Vet on Call: When cancer strikes cattle

As we all know, white is a beautiful colour. It is loved by majority of people and associated with good tidings. White is a colour of purity the mantra “white like snow” illustrating this.

In my experience in Kenya, many dairy farmers cherish white animals. The cows are uncommon but are usually high milk yielders.

White cows are usually seen in the Friesian and Ayrshire breeds or crosses of the two. In most cases, the cattle are predominantly white with some patches or patterns of the breed colour, black for Friesians and brown or red for Ayrshire.

I must admit I also find the snow-white colour of the animals appealing. Since such animals are rare in herds and I always vividly remember each animal I have seen.

Unfortunately, many farmers are not aware that predominantly white animals are vulnerable to the sun’s ultraviolet radiation and their lives may be cut short by damage caused by sun rays to the animals’ bodies.

In this article, I will share with you the case of Nyamweru, a predominantly white Ayrshire that I handled last week. When Jane, the farm manager at Patrick’s farm in Ruiru, called me, Nyamweru’s image was fresh in my mind.

I had recommended the cow to be removed from the herd about a year ago but the owner had decided to retain her for her beauty and high milk yield. He had said he preferred to breed her with colour-balanced Friesians rather than cull her.

Nyamweru in Kikuyu means “the white one”. Jane said the cow had a wound in the vulva that had not responded to treatment and kept spreading.

She further said the wound started off as a pimple in December last year, got red and then ulcerated. It never closed again despite treatment.

The farm manager had noticed the pimple while she was inseminating the cow. Afterwards, she would often see a small ball of faecal material hanging on the hairs of the vulva and covering the pimple. She never realized the pimple was quickly growing until it ruptured and started attracting flies.

Once I arrived at the farm, I examined the cow starting with the eyes and finishing with the vulva wound. For the eyes I checked the eyeball, upper and lower eyelids on the inside and outside and the third eyelid.

The third eyelid is a membrane found inside the inner corner of the eyes in many animals. I was looking for growths or swellings in the eye structures but I found all of them normal.

SCIENTIFICALLY INVESTIGATED AND UNDERSTOOD

On the right lip of the vulva, I found the offending wound as Jane had described. The wound was round and about two centimetres wide. It invaded deep into the tissues of the vulva but had not ruptured into the organ’s cavity.

As happens with most of the predominantly white dairy cattle, Nyamweru’s skin around the eyes and vulva was so pink that I could see blood vessels below the skin illuminated by the sun.

This is the major problem with such animals. Their skin lacks the protective pigment that neutralizes the harmful effects of sun rays.

“Jane, I am sorry your favourite cow has vulva cancer that has spread into the deeper tissues.” I announced as I completed the examination. I explained to Jane that surgery or any other treatment was not advisable as the cancer was likely to recur or the wound may fail to heal.

The deep spread of the cancer meant that if I surgically removed the affected tissues, I would leave the cow grossly disfigured and make calving very difficult.

In addition, it was unlikely that I would be able to remove all the affected tissues. The cancer could therefore recur and spread to more tissues.

I advised Jane to sell the animal for slaughter before the wound rendered the meat unfit for human consumption. “At least she left us one normal pigmented Friesian-looking heifer calf,” Jane consoled herself as she resigned to the fate their favourite white cow will be no more.

Nyamweru had been inseminated about a month before I was called to treat her. I could, however, not recommend waiting for her to carry the pregnancy to term because the action would result in suffering of the animal and possibly even death from the cancer before she was due for calving.

Vulva and eye cancers, medically called carcinomas, are common cancers in cattle. They are mainly seen in Friesian and Ayrshire dairy cattle and the Hereford beef cattle. Affected animals have low or no pigmentation in the affected organs.

Poor or no pigmentation is seen as very pink skin which gets inflamed by sunlight. The reaction has been scientifically investigated and understood.

Good pigmentation blocks ultraviolet (UV) rays in sunlight from reaching the genetic material of cells.

In poorly or non- pigmented animals, UV rays damage the genetic material of the eye and vulva skin cells causing mutations that produce cancer cells.

CONSTANLY OBSERVE YOUR LIVESTOCK

Once the mutations are large enough, they overwhelm the body’s damage repair mechanism and the cancer cells multiply uncontrollably to cause the spreading non-healing wounds.

If left untreated or the animal is not disposed of, the cancer spreads from the initial site to the rest of the body and kills the animal by replacing normal tissues.

Animals with cancer are unable to feed properly, become weak and die of long term loss of weight and starvation.

Eye and vulva cancer can be surgically treated by a veterinary doctor if the farmer reports the disease early in the pimple stage or before it spreads into the deeper tissues.

In some cases, the whole eye may have to be removed if the cancer has started in the surface of the eyeball.

We advise farmers not to keep animals with the eye and vulva cancer, or any other cancer, because the disease lowers the welfare of the animal by causing pain, inability to eat well and suffering from bacterial infection and fly invasion of the wounds.

Some of the wounds are unsightly, discharging and foul smelling. Keeping such animals would also be an offence as it contravenes animal welfare laws.

Some farmers will want to keep cows with cancer for them to complete pregnancy or to get the benefits of milk yield if the animal is in early lactation. Farmers should desist from such temptation and consider the welfare of the affected animal first.

I advise farmers to constantly observe their animals’ eye and vulva areas and report any swellings or abnormal reddening they notice to their veterinary doctor.

Early detection of vulva and eye cancer is the key to saving an affected animal because the cancer can be surgically removed. Animals with normal pigmentation may get the cancer but it happens rarely.

Farmers should avoid keeping and breeding white non-pigmented animals or poorly pigmented ones. Granted such animals may be born, the best