Text 31. Wounds and traumata

Wounds of the skin and underlying tissues are common problems in both large and small animal practice, are frequently infected, and must therefore heal by granulation. This process is often impaired by movement, irritation, infection, necrosis, poor circulation and even the inflammatory process itself. The latter, with its traditional cardinal signs, reflects the mobilization of the body's defences necessary for ultimate resolution. The associated pain, swelling, and interference with function may, however, have adverse effects.

The therapeutic regimen, in addition to specific surgical procedures, should manipulate such target-areas as etiologic factors, including those secondary to the initial insult, the mediators of inflammation, the non-specific inflammatory process, and reparative process. Such a regimen can well necessitate a 'therapeutic cocktail'. During the last several years work has been conducted on various anti­inflammatory (steroidal and non-steroidal) drugs, dimethyl sulphoxide (DMSO) and antihistamines. This pharmacological polyglot, along with the complexity of inflammation has created a need to clarify a confusing interaction and to justify the logic of utilizing such drugs either alone or in combination.

Text 32. Mastitis

We think that the cow of the future will be taller than in the past. The taller cow will have an udder higher off the ground and less chance to injury. To produce higher yields year after year, our cows must have the high dairy capacity and strength.

In order to maintain maximum levels of production, it is necessary to supplement a dairy cow with large quantities of grain and concentrates. Though some cows have lived 17 years or more, the average cow is culled or dies between five and six years of age. Each year, 20% of the animals more than two years old are culled or lost from the milking herd because of low production, infertility, mastitis and so on.

Mastitis is an inflammation of the udder, caused either by infection or udder stress on the delicate mammary tissues, or a combination of both. In most areas, it is common to practice to conduct routine tests for mastitis. Udders or individual quarters of the udder infected with bacteria are treated with certain antibiotics that are effective in eliminating the bacteria.

It is becoming evident that the most important factors controlling mastitis are proper milking equipment and good milking practices. Most cows are now milked by machine. To avoid abnormal stress on the mammary tissues, it is important to operate milking machines in accordance with the recommendation of the manufacturer and to keep equipment in proper operating condition.

Text 33. Tuberculosis

Tuberculosis, MTB, or TB (short for tubercle bacillus) is a common and in many cases lethal infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis.

This is a chronic contagious disease of man and animals. Of the latter cattle, hogs, and poultry are the commonly affected ones. Man, poultry, and the remaining groups of commonly affected animals are each most easily infected by their own specific bacillus of tuberculosis (Mycobacterium tuberculosis). Thus the human, avian, and mammalian strains are recognized. There is, however, inter communicability of the germ so that man may also contract the cattle infection; swine the cattle, human and avian infection. Infection takes place by the consumption of tuberculosis germ contaminated liquid and solid food, and by breathing germ laden air. Thus calves may get the disease by drinking milk from tuberculosis cows.

Tuberculosis can be carried by mammals; domesticated species, such as cats and dogs, are generally free of tuberculosis, but wild animals may be carriers. For instance, it was found that cattle herd bovine TB infection at one of the farms in New Zealand was caused by Australian brush-tailed possums which had come into contact with domestic livestock at farm-bush borders. Another example is that in Ireland and the United Kingdom, badgers have been identified as one vector species for the transmission of bovine tuberculosis.

The symptoms of tuberculosis in animals vary greatly, depending upon the infected organ or organs. If the disease is in the lungs there may be a cough; in the intestines; chronic diarrhea; in the brain, nervous symptoms; in the udder swellings; in the joints, and testicles, enlargement; and if the disease is of very long standing there is usually evidence of unthrifty animals. An autopsy shows that evidence of TB presence in infected animals is in most instances found in the lymphatic glands.

A very important point is that infected animals may show no outward signs of the disease, many of them seem to be perfectly healthy. A diagnosis of tuberculosis in infected animals may be established by the inoculation method, and by a reaction to a tuberculin test.

Vaccination against tuberculosis of man and animals has been tried, and it appears to be in a measure successful in man; but in animals this has not been practical or reliable.