PATHOLOGY - Bovine Respiratory Disease Flashcards
What is bovine respiratory disease/calf pneumonia?
A multifactorial disease caused by interactions between viral and bacterial pathogens together with environmental risk factors
What are the environmental risk factors for bovine respiratory disease?
Housing
Transport
Nutrition
Stocking density
Ventilation
Weather
What are the potential clinical signs of bovine respiratory disease?
Depression
Anorexia
Tachypnoea
Hyperpnoea
Mouth breathing (dyspnoea)
Coughing
Ocular discharge
Nasal discharge
Pyrexia
Adventitious lung sound on thoracic auscultation
Upper respiratory tract noise on auscultation
Decreased body condition score (BCS)
What can be indicated by a decreased body condition score (BCS) associated with bovine respiratory disease?
A decreased body condition score (BCS) can indicate a more chronic disease process
Which questions can be useful to ask when investigating a calf exhibiting respiratory clinical signs?
Are there any other animals in the herd affected?
Has this patient had any previous episodes like this? If so were they treated for it?
Is this patients currently housed or out on grass?
What are your main aims during your clinical exam of a calf exhibiting respiratory clinical signs?
Determine if this is acute or chronic disease
Determine if this is upper or lower respiratory disease
How do you diagnose bovine respiratory disease?
You diagnose bovine respiratory disease based on history, clinical signs and clinical examination. You can also use diagnostic tests but think about if specific diagnostics are really necessary and if they will have any affect on your treatment plan
Which diagnostic tests can you do to investigate bovine respiratory disease?
Serology
Culture
Post mortem (PM)
Ultrasound
Diagnostic testing is generally more useful for future prevention of specific pathogens then treatment of individual animals
What is serology?
Serology is a diagnostic test which assesses for the presence of antibodies in the blood
What are the limitations of serology in calves?
The presence of maternal-derived anitbodies in calves can limit the effectiveness of serological tests as they can intefere with the detection of the calve’s own immune response, making it difficult to accurately assess disease expousre and immunity in calves. Because of this, you have to take paired blood samples three weeks apart to do serological testing, however this is impractical
Which sampling methods can be used for culture when investigating bovine respiratory disease?
Nasopharyngeal swabs
Ocular swabs
Bronchoalveolar lavage (BAL)
What are the benefits of bronchoalveolar lavage (BAL) for diagnosing bovine respiratory disease?
Bronchoalveolar lavage is a useful sampling method for PCR to isolate primary viruses which can cause calf pneumonia
Which virus is bronchoalveolar lavage (BAL) not an appropriate sampling technique for isolating?
Infectious bovine rhinotracheitis (IBR)
Which sampling techniques are most appropriate for isolating infectious bovine rhonotracheitis (IBR)?
Nasopharyngeal swab
Ocular swab
When is bronchoalveolar lavage (BAL) not an appropriate sampling method?
Bronchoalveolar lavage (BAL) is not appropriate for patients with clinical signs of a secondary bacterial infection such as purulent or mucopurulent discharge, as the secondary bacteria will obscure the results. Furthermorem bronchoalveolar lavage (BAL) is not appropriate for patients that have received any treatment as this will obscure the results
Which primary viruses are associated with bovine respiratory disease?
Infectious bovine rhinotracheitis (IBR)
Respiratory syncytial virus (RSV)
Parainfluenza virus - 3 (PI3)
Bovine viral diarrhoea virus (BVD)
Remember viruses suppress the immune system and predispose to secondary bacterial infections
Which primary bacteria are associated with bovine respiratory disease?
Mannhaemia haemolytica
Pateurella multocida
Histophillus somni
Mycoplasma dispar
Mycoplasma bovis
Which two conditions are associated with bovine respiratory disease but only present in calves on grass?
Dictyocaulus viviparus
Fog fever
What are the classifications of bovine respiratory disease?
Chronic ‘cuffing’ pneumonia
Chronic necrotising pneumonia
Enzootic pneumonia
Infectious bovine rhinotracheitis (IBR)
Pneumonic pasteurellosis (‘shipping fever’)
Parasitic bronchitis
Fog fever
Chronic suppurative pneumonia
Which primary pathogens cause chronic ‘cuffing’ pnuemonia in calves?
Mycoplasma
Give an example of a mycoplasma which causes chronic ‘cuffing’ pneumonia
Mycoplasma dispar
What are the clinical signs of the mild form of chronic ‘cuffing’ pneumonia?
Occasional cough
Tachypnoea
Decreased growth rate
What are the clinical signs of the severe form of chronic ‘cuffing’ pneumonia?
Frequent cough
Tachypnoea
Hyperpnoea
Depression
Excercise intolerance
Decreased growth rate
Anorexia
Pyrexia
Adventitious lung sounds over cranioventral lung fields (usually a general harsh sound)
Lameness (can cause joint ill
signs of vestibular disease?
What is the prognosis for chronic ‘cuffing’ pneumonia?
