Preventing Fish Diseases
Fish diseases caused by parasites, bacteria or viruses can be spread from pond to pond or from farm to farm by the transfer of infected fish and by animals, people, equipment and contaminated water.
A diseased fish can be recognized by its listless behaviour or by spots on its skin.
Diseases can cause serious problems on fish farms and the farmer could lose most or all his stock.
Simple changes in farm management practices that help prevent the introduction and spread of diseases most times reduce losses.
Biosecurity also applies to fish farms. Proper sanitation, control of movement in and out of the farm, and isolation facility for sick or new stock are all good practices to prevent the introduction and spread of diseases in your farm.
Sources of infection/disease to your fish include equipment, boots, workers, yourself, birds, wild fish, new stock, contaminated feed and water.
Equipment
Use warm water and detergent to clean equipment such as buckets, boots and vehicles and then dry them.
It is important to know that some disinfectants will not work effectively in the presence of dirt and organic matter such as fish mucus. Equipment must be thoroughly washed before applying disinfectant and sun dry to eliminate remaining bacteria or viruses.
Most detergent-resistant bacteria and viruses can be killed with a broad-spectrum disinfectant
such as sodium hydroxide, formalin, chlorine, iodine, or a peroxide product.
Pond may be drained with all fish and vegetation removed. Add hydrated lime and dry.
Most viruses and bacteria may be killed by adding hydrated lime to raise water pH to 11 for at least 1 hour.
Consult with your veterinarian to determine the best choice of cleaning and disinfecting agents to use on your farm.
Animals and birds
A number of animals that live in or move around fish ponds can carry fish diseases. Birds can transmit diseases to fish via their droppings. This is also of public health concern for those that feed their fish with poultry or bird excreta.
Several species of fish-eating birds can carry the life stages of parasites that develop into parasites of fish.
Control of snails in your fish pond is very essential as they serve as host for fish parasites to develop.
Some farmers use netting of the pond surface to keep birds away from the pond.
Water
The safest water for fish production is water pumped straight from a well to the pond.
Water must be tested to ascertain its quality.
Pond water contains two major groups of substances namely dissolved substances made of gases, minerals and organic compounds; and suspended particles made of non-living particles and very small plants and animals, phytoplankton and zooplankton respectively .
The composition of pond water changes continuously, depending on climatic and seasonal changes, and on how a pond is used.
during the day , oxygen production is increased while carbon dioxide content is decreased through photosynthesis;
during the night , oxygen content of the water is decreased and carbon dioxide content is increased through respiration in the absence of photosynthesis.
Therefore, it is important to feed your fish during the day when there is abundance of oxygen in the pond.
Decomposition of plant and animal matter in the pond reduces available oxygen.
The amount of oxygen that is dissolved in the water is critical for fish and other pond life. The maximum amount of oxygen that can be dissolved is controlled by the water temperature. Warmer water can hold less dissolved oxygen than colder water.
Fish diseases may cause severe losses on fish farms through:
reduced fish growth and production;
increased feeding cost caused by lack of appetite and waste of uneaten feed;
increased vulnerability to predation;
increased susceptibility to low water quality;
death of fish.
mastitis in gilts and sows
Mastitis is the inflammation of the mammary glands. It is one of the major causes of failure to lactate and sow not letting its piglets suckle .
It is a common condition that occurs sporadically in individual sows or sometimes as herd outbreaks.
Mastitis in sows is caused by ascending infection of the teats by bacteria. The organism most commonly involved is Escherichia coli or other coliforms.
Predisposing factors
Traumatic injury resulting from unclipped piglet teeth, sawdust bedding, or poor quality flooring predisposes to infection.
Poor farrowing pen hygiene, bad drainage.
A warm temperature for the organisms to multiply and a wet pitted farrowing floor.
Build up of faeces in the sow’s pen and contaminated drinking water.
Infection enters via the teat canal following teat contamination and bacteria multiply in the gland.
Occasionally mastitis will arise from a blood borne infection associated with the farrowing process.
Acute and severe mastitis caused by Klebsiella spp. may occur following trauma to the teats caused by rough sawdust bedding.
One or both glands supplying a single teat may be affected.
Bacteria such as Arcanobacterium pyogenes , streptococci and staphylococci may cause infections of single glands.
Mastitis will recur in successive batches of animals after farrowing if the environmental factors are not well managed.
Clinical Signs
Acute Mastitis
Fever, loss of appetite and depression are observed.
The udder is usually swollen and oedematous and congested.
In severe cases, lactation may cease completely
The sow may be restless as a result of the pain in the udder during suckling. This will make the piglets not to thrive well. The litter will appear malnourished.
