Reducing the risk of a pneumonia outbreak
Bovine respiratory disease, commonly referred to as BRD, is a complex disease entity involving interactions between the animal, infectious agents (viruses, bacteria and parasites) and the environment. Pneumonia is the main feature of the BRD complex. There is a seasonal peak of BRD cases in Ireland from September to February. Bacteria and viruses often result in concurrent infections. A primary viral infection compromises lung defence mechanism. Subsequently, cattle are predisposed to bacterial infection of the lower respiratory tract.
Clinical cases may present with all or some of the following signs:
- Nasal discharge;
- 0cular discharge;
- Increased rate and effort of respiration (pant);
- Fever (greater than 39.5⁰C); and
- Off-form, poor appetite and coughing.
Interestingly, the cases you see on your farm are only the tip of the iceberg as there are often subclinical cases.
Importance of reducing risk
Why is it important to reduce the risk of pneumonia in stock? Firstly, each year it is the most significant cause of death among cattle greater than one month of age and secondly there are substantial economic implications of respiratory disease both in the short and long-term. Furthermore, reducing the risk of pneumonia will positively impact the health and welfare of the animals.
Autumn is a particular risk period as cattle are routinely housed and spring-born beef calves are weaned, both housing and weaning elicit a stress response in cattle. Stressors negatively impact immunity of cattle resulting in increased susceptibility to disease, notably BRD. Therefore, it is imperative to mitigate stress and implement control measures. Controlling BRD involves a multifaceted approach which incorporates hygiene, housing, management, biosecurity measures and vaccination.
Housing
Good natural ventilation, avoiding draughts, providing dry bedding (for youngstock), comfortable temperature and practising good hygiene are vital components in housing facilities. Air movement within the shed is vital to remove noxious gases, heat, moisture and pathogens, for example bacteria and viruses. Prevent disease transmission from adult dairy cattle to naïve young animals by maintaining housing with separate airspace, though this is not possible with suckler herds. Adequate lighting is required to detect sick animals early in the disease process. Ideally, the long axis of the housing facility should be at right angles to the south-west to maximise natural ventilation efficiency.
Management
Avoid additional stressors during the housing period, for example, do not castrate, dose and vaccinate animals at housing. These should be separated to prevent exacerbation of stress. Animals observed with any of the clinical signs outlined above should be monitored. It is crucial to identify cattle in the early stage of the disease process to enable a timely diagnosis and subsequently treat the animal with the correct veterinary medicinal products for the correct length of time.
The onset of immunity of Bovilis Bovipast RSP is two weeks after the second dose, while for Bovilis Nasalgen-C it is five days. Bovilis Bovipast RSP protects against both viral and bacterial agents namely PI3, RSV and provides the broadest protection on the market against Mannheimia haemolytica. Bovilis Bovipast RSP is the only cattle vaccine licensed to protect against serotypes A1 and A6. The primary course for Bovilis Bovipast RSP involves two subcutaneous injections administered four weeks apart. For calves the second injection should be given two weeks before the known risk period of weaning, housing or sale. For bought-in animals Bovilis Bovipast RSP can be administered any time after arrival, ideally allowing a short rest period before handling, and followed up with a second dose four weeks later. Bovilis Bovipast RSP can be administered at the same time as Bovilis IBR marker live but in different sites.
Bovilis IBR marker live, provides protection against bovine herpesvirus-1 (BHV-1), can be administered intranasally or intramuscularly two weeks before the risk period and provides six months protection.
A vaccine option to consider, when there is a short timeframe before the known risk period, is Bovilis INtranasal RSP Live. This live vaccine provides fast protection against RSV and PI3 with an onset of immunity of five days and seven days, respectively. Bovilis INtranasal RSP Live is a single 2ml dose vaccine, lasting 12 weeks and can be administered at least one week before the risk period and can be given on the same day as Bovilis Nasalgen-C, which was recently introduced by MSD Animal Health.
Bovilis Nasalgen-C is a live intranasal vaccine for the active immunisation of cattle from the day of birth onwards to reduce clinical signs of upper respiratory tract disease and nasal viral shedding from infection with bovine coronavirus. This vaccine is a 2ml dose administered intranasally. The vaccine has an onset of immunity of five days and a duration of immunity of 12 weeks.
Tailoring a correctly timed well suited vaccine protocol in conjunction with good farm management will positively impact animal’s health and welfare. Disease preventative strategies are key to ensure animals are healthy, productive and profitable. Always consult with your veterinary practitioner to establish a vaccination protocol.
Biosecurity
Ideally, a closed herd is advised. However, if purchasing animals, it is important to monitor for clinical signs of BRD while quarantining, for at least four weeks, preferably in a separate shed or, weather permitting, a well sheltered pasture.
Vaccination
Vaccination is a vital component of the control measures to reduce the risk of pneumonia as it enhances immunity by stimulating production of antibodies. Vaccination will reduce infection and clinical signs of BRD. There is a broad range of infectious agents implicated in BRD highlighting the importance of providing broad spectrum cover against the infectious agents relevant to your farm.
Vaccine programmes
Vaccines incorporated into a vaccination regime will vary from farm to farm and should take into account the farm system, history of disease, risk factors associated with the farm in question, previous diagnostic lab results and/or post-mortem results. Engaging with your own veterinary practitioner to advise which vaccines are suited to your herd is highly recommended.
Vaccination programmes will vary depending on the product used. It is recommended to vaccinate in advance of the autumnal risk period. This is to enable the animal to respond as each vaccine takes a certain period of time to become effective.