Scour in indoor cattle Flashcards
Infectious causes of d+ in cattle
- Salmonella
- Eimeria species
- Rotavirus
- Coronavirus
- Mycobaterium avium subspecies paratuberculosis
- Cryptosporidium parvum
- E. Coli
- Bovine viral diarrhoea virus
- Rinderpest
- Clostridium species
- Nematodes
- Yersinia
- Malignant Catarrhal Fever
- Secondary to septicaemia
Non-infectious cases of d+ in cattle
- Nutritional
- Poisonous substances
- Mycotoxins
- Acidosis
- Copper deficiency/toxicity
- Cobalt +/or selenium deficiency
- Secondary to Das, peritonitis
Differentials for Infectious Causes of D+ in pre-weaning calves
Within 14 days of age:
- Rotavirus
- E. Coli
- Coronavirus
- Cryptosporidium parvum
From a few weeks old:
- Eimeria species
Any age pre-weaning:
- Clostridium species
Differentials for Infectious Causes of D+ in post-weaning calves
- Eimeria species
Differentials for Infectious Causes of D+ in adults
- Winter Dysentery (coronavirus)
- MAP (Johne’s)
Differentials for Infectious Causes of D+ in any age
- Salmonella*
- Rinderpest*
- BVD
Clostridial species
- affects any age pre-weaning
Clostridium perfringens
- Types A, B, C or D
- Commensal of GI tract and soil
- Proliferates if sudden diet change
- no real tx -> animal likely to die anyway
C. perfringens CS
death +/- severe D+
C. perfringens pathology
- haemorrhagic to necrotising enteritis
- intestinal mucosal ulceration +/- perforation resulting in fibrinous peritonitis
- D+ in intestines
C. perfringens pathophysiology
- rapid bacteria overgrowth and enterotoxin release
C. perfringens diagnosis
- PM (pathology found as described in another slide)
Eimeria
= coccidiosis/coccidia
Who is susceptible?
- 3 weeks to 6 months
Shedding
- shedding can occur transiently throughout life in low numbers
Which species?
- Numerous species of Eimeria – not all are pathogenic
– Eimeria bovis
– Eimeria zuernii
– Eimeria alabamensis
The of oocysts is not indicative of disease, but species is.
Eimeria CS
- D+ and poor DLWG
- Infection location: cecum, colon and the terminal part of the ileum
- Mucosa = congested, oedematous and thickened with haemorrhages; later on sloughed away
Bloat 6-8w/o - high suspicion of cocci
Eimeria immunity
- yes
- depends on the quantity of oocysts picked up during the primary infection
- species specific
Eimeria predisposing factors
- High stocking densities
- poor hygiene
- mixed aged groups
- stress factors
- wet and warm weather
- mixing calf groups
Eimeria prevention
HYGIENE:
- Bedding management
- Stocking densities
- Group management etc
MEDICAL:
- Oral Drench: Diclazuril, Toltrazuril, Decoquinate in feed
Eimeria tx
- Supportive therapy
- Diclazuril: 1 mg diclazuril per kg bodyweight
- Toltrazuril: 15 mg toltrazuril/kg body weight
Eimeria diagnosis
McMasters test
Winter dysentery
- affects adults
- Same pathogen that causes D+ in calves and mild BRD in post-weaning calves
- Most cattle are seropositive
- Virus can cycle around cattle of all ages
Winter dysentery: Disease presentation
- Highly contagious – most of the herd
- Short-lived explosive D+
- Predominantly in the winter
- Cattle in close confinement
Winter disentery pathophysiology
- Faeco-oral transmission + suspected change in the rumen microbiome
- Colonisation of small intestine and colon
- Voluminous D+ from hypersecretion due to inflammatory response
- Destroy epithelial cells
Winter disentery tx
- most of the time is self-limiting
- try to avoid stress factors and sudden change in diet
- faecal samples sent to lab to ensure diagnosis is important
Salmonella
- affects all ages
- zoonotic
- reportable
- Multiple different species and serovars of Salmonella species
– Salmonella enterica subsp enterica serovars (serotypes) clinical importance in ruminants
– Dublin = host adapted
– Commonly isolated = Newport, Typhimurium, Mbandaka
Salmonella risk factors
Dairy cow
- state of immune system
- natural immunity
- vaccination
- gut health
Salmonella Bacterium
- amount of bacteria consumed
- virulence of serotype
Environment
- stressors (e.g. heat stress, transportation, pen moves, diet changes, calving, overcrowding)
- hygiene of feed and water
- nutrition
Salmonella pathophysiology
- Once ingested,Salmonellaattaches to mucosal cells and is capable of destroyingenterocytes
- Stimulate inflammatory response and ingested by macrophages and PMNs
- Rapid dissemination throughout the body including lymph tissue
- Bacteraemia
Salmonella CS
- Clinical signs associated with salmonellosis in adult ruminants include pyrexia
and diarrhoea. - The diarrheic faeces may vary from watery to mucoid and may
contain fibrin and blood - Due to the presence of significant concentrations of proteins, the diarrheic faeces have a putrid, foul odour
Diseases caused by salmonella:
- septicaemia
- enteritis
- abortion
Salmonella - diagnostic options
- Individual faecal culture using enrichment and selective media
- Composite faecal sampling
- PCR: faeces, milk, tracheal or bronchoalveolar lavage fluid
- Blood, trans tracheal wash, BAL, or joint fluid culture when (suspected bacteriemia)
- Culture or post-mortem sample: gastrointestinal tract, mesenteric lymph node, bile and lung
- Environmental culture: less useful, will be found on another option
- Immunoassorbent assay: serum or milk
Healthy rumen pH
- 5.6-6.5
Normal time spend ruminating per day
- 10-12h
Normal volume of saliva produced by cows a day
- > 70L
Normal ruminal contractions
- 3 in 2 minutes
Normal end product produced by the rumen that is energy
- VFAs
– propionate
– acetate
– butyrate
Normal no. of microorganisms per ml in the rumen
- 10^9 to 10^11 cfu/ml
SARA
= sub-acute ruminal acidosis
(- has its own page)
Mycotoxins
- Significance: Unknown
- Fusarium, Aspergillus and Penicilliumare in silage
- Deoxynivalenol and zearalenone were the most commonmycotoxins in UK
Mycotoxins CS
- loss of appetite
- reduced milk yield or poor weight gain
- feed refusal
- diarrhoea
- pyrexia
- pruritis
- bleeding
- ill thrift
Mycotoxins diagnosis
- difficult due to the lack of specific clinical signs and overlapping symptoms of other metabolic diseases, such as acidosis in cattle
- Not contagious, but usually a good portion of the herd is affected
- Conventional medicines have little effect in controlling the disease
- Outbreaks are often seasonal
- The problem is associated with a specific feed
- An analytical assay of the feed indicates the presence ofmycotoxins
Mycotoxins prevention
- Harvesting crops as early as possible in the season (especially forage maize) avoiding soil contamination
- Minimising top spoilage through the use of an oxygen barrier covering film
- Mycotoxin binder in TMR
