Dopey Daisy Test Flashcards
Calf mortality rates by age
Perinatal (<48h) = 5-10%
Pre-weaning = 5-10%
Post weaning = 1-2%
6 species causing diarrhoea
- Rotavirus
- E coli (Enterotoxigenic and EPEC)
- Coronavirus
- Cryptosporidium
- Salmonella (mostly dublin)
- Coccidia (eimeria spp)
Common agents causing diarrhoea in early days
Rotavirus
E. Coli (k99 enterotoxigenic)
Crypto starts slightly later
Others bubble away in the background thorughout
ETEC age affecting, incubation period
1-3d of age
Incubation 12-24 hours
ETEC pathophysiology
Produces k99 adhesion antigen and heat stable enterotoxin
Colonisation in lower GIT causing disruption to K+, HCO3- and Cl- ion secretion (low bicarb and chloride ions)
ETEC diarrhoea type
Secretory diarrhoea - watery
Absorption also impaired
It colonises the lower GIT - impact Cl- and bicarb
EPEC age
about 12 days old
EPEC pathophysiology - where does it colonise?
Adhere to enterocytes and efface microvilli
No cytotoxins
Colonisation causes villous atrophy and Cl- ion is disrupted
Typically in caecum, colon and distal SI
May get haemorrhage with this type
EPEC type of diarrhoea
Malabsorption and secretory diarrhoea
Can get haemorrhagic
Rotavirus age, incubation period and clinical period
3-14d old
12-24h incubation
5-7d clinical period
Rotavirus pathophysiology and type of diarrhoea
Replicates in enterocytes, destroys cells, villous atrophy
Disrupts brush border that contains lactase = maldigestion
Malabsorptive diarrhoea
Coronavirus age, incubation period and clinical period
4-14d old
12-24h incubation
5-10d clinical period
Coronavirus pathophys and what it causes in young and adult animals
Destroys cells of small AND large intestine
Replicates in enterocytes and causes villous atrophy and damages crypts
Respiratory disease in 2-6month old calves and winter dysentery haemorragic diarrhoea in adults
Coronavirus diarrhoea type
Malabsorptive (damages crypts and causes villous atrophy)
Cryptosporidium age and route of transmission, clinical period
5-18d
Faeco oral
2-3d clinical period
Cryptosporidium pathophysiology
colonosises SI, Destroys enterocytes, villous atrophy
sheds 40 billion oocysts over 6-9d
Oocysts survive for a month in envrionment
ZOONOSIS
5-18d, malabsorptive
Crypto diarrhoea type
Malabsorptive
Salmonella types
Salmonella enterica serovar typhimurium
Salmonella enterica serovar Dublin (main one)
Salmonella age, route
10d-3 months but can be any age
Faeco oral
Salmonella diarrhoea
Haemorrhagic and malabsorptive diarrhoea
Can also be asymptomatic or watery mucoid
Salmonella pathophysiology
Invades intestinal mucosa and lymphoid tissue leading to systemic spread
Coccidia age, route, incubation period, clinical period
3w-6m age
Faeco-oral
Incubation 5-20d
Clinical period 5-14d (can also be subclinical)
Coccidia (eimeria spp) pathophysiology
Always associated with poor hygiene and contaminated water
E.bovis and E.zuernii schizonts reproduce in lower SI
Second gen shizonts and gamonts then produced in caecum and colon
Attack crypt cells, local and extensive lesions
What can coccidia cause?
Tenesmus and haematochezia
Decreased growth rates in subclinical disesase
Clinical disease can be chronic or acute
3 environmental stressors
Poor housing
Poor hygiene
Mixed age groups -> stick to batching to avoid this transfer from older animals to younger ones
Describe secretory diarrhoea
Enterotoxins -> cAMP in cells -> open Cl gates and secrete H2O from crypts
Cant use Na-H exchanger to absorb Na+
Lose Cl- and HCO3
Describe malabsorptive diarrhoea
Loss of epithelium and absorptive area, villous atrophy, crypt damage
Absorption of NA and H2O can still occur if coupled with glucose or amino acids
NaCl pumps and Na-H exchanger dont work = lose water
Clinical signs of dehydration + hypovolaemia
Increased HR, CRT, PCV, creatinine, blood L-lactate, skin tent
Hyperkalaemia, hyponatraemia
Hypoglycaemia
decreased urine output, cold extremities
Causes of metabolic acidosis in calves with diarrhoea
Loss of bicarbonate
Accumulation of organic acids - D-lactic acid (bacterial fermentation of ingested milk) and L-lactic acid
D-lactic acid is absorbed from rumen or intestine and can accumulate, slowly metabolised and excereted (bacteria can stop the metabolism of it into safe compounds and add to build up)
How can we assess dehydration?
Enophthalmos
Skin elasticity on neck
Plasma protein concentration
Signs of 5-7% dehydration
Mild depressed, slightly high CRT, slight high HR, increased blood lactate, concentrated urine
Signs of 10% dehydration
Depression, cold extremeties, dry MMs, CRT>3s, heart rate >50% above normal, increased lactate, small volume of very concentrated urine
Signs of 12-15% dehydration
Depression, cold extrems, dry MM, CRT >4s, HR >100% above reference, increased lactate, creatinine and unlikely to produce urine
What causes loss of suck reflex?