Chronic ‘cuffing’ pneumonia has up to 100% morbidity but a very low mortality. Mild cases can resolve without treatment, however chronic ‘cuffing’ pneumonia can predispose calves to secondary infections
Which primary pathogen causes chronic necrotising pneumonia?
Mycoplasma bovis
How does chronic necrotising pneumonia present on post-mortem?
Well demarcated foci of caseous necrosis
Which disease has a similar post-mortem appearnace to chronic necrotising pneumonia?
Contagious bovine pleuropneumonia which is a notifiable disease
What is one of the potential clinical presentations of chronic necrotising pneumonia?
Mycoplasma bovis can also cause joint lesions and present as lameness
Which pathogens typically cause enzootic pneumonia?
Respiratory syncytial virus (RSV)
Parainfluenza virus - 3 (PI3)
Which virus causes more severe enzootic pneumonia?
Respiratory syncytial virus (RSV)
What are the clinical signs of acute enzootic pneumonia?
Frequent cough
Tachypnoea
Hyperpnoea
Nasal discharge
Depression
Anorexia
Pyrexia
Adventitious lung sounds over cranioventral lung fields (usually crackles and fluid sounds)
(T/F) Infectious bovine rhinotracheitis (IBR) causes lower respiratory disease
FALSE. Infectious bovine rhinotracheitis (IBR) causes upper respiratory disease, specifically acute laryngeotracheitis
Which bacteria are most commonly isolated in calves with pneumonic pasteurellosis?
Mannheimia haemolytica (most common)
Pasteurella multocida
Histophilus somni
Describe briefly the pathogenesis of pneumonic pasteurellosis
An environmental stressor and/or by a viral infection results in the suppression of the host immune system and the combination of stressors and primary infections is thought to break down the mucosal barrier integrity of the lower respiratory tract, allowing commensal bacteria of the upper respiratory tract, such as Mannheimia haemolytica, pateurella multocida and histophilus somni, to colonisee, proliferate, and induce a secondary bacterial infection in the lower respiratory tract
Which other disease can be caused by Histophillus somni?
Thromboembolic meningoencephalitis
So, if you have a group of cows presenting with both respiratory and neurological signs, it could be histophilus somni
Which are the clinical signs of pneumonic pasteurellosis?
Depression
Anorexia
Tachypnoea
Hyperpnoea
Pyrexia
Nasal discharge
Mild or absent coughing
Mild or absent adventitious lung sounds
What is fog fever?
Fog fever is acute bovine pulmonary emphysema and oedema
What causes fog fever?
Fog fever is caused by the ingestion of L-tryptophan, which is a protein found in grass. When cattle are suddenly moved to grazing on lush pasture, they can consume large quantities of L-tryptophan which is rapidly metabolised in the rumen into 3-methylindole (3-MI), which is toxic to alveolar cells. When cattle ingest large quantities of lush grass, the body can become overwhelmed and unable to metabolise 3-methylindole (3-MI) and it can cause severe pulmonary damage and respiratory disease
What are the clinical signs of fog fever?
Mouth breathing (dyspnoea)
Couging
Frothing at the mouth
Seperated from the herd
Collapse
Sudden death
Note these patient’s WILL NOT be pyrexic
How do you treat fog fever?
Corticosteroids
Remember to consider if cow is pregnant as steroids can cause abortion
What is the prognosis for fog fever?
Many cattle with fog fever respond poorly to treatment
How do you prevent fog fever?
Gradually introduce lush pasture using strip grazing where the animals graze along a narrow strip of grass between two mobile fences which are gradually moved to give the cattle gradual access to more fresh grass
What is chronic suppurative pneumonia?
Chronic suppurative pneumonia is abscessation of the lungs
What causes chronic suppurative pnuemonia?
Chronic suppurative pneumonia has an unknown aetiology but it often the endpoint of bovine respiratory diseases in combination with secondary bacterial infection
What are the clinical signs of chronic suppurative pneumonia?
Weight loss
Repeated episodes of acute pneumonia
Epistaxis
How can chronic suppurative pneumonia cause epistaxis?
The abscesses that form with chronic suppurative pneumonia can grow large enough and erode nearby arteries, resulting in epistaxis
What is the prognosis for chronic suppurative pneumonia in cattle?
Cull
How do you treat bovine respiratory disease?
Antibiotics
NSAIDs
Vaccination (if there is a viral outbreak)
Corticosteroids if indicated
Clenbuterol if indicated
Fluid therapy if indicate
Which ten questions should you ask yourself when selecting an antimicrobial to treat calf bovine respiratory disease?
- Are the probably pathogens likely to be sensitive to the chosen antimicrobial
- Will the antimicrobial reach therapeutic concentrations in the infected tissue
- Is this antimicrobial available in a preparation licensed for use in this animal?
- Is the route licensed of administration appropriate for the animal and dose the dosing interval suit the current management situation?
- What is the minimim withdrawal period for thus antimicrobial?
- Are there any risks to human health with the use of this antimicrobial?
- Have you had any previous success when using this antimicrobial?
- Have the animals on this farm previously shown a good clinical response to this antimicrobial?
- How much does this antimicrobial cost?
