Pink Eye Season – See Our Specials On Piliguard, QuickBait and QuickSpray
Pink Eye (Infectious Bovine Keratoconjunctivitis) is a highly infectious disease caused mainly the bacterium Moraxella bovis. After initial infection, the bacteria attaches to the surface of the eye where it produces toxins that erode the cornea causing ulceration, severe inflammation (uveitis) and pain. The economic cost of Pink Eye in Australia has been estimated at $23.5 million annually through loss of production, reduced weight gain, decreased fertility, increased culling and treatment costs etc. As Pink Eye causes significant pain in affected stock, it has important animal welfare implications as well.
Predisposing factors for the development of Pink Eye include flies, UV light, long grass or hay, dust, viral infections (IBR), reduced immune status and stress. The clinical signs of Pink Eye vary with the severity and progression of the disease:
Stage 1 – cattle have excessive tearing, blinking and squinting due to increased sensitivity to light and pain. As the disease progresses, a small ulcer will appear in the centre of the cornea which appears cloudy.
Stage 2 – The ulcer becomes large and deeper and the eye becomes increasingly cloudy. Blood vessels begin to grow across the cornea which make the eye look pink.
Stage 3 – The ulcer covers the entire surface of the eye and extends into the inner structures of the eye. This leads to severe inflammation which makes the eye appear yellow.
Stage 4 – The ulcer extends completely through the cornea resulting in the eye rupturing. The iris will plug the rupture and may protrude through the ulcer. At this stage the animal will not regain sight in this eye and the eyeball may collapse or end up being permanently swollen (glaucoma).
Prevention of pink eye revolves around controlling flies, reducing competition around hay and grain feeders, minimising yarding, optimising health and nutrition, vaccination and isolating affected animals from the rest of the mob to reduce spread if possible.
Fly control needs to be a multi-pronged approach utilising baits (Quickbait), surface sprays (Quickspray) and topical repellents. An effective fly control program needs to be started early in the fly season to prevent a build-up of larvae and pupae that will continue to hatch over summer.
Vaccination with Piliguard is an important part of the control of pink eye. Piliguard covers 3 of the 5 strains of Moraxella bovis present in Australia – so it is not 100 percent effective in preventing Pink Eye but surveys have shown that in about 70 % of outbreaks of Pink Eye, at least one of the three strains present in Piliguard is responsible. Piliguard needs to be administered 3 – 6 weeks before the start of the Pink Eye season as a single vaccination. Immunity will last for about 5 – 6 months. Calves as young as 2 weeks old can be vaccinated. Piliguard is an oil emulsion vaccine and accidental “self-inoculation” is serious – seek immediate medical advice if this occurs!
Occasionally, outbreaks of Pink Eye are caused by a different bacteria – Moraxella bovoculi. Unfortunately, Piliguard does not cover M. bovoculi and outbreaks can only effectively be controlled through general control measures and prompt identification and treatment of affected stock. M. bovoculi tends to cause severe Pink Eye that often affected both eyes in an animal. If you are experiencing a severe outbreak despite vaccination with Piliguard, it is important to get some eye swabs cultured to determine the exact cause of the outbreak.
Treatment of Pink Eye is often frustrating and time consuming. If small number of animals are affected, Orbenin Eye Ointment is the treatment of choice. It only needs to be applied every second day, reducing the stock handling needed. If a high percentage of a mob of cattle are affected, it is often more time and cost effective to treat the entire mob at once with an injectable antibiotic such as Bivatop. Metacam should be administered to any affected animals to control the pain and reduce the inflammation in the affected eye(s) and a patch applied to protect the eye from sunlight and reduce spread to other stock.
In severely affected animals (stage 3 and 4) or valuable individual animals, effective treatment and improved healing can be achieved with an injection of antibiotics and cortisone under the sclera (white part of the eye) and a third eye lid flap to protect the eye and promote healing.
For more information on Pink Eye control or treatment, contact the Livestock and Equine Centre on 5662 2251 extension 2 and talk to one of our cattle vets. Summer specials until the end of January are Piliguard 100 ml for $262, Quickbait 2 kg for $192 and Quickspray 1 kg for $211 (all including GST).