Dehydration and metabolic acidosis
What causes reduced palpebral reflex?
D-lactic acidosis
What causes weakness?
D-lactic acidosis
Hyperkalaemia affecting cardiac output
Recognition of sepsis (any two of)
- Core temp abnormal
- Heart rate abnormal
- Tachypnoea
- Leucocyte count abnormal
3 signs of disseminated intravascular coagulation
Infarctions
Ischaemia
Haemorrhage
When is neonatal sepsis and what are common causes?
2-6d (less than 2 weeks old)
Infected umbilicus, septic arthritis, GIT abnormality, pneumonia
Clinical signs of neonatal sepsis
Lack of suck reflex
Fever, hypothermia
Tachypnoea, tachycardia
Hyperaemia of MMs
Diarrhoea
Poor cardiac output
Signs of neonatal bacterial suppurative meningitis
As a complication of bacterial sepsis:
Loss of suck, fever
Extension of neck, tonic and thrashing
Hyperaesthesia
Opisthotonus (abnormal posture due to spasmic contraction)
Comatose
Seizures
Lab tests for diarrhoea
Haematology
Biochemistry
Blood gas analysis
Faecal sample
Goals of treatment
- Correct dehydration and hypovolaemia
- Correct electrolytes and acid base balance
- provide nutritional support
- Eliminate bacteraemia and toxaemia
When are oral fluids warranted and how much is given?
<8% dehydration with suck reflex and at least sternal recumbancy
5% body weight per feed
When are IV fluids warranted?
> 8% dehydrated
Severely obtunded
No suck reflex
Anorexia >24h
Hypothermia <37.5
Why is it bad to alkalise the abomasum in neonates?
Defence mechanism to colonisation of pathogens is pH of the stomach
It is not acidified in the first few hours of life though to facilitate immunoglobulin absorption -> ETEC colonisation can occur easily
What fluids provide rehydration and alkalinsation?
Isotonic sodium bicarbonate - no commercial available solution
What is lactated ringers not recomended for?
Animals with acidaemia
What % is isotonic fluids?
0.9
slightly acidifying
What % is hypertonic saline? What rate is it given?
7.2%
5ml/kg in 5 mins
Oral fluids must be provided and diarrhoetic calves need alkalinising agents as well
Hypertonic sodium bicarbonate (8.4%) use and administration rate, when should it not be used
rapid alkalinisation
No faster than 1ml/kg/min
Can be used with oral fluids or as bolus prior to spiking isotonic solution
Do not use in calves with respiratory distress
What is the focus for younger vs older calves?
Younger = fluids
Older = more severe D-lactic acidosis so need NaHCO3
Bicarbonate requirement
BW(kg) x BE x 0.6
1ml of 8.4% NaHCO3 = 1 mmol of NaHCO3
Can D-lactic acidosis be present without diarrhoea?
yes
and thus without dehydration
Floppy kid syndrome or drunken lamb disease
What can we do as well as oral rehydration therapy?
Give milk -> improved intestinal morphology compared to ORT alone
More energy dense than ORT solutions and contains growth factors for repair
When are oral antimicrobials contra-indicated?
Viruses
Protozoa - crypto, coccidia
ETEC
When to use antimicrobials
severe systemic illnes
What antimicrobials to use
Ampicillin, amoxicillin, cephalosporins (ceftiofur)
Coccidiosis -> suphadimidine
NSAIDs for use
Meloxicam, ketoprofen, flunixin meglumine
decreased pain + GI inflammation, improved suckling and behaviour
What can be used for cryptosporidium?
Halofuginone
Fluid deficit calculation
BW x % dehydrated as decimal (eg 0.08 for 8%) = Litres
Maintenance fluid levels
50-100ml/kg/d
40kg calf = 40x70 = 2800ml = 2.8L/d
Diarrhoea fluid loss per day
1-4L (go with 4)
How to get fluid requirements for diarrhoea calf
Maintenance per day + fluid deficit + diarrhoea losses
How to determine base deficit
Calf less than 8 days -> Standing with suck (0), standing with no suck (5), sternal or lateral (10)
More than 8 days -> standing with suck (5) standing with no suck (10), sternal (15), lateral recumbency (20)
How much fluid is safe to give per hour?
up to 2L
What electrolyte deficiency occurs in calves with diarrhoea?
Hyperkalaemia -> due to switching with H+ ions in acidosis and also lost in diarrhoea
cardiac arrest potentially
What causes l-lactate buildup?
Hypovolaemia with diarrhoea -> tissue not perfused properly, cells go into shock and anaerobic respiration
What antiobiotic is not appropriate for young calves?