Acute mastitis usually occurs within 1-3 days of farrowing.
The affected animal may become recumbent and unable to rise and respiratory distress sets in and frequently leads to death.
Acute mastitis is easily recognisable as affected sows are off their feed and have obvious swelling of the udder, sometimes with reddening and oedema.
Sub acute mastitis
This type is most times not noticed by the farmer. But the piglets usually look malnourished.
Usually it is noticed when the affected teat fails to return to normal size after weaning.
Individual affected glands feel firm and hot When touched or palpated.
Prevention and Treatment
Severely affected sows may need rehydration with hypertonic saline .
Anti-inflammatory drugs are also recommended as supportive treatment .
In sub acute mastitis, rehydration is not necessary.
Organisms that cause mastitis are sensitive to neomycin, tetracyclines, ampicillin, amoxicillin, streptomycin, fluoroquinolone (all injections)
Oxytocin should be given to aid lactation.
Control depends upon early diagnosis and treatment, hygiene, use of soft bedding other than sawdust, clipping piglets’ teeth and culling of severely affected sows.
Acute mastitis is not a disease to be handled by an inexperienced farmer. Always work with your local veterinarian to keep your livestock and investment protected.
Scours in sheep and goats
There are many conditions that cause diarrhoea. These include colibacillosis, paratyphoid, Johne’s disease, Rift Valley fever, coccidiosis, worms and poisonous plants.
Coccidiosis
This usually affects younger animals. The disease is most severe in lambs/kids 2-8weeks of age.
Predisposing factors
Overcrowding
Sudden change of feed
Keeping animals on wet and dirty floors
Clinical Signs
The first sign is diarrhoea.
Sheep and goats are depressed and do not eat.
They become severely dehydrated and may die.
Colibacillosis
This condition is caused by a bacterium (Escherichia coli).
It usually affects lambs/kids under 2 weeks of age.
Predisposing factors
When lambs/kids do not drink enough colostrum (first milk) after they are born.
Dirty and wet pens.
Other diseases may make them more vulnerable to become infected
Overcrowding and stress.
Clinical Signs
They have a watery, whitish-yellow or greyish diarrhoea
Affected lambs salivate and have a cold mouth.
The animals are depressed and not eating.
The umbilical cord is sometimes inflamed and swollen.
Lambs/kids usually die as a result of dehydration.
Salmonellosis
This is caused by salmonella organism and occurs mostly in older animals
Change in environment, feed and stress and presence of the organism predisposes to the disease.
Clinical Signs
There is fever and the animals are off feed.
Watery green diarrhoea that is sometimes spotted with blood can be seen.
Animals usually die from dehydration or septicaemia.
Pregnant ewes may abort.
Treatment of diarrhea in small ruminants
In livestock, diarrhea is called scours. There can be many causes of diarrhea: bacterial, viral, parasites, and diet.
Treatment depends on the causative agent.
The first step would be to separate the affected animal. And then conduct some diagnosis to find out the cause of the diarrhea. Usually it is best to consult a trained personnel (veterinarian)
In a situation where diarrhea is caused by diet. Removing the particular ingredient is advised.
Change in feed should be done gradually over a period of time.
You must have to weed out poisonous plants from around your goat pens. This is very important during the dry season when animals are forced to graze on any available plant.
Antibiotics are used for both treatment and prevention of E. coli scours in lamb and kids.
Same applies for coccidiosis and salmonellosis.
Diarrhea caused by viral agents has to be managed with antibiotics and fluid and electrolyte therapy. Most times, if you are able to keep the animal alive until the disease runs its course, you may be able to save the animal.
Heavy worm burden can cause diarrhea in sheep and goats.
Control of gastro-intestinal parasites is best achieved via good pasture, grazing, and animal management, and strategic and/or selective deworming of affected individuals with effective anthelmintics (dewormer).
Treatment of diarrhea with antibiotics in goat is not usually effective without supportive fluid therapy. Usually the animals die due to fluid and electrolytes loss. Therefore fluid and electrolyte therapy is indicated to replenish lost fluid and mitigate dehydration.
Deficiency Diseases in poultry
Different elements and compounds are required for the normal growth and development of poultry. If one or more of them are not present in the diet in adequate quantity, the normal functioning of the body will be impaired.
- Vitamin A deficiency
Rate of growth falls below normal
droopiness, a staggering gait
ruffled appearance of the feathers.
the eyes become inflamed and there is a discharge from the nostrils.
In some there are swellings around the eyes and sticky exudate beneath the lids.
These symptoms may appear as early as the end of the third week.
Some of the chicks die before the 4th week .
