Download Pneumonia - Market Vets

Calf Health
Pneumonia in Calves
Calf pneumonia is a disease of considerable financial significance to the cattle industry. Losses arise from
the cost of treatment, reduced weight gain, increased work for those looking after the calves and most
significantly from calf deaths. As with all disease prevention is better than cure and the most cost
effective approach to managing pneumonia lies in a preventive programme involving positive management to
control the contributory factors. The disease is multifactorial which means that in addition to infectious
viruses and bacteria, husbandry and management factors have an essential role in outbreaks. This is
demonstrated by the fact that the bugs that cause pneumonia are to be found in every herd of cattle
whether or not pneumonia is a problem.
Viruses
RSV, Pi3 and IBR are the important respiratory viruses and are usually responsible for the early phases of
disease. BVD virus does not damage the respiratory tract directly but lowers the immunity of the calves and
so makes them more susceptible to the effects of the other infections. The RSV virus can cause pneumonia of
such severity that calves can die after a very short illness.
Bacteria
The bacteria that cause pneumonia usually do so following viral infection but they
can act alone when the air quality or husbandry is very poor. The important
bacteria are Pasteurella haemolytica (now known as Mannheimia haemolytica),
Pasteurella multocida, Histophilus somni and
Mycoplasma bovis. All can be found in the nasal passages of groups of healthy calves
but they cause severe lung damage when they are allowed to penetrate the lower
airways and it is this part of the disease that causes the majority of deaths
arising from pneumonia. A further cause of pneumonia that has to be considered is
lungworm –see
separate fact sheet.
Signs of pneumonia
The first sign of pneumonia in a calf is reduced in feed intake. At this stage the calf will almost certainly
have a fever (rectal temperature more than 39.5 degrees C.) and a watery discharge from the nose may be
apparent. As the disease progresses coughing may occur and the animal shows increased effort to take air
into the damaged lungs. The nasal discharge may now become thicker and flecked with white material (mucus
and pus). By the time a calf is seen to be clearly ill there is likely to be several other calves already in the
early stages of the disease. At its most severe pneumonia causes so much lung damage that the animal can no
longer breathe effectively and dies because of oxygen starvation. A number of affected calves will suffer
lung damage that will not repair and will appear ill-thriven and suffer recurrent bouts of pneumonia
(‘respiratory cripples’).
Pneumonia in Calves
Environment
Naturally ventilated buildings rely on air warmed by the calves rising to exit the building through the outlets in the roof and fresh air
being drawn in through inlets in the walls. This system must be able to provide the calves with the required air changes even on the
stillest of days. In a well-ventilated building the air will appear fresh without excessive smells of ammonia or slurry gasses and
cobwebs will not be evident. If pneumonia is a recurrent problem in a building then it is necessary to review the ventilation. There are
standards for design and the inlet and outlet areas can be measured for the numbers and type of stock housed. Your vet or a buildings
engineer will be able to advise on the adequacy of the ventilation and suggest ways in which ventilation can be improved. Sources of
dust should be avoided. Rations should not be ground or mixed in the same air space as the calves. Drainage too is critical. If surfaces
within the building are constantly wet then the relative humidity within the building will increase and favour the survival of the
bacteria and viruses that cause pneumonia.
Prevention
• Adequate colostrum at birth (6pints in the first 6 hours of life) is the essential first step in pneumonia control. This
provides the calf with antibody protection for the first three to four months of its life. After this, the immune system can
be enhanced by providing adequate nutrition (proteins, energy, vitamin E and selenium) and ensuring good general
health by reducing the incidence of other diseases, such as scours, parasitism and, very importantly, BVD, as this
weakens the animal’s immune response.
• Mixing calves of different ages increases the stress on younger calves and exposes them to bugs shed by the older calves
before their immune systems are developed. Where calves of mixed age groups have to be housed in the same airspace,
house the younger ones upwind of the older ones or try to
create a barrier between airspaces in order to limit air movement between the two.
• Avoid overcrowding since this cannot be compensated for by increased ventilation. The space
requirements for air are a minimum of six cubic metres of air space for small calves and ten cubic
metres for larger calves. This air needs to be moving.
• Avoid stress especially at the times of the year when there is a high risk of pneumonia e.g. the month after housing.
Dehorning and castration should be done when calves are young and ensure that the
introduction of any concentrate ration is done as gradually as possible to minimise the risk of acidosis.
90% of UK farms have one or more of the respiratory viruses, so when buying in animals from
multiple sources, pneumonia is a constant risk.
Vaccination
In addition to a management programme that seeks to minimise stress and improve air quality, vaccines can help control of
pneumonia. Vaccination programmes should be timed to occur ahead of the main risk period so that the calves’ immune systems are
ready for a fast specific response at the time of viral challenge. Vaccines cannot however compensate for poor management. A range
of vaccines are available and their use should be discussed with your vet.
Treatment
Antibiotics are very useful in the treatment of pneumonia and in many cases a response may be seen within 24 to 48 hours. Blanket
treatment of the group is sometimes employed, but antibiotics should be used responsibly and should only be administered on the
advice of the vet.
Anti-inflammatory agents are also to reduce the damage caused by inflammation within the affected lung.
The Surgery, Southley Road, South
Molton, Devon, EX36 4BL
01769 572176/574250
Farm Section—01769 575290
www.marketvets.co.uk