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Vet on call: Unveiling the wolf in your sheep’s wool

Saturday August 24 2019

Joseph Kiptarus sheers sheep at the Chemosong Young Farmers Cooperative Society in Elgeiyo Marakwet.

Joseph Kiptarus sheers sheep at the Chemosong Young Farmers Cooperative Society in Elgeiyo Marakwet. Wool sheep should be sheered regularly and washed with suitable acaricide to control ticks, keds and mites. FILE PHOTO | NMG 

DR JOSEPH MUGACHIA
By DR JOSEPH MUGACHIA
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In April, Joan bought two sheep that she introduced into her herd of 30 of mixed breeds, a majority of which are of the Dorper variety.

Some people call the sheep the Blackhead, but for clarification, there is a breed called the Blackhead Persian sheep, believed to have originated from Somalia.

Dorper, on the other hand, is a breed that was developed in South Africa from The Blackhead Persian and the Dorset Horn sheep breeds. The name Dorper was coined from two words, ‘Dorset’ and ‘Persian’.

The Dorper has a characteristic charcoal-black head and a snow-white body. It also has a sturdy muscular rectangular body block and an elegant fast-paced gait when running or walking. A herd of pure Dorpers in top body form is a marvel to watch for the livestock lovers, a proud scientific presentation for sheep breeders and a mouth-watering fantasy for the meat eaters.

Dorpers breed well with other sheep and always retain the black head in the offsprings, with hair very close to the skin.

This is the trademark of the breed. Scientifically, it means that the black head is a dominant genetic trait of the Blackhead Persian Sheep and hence the Dorper. Other parts of the body in a Dorper cross have the expressions of various traits of the other sheep breed or breeds involved.

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The Dorper also does well under zero-grazing conditions. It has a lot of soft juicy meat on its frame. Customers of roast meat joints in Kenya love the Dorper and call it “Domba or Doba”.

Joan called some two months ago to inform me that the two new sheep appeared to be sheering themselves. They were crosses of Dorper and Merino breeds.

The head was typical Dorper but the body was covered with a mixture of fairly long Merino wool around the neck, along the backline and the sides while the underside had short Dorper hair.

She said the wool on the animals was detaching from the skin starting from the boundaries of the Merino wool fibres and the Dorper hairs. “Doctor, the sheep look like they are taking off their wool coat,” she concluded.

LOW BLOOD LEVELS

The site of Joan’s sheep was quite interesting. They actually appeared to be undressing. The wool was dishevelled and tainted brown in some areas.

Occasionally, the sheep would bite the wool and scratch against the pen wall. My two interns that I visited the farm with made jokes of the situation wondering how the sheep appeared undressing.

I told them the farmer was right to be mesmerised by the situation but what she needed from us was a diagnosis, treatment and prevention solution for the condition. The interns quickly examined the sheep after taking thorough history from Joan.

Joyce, one of the interns, after checking the sheep announced that they were emaciated and had low blood levels. She also said there were lots of sheep keds in the wool and mite infestation.

The interns advised the correct treatment of ivermectin injection, acaricide wash, vitamin and iron injection. The two sheep would be fully sheered before being washed to ensure good penetration of the acaricide onto the skin.

They also told the farmer she would need to increase the daily intake of feed and mineral salt for the sheep to help them recover the lost blood and weight.

All the other sheep would also be washed with acaricide once or twice per month as a parasite control routine for the whole of their lives on the farm.

Joan was further advised to always keep new animals segregated from the residents for at least two weeks for observation and treatment of any diseases they may have.

The activity is called quarantine. It protects the resident animals from being infected with diseases that new stock may be carrying. During quarantine, animals should be dewormed, washed with acaricide and also given appropriate identification if they do not have.

They executed the treatment and gave the farmer an acaricide that would kill the whole range of external parasites on the sheep’s skin including ticks, flies and mites.

THEY GET IRRITATED

I visited the farm with the interns one month later and found the sheep had recovered fully. Sheep ked is a flightless insect parasite that infests the skin of sheep and hides in the wool.

It has strong biting jaws which it uses to pierce the skin and suck blood. It has a brown or red body with sturdy long claws to provide good grip on the skin. In Joan’s case, the sheep must have come with the parasites because none of the others had them.

If the ked infestation is heavy and prolonged, the sheep loses a lot of blood, they get irritated from the bite wounds and keep biting the wool and scratching against objects.

The combined infestation of mites and keds causes breakage of wool fibres close to the skin. The broken fibres lift off the skin.

The detached wool fibres cannot fall off since they are entangled with the unbroken wool and therefore create the undressing spectacle if the area affected is large enough.

Ked droppings contain fully and partly digested blood. It stains the wool brown and red making it look dirty. In some cases, the bites and scratching may create skin wounds and cause bacterial infection.

Sheep heavily infested with keds become unthrifty, lose weight and may die of long-standing blood loss anaemia. Such sheep will have pale mucous membranes and a wasted body.

The keds tend to feed on the neck, breast, shoulders, flanks and rump. They avoid the back because of the dust that accumulates on the wool.

Wool sheep should be sheered regularly and washed with suitable acaricide to control ticks, keds and mites.