Oxytetracycline -> doesnt cross gut well, can cause teeth issues,
Good for older cows and their resp issues
High Vd
Aetiology of Bovine syncytial virus
RNA virus
3-5d incubation
Aerosol
>6month olds mostly
Pneumonia
Bovine herpesvirus 1 aetiology and lesion location
Secondary bacterial pneumonia life threatening
Enveloped DNA virus, aersol
Many manifestations (abortion, pneumonia, mastitis)
Lesions of MMs of upper resp tract
Parainfluenza 3 aetiology
RNA
Mild-subclinical infections, maybe secondary pneumonia
Cranioventral lung consolidation
BVDV aetiology
RNA
Immunosuppressive
Mucosal disease (cytopathic) fatal -> oral and nasal lesions
Non-cytopathic -> PI calves no cellular damage
BVDV diagnosis
AGID test
ELISA of blood
M. Haemolytica aetiology
Gram negative aerobe
Commensal of nasopharynx - opportunistic
Endo and exotoxins that kill leucocytes
Septicaemia before bronchopneumonia, necrosis and thrombosis
Pasteurella multocida aetiology
Gram negative
Commensal of nasopharynx
capsule - resistant to phagocytosis
BAL, TTW, culture, serology (Same as m. haemolytica)
NaCl fluid rate
80ml/kg/h or up to 2L per hour
List four organisms responsible for infectious pneumonia in calves up to one month of age. (Ensure they are spelt correctly, clearly, and written in scientific format.) (2 marks)
- Mannheimia haemolytica
- Pasturella Multocida
- Histophilus somni
- Mycoplasma bovis
For any one infectious pneumonia organism listed, briefly evaluate the epidemiology and aetiopathogensis of the disease it causes. (3 marks)
Mannhemia haemolytica is a gram negative aerobe that is a commensal of the nasopharynx. It produces endotoxin and exotoxin which kills leucocytes. It normally develops secondarily to infection with a respiratory virus (such as BRSV), as the cilia are no longer able to remove bacteria from the LRT, so it can opportunistically colonise.
Fibrinous pneumonia, bronchopneumonia and pleuritis.
List four organisms that may be responsible for infectious diarrhoea in neonatal calves up to 14 days of age. (Ensure they are spelt correctly, clearly, and written in scientific format.) (2 marks)
Rotavirus
Coronavirus
Escherichia coli
Salmonella enterica serovar Dublin
For any one of the listed organisms, briefly describe the aetiopathogensis of the resulting diarrhoea. (3 marks)
Enterotoxigenic escherichia coli -> affects calves of 1-3d of age. Contains the k99 adhesion antigen allowing colonisation in the lower GIT causing secretory diarrhoea and heat stable enterotoxin. The toxin increases cAMP which opens chloride gates and results in secretion of water, as well as bicarb losses and prevents Na-H exchanger from functioning. K+ is also disrupted.
It also causes some malabsoritcve diarrhoea due to brush border being disupted from inflammation.
Impaired immunity through FPT is often the cause, as well as the abomasum being alkaline in the first few days of life.
Incubation 12-24h
What is colostrum, as defined by the properties it has according to animal and veterinary scientists? (1 mark)
Colostrum is a special milk produced following parturition by the dam which contains IgG, IgM and IgA to confer some maternal immunity to the calf, as well as white blood cells, antimicrobial factors, nutrients, and growth factors.
It must contain at least 50 g/L IgG, and be 21% total solids.
Colostrum requirements makeup
50 g/L IgG
21% total solids
What is the importance of colostrum to the bovine neonate, and why is this the case? Succinctly, how and why should a calf obtain colostrum?
Due to the placentation of the bovine, there is no transfer of immune factors from the mother to the calf during pregnancy.
Therefore, all immunity is conferred during the first 12 hours of life through consumption of colostrum.
A calf should have a total protein ≥55 mg/mL for adequate passive transfer.
10% to 12% of their body weight (BW) of colostrum at first feeding
Colostrum amount needed
10% to 12% of their body weight (BW) of colostrum at first feeding
Regarding (Bovine Virus Diarrhoea Virus) BVDV/Pestivirus, what is a ‘persistently infected’ or PI animal? Briefly explain how a PI animal arises, and its significance regarding the transmission of disease within a population of cattle. (5 marks)
A PI animal is an antibody negative, antigen positive beast. This occurs during pregnancy, if the dam is infected between 40 – 120 days. BVDV infects the calf, however, it is not able to mount an immune response and therefore is not immunocompetent.
A PI sheds 1000x as much viral particle/mL of excretion than an acutely infected animal for life, and is the main source of infection of a herd of cattle.
PI calves contain the non-cytopathic version of BVDV that can seroconvert to cytopathic
Briefly list and explain the use of two laboratory tests for BVDV in NSW. (4 marks)
In NSW - Agar gel immunodiffusion (tested on serum), which only detects antibody that is not from vaccination. It confers some temporal knowledge, 1 – 2 infection in the past 12 months, 3 = infection in the last 3 – 9 months. It cannot be used to identify a PI.
PCR is used on serum and bulk tank milk and can be used to identify a PI.
IgG requirements for calf
100g in first 6 hours
100g in next 12 hours after that
Should have 10mg/ml in serum IgG if successful
