Mastitis
By definition, mastitis is the inflammation of the mammary glands where the udder is observed to swell.
Causes
The majorly known predisposing factor is poor levels of hygiene in the animal’s environment, when the bacterial population becomes overwhelming. Mechanical injuries to the udder and the teats is the commonest factor facilitating the cause. 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). Mastitis risk factors or disease determinants can be classified into three groups: host, pathogen and environmental determinants.
Symptoms
- Somatic cell counts measure in milk can be used as an indicator of mastitis level.
- The most obvious symptoms of clinical mastitis in the udder are swelling, heat, hardness, redness or pain and inconsistency of the milk secretion from the affected quarter.
- Milk takes on a watery appearance, flakes, clots pus or even blood 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.
Diagnosis
Based on the signs above
- Use strip cup to check for mastitis as below
- Thoroughly clean the udder and the teats
- Strip the first few drops of milk from each quarter on the ground
- Strip about 3ml of milk onto the pots of the plate each corresponding to a quarter.
- Add equal amount of the reagent
- Gently shake and tilt to observe. The positive result is when there is formation of a gelatinous/mucus-like substance at the center of the cup
Treatment
Intramuscular (IM) injection of pen strep (penicillin and streptomycin) accompanied by intra-mammary infusion of terrexin/ multject.
Prevention
- Hygienic teat management: which includes good housing management, effective teat preparation and disinfection for good milk hygiene, teat health and disease control.
- Prompt identification and treatment of clinical mastitis cases: including the use of the most appropriate treatment for the symptoms.
- Dry cow management and therapy: where cows are dried off abruptly and teats are cleaned well before dry cow antibiotics are administered, including the use of teat-end sealants if appropriate.
- Culling chronically affected cows: cows that become impossible to cure and represent a reservoir of infection for the whole herd. More than 5 times affected in one lactation
- Remove materials that can cause teat/udder injury
- Test for mastitis before milking
- Milk affected cows/quarter last
- 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.
Pseudocowpox (false cowpox, milker’s nodule)
This is the most common infectious cause of teat disease in cattle. Because immunity is short-lived, cows can get infected fairly soon (often less than six months) after recovering from the disease). Pseudocowpox, caused by a parapox virus, should not be confused with true cowpox, which is a rare disease.
Symptoms
- Initially infection causes a small area of swelling and reddening on the teat.
- This is painful and makes the cow difficult to milk.
- Over the next two days, the affected area elevates into an orange papule, which then scabs over.
- Tissue developing under the scab pushes it up further.
- Once the lesion has scabbed over, it becomes much less painful and milking is no longer so difficult.
- Seven to ten days after first signs the scabs start dropping off.
- This often leaves a horse-shoe or ring shaped area, which is very characteristic of pseudocowpox.
- Affected areas may grow together leading to scabs covering the entire length of the teat.
- Damaged teats are usually healed around a month after first signs.
- Most pseudocowpox is found on the teat. However up to 10 per cent of affected cows may have lesions on the udder skin.
- Pseudocowpox can spread from cattle to man by contact. Skin infection in man is known as milker’s nodules, and is a painful localized infection.
Treatment
- Removal of the scabs followed by the application of an astringent disinfectant has been suggested for severely affected individual cases.
- Locally applied teat ointments appear to have little effect.
- Emollient teat sprays and dips can have a beneficial effect by reducing the numbers of bacteria and viruses on the teat skin and by aiding the healing of damaged skin.
Prevention
- Prevent infected cows getting in your herd – Quarantine cows for at least 14 days before they enter the milking herd
- For pseudocowpox, effective teat dipping with an iodophor teat dip is probably the most effective means of control
- Improving parlour hygiene by using disinfectable gloves, disposable towels and teat cup disinfection may reduce disease spread
- 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.
- 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.
Bloat
The least common type is gassy bloat, which occurs when the gullet is obstructed (often by foreign objects such as raw pieces of potatoes) or when the animal can’t burp (such as with milk fever or tetanus). The second type of bloat is frothy bloat, which happens as the result of a stable foam developing on top of the rumen liquid, which blocks the release of the gas. This is by far the most common form of bloat, and unlike gassy bloat.
