blind cow

Mr James Gichohi, a dairy farmer in Kabaa village in Nyandarua West, with one of his blind cows. 

| Steve Njuguna | Nation Media Group

Why some cattle go blind and all the possible remedies

 On Monday this week, the Daily Nation reported that cattle in Nyandarua and Laikipia were mysteriously losing sight. A picture of one of the cows showed the vagaries of blindness in cattle.

The animal was obviously blind with a bluish-white spot in the right eye where the iris and pupil should have been visible. The iris is a circular muscle that works like a camera shutter and regulates the size of the pupil. The pupil is the hole that admits light into the eye depending on the environmental light intensity to facilitate vision and prevent damage to the eye.

The animal was also very thin and the owner complained its milk production was very low. In addition, it tended to pull itself together like though it was minimising its body size. That was a show of fear of the unknown because the animal can only feel, hear and smell environmental threats. Therefore, its posture and movements are always extremely guarded.

The situation interferes with the animal’s ability to eat and make choices of nutritious herbage. That in turn leads to lowered production, including weight loss. Such animals should be kept in zero-grazing, fed well and be separated from animals with normal eyesight. They tend to be harassed by the normal animals causing them a lot of stress. They should be fattened and sold for meat.

Lose sight

I analysed the farmers’ history of their animals’ blindness and the inconclusive solutions proposed by various animal health service providers. The conclusion was that they were waiting for an investigation by the local agricultural officers, who needed facilitation to reach them. Meanwhile, the animals continued to lose sight and the farmers were not even reporting the disease any more.

Farmers in these two counties and their valuable animals need not suffer any longer. From the descriptions given by the farmers and the service providers, the problem is pink eye disease or infectious bovine keratoconjunctivitis (IBK) or New Forest Disease. It is caused by highly infectious bacteria called Moraxella bovis.

I have successfully dealt with this problem in many parts of the country by remote consulting. I have also physically seen numerous cases in the course of my practice. The animals start by shedding thin tears around the eyelids. They tend to close the eyes to shield them from solar irritation. The eye starts reddening from the margins of the eyeball and gets engorged with numerous blood vessels running to the central area of the pupil and iris.

As more blood is taken to the eye, there are more nutrients to help the bacteria to thrive. More tears are produced and they run down the edge of the eye closest to the nose and drain out onto the skin surface before dropping down or drying off.

This attracts more flies that transmit the bacteria and the disease intensifies.

The discharge turns into pus, tends to glue the eyelids together and the animal initially gets functional blindness and lots of pain. Animals at that stage look miserable. As the disease progresses, it destroys the architecture of the eye particularly at the position of the iris and pupil.

Some animals may heal without treatment and become immune to the infection naturally. Such animals lose their eyesight because the disease leaves a scar tissue deeply sitting over the iris. It is the white spot that was seen in the Nyandarua and Laikipia blind cattle.

Antibiotics

The cows get permanently blind because the scar tissue does not allow the iris and pupil to function. It also does not allow light to pass through into the eye.

Some animals may die if untreated especially when the original infection is complicated with bacteria that get into the eye and the brain. In addition to flies, dust also transmits the disease.

Treatment of IBK requires good choice of antibiotics and a proper administration regime. Topical antibiotic applications are more recommended than intramuscular injections because a high concentration of the antibiotic is required in the eye and the tears.

From the history given in the story, animal health service providers did not appear to have diligently followed structured treatment regimes.

The farmers should also report the disease early at the first-tears stage. It becomes more difficult to restore eyesight when treatment begins at the advanced stage, especially if the scar tissue has already started forming.

East Coast Fever blindness is different from that of IBK. It is caused by aggregation of lymphocyte cells in the eye. The cells disappear over time once the invading parasites are cleared from the body.

The animal also gets generally very sickly and shows many other signs of the disease including swollen external lymph nodes, high fever and frothing from the mouth.

Farmers should control flies on their animals and sheds to prevent IBK. They should also ensure their animal environments are free of excessive dust.