- What is the likely cost-benefit of using this antimicrobial
How do you approach a calf bovine respiratory disease herd investigation (to improve herd health)?
- Farm history
- Analyse current and previous drug and vaccination use (including anthelmintics)
- Analyse colostrum management
- Assess housing
- Define disease pattern
- Summarise findings
- Suggest control measures
Which history questions should you ask when investigating calf bovine respiratory disease?
What is the farm’s current disease status?
How do you source you calves?
Are the calves treated/vaccinated on arrival?
Has there been previous disease outbreaks?
Are the calves housed or on grass?
How do you manage sick calves?
What is the routine calf management?
Which specific questions should you ask about routine calf management when investigating calf bovine respiratory disease?
What do you feed the calves?
How do you wean the calves?
When and how do you castrate the calves?
When and how to you dehorn the calves?
Do you carry out creep feeding?
What is you anthelmintics protocol for the calves?
Remember, if these management practices aren’t carried out correctly, they can be stressors for the calves, impairing their immune systems and predisposing them to infection
What is creep feeding?
Creep feeding is the provision of supplemental feed in addition to milk to nursing calves
Which specific questions should you ask about drug and vaccine use when investigating calf bovine respiratory disease?
Which drugs are being used?
Which vaccinations are being used?
What is the duration of treatments?
How are drugs and vaccinations being stored?
You can also analyse the practice management system to see which drugs have been supplied to the farmer
What are the two main vaccination protocols for bovine respiratory disease pathogens?
Intranasal vaccinations
Intramuscular vaccinations
What are the features of intranasal vaccination protocols?
Can be used in very young calves
Stimulate local immunity in the upper respiratory tract
Requires a single dose at a time (useful for treatment in the face of an outbreak)
Immunity lasts 9 - 12 weeks
What are the features of intramuscular vaccination protocols?
Requires two doses 4 to 6 weeks apart (so cannot be used for treatment in the face of an outbreak)
More effective in calves over 6 months old where materal derived antibodies will have waned
Immunity lasts approximately 6 months
Why is it so important to assess housing when investigating calf bovine respiratory disease?
It is important to assess housing as their is an increased prevalance of bovine respiratory disease in housed calves, so there is a strong association between the two
Which housing factors should you assess when investigating calf bovine respiratory disease?
Ventilation
Stocking density
Mixing of calf age groups
Availability of feed and water
Bedding type and dryness
What are the requirements for a good ventilation system?
To ensure good ventilation, it is essential to maintain a uniform airflow regardless of the external conditions. The design should allow heat to rise, carrying moisture, pathogens, and noxious gases upwards and out of the shed via the outlets, as heat naturally rises. Fresh air should then flow in through the inlets at the sides of the shed, allowing the calves to breathe in clean air
How does stocking density influence ventilation?
Stocking density is crucial as overstocking can lead to excessive heat, pathogens, moisture and noxious gases, while understocking may not generate enough heat to effectively expel pathogens, moisture and noxious gases via the outlets
Why are open doors ineffective air inlets for ventilation?
Open doors are ineffective air inlets for ventilation as they are neither controlled nor efficient and create draughts which will lower the body temperatures of the calves
What are some key indicators of a poor ventilation system?
Steam visibly rising
Wet bedding
How can you demonstrate to farmers that the ventilation system is poor?
You can use smoke bombs to visually demonstrate to farmers that the ventilation system is poor. The smoke should clear from the shed within 2 to 5 minutes, if it doesn’t this indicates poor ventilation
What is one of the main disadvantage of slatted floors in sheds?
While slatted floors help to keep bedding dry, they typically provide minimal insulation compared to solid floors with bedding. The gaps between the slats allow cold air to flow more easily beneath the animals which can result in heat loss from the calves
What are three of the main problems associated with calf housing?
Too much moisture
Too cold
Poorly ventilated
What is the lower critical temperature for calves less than one month old?
10°C
What can be done to help keep calves warm?
Improve housing
Provide extra bedding
Calf jackets
Improve nutrition
Increase milk feeding
Increase milk replacer concentrations
Feed warm milk
How do you define the disease pattern when investigating bovine respiratory disease?
- Examine the affected groups and establish prevalance and incidence
- Assess younger age groups to assess disease onset and risk factors
- Assess older age groups to assess the effectiveness of previous treatments
- Diagnostic testing to determine which pathogens are on the farm
- Determine the age and weight at sale, along with daily liveweight gains
- Analyse abattoir feedback on carcasses
Determining the age and weight at sale, along with daily liveweight gains can be useful to show the farmer how things are improving when you implement control measures
Which can be used to help define the disease pattern when investigating bovine respiratory disease?
Bovine respiratory disease composite scoring systems. This allows for standardisation of disease scoring across several groups of animals and can be used to monitor the effectiveness of interventions and changes in management practices
Which online tool can you use to generate farm risk assessment reports?
Rispaudit app by zoetis
It is downloaded on your phone
(T/F) There are vaccinations developed against all of the bovine respiratory disease pathogens
TRUE.