This is because the foam is formed by breakdown products from rapidly growing forages (particularly legumes such as clover and alfalfa). These increase the viscosity (stickiness) of the rumen fluid and prevent the small bubbles of gas formed by rumen fermentation from coming together to form free gas that can be belched off
Symptoms
- Distended left abdomen is the most obvious sign
- Depressed appetite
- Usually associated with pain, discomfort, and bellowing.
- Death can occur within 15 minutes after the development of bloat
- Gaseous bloat is usually seen in one or two animals. Frothy bloat can affect up to 25% of cases
- In some cases sudden death may be the first sign seen by the stockman, although in such cases it is likely that there will be other cattle with bloat that are still alive
- A=Mild | B=Moderate | C=Severe
Diagnosis
- On the clinical signs described above
- History of access to lush pasture
- Passing a stomach tube will distinguish between gassy and frothy bloat. If it’s gassy bloat a stomach tube passed into the rumen will allow the gas build-up to escape through the tube. No such gas is seen in frothy bloat.
- The stomach tube
Treatment
- Passing a stomach tube is the best treatment for gassy bloat. Once the gas has been released, the cause of the obstruction should be determined.
- Running after the affected animal
- Use of trocar and cannula as the last resort.
- For frothy bloat, antifoaming agents that disperse the foam should be given by stomach tube. Old-fashioned remedies such as linseed oil and turpentine are effective but newer treatments such as dimethicone or polaxolene are easier to give as the effective dose is much smaller.
- If an outbreak of frothy bloat occurs all cattle on that pasture should be removed immediately and put onto a high fibre diet (hay or straw), and any cows showing bloating signs treated with an anti-foaming agent. The pasture should not be grazed for at least ten days.
Prevention
- It is much more effective to prevent bloat than treat affected animals. Management and planning can significantly reduce the number of cases. To prevent frothy bloat:
- Pastures with a history of bloat problems or with a high clover content should not be used for cows soon after turnout.
- Stagger turnout with buffer feeding as this will allow the rumen to adapt to the new diet.
- If you have to use high-risk pastures, introduce the cattle to them slowly. In some cases restricting access to as little as ten minutes per day at the start may be necessary to prevent bloat.
- Avoid starting to graze high-risk pastures when they are wet.
- Administer anti-foaming agents daily if bloat is a severe problem.
- Remove high-risk animals. Some animals have recurrent bloat despite prevention and treatment.
Rift Valley Fever
Clinical Signs
- Fever
- Anorexia (poor appetite)
- Weakness
- Death in young animals
- Abortion (may be 100% in the herd)
- Enlarged kidney
Treatment
- There is no specific treatment for Rift Valley Fever since it is viral
- Any animal suspected of having Rift Valley Fever should be reported to the State Veterinarians or USDA Area Veterinarian in Charge immediately.
Prevention
- Human and animal vaccines exist for those areas where Rift Valley Fever is endemic.
- Control of the mosquito population is also necessary to prevent the spread of the disease.
- Removal of animals from a low lying area to a higher altitude.
Public Health
- Rift Valley Fever is a highly zoonotic and can be transmitted from animals to people readily.
- The disease is typically mild with patients showing flu-like symptoms and photophobia (sensitivity to light).
- In rare cases, people with Rift Valley Fever may develop severe complications including eye disease, meningoencephalitis (inflammation of the brain and surrounding tissue) or hemorrhagic fever.
- Patients who develop eye disease as a result of Rift Valley Fever often experience permanent vision loss, but the disease is not fatal.
- However, those patients who develop hemorrhagic fever often have vomiting and diarrhea with blood and may bleed from the gums. These patients also may develop liver complications. The mortality rate is approximately 50% in patients with hemorrhagic fever.
- Rift Valley Fever may be prevented by taking appropriate measures to control mosquitoes and using personal protection equipment (gloves, surgical masks, etc.) when handling affected stock or carcasses.