In mature chickens the symptoms develop much more slowly than in growing chicks, but the inflammation of the eyes becomes more pronounced.
Often there is a white membranous film over the nictating membrane, or third eyelid, and a cheesy discharge, in the conjunctival sacs. There may also be a sticky discharge from the nostrils. - Vitamin D
Poultry requires vitamin D to effectively utilize calcium.
Vitamin D helps in the synthesis of calcium-binding proteins.
Calcium-binding proteins enhance Calcium absorption in the intestines especially.
Deficiency of vitamin D is evident in laying birds as egg production and egg weight decrease.
In growing birds, the symptoms are similar with that of calcium deficiency. There is bone weakness and retarded growth.
Vitamin D in feed may not be totally available to the birds due to destruction by oxidation and mycotoxin interference. - Vitamin E
Vitamin E is an antioxidant. It protects the body from free radicals that may cause harm. Just as selenium, its deficiency will lead to myopathies of the gizzard, the heart and skeletal muscles .
Other signs may include prostration with legs and head outstretched.
Males become infertile.
There is reduced egg production and hatchability of eggs . - Vitamin K
Vitamin is necessary for blood clotting.
Deficiency of vitamin k will lead to bleeding (hemorrhage) which may be internal and will lead to anemia.
An extended blood clotting time will lead to death of the bird.
Transmissible gastroenteritis
Transmissible gastroenteritis is a highly infectious disease in pigs, and is caused by a coronavirus.
It is a common viral disease of the small intestine that causes vomiting and profuse diarrhea in pigs of all ages.
Once the virus enters the host, it disrupts the lining of the small intestine. The infected swine then have reduced capability for digesting food and die from dehydration.
The disease spreads rapidly and often fatal in piglets less than one week old.
In some places the disease may end up being endemic, always present but with low mortality. This is especially true for a piggery where susceptible animals are constantly introduced into the herd.
Large amounts of the virus are excreted through faeces. Therefore, faeces is the main source of infection.
The virus can also be spread from one pen to another through boots, brushes, shovels, clothes, etc.
Some birds and dogs have been known to aid spread of the virus.
Outbreaks occur mainly during the cold weather (winter).
Clinical signs
In Piglets
The piglets often vomit and have severe greenish-yellow watery diarrhoea.
The piglets are dehydrated and die in their numbers.
In older pigs
prevention and treatment
Vomiting and greyish diarrhoea.
Abortion may occur in pregnant sows.
Usually mortality is low.
There is no specific treatment for transmissible gastroenteritis.
Electrolytes and access to water are provided to prevent dehydration.
Try as much as possible to keep the piglets warm.
Antibiotics are given to prevent secondary bacterial infection.
Maintain good biosecurity to prevent the disease.
The virus in the environment is susceptible to disinfectants such as iodine.
Hardware disease in cattle
This is also called traumatic reticuloperitonitis
It is caused by the ingestion of a sharp, metallic object such as nails and wires.
The metal objects settle in the reticulum and can penetrate the wall of the reticulum.
Cattle are normally prone to swallowing metal objects because of their feeding habit. Farms that adopt open grazing record more cases of the condition.
Contractions of the reticulum can push the object through part of the reticulum wall into the peritoneal cavity causing severe inflammation. Sometimes, the heart maybe affected.
Clinical signs of hardware disease vary depending on where the object is lodged.
The cow may show an arched back and affected animal is reluctant to move.
The cow may show signs of pain groaning when lying down and when defecating.
Treatment
Usually Surgery is necessary in some cases and involves opening the rumen and removing the object.
Some treatment can be effected with the use of magnets which are introduced orally.
After removal of the object, it is important to give antibiotic treatment.
Severely affected animals should be slaughtered.
Prevention
Feed should be inspected to remove all metallic objects before feeding to the animals. A magnet is important for this.
Always inspect your farm and remove objects that can be swallowed by your cattle.
Cow magnets are available for prevention of hardware disease. A magnet is usually introduced into the reticulum of a cow and the magnet stays there for the rest of the cow’s life. This will help prevent lodging of sharp objects in the wall of the reticulum.
Contagious bovine pleuropneumonia
Contagious bovine pleuropneumonia (CBPP) is a very important infectious disease of cattle in tropical Africa.
This disease can result to mortality reaching 80% in a naive herd.
Many cattle that survive will eventually become carriers. Uninfected herd may get the infection from the carriers.
Contagious bovine pleuropneumonia is caused by Mycoplasma mycoides subsp. mycoides, Usually the small colony type.
Cattle and buffalo are the primary hosts for M. mycoides SC.
