left for a whole week until the next dipping day, the wound is usually back to its original state with a new invasion of maggots, and the problem goes on and on. Animals suffering from screw-worm strike often lose a lot of weight. It is important on dipping days to observe all the animals properly. The presence of screw-worm can often be detected by the typical foul smell. Screw-worm infested wounds nearly always drip blood. Such evidence should be looked into more closely.
The fly never attacks healthy skin but lays its eggs only on wounds, even small ones. Tick-bite wounds often serve the purpose, especially those of bont-legged ticks where there is some skin necrosis. Within two weeks the maggots can change a wound as small as a tick bite into a large, unsightly bleeding cavity. If not treated, this may finally cause death
Good tick control is a most important preventative measure. Furthermore, castration by knife should be avoided during the rainy season, while calves should not be dehorned or branded during a wet spell. Always check for screw-worm for at least two weeks following such operations. Any wound, whether affected or not, should be treated with a screw-worm remedy.
This is an inflammation of the surface of the eye. There are various causes. ‘Infectious Ophthalmia’ is caused by a Rickettsia carried by flies and moths. In the early stages the eye is red, painful and weepy. At this stage response to treatment (sufficient applications) is usually good. In cases where the cornea is already opaque and ulcerated, response is slow. Daily treatment is then seldom justified. Time is the best healer: after a few months even fairly bad cases return to a reasonable state.
Outbreaks of opthalmia have occurred in association with heavy eye worm (Thelazia) infestation. The worm can often be seen moving across the surface of the eye. In any outbreak of opthalmia the animal must be checked for Thelazia. Some anthelmintics are very effective when applied to the eye. Consult a veterinarian for further information.
Some outbreaks appear to be associated with a Vitamin A deficiency in the dry season. Occasionally sore eyes are the result of injury by grass-seeds or dust.
Numerous opthalmia remedies are available, containing antibiotics or sulphonamides, in powder, liquid and ointment form. In these forms the frequency of application is the crux of the matter (at least three treatments per day). In the pellet form, or after injection under the eyelid, treatment may have to be repeated once.
Flies often aggravate the condition of sore eyes. Accordingly, a fly repellent or insecticide such as screw-worm remedy should be smeared on the skin around the eye.
Eye cancer can be a serious problem with certain breeds of exotic cattle in the tropics. It appears to affect animals that have light coloured skin around the eye. The cancer appears as a running sore on the eyelid and will spread to the eye itself. There is no cure, and affected animals must be culled from the herd.
Most chemical compounds used on farms as pesticides, herbicides or fertilizers are poisonous to stock. The main causes of poisoning are:
Dips, lead, urea, nitrate, fungi on food, plants.
Basic Safety Precautions
- Keep all poisons locked up
- Make sure that only responsible persons handle poisons
- Do not store poisons near feed stuffs
- Follow the maker’s instructions exactly when mixing dips, herbicides etc
- Make sure that all empty containers are safely disposed of: burn or put them out of reach of animals or people.
- Remember that cattle are curious animals and like to smell and lick any unusual materials.
Have caused hundreds of cattle deaths and cases of scalding; symptoms are that the animal shows obvious pain in its intestines (colic) by groaning, restlessness and trembling muscles. In the case of arsenical scalding the coat is very rough, hair comes of easily and the skin is red and painful.
Treatment is to dose the animal with hypo (sodium thiosulphate) by the mouth. Scalded skin should be treated with carron oil or healing oil. Arsenical dips should no longer be available for purchase.
ORGANO – CHLORIDE DIPS
BHC and Toxaphene. Also DDT, Aldrin, Dieldrin and Chlordane. These poisons affect the nervous system. The animal appears to be more alert, followed by muscle twitching, shivering and convulsions which progressively worsen, accompanied by excessive salivation.
If the animal has been dipped in over-strength dip it should be washed down and kept in a quiet place. Barbiturate anaesthetics can be given by a veterinary surgeon. These dips have also been taken off the market in most countries.
Parathin, Diazinon, Asuntol, Bromophos, Dioxathion. Some of these chemicals are extremely toxic, particularly those used as insecticides on plants. Symptoms are dilated pupils of the eyes, profuse salivation, abdominal pain and diarrhoea. Animals suffering from this type of poison must be treated by a veterinary surgeon.
