BY DR TONY M. MONDA
NGOs operating in most parts of Africa, including Zimbabwe, have long advocated goat farming as a quick and low-cost alternative to cattle ranching or crop farming. But is it really so?
Goats and other small ruminants (e.g sheep, rabbits, etc.), are prey to 28 protozoal and nine rickettsial diseases whose main vectors are ticks, tsetse flies/flies, midges and mosquitoes; 83 diseases caused by viruses and virus-like diseases and 80 diseases caused by bacteria (including mycoplasmas), fungi and algae, as well as a small number of conditions of unknown or uncertain aetiology. I
mported goat breeds are particularly more vulnerable than the indigenous Mashona, Shangaan or Boer goats that have built some resistance to some diseases over the course of time. Some of the major diseases in goats include pneumonia, bloat, diarrhoea and foot rot.
The current wet spell has given rise to many diseases and ailments for both, free-range and penned livestock, including the sturdy goat. As with cattle and other livestock, goat breeder need to judiciously follow basic goat and other small ruminants management practices. Goat farmers should pay close attention to their flock’s behaviour, for this will give the farmer the first indication of illness in his flock.
As a rule, once identified, a sick animal should be separated and quarantined instantly from the rest of the head and treat immediately. This is crucial because some diseases are contagious and can rapidly spread to the other healthy animals. Since goats are social animals, if one goat gets sick, most of the goats will fall ill too. It is a good idea to have a pen or two set aside for sick animal quarantine, especially if a disease is contagious.
Some of the most common diseases that affect goats are: respiratory disease, common in goats [and sheep], and is usually the result of a series of complicated interactions involving stress inducers, both physical and physiological, and a variety of infectious agents.
The most common form of respiratory disease is Pasteurellosis, which can have a significant impact on the productive value of small stock.
Signs of the acute disease in affected kids (young goats) and lambs (young sheep), include fever, dyspnoea, anorexia, recumbence and sudden death. If the animals survive, they can become chronically affected with resultant reduced ability to thrive and survive further infections.
Pneumonia – an infection of the lung tissue with multiple causes in goats of all ages. In younger animals, various bacteria, viruses and parasites of the upper and lower respiratory tract are often responsible for development of pneumonia while in adult animals these same disease-causing agents can create pneumonia.
A systemic virus, the Caprine Arthritis Encephalitis (CAE) in goats can cause pneumonia and can affect multiple organs, including the lungs, brain, udder and the joints. CAE is incurable, contagious, and devastating to goat herds. It is similar to the human AIDS virus and compromises goat’s immune systems. CAE can be tested for and only CAE-free goats should be traded/purchase.
Some of the conditions that can predispose goats to pneumonia include overcrowded housing with poor ventilation; poor sanitation which may result in urine and faeces that release gases that harm the goat’s respiratory tract and wet bedding that can cause the animals to become cold.
Equally harmful are excessive dust and extreme variation in environmental temperature, such as cold nights followed by hot days; stress during transportation, obstetrics, heavy milk production and weaning. Failure to get adequate amounts of colostrum (first milk) may also cause pneumonia in young animals.
The earliest sign of pneumonia is when the affected animal is less active than normal. Other symptoms include high temperature/fever, coughing with thick and dark nasal discharge, rapid or laboured breathing and falling behind from the rest of the flock. It is necessary to prevent bacteria from causing pneumonia as a complication to a viral infection.
Three Theileria species infecting small ruminants have been shown to be responsible for heavy mortality. Ovine and Caprine Theileriases in sheep and goats is similar to Theileriosis in cattle produced by Tannulata, with which it is closely related.
The disease is transmitted by the ticks Theileria lestoquardi of the genus Hyalomma. The parasite is transmitted to its vertebrate host by the bite of an infected tick. Depending on the species, they develop into schizonts release merozoites into the circulation. Some species have the ability to transform the host cell so that it can proliferate and disperse throughout the body,
Affected animals show sustained fever and anemia, and mortality rate can approach 100%. Heartwater, caused by the Bont tick, is another disease that afflicts goats. Some of the symptoms include a rise in temperature, depression, loss of appetite, increases in pulse and respiration, prostration, convulsion and death. Tick control is a vital preventative measure for this disease.
Caseous Lymphadenitis (CL) – is a chronic, contagious disease also called ‘Abscesses’. Pus-filled infections, or abscesses, form around a goat’s lymph nodes; when the abscesses burst, the pus can infect other goats.
Diarrhoea is very common in goats, especially small kids. It is important to note that diarrhoea itself is not an illness but rather a symptom of other health problems in goats. Before treating goats for diarrhoea, farmers must first determine why the animals are scouring as it may be the body’s way of purging itself of toxicity.
There are four major causative agents of diarrhoea in goats – namely bacteria, viruses, parasites, and poor management practices such as overcrowding, poor sanitation or over-feeding. In small kids, diarrhoea could be caused by consuming impure milk, too much milk or colostrum (first milk). Changes in the environment may also trigger diarrhoea in goats.
The symptoms for diarrhoea include pain in the belly, loss of appetite and watery faeces. Acute diarrhoea may result in dehydration and related problems. Where the goat is experiencing dehydration, it should be given adequate water and liquids.
Enterotoxemia in goats is caused by a bacterial imbalance in the animal’s rumen. It can result from sudden feed changes, overfeeding, sickness, or anything that causes a digestive upset. Goat farmers should vaccinate their herd against it as Enterotoxemia can kill a goat Blue Tongue is a disease that affects mostly sheep and goats, but rarely affects cattle. It is caused by several species of virus brought about by midges.
Although not contagious, it is an acute infectious disease, characterized by high fever, eye and nasal discharge, inflammation and ulceration of the lips, mouth and tongue. Hooves become affected and the animal becomes recumbent (yakarara pasi), and dies.
A few animals may recover, but recovery is usually very slow. Abortion in pregnant females is also a result of blue tongue.
Consequently, it is important for goat and other small ruminant farmers to control midges, and
move their animals to high ground in rainy seasons, especially with the rains and intermittent heat and humidity we are experiencing this year.
Dr Tony M. Monda BSc, DVM, is currently conducting Veterinary epidemiology, Agronomy and Food Securityand Agro-economic research in Zimbabwe. E-mail: tonym.MONDA@gmail.com
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