Prevention of calf enteritis

Prevention of calf enteritis is a year-round effort; not customary (routine)
activities focused around calving.

Introduction


The battle between the infectious agent and the infected host constitutes a balance between
microbial virulence factors and host defense mechanisms. Highly virulent organisms may
propagate rapidly in host tissues and cause death before the immune system has time to respond.
On the other hand, many infectious agents are controlled by the host’s immune response, and
after a period of illness, the organisms are killed and eliminated. The hosts tissues may be fully
build again, or in some instances, permanent damage may occur. Other infectious agents may
chronically infect the host for years or months without causing death; a subset of these agents
may reside within the host tissues and the animals become reservoir of infection, in a process
known as the carrier state and or latency.
Calf enteritis is not a single disease entity; as a clinical syndrome, it is associated with several
diseases characterized by diarrhea. Regardless of the cause of enteritis, absorption of fluids from
the intestine is altered, and life threatening electrolyte imbalances occur; that is, the scouring calf
loses fluids, rapidly dehydrates, and suffers from electrolyte loss and acidosis. Infectious agents
may cause initial damage to the intestine, but actual death from scours usually results from
dehydration, acidosis, and loss of electrolytes.
Identification of infectious agents which cause scours is essential for implementing effective
preventive and treatment measures.

Neonatal calf diarrhea is a common disease affecting the newborn calf. The most critical
period is in the first few days following birth of the calf. Greatest losses occur when calves are
kept in close confinement, where the opportunity for transmission of the causative agents is
enhanced by their build-up in the environment.
The diarrhea and other clinical signs seen with the disease are caused by the interaction of
any of several possible infectious causes and predisposing factors such as lack of colostrum,
failure to absorb colostral antibody, poor nutrition and environmental effects.
In this research article the different aspects of disease causation will be investigated for better
understanding the preventive activities required for reducing or control calf enteritis.


Problem of enteritis (clinical point of view)


Diarrhea
Diarrhea or scouring occurs when the capability of the intestine to absorb fluid is impaired.
Interference with this absorptive function of the intestine may occur in two ways. Damage to the
cells lining the intestine may result from cell destruction by certain infectious agents, resulting in
loss of the digestive and absorptive capability of the intestine as well as inflammation. Other
infectious agents produce toxins that cause the cell lining of the intestine to produce fluid rather
than absorb it. Diarrhea, dehydration and electrolyte loss occur in both instances and have
especially severe effects in the newborn animal. Simple exposure to infectious agents is not
sufficient cause for the development of diseases in calves. The difference between health and
disease is very often just a slight tip of a delicate balance that weighs calf and environmental
factors with the bacterial, viral or parasitic agents to which the calf will be exposed.

Calves will inevitably be exposed, several may become infected but only a few should get
disease. Diarrhea is the most common cause of death in young calves and is almost entirely
avoidable by good management. The highest risk period for diarrhea is from birth until about 1
month of age. Clinical signs of diarrhea begin with loose feces and can progress to a semicomatose state. In most cases of fatal diarrhea, the calf dies of dehydration and loss of
electrolytes not from the infectious agents that triggered the diarrhea. Blood glucose levels are
low and hypoglycemic coma can develop in calves that are in cold housing and have milk or
milk replacer withheld for more than one feeding. Electrolyte abnormalities involving potassium,
bicarbonate and sodium are frequently found but these resolve rapidly when fluids are given to
correct the dehydration and calves have access to water.
Septicemia
Septicemia in calves is usually the result of a bacterial infection that occurs while the calf is in
the uterus, during, at or immediately after birth. The route of infection can be the blood of a sick
dam, an infected placenta, the calf’s umbilical stump, mouth, nose (inhalation) or wound.
Septicemia is the most severe medical problem that a calf can develop because the blood-borne
infection disseminates and damages many different organs leading to what is called post
sepicemic localization. The bacteria that cause septicemia in calves, many of which are
characterized as gram-negative bacteria like
E. coli and Salmonella spp. Early signs of
septicemia may be subtle but affected calves are usually depressed, weak, reluctant to stand, and
suckle poorly within 5 days of birth. Swollen joints, diarrhea, pneumonia, meningitis, cloudy
eyes and/or a large, tender navel may develop. Fever is not a consistent finding in septicemic
calves; many have normal or subnormal temperatures. Most septicemic calves have a history of
inadequate colostrum intake.
Risk Factors
While the immune system of a calf is functional at birth, it is less responsive than an adult cow,
naive and easily overwhelmed by the bacteria, viruses or parasites in the environment. This is
due to:
The immune system is less mature than in adults at least for the first 30 days of life. Over
the first months of life, the immune responses usually revert to the balanced adult
pattern.
Newborn calves are born agammaglobulinemic.
The high level of hydrocortisone that probably due to transplacental transfer, as well as
the fetus produces large quantity of corticosteroids beginning 8–10 days before birth, this
leads to immunosuppression and decreased resistance.
Tissues of newborn calves are poor interferon producers.
The newborn has an increased number of suppressor T cells.
The immune response of newborn calves is a primary response with a prolonged lag