Is usually associated with cattle licking old car batteries or lead based paints. The animal becomes excited, tends to walk in circles, staggers and salivates. Affected animals may become blind, and a veterinary surgeon should be consulted about treatment.
Occurs when animals are being fed a urea supplement which has been mixed badly. Animals that are used to urea and on a high carbohydrate diet can consume over 160 grams per day of urea whereas 50 grams can kill an animal that is not used to urea. In the rumen, urea is broken down to ammonia which the rumen bacteria build up into amino-acids and protein. Too much urea in the rumen causes an excess of ammonia which passes into the blood stream, and the animal dies of ammonia poisoning. Animals should be introduced to urea gradually so that the rumen bacteria can adapt.
Symptoms of urea poisoning are affected breathing, staggering, muscle tremors and sometimes aggressive behaviour and bloat. Treatment is to drench the animal by mouth with 750ml of vinegar + 350ml water. This dose can be repeated within 30 minutes.
Is caused by animals eating fertilizer and can kill the animal. Never allow cattle to have access to fertilizers either in farm buildings or in the field.
POISONING BY FUNGI
There are many types of fungi that can cause food to become mouldy, and mouldy food should be fed very carefully to animals, and withdrawn at the first sign of trouble. These can be nervous symptoms and diarrhoea. The main problem is the white diplodia fungus found on maize. The black fungus maggot affects small grains, barley, wheat, rye, millet, sorghum and grass seeds. If any type of fungal poisoning is suspected a veterinary surgeon should be consulted before treatment is started.
POISONING BY PLANTS
There are a number of plants growing in Southern Africa that can poison animals grazing in the veld or on pastures. Symptoms vary according to the plants that have been eaten and if plant poisoning is suspected, a veterinary surgeon should be consulted at once. Some poisonous plants are:
|Albizia||Trees found in the middle veld whose unripe pods are toxic.|
|Lily and Tulp||Grow from bulbs just before the rains and are eaten because they are the only green material on the veld. Any plants growing from bulbs can be dangerous.|
|Lantana Camara||Damages the liver and causes photosensitisation of the skin of the animal.|
|Senecio||is common and the young, spring shoots are most poisonous|
|Crotalaria||Are small legumes that are readily grazed by cattle and which cause acute laminitis.|
|Sorghum Stargrass Couchgrass||Can cause prussic acid poisoning in cattle. This is associated with lush, young growth, high levels of soil nitrogen and low phosphorous, wilting and frost damage.|
Ticks cause damage to cattle in the following ways:
- They transmit certain important diseases such as Babesiosis (Redwater), Anaplasmosis (Gallsickness), East Coast Fever, Theileriosis and Heartwater.
- Their bites can be toxic and cause Sweating Sickness, Tick Toxicosis and Calf Paralysis.
- Their bites cause abscesses and also open the way for screw-worm strike.
- They are blood parasites and they suck the blood of their hosts causing anaemia and un-thriftiness. An average infestation of 50 adult ticks can cause a growth set back of 36kg a year.
- The irritation and restlessness caused by ticks can affect growth rates of cattle.
- Tick damage to hides represents a loss of income to farmers
|THE COMMON TICKS|
|Blue Ticks||Transmit Redwater and Gallsickness, and they are 1-host ticks. They are always the first species to develop resistance to dips.|
|Brown Ear Ticks||Transmit Theileriosis, East Coast Fever, Spirochaetosis and Redwater. They are 3-host ticks.|
|Red-legged Ticks||Transmit Redwater and are 2-host ticks.|
|Bont Ticks||Transmit Heartwater and are 3-host ticks. They have long mouth parts which cause wounds and abscesses.|
Ticks can be controlled only by dipping, spraying, pour-ons or injecting cattle with a recognised and approved dip/medication (acaricide). The following points should be observed:
- Use the right dip, suitable for the tick species on the farm. In some cases ticks have developed resistance to certain dips.
- Follow the manufacturer’s instruction exactly regarding the strength, premixing and precautions to be taken or quantities to use.
