COMMON DISEASES AFFECTING CATTLE

There are many causes of losses in cattle but they tend to be isolated. Sometimes these losses may be severe on individual farms and immediate help should be sought in identifying the cause. Here are some of the diseases. As always, consult your veterinarian if you are concerned.

  • Footrot

Footrot is a common cause of lameness in cattle and occurs most frequently when cattle on pasture are forced to walk through mud to obtain water and feed. However, it may occur among cattle in paddocks as well, under apparently excellent conditions. Footrot is caused when a cut or scratch in the skin allows infection to penetrate between the claws or around the top of the hoof. Individual cases should be kept in a dry place and treated promptly with medication as directed by a veterinarian.

Treatment

If the disease becomes a herd problem a foot bath containing a 5% solution of copper sulphate placed where cattle are forced to walk though it once or twice a day will help to reduce the number of new infections. In addition, drain mud holes and cement areas around the water troughs where cattle are likely to pick up the infection. Keep pens and areas where cattle gather as clean as possible. Proper nutrition regarding protein, minerals and vitamins will maximize hoof health.

  • Trypanosomosis/ Sleeping Disease/ ‘Nagana’

Mainly occuring in Africa, Trypanosomosis, or Sleeping Disease, is an infection affecting both animals and humans.
The disease mainly occurs in areas where Tsetse flies inhabit. Tsetse flies infest 10 million square kilometres and affect 37 countries, mostly in Africa, where it is known as ‘Nagana’.
It is the most economically important livestock disease of Africa, as it can have a devastating impact on rural areas.

Cause

Trypanosomosis is usually transmitted through blood lymph and other fluids of infected animals. It is caused by Flagellated protozoan parasites that live in the fluids and tissue of its host animal.
Often the disease is transmitted through the bite of an infected tsetse fly which has been feeding on an infected animal.

Symptoms

Symptoms often begin to show four to 24 days after infection. The most important clinical sign is non-regenerative anaemia.

The major clinical signs are:

  • intermittent fever
  • anaemia
  • oedema
  • lacrimation
  • enlarged lymph nodes
  • abortion
  • decreased fertility
  • loss of appetite, body condition and productivity
  • early death in acute forms
  • emaciation and eventual death in chronic forms often after digestive and/or nervous signs

Prevention and treatment

At present no vaccine is available.
If detected early, Trypanosomosis can be treated with trypanocidal drugs for therapeutic and prophylactic purposes.
Therapeutic drugs for cattle include diminazene aceturate, homidium chloride and homidium bromide. Prophylactic drugs for cattle include homidium chloride, homidium bromide and isometamidium.
However the effectiveness of these drugs is now questionable following years of use, causing resistence and now variuos strains of Trypanosomosis to occur.
Another area of control that has been studied is to eradicate the tsetse flies which transmit the disease.
The most common of the procedures that have been deveoped are: spraying insecticide on tsetse habitat, destruction of tsetse habitat and alteration of vegetation so that it becomes unsuitable for tsetse flies.

  • Foot and mouth disease

Foot and mouth disease is an acute infectious viral disease of livestock causing fever, followed by the development of vesicles (blisters) chiefly in the mouth and on the feet. It is one of the most infectious diseases affecting livestock and spreads rapidly if uncontrolled. It affects cloven-hoofed animals (those with divided hoofs) including cattle, buffalo, camels, sheep, goats, deer and pigs.

  • Mastitis

Mastitis is the inflammation of the mammary gland and udder tissue.
It usually occurs as an immune response to bacterial invasion of the teat canal by variety of bacterial sources present on the farm (commonly through bedding or contaminated teat dips), and can also occur as a result of chemical, mechanical, or thermal injury to the cow’s udder.
Mastitis is a multifactoral disease, closely related to the production system and environment that cows are kept in. Mastitis risk factors or disease determinants can be classified into three groups: host, pathogen and environmental determinants.

