Pathogen elimination through Partial Depopulation

Example – Mycoplasma hyopneumoniae

Science Assumptions re Mycoplasma hyopneumoniae
Mycoplasma pneumonia			Sows remain infected all their lives
			Mycoplasma hyopneumoniae colostrum antibodies remain for 14 day post-consumption
			M. hyopneumoniae can be killed with Tilmicosin, Tiamulin, Tulathromycin or Chlortetracycline
			M. hyopneumoniae survives in the environment for only a couple of days
			The absence of M. hyopneumoniae antibodies, PCR and/or IHC are effective diagnostic tools at 12 weeks of age
			Source of Mycoplasma hyopneumoniae negative pigs is available.
			Mycoplasma hyopneumoniae only spreads 3 km between farms
Preparation of the programme
	All animals older than 10 days of days and less than 10 months of age will be removed from the farm
	Farrow to finish farm – review protocols of partial depopulation with the inclusion of the need to care for piglets from 10 days of age.
	Review the pig flow programme to ensure that sufficient young sows will be available to compensate for the shortfall of gilts that will occur for a 3 month period.
	Cull all sows/boars where necessary to reduce the herd size if appropriate – with considerations for maintaining pig flow.
	Cull all unhealthy sows and boars.
	The eradication should be programmed for the summer months which will aid environmental removal of the mycoplasma.
	As buildings become empty ensure that a full cleaning, repair and refurbishment programme is instigated.
8 weeks pre-start programme
		Vaccinate the sows and boars with Mycoplasma hyopneumoniae. It is essential to ensure that all piglets get colostrum and are not shedding Mycoplasma hyopneumoniae while in the farrowing house. The success of the programme relies on colostrum antibodies and the key to this is vaccination. Ensure vaccines are stored properly and administered using a 1.5 inch 16 gauge needle.
		Provide the sows and boars with feedback – using nursery faeces and diarrhoea from the farrowing house. It is essential to have all the adults immune to Mycoplasma hyopneumoniae.
4 weeks pre-start of the programme
		Repeat the vaccine and feedback programme

Start of the 6 week eradication programme
	Ensure that all sows and boars will be provided with 3 kg a day of medicated feed. Boars may require more to ensure adequate medication for their weight or use in combination with injection.
	Boar alternative medication is via injection – consider using Tulathromycin (2.5 mg/kg) injection once every 7 days. Weigh boars as necessary.
	Provide in-feed medication of Tilmicosin 400g/tonne and Chlortetracycline 800g/tonne to the sows. This will be provided for a period of 6 weeks. Tilmicosin may be very bitter – provide Talin in the feed to assist palatability of feed.
	In the farrowing house provide 3 kg of medicated feed in the morning feed with unmediated feed in the evening feed.
	Any sick or inappetant sow (in oestrus for example) injection with Tulathromycin (2.5 mg/kg). If a sow is sick for 3 days euthanase. It is essential that Mycoplasma hyopneumoniae be not allowed to remain in weakened adults.
Management of piglets in the farrowing house to assist survival of 10 day weaned piglets
Day of life
1		Iron		200 mg injection by a 21G 5/8" needle intramuscularly into the neck
		Colostrum		All piglets must receive colostrum from sows. If there is any suspicion that a piglet failed to get adequate colostrum euthanase.
2		Ceftiofur		5 mg/kg by a 21G 5/8" needle intramuscularly into the neck
		Enrofloxacin or Tulathromycin		Oral medicator – 10mg (not legal in Australia) Tulathromycin is by injection – note small dose 2.5mg/kg
4		Toltrazuril		7mg/kg oral dose – to control coccidiosis
5		Ceftiofur		5 mg/kg by a 21G 5/8" needle intramuscularly into the neck
9		Tulathromycin		2.5 mg/kg by a 21G 5/8" needle intramuscularly into the neck
10		Weaned move to the off-site nursery - note biosecurity of truck and site
Management of the early weaned sow
			Place the early weaned sow onto Regumate a day before weaning. Maintain Regumate until normal expected weaning day. This is essential to maintain pig flow. It is possible to provide Regumate via toasted bread.
Confirming eradication of Mycoplasma hyopneumoniae
Deaths			All deaths should be post-mortemed
Coughing			Investigate all cases of coughing and sneezing. Note Post-weaning sneezing may occur
12 weeks of age			The pigs should be tested to ensure that they are negative. Ensure that the testing does not detect maternal colostrum antibodies.
Sentinel			Place known negative gilts into contact with grow/finish pigs and blood test after one month. Note any coughing experienced by these gilts.
Time			The farm should be examined serially over a period of at least one year. Utilising clinical examination, blood serology and slaughterhouse tests. Immunohistochemisty of any suspect lesions