Coccidiosis
Coccidiosis is caused by single-celled parasites (not bacteria) known as coccidia. There are several species in cattle, not all of which cause disease. The species that cause disease are primarily found in the large intestine, and the diarrhoea results from damage to the cells lining. Coccidiosis is seen in animals up to two years old, and is particularly common in calves between three weeks and six months of age.
Cattle become infected when placed in environments contaminated by older cattle or other infected calves. This can happen either indoors on bedding, or outdoors around drinking or feeding troughs. In order for the coccidial oocysts (the egg stage of the parasite) to become efective they require warmth and moisture.
Poor hygiene, high stocking density, poor health and poor nutrition will all contribute to a calf picking up the parasites and subsequent disease.
Symptoms
Symptoms are not always specific to coccidiosis.
- Diarrhea (often very watery)
- Depression
- Loss of appetite
- Weight loss
- Dysentery (passing blood stained faeces)
- Death is rare. Infections that fail to produce diarrhea can, nevertheless, result in reduced growth and weight gain.
Treatment
In most cases calves will recover without treatment. Treatment is better given to in-contact animals that have not yet started showing signs, or to combat secondary infection.
Prevention
- To achieve effective control of coccidia, good management and hygiene is vital.
- Young susceptible animals should be kept as clean and dry as possible.
- Feeding and watering equipment should be cleaned and protected from fecal contamination.
- Avoid feeding cattle on the ground, especially calves, so manure does not contaminate the feed.
- Excessive moisture in pens should be drained, and dry bedding should be provided.
- Use pastures that are well drained, and avoid grazing down to the roots of the plants so they do not eat large numbers of parasites.
- Try to keep grazing to a minimum in areas where cattle congregate (e.g. by water).
- Whenever possible, infected animals should be isolated as soon as possible to avoid exposure of infected manure to other cattle.
- In some places, medication can be placed in the water or feed to prevent infection. These are called coccidiostats
Brucellosis
Brucellosis is an infectious disease that occurs from contact with animals carrying Brucella bacteria. Brucella can infect cattle, goats, camels, dogs, and pigs. The bacteria can spread to humans in contact with infected meat or the placenta of infected animals, or if you eat or drink unpasteurized milk or cheese. Brucella is highly contagious, spreading very easily between cattle as the calf, the membranes and the uterine fluids all contain large quantities of bacteria.
Symptoms
- Abortion
- Still births
- Weak calf born
- Retention of fetal membranes.
- Signs of infection in the membranes.
- Swollen testicles in bulls
- Diagnosis can be done by laboratory testing of blood or milk samples or by laboratory culture of Brucella abortus from the placenta, vaginal discharge or the milk of infected cows
Treatment
- No treatment is available, which makes detection and prevention essential.
Prevention
- Brucellosis is a notifiable disease. Because of this most countries have strict regulations in place to control brucellosis; however it is still a threat.
- Testing herds regularly and culling has been an effective way of eradicating the disease in individual herds before.
- Quarantines are placed on infected herds and good sanitation and biosecurity will protect uninfected herds.
- Vaccination is not a guarantee but can increase resistance to infection.
- Adopt artificial insemination rather than natural mating
Vibriosis (Campylobacter infection)
Vibrosis is an important infectious venereal disease of cattle. It is a cause of infertility and abortion
Cause
- Vibriosis is caused by the bacterium Campylobacter fetus and is spread by infected bulls when they mate susceptible cows and heifers on natural mating program
- Once infected, a bull remains an asymptomatic carrier of the condition. Non-venereal transmission of campylobacteriosis is unlikely to occur.
- When introduced to a herd, the disease spreads rapidly, as cows and heifers in such herds have no immunity.
- Conception rates can then drop to around 40 per cent.
- Conception rates in these chronically infected herds are usually between 65 per cent and 75 per cent, with replacement heifers typically the most severely affected.
- Infertility normally occurs from an infection in the uterus after the heifer has mated with an infected bull.
- This infection can prevent the implantation of a fertilized egg, or more commonly results in the loss of the developing embryo in the uterus.
- When this happens, the animal usually returns to estrus, but often with prolonged and irregular cycles.
- Occasionally the disease results in permanent infertility.