2. Environment and management: Prolonged exposure or an increased level of exposure occurs
when susceptible dairy calves remain in the calving area, have continued contact with adult
cattle, or are housed in facilities that are under-bedded, damp, humid, or poorly ventilated. Calf
to calf contact, crowding, or continuous use of facilities prolongs the survival rate and increases
the numbers of pathogens in the environment of the calf, even with cold housing.
3. Inadequate colostrum intake or absorption puts calves at significant risk of infection. Dairy
calves should be hand fed 3 liters (Jerseys, Guernseys, and Ayrshires) or 4 liters (Holsteins,
Brown Swiss) of colostrum. The entire volume should be from the first milking of a single cow.
Colostrum can be delivered in one or two feedings prior to the calf reaching 12 hours of age. The
entire volume can be delivered safely and effectively in a single feeding. Calves can suckle, be
fed by esophageal feeder or receive colostrum by a combination of the two methods. Fresh or
refrigerated colostrum provides the best combination of antibodies (immunoglobulins), immune
cells, other important immune factors (lactoferrin, lysozyme, and complement), vitamins and
minerals important to the immune system of the calf. Refrigerated colostrum should be used
within 1 week and frozen colostrum within 1 year of collection.
Common infectious causes of calf enteritis
• Escherichia coli (E. coli) E. coli appears to be the single most important cause of bacterial
scours in calves. There are numerous serotypes (kinds) of E. coli.

• Salmonella spp. is an important cause of bacterial scours in calves; it produces a potent toxin or
an endotoxin (poison) within its own cells. Antibiotic treatment damages the salmonella
organism, causing it to release the endotoxin. This endotoxin is potent and will result in
endotoxic shock, and severe illness. Therefore, treatment should be designed to combat
endotoxic shock.
Clostridium perfringens infections are commonly known as enterotoxemia and considered as
important cause of bacterial scours and mortality in newborn calves.
• Coronavirus and Rotavirus viruses possess the ability to disrupt the cells which line the small
intestine, resulting in diarrhea and dehydration. Coronavirus also damages the cells in the
intestinal crypts (where new intestinal cells are produced) and slows the healing process in the
intestinal lining. Furthermore, the damage caused by either corona or rotavirus is often
compounded by bacterial infections.
• Bovine Virus Diarrhea (BVD) Virus The BVD virus can cause diarrhea and death in young
calves.
• Cryptosporidium spp. is a protozoan parasite. It has the ability to adhere to the cells which line
the small intestine and to damage the microvilli. Cryptosporidia can be a primary pathogen, but
they are often found to be part of a mixed infection in combination with coronavirus, rotavirus,
and/or E. coli.
Prevention of calf scours
Management aspects
All facets of management are important. Particular attention should be paid to nutrition,
environment, sanitation, and care of the newborn calf.
• Nutrition: The ration of the pregnant female should be balanced in energy, protein, minerals,
and vitamins. Particular care must be taken to provide them with sufficient feed energy for
maintenance and growth. Failure to meet energy needs will not only result in a weak calf at birth,
but also contributes to increased dystocia (difficult calving), delayed return to estrus, and
lowered conception rates. Special attention should be given to energy deficiencies and/or vitamin
A and E shortages.
• Environment and sanitation: severe outbreaks of scours are associated with “bad weather,”
storms, slush, and mud. The newborn calf needs a dry, clean place if we expect it to survive free
of scours.
To ensure a healthy calf, the aim is to minimize the calf’s exposure to disease, and maximize its
defense against disease.

In minimizing a calf’s exposure to disease, control measures include:
Providing a clean, disease-free environment. This involves:
Providing a clean, straw-bedded lying area with no draughts and good ventilation.
Avoiding introduction of disease from sources such as purchased calves.
Isolate all purchased animals from young home-bred calves.
In maximizing a calf’s defense against disease, control measures include:
Adequate nutrition of the pregnant cow.
Vaccination of cows for control of any organism(s) known to be responsible for infection
on the farm in calves e.g. E. coli, rotavirus and coronavirus.

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