- Know the exact capacity of the dip tank and use a calibrated dip tank measuring stick.
- Replenish the dip-wash when 1 000 head have been dipped in a plunge dip. In the case of a spray-race, make up a fresh dip-wash solution after 500 head have been through the spray-race.
- Stir the dip before putting cattle through a plunge dip so that the dip is well mixed. Have a well-drained entrance pen with a cement floor so that the dip in the tank does not become too dirty.
- Dip all cattle every dipping day. Missing animals allows ticks to build up on the farm.
- Dip each week in areas where this is necessary, unless there is a problem build-up of ticks, in which case, dip every 5 days and apply tick grease by hand to areas of heavy infestation, such as under the tail, between the legs and inside the ears.
- In the case of a spray-race, see that the nozzles are the correct size, and do not become blocked. The dip must be well filtered and maintained at the correct pressure.
Massive infestation of worms can cause deaths in cattle, but the biggest loss to farmers is caused by moderate infestations which cause poor growth and production. The three groups of worms are Roundworms (Nematodes), Tape-worms (Cestodes) and Flukes (Trematodes).
The important roundworms in Southern Africa are:
|Wire-worms||Found in the abomasum (true stomach). They are slender and red from the blood that they suck. A single worm can suck 0.5 ml of blood a day so that a large infestation can cause severe anaemia.|
|Bankrupt worms||Are very thin, hair-like worms that are difficult to see. They live in the first section of the small intestine.|
|Hookworms||Are found in the first part of the small intestine, usually attached to the intestinal wall. They are relatively thick, up to 20mm long and appear red from the blood inside them. The end of the worm near the mouth is bent to form a hook.|
|Nodular worms||Are found in the large intestine mainly in the mucus on the surface of the faeces. The immune reaction of the host causes the formation of small abscesses or nodules which can impair absorption through the gut wall. These worms produce a toxin which affects the host|
Severe infestation of roundworms causes a loss of condition, harsh poor-looking coat, anaemia and bottle jaw. Any animal that dies on the farm should be inspected for worms as a routine. Faeces samples can be sent in to the local Veterinary Department to be examined for worm eggs. A dosing programme should be carried out, using one of the many worm remedies (anti-helminthics) available from any agricultural merchant or supplier of veterinary products. The routine should be:
- Dose all weaners, yearlings and first calving heifers 3 weeks after the first rains have fallen. This will destroy the young worms that have hatched after the first rains.
- Dose these groups again at the end of the rainy season so that they go into the winter free from worms.
- Dose any older animals that look as if they may have a heavy infestation.
- In high rainfall areas and on irrigated pasture it may be necessary to dose during the grazing season.
- After dosing, cattle should be moved into camps that have been rested for at least a month.
The main danger from these worms is the cyst or bladder worm stage which causes measles in cattle. These are found in the muscle of the carcass and can cause tapeworm infestation in the people who eat the meat. Meat containing measles is condemned for human consumption. Small, white segments of the worms can be seen in the faeces of cattle that are infested. If these are seen, the animals should be dosed with a tapeworm remedy, and young calves can be dosed as a routine.
LIVER FLUKES (TREMOTODES)
In Southern Africa the cattle fluke is Fasciola gigantica which is much larger than Fasciola hepatica, the European fluke. The life cycle of the liver fluke depends on a secondary host, the fresh water snail. Young flukes are eaten by cattle along with grass and once inside the animal they penetrate the tissue until they reach the liver. They spend up to two months growing in the liver and leave a trail of damage. Once the flukes are mature, they enter the bile duct of the liver and remain there for many years. Cattle can accumulate more flukes over the years and older cattle are worst affected. Liver flukes cause cattle to become unthrifty and, when the cattle are slaughtered, their livers are condemned.
Cattle pick up liver flukes by grazing on vleis, and ponds and dams on the farm – any areas where there is enough shallow, standing water to encourage the presence of the fresh water snail. The farmer should know the fluke situation on his farm by checking the livers of animals that die on the farm and those sent for slaughter. Where fluke is suspected, cattle should be dosed with a fluke drench at the beginning, in the middle and at the end of the rainy season.