Symptoms
- Abortion
- Poor conception rates
- Long calving interval
- Uterine infection
- The disease is confirmed by measuring antibodies in the vaginal mucus of infected cows and heifers.
- Bulls can also be tested for the presence of infection
Treatment
- Where available, all breeding animals can be vaccinated to eliminate the disease from an infected herd.
- In many instances vaccinating and treating only the bulls can break the transmission cycle, with the disease gradually dying out in the herd.
- Natural immunity will eliminate the disease from the herd, however replacement heifers will still remain at risk.
Prevention
- Bulls can be vaccinated annually against the disease.
- Vaccinations are also available for cows and make the animal highly resistant to infection.
- Biosecurity and screening of bulls to identify the disease
- If a bull has to be bought the best policy is the younger the better.
- If you have to buy in a mature bull, treat it with antibiotics before it is used to mate cows and use it on a small number of cows only so that its fertility can be monitored before it is used for service in the main herd.
- Adopt AI instead of natural service.
Anthrax
Anthrax, a highly infectious and fatal disease of mammals and humans, is caused by a relatively large spore-forming rectangular shaped bacterium called Bacillus anthracis. Anthrax occurs on all the continents, causes acute mortality in ruminants and is a zoonosis.
The bacteria produce extremely potent toxins which are responsible for the ill effects, causing a high mortality rate. While most mammals are susceptible, anthrax is typically a disease of ruminants and humans.
It does not typically spread from animal to animal nor from person to person. The bacteria produce spores in the presence of oxygen. This spore is resistant to extremes of temperatures and light
Clinical Signs
- Sudden death (often within 2 or 3 hours of being apparently normal) is by far the most common sign;
- Occasionally some animals may show trembling, a high temperature, difficulty breathing, collapse and convulsions before death. This usually occurs over a period of 24 hours;
- After death blood may not clot, resulting in a small amount of bloody discharge from the nose, mouth and other openings
- Bloated stomach
Diagnosis
On the clinical signs described above;
- Rod-shaped bacteria surrounded by a capsule are visible in blood smears made from surface blood vessels
- Post-mortem examinations should not be undertaken on suspected anthrax cases (including any cow that has died suddenly for no apparent reason) until a blood smear has proved negative);
- If a carcass is opened accidentally, the spleen is usually swollen and there is bloodstained fluid in all body cavities.
Treatment
Due to the morbidity of the disease, treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks.
Prevention
Infection is usually acquired through the ingestion of contaminated soil, fodder or compound feed. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested or inhaled by ruminants the disease reappears.
Where an outbreak has occurred, carcases must be disposed of properly. The carcase should not be open (exposure to oxygen will allow the bacteria to form spores) and premises should be quarantined until all susceptible animals are vaccinated.
Vaccination in endemic areas is very important. Although vaccination will prevent outbreaks veterinary services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present.
Foot-and-Mouth disease (FMD)
Foot-and-mouth disease (FMD) is a severe, highly contagious viral disease of cattle and swine. It also affects sheep, goats, deer, and other cloven-hooved ruminants. FMD is not recognized as a zoonotic disease. The disease spreads very quickly if not controlled and because of this is a reportable disease.
Cause
The disease is caused by a virus of which there are seven ‘types’, each producing the same symptoms, and distinguishable only in the laboratory. Immunity to one type does not protect an animal against other types. The interval between exposure to infection and the appearance of symptoms varies between twenty-four hours and ten days, or even longer. The average time, under natural conditions, is three to six days.
The virus survives in lymph nodes and bone marrow at neutral pH, but is destroyed in muscle when pH is less than 6.0, i.e., after rigor mortis. The virus can persist in contaminated fodder and the environment for up to one month, depending on the temperature and pH conditions.
Airborne spread of the disease can take place and under favorable weather conditions the disease may be spread to considerable distances by this route. Animals pick up the virus either by direct contact with an infected animal or by contact with foodstuffs or other things which have been contaminated by such an animal, or by eating or coming into contact with some part of an infected carcase.
Outbreaks have been linked with the importation of infected meat and meat products. The disease can also be spread by people, vehicles and other objects that have been contaminated by the virus.