Transmission
M. mycoides SC is mainly transmitted from animal to animal in respiratory aerosols.
The organism can be found in saliva, urine, fetal membranes and uterine discharges of infected animal.
Close contact is necessary for transmission but M. mycoides SC might be spread over longer distances under favourable climatic conditions.
Carrier animals can harbour the organisms in encapsulated lung lesions for several months or more which can be shed when stressed.
Clinical Signs
Acute cases in cattle are characterized by fever, loss of appetite, depression, drop in milk production.
Respiratory signs, which may include coughing, purulent or mucoid nasal discharges, and rapid breathing.
Severely affected cattle may stand with their head and neck extended and forelimbs apart, breathing through the mouth.
Severely affected cattle may die within 3 weeks.
A few cattle with CBPP may die peracutely with no clinical signs other than fever.
Diarrhoea, abortion and stillbirth have been reported.
In calves of about 6 months of age, it presents with arthritis. Respiratory signs may not be apparent. The affected joints may be so painful that the animal is very reluctant to bend them.
Chronic CBPP is characterized by recurrent fever, loss of condition, and respiratory signs that may be apparent only when the animal is exercised.
Prevention
The organism is generally fragile in the environment.
They are susceptible to many disinfectants including 1% sodium hypochlorite, 70% ethanol, phenol based disinfectants, formaldehyde.
Outbreaks are eradicated with strict biosecurity measures including quarantines, movement controls, slaughter of infected and in-contact animals, and cleaning and disinfection ( see biosecurity http://farmgrid.org/farm-biosecurity )
Vaccines may be used to control CBPP in endemic areas.
Tetracycline and fluoroquinolones are effective in treating but may not eliminate the infection. Chronic cases may be resistant to antibiotic treatment.
Contagious caprine pleuropneumonia
This is a very contagious bacterial disease of goats caused by Mycoplasma species with very high mortality rates, causing an interstitial fibrinous pleuropneumonia in infected goats.
Mortality rate can be as high as 80% in a naive flock.
Overcrowding increases disease incidence as it is spread through aerosol when animals are in close contact.
Stress factors such as long transport can also predispose animals to the disease.
CCPP is one of the most severe diseases of goats and affects the respiratory tract, and frequently fatal.
Transmission
Contagious caprine pleuropneumoniae is highly contagious.
Animals get infected by the inhalation of respiratory droplets.
Outbreaks of the disease often occur after heavy rains or after transportation over long distances.
Clinical Signs
Affected animals have respiratory signs including nasal discharges, breathing difficulties , rapid breathing and coughing.
Sudden death.
Affected animals also have general signs such as depression, dullness, weakness and lethargy, fever and weight loss and decreased productivity.
Prevention
Contagious caprine pleuropneumoniae is most likely to enter a flock through an infected animal.
Outbreaks in an endemic areas have occurred when apparently healthy goats were introduced into a new flock.
Prevention of outbreaks can be achieved through quarantine of new animals, biosecurity measures, cleaning and disinfection of premises.
Infected and exposed animals should be slaughtered.
Vaccines help prevent disease in endemic areas.
Some antibiotics, such as tetracycline and tylosin, can be effective if administered early.
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Fowl pox
Fowl pox is a contagious viral disease of various bird species including chicken, turkey etc, that causes skin lesions around the comb, wattle, ear lobes, and eyes.
There is also the wet form associated with lesions in the oral cavity and the upper respiratory tract, especially the larynx and trachea.
Fowlpox lesions, when in the respiratory tract can cause difficulty in breathing and even death
Wet pox is more serious and results in higher mortality.
Fowl pox if introduced in a flock can remain up to 10 weeks causing lesions on affected birds.
Fowl pox can cause decrease in productivity in terms of egg and weight.
While the wet form can cause mortality of up to 60% in an unvaccinated flock.
Transmission
The virus contained in the scabs contaminates the environment and remains infective for several months.
Infection can occur through injured or lacerated skin and through mechanical transmission by biting insect vectors such as mosquitoes.
Flies may deposit the virus in the eyes of susceptible bird.
The wet form seems to be spread by air when birds inhale the virus.
Prevention and control
There is no specific treatment for fowl pox, therefore prevention is the best option.
Employ strict biosecurity measures in your farm.
An effective insect control program should be in place.
Chicken houses and equipment should be well disinfected.
Sharp objects that may cause injuries should be removed from chicken pens.
Vaccinating your flock will certainly introduce the virus to your farm.
Usually vaccination starts after you have had a first case of fowl Pox.
It has been observed that vaccinating birds during a fowl pox outbreak can lead to reduction in losses due to the disease.
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