Symptoms

The most obvious symptoms of clinical mastitis in the udder are swelling, heat, hardness, redness or pain.
Milk takes on a watery appearance, flakes, clots or pus is often present.
A reduction in milk yields, increases in body temperature, lack of appetite, and a reduction in mobility due to the pain of a swollen udder are also common signs.

Prevention

  1. Hygienic teat management: which includes good housing management, effective teat preparation and disinfection for good milk hygiene, teat health and disease control.
  2. Prompt identification and treatment of clinical mastitis cases: including the use of the most appropriate treatment for the symptoms.
  3. Dry cow management and therapy: where cows are dried off abruptly and teats are cleaned scrupulously before dry cow antibiotics are administered, including the use of teat-end sealants if appropriate.
  4. Culling chronically affected cows: cows that become impossible to cure and represent a reservoir of infection for the whole herd.
  5. Regular testing and maintenance of the milking machine: with regular, recommended teatcup liner replacement and milking machine servicing and attention paid to items which must be checked on a daily, weekly or monthly basis.
  6. Good record keeping: of all aspects of mastitis treatment, dry cow therapy, milking machine servicing, Somatic Cell Counts and Bactoscan results, and clinical mastitis cases
  • Rumen Acidosis

Rumen acidosis is a metabolic disease of cattle. Like most metabolic diseases it is important to remember that for every cow that shows clinical signs, there will be several more which are affected sub-clinically.
Acidosis is said to occur when the pH of the rumen falls to less than 5.5 (normal is 6.5 to 7.0). In many cases the pH can fall even lower. The fall in pH has two effects. Firstly, the rumen stops moving, becoming atonic. This depresses appetite and production.
Secondly, the change in acidity changes the rumen flora, with acid-producing bacteria taking over. They produce more acid, making the acidosis worse. The increased acid is then absorbed through the rumen wall, causing metabolic acidosis, which in severe cases can lead to shock and death.

Symptoms

Acute acidosis often results in death, although illness and liver abscesses may be seen before hand. Cattle may become depressed, go off feed, have an elevated heart rate or diarrhea.

Treatment

Because subacute ruminal acidosis is not detected at the time of depressed ruminal pH, there is no specific treatment for it. Secondary conditions may be treated as needed.

 

Diseases of young dairy calves

All calves are exposed to a variety of micro-organisms such as viruses, bacteria and protozoa as soon as they are born. These micro-organisms are part of the environment in which cattle live and calves have to develop immunity to them.

The two major types of problems seen in calves are:

  1. Gut problems leading to scouring
  2. Pneumonia

These two problems account for over 80% of all losses in calves, with scouring being the most common. Bloat, navel-ill, accidents and poisoning make up most of the rest

  • Gut problems (scouring)

These can be divided into four major causes:

  1. E. coli (white scours)
  2. Salmonella
  3. Rotavirus
  4. Cryptosporidia

Scouring is the result of changed gut function; that is, the germ makes the gut stop digesting, which increases the amount of manure and fluids the calf passes. Calves on a milk diet normally pass only a small amount of droppings. If the gut is affected, the amount passed can increase markedly. For example, the amount of water passed in a scouring calf can be 20 times normal. This extra water is mixed with salts and other food, so the calf is losing more than it can eat.

The loss of water and salts leads to dehydration. This causes shock and death. In other words, the germ that started the scour is usually not the direct cause of death. It is the shock caused by the loss of body water and salts that is the actual cause of death.

  • Pneumonia

Pneumonia is infection of the lungs and has many causes. Lung worms can play an important role in allowing infection to enter the lungs. A calf that survives pneumonia takes a long time to recover. This usually means stunted growth and poor production as an adult. Prevention is most important and this is by having suitable housing with adequate ventilation. Stress caused by exposure to cold, wet conditions, overcrowding and inadequate feeding can allow a calf to pick up pneumonia.

Treatment depends on the cause of the infection. If pneumonia is occurring, consult with your veterinarian for a diagnosis (which is often difficult as several causes may be occurring together). They will recommend a treatment program.

 

 

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