8th October 2019

It is that time of year again and with the continued dry conditions the coming Spring & Summer period is shaping up as a repeat of last year in regards to the prevalence of Pink-Eye in cattle herds across the region. Dusty conditions, supplementary feeding, early weaning and high fly burdens are all factors which may exacerbate the situation.

In the subsequent 12 months we have spoken to many producers who went through large outbreaks of pink-eye last year and the following is a summary as to how best to try and manage the disease this year.

Management Strategies – Prevention is better than cure!!

Management strategies to try and minimise the incidence of the pink-eye are key. Whilst it is an endemic disease and you will likely always have a few cases regardless of what you do, treating 10 cases is better than treating 100!

1. Environmental – MINIMISE DUST!!!

• Spend the time to water down yards prior to getting susceptible stock in (especially when it is to treat existing cases) and if young stock are being lot fed post weaning try and set up some sprinklers in the pen which can be moved around to minimise the amount of dust as much as possible.
• If possible keep paddocks with the most amount of ground cover (if there is any at all) for weaners to help keep the dust to a minimum.
• If feed troughs are mobile move them periodically to harder ground
• Feed hay on the ground/in bunkers rather than overhead racks which will minimise the number of grass seeds/etc getting into eyes (a common precursor to pink-eye). Will also improve respiratory disease as eating from ground facilitates mucosal clearing.

2. Vector Control – Flies are responsible for spread of the bacteria

• Backline fly & lice products can help to reduce fly irritation for up to 6 weeks (consider applying to all weaners every 4-6 weeks)
• Products can also be carefully applied around the eyes with a paintbrush for more localised affect
• Fly traps can be useful in feed-lot situation

3. Vaccination – Piliguard®

• The major causative agent of pink-eye is the bacteria Moraxella bovis. There are many different strains of the bacteria which can cause the disease and several strains may be present at the same time. Other bacteria such Chlamydia spp can also cause pink-eye.
• The Piliguard® vaccine is developed for 3 of those strains, and whilst it may confer some cross-strain protection, it will not prevent all cases due to other strains and bacteria
• The vaccine is a single shot, ideally given at marking if carried out prior to early weaning
• Responses to the vaccine across the area have been widely varied, likely due to the presence of differing strains. It is possible to culture the causative bacteria and type the strains to see if vaccination may be suitable for you – something that may provide useful information in future years.

4. Injectable Vitamin ADE supplementation

• Vitamins A and E are both gained from greed feed and stored in the liver with approx. 4-6 months of reserve. If stock have not had access to green feed for >3-4 months, supplementation with injectable Vitamin ADE or feed additives are recommended. Serum testing can be done to assess the vitamin A and E status of stock.

Treatment Options – Early intervention is key!!

No matter what treatment you opt to use, the most important factor regarding outcome is time of treatment – the earlier the treatment, the less permanent damage that will be done. In most cases where producers report a treatment failure, the real issue is the large degree of damage done prior to treatment being initiated.

Treatment of pink-eye consists of antibiotic therapy (to kill the bacteria) and ideally anti-inflammatory therapy (to improve healing of the eye) as well as eye patches (protection from sunlight/further dust/etc).

1. Antibiotics

• Topical ointments (Orbenin/Ampiclox/etc)
  • Typically the easiest method to apply to large numbers and generally good have a good response to treatment
  • Recommend use of Orbenin Eye Ointment and it is specifically designed for use in the eye and is less irritating than ointment made for mastitis treatment
  • Recommend 2 doses 48 hours apart (eye patch can be glued along 2 sides of the patch at first treatment then fully glued on at second treatment
• Sub conjunctival injections (typically penicillin +/- cortisone)
  • More difficult to administer and requires more experience and better facilities (often a halter)
  • Longer lasting effect that ointments and single dose usually enough
• Intramuscular injections (Alamycin/Engemycin/Etc)
  • More expensive and more time consuming to administer to large numbers
  • May not get required doses concentrated in affected area
• Powders and sprays (Alamycin spray/Terramycin powder)
  • Whilst these options may work against the bacteria we do not recommend their use due to the irritation that they cause to the eye – often slowing down healing and attracting more flies to the area in the process

2. Anti-inflammatories

• Injectable (Metacam)
  • Subcutaneous (Metacam) or intramuscular (Tolfedine/Key) injections which help reduce the inflammatory process in the eye and speed the healing process as well as helping to reduce long term scarring
  • Also help reduce the associated suffering/weight loss of affected animals
  • Recommended in any severely affected animals
• Sub conjunctival injections (cortisone, usually injected with penicillin)
  • Delivers a more potent anti-inflammatory action to the site of action which can further reduce scarring long term.
  • Difficult to apply and the treatment is controversial as cortisone can inhibit the healing of corneal tissue in some cases. As such is becoming less used as an option.
  • Maybe suitable for high value animals with severe infections to improve long term outcomes

3. Eye Patches

• Protect affected eyes from sunlight and dust which exacerbates pain
• Stops flies from accessing infected eyes and spreading the bacteria to other cattle
• Ideally applied to all affected animals
• Old jeans/clothes work just as well as more expensive specially made patches
• To ensure maximum adhesiveness, make sure glue is warmed up before use

Our standard recommendation for a treatment protocol would be using Orbenin Eye Ointment as a first line option with 2 doses administered 48 hours apart and an eye patch applied as described above in addition to an injection of Metacam for severe or bilateral cases.

If you feel that results are not as you would expect then a change of approach to sub conjunctival injections of long acting penicillin +/- Dexason would be warranted.

If you have any queries or are interested in doing some testing to identify the causative agent of pink-eye on your property please do not hesitate to call us at the clinic on (02) 6377 1258.