Occasionally, like humans, cattle can get hypersensitivity reactions. It appears that these are more common during the hotter, drier summer months rather than at other times of the year.

It is easily diagnosed, as the farmer can see the affected animal isolated from the herd, often lying down, with a swollen head and vulva. This will happen acutely.

The swelling is called oedema, which means that the space between the cells of the tissue have filled with fluid.

ADVERTISEMENT

The lips and eyelids are worst affected, causing inappetence and reduced vision – as the eyelids can be almost swollen shut.

Oedema is easily demonstrated by squeezing the tissue gently between your finger and thumb. You can make quite a significant depression and when you release the gentle pressure, the finger marks remain.

The swelling around the head can be of such an extent that it can reduce or squeeze the airway, interfering with breathing.

This condition often resembles brown nose or photosensitisation and while there may be some overlap in the causal agents, with these hypersensitivity reactions, the clinical signs usually have come and gone within 24 hours.

It is mostly seen in animals over 12 months of age. The causes of these reactions are wide and varied.

Sun, stress, heat and chemicals have all been associated with these reactions, but maybe during these conditions, biting insects are more active and also there is maybe unusual weeds flowering at this time of year.

When these weeds are ingested, they can cause a hypersensitive reaction.

Some of these animals will recover as quickly as they are affected and may never be noticed.

Others can be severely debilitated and will benefit from treatment that can reduce this oedema quickly.

The animals can be quite distressed, swishing their tail, shaking their head and ears; this is because the oedematous tissue is sore, inflamed and itchy.

Topical treatments to keep flies and insects off the whole herd are of benefit.

The individual affected animal can also benefit from fluids orally, as they may have not drank in the heat for a day or so and continue to froth and salivate from the swollen lips.

Sean Coffey works at Mulcair Vet Clinic, Newport, Co Tipperary. Mulcair Vet Clinic is part of XLVets. XLVets is a group of progressive practices working together to achieve a better future for agriculture and veterinary in Ireland. For further information, go to www.xlvets.ie.