Neonatal septicaemia and meningitis in calves

Question 1

Meningitis

Answer 1

• inflammation of 1 or more of the 3 covering layers of the meninges (dura mater, arachnoid, and Pia mater) in the CNS

Question 2

Mortality for neonatal septicaemia & meningitis

Answer 2

• invariably high for both conditions

Question 3

Neonatal septicaemia/sepsis

Answer 3

• term used to describe new born calves with a systemic infection

Question 4

Age predisposition

Answer 4

• normally within the 1st few days of life but older calves of 2-3w may become septicaemic following compromise of intestinal mucosa attributed to enteric pathogen colonisation and infection or from chronically infective focus

Question 5

Public health considerations

Answer 5

• E.coli and other causal agents e.g. Salmonella are zoonotic

Question 6

Cost considerations

Answer 6

• intensive tx and hospitalisation of affected calves

Question 7

Special risks

Answer 7

• pts high compromised and so no further interventions should be undertaken until sepsis is resolved

Question 8

Aetiology

Answer 8

• neonatal calves are born reliant on ingestion of adequate volume of high quality colostrum
• inadequate colostrum supply serves as a major risk factor for the development of neonatal septicaemia and associated meningitis, this is particularly so for those calves born to heavily contaminated environments
• E.coli has been found primarily responsible for neonatal septicaemia in bovine
• Salmonella spp will also cause clinical dz

Question 9

Predisposing factors

Answer 9

• born into highly contaminated, unhygienic environment
• FPT
• omphalophlebitis (inflammation of the umbilicus/umbilical vein)
• septic arthritis

Question 10

Pathophysiology

Answer 10

• calves born to heavily contaminated environments are susceptible to dz
• entry of pathogenic bacteria can occur in utero, during calving or shortly after birth
• entry points including resp epithelium, oropharynx, nasopharynx, umbilicus and intestines via the faecal oral route
• in the 1st postnatal hours, non-specific pinocytosis allowing immunoglobulin entry may also allow bacterial entry to the systemic circulation and so this is a common route of infection
• older calves 2/3w can succumb to sepsis or meningitis from a chronic septic focus such as joint infection or omphalophlebitis

Question 11

Timeline

Answer 11

• clinical signs usually commence within 24h of pathogen entry
• duration of CS dependent on infective load, degree of passive transfer and time to instigate therapy
• return to clinical normality will normally be a number of days

Question 12

History

Answer 12

• sudden onset depression
• loss of suckle reflex
• lethargy
• recumbency
• increased neonatal calf morbidity and mortality

Question 13

Clinical signs

Answer 13

• depression
• loss of suckle reflex
• hypopyon & blindness
• pyrexia
• hyperesthesia
• scleral injection
• congested mm
• increased CRT
• cold extremities
• progression to collapse
• tonic clonic seizure activity
• coma
• death

Question 14

Diagnostic investigation

Answer 14

• CS consistent with dz
• presence of septic focus on CE e.g. septic arthritis or omphalophlebitis
• evidence of FPT

Question 15

Definitive diagnostic features

Answer 15

• septicaemia: blood or other body fluid culture, e.g. joint fluid
• meningitis: abnormal CSF, e.g. neutrophilic (often as high as 80%) and marked elevation in nucleated cells and protein content taken from LS space

Question 16

Gross autopsy findings

Answer 16

• congested membranes
• injected sclera
• pallor of carcass
• presence of omphalophlebitis or poly arthritis
• D+
  = intestinal haemorrhage

Question 17

Histopathology findings

Answer 17

• initially a neutrophilic with a left shift, early in the dz process
• in more advanced cases a leukopenia is most often present
• reduced platelet counts
• pathogens may be visible attached to intestinal brush borders

Question 18

Differential diagnosis

Answer 18

• neonatal calf acidosis
• irrecoverable CNS signs attributed to severe foetal hypoxia
• congenital CNS deficits e.g. cerebellar hypoplasia

Question 19

Tx

Answer 19

• broad spec (gram +ve and -ve) antibiotics: TMPS and amoxicillin, cephalosporins or fluoroquinolone used with caution
• IVFT
• NSAIDs or dexamethasone to reduce inflammatory response and reduced secondary effects of septic shock
• diazepam for seizure control
• different antimicrobials based on C&ST
• warmth & protection from elements
• oesophageal tubing for feeding
• plasma transfusion to be considered in valuable animals with FPT

Question 20

Prevention

Answer 20

• good hygiene in calving pens
• adequate colostrum intake and passive transfer
• good colostrum storage and hygiene
• vaccination of periparturient dams with inactivated E.coli K99 adhesion
• group eradication is difficult

Question 21

Why is septic meningitis common in very young calves?

Answer 21

• immature immune system
• incomplete BBB
• concurrent infections (e.g. omphalophlebitis) provide a nidus for infection are common

Question 22

Why is amoxicillin a good antibiotic choice?

Answer 22

• crossed BBB when inflamed
• licensed
• effective against e.coli
• broad spec

Question 23

Why is oxytetracycline not a good antibiotic choice?

Answer 23

• doesn’t cross BBB well, even when inflammation present

Question 24

Why is TMPS a good antibiotic choice?

Answer 24

• crosses BBB very well
• licenced
• can give IV (good for very sick calves)
• effective against e.coli