Symptoms
- Fever
- Blisters/sores in the mouth and on feet( hence the name foot and mouth)
- Drop in milk production
- Weight loss
- Loss of appetite
- Quivering lips and frothing of mouth
- Cows may develop blisters on teats
- Lameness
Treatment
Treatment is not given. Affected animals will recover. However because of the loss of production and the infectious state of the disease, infected animals are usually culled.
Prevention
- Export restrictions are often imposed on countries with known outbreaks.
- FMD outbreaks are usually controlled by quarantines and movement restrictions, euthanasia of affected and in-contact animals, and cleansing and disinfection of affected premises, equipment and vehicles.
- Infected carcasses must be disposed of safely by incineration, rendering, burial or other techniques. Milk from infected cows can be inactivated by heating to 100°C (212°F) for more than 20 minutes. Slurry can be heated to 67°C (153°F) for three minutes.
- Rodents and other vectors may be killed to prevent them from mechanically disseminating the virus.
- Good biosecurity measures should be practiced on uninfected farms to prevent entry of the virus.
Vaccination
- Vaccination can be used to reduce the spread of FMD or protect specific animals.
- Vaccines are also used in endemic regions to protect animals from clinical disease. FMDV vaccines must closely match the serotype and strain of the infecting strain.
- Vaccination with one serotype does not protect the animal against other serotypes, and may not protect the animal completely or at all from other strains of the same serotype. Currently, there is no universal FMD vaccine.
Foot Rot
Cause
Foot rot or foul in the foot is a subacute or acute necrotic infection originating from a lesion in the interdigital skin that leads to a cellulitis in the digital region. Mechanical injury or softening and thinning of the interdigital (between the toes) skin by puncture wounds or continuous exposure to wet conditions are predisposing factor to provide entrance points for infectious agents.
Fusobacterium necrophorum is considered to be the major cause of footrot. It can be isolated from feces, which may explain why control is difficult. Other organisms, such as Staphylococcus aureus , Escherichia coli , Arcanobacterium (Actinomyces) pyogenes , and possibly Bacteroides melaninogenicus , can also be involved.
The incidence varies according to weather, season of year, grazing periods, and housing system. On average, foot rot accounts for around 15% of claw diseases.
Symptoms
- Severe lameness
- Animal holds leg in air to relieve pressure
- Swelling of interdigital space
- Fever
- Anorexia
- Reduced milk yield
- Bad odor from the affected foot/feet
- Hind feet are affected most often and cattle tend to stand and walk on their toes.
Treatment
- Treatment of footrot is relatively straightforward and if instituted early in the course of the disease is usually successful. Remember all lame feet are not necessarily footrot however; there are other conditions that look similar.
- Historically, an antiseptic and bandage were applied after cleaning and trimming the foot, but topical treatment and bandaging are considered less important than systemic therapy.
- Prompt diagnosis and initiation of antimicrobial therapy are essential to achieve a satisfactory response. The treatment of choice is parenteral antibiotics administered for three to five days.
- In cattle that are difficult to handle, feed additives can be used to treat large numbers – however veterinarian advice should be sought.
- If improvement is not evident within three to four days, it may mean the infection has invaded the deeper tissues. Infections that do not respond to initial treatments need to be re-evaluated by your veterinarian in a timely manner. He or she will want to determine if re-cleaning, removing all infected tissue, application of a topical antimicrobial, and bandaging are appropriate, along with an antimicrobial change.
- In the more severe cases, management of the animal will be between salvaging for slaughter (following drug withdrawal times), claw amputation, or in valuable animals, claw-salvaging surgical procedures.
Prevention
- Preventive measures include removing sources of injury and keeping feet dry and clean. No effective vaccine
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
Symptoms
Symptoms often begin to show four to 24 days after infection. The most important clinical sign is nonregenerative 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
- Currently, 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 resistance and now various 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 developed are: spraying insecticide on tsetse habitat, destruction of tsetse habitat and alteration of vegetation so that it becomes unsuitable for tsetse flies. Some also use tsetse traps followed by rendering the males sterile before release
- However, these methods are costly and require a high level of management, organization and specialist expertise.