VET ON CALL: This skin disease can take your prized cow to early slaughter

Dairy cows graze in a farm. Brookside trained women groups from Kajiado on how to reap from their dairy enterprises. PHOTO | FILE

What you need to know:

  • The common thread in the infections caused by all the micro-organisms is that they have no malice on our animals. They are only driven by the natural urge to thrive, multiply and propagate their species.
  • Benjamin, a farmer from Maseno, shared his frustrations in an e-mail two weeks ago. His one-year heifer had developed a strange rash with itchy swellings on the inside of the ear. He had slaughtered the heifer’s mother because of the same condition.
  • After reviewing the history of Benjamin’s cow and his photograph, I concurred with his service provider that the problem was BPV infection. The disease is common in cattle. It spreads in herds mainly among young animals below 15 months, once it establishes in the index or initial case.

The creatures that cause disease in animals, humans and plants live with us in the environment. Some of the disease-causing organisms are visible to our unaided eyes while others like bacteria, fungi, protozoa and viruses require the use of equipment such as microscopes to be seen.

The common thread in the infections caused by all the micro-organisms is that they have no malice on our animals. They are only driven by the natural urge to thrive, multiply and propagate their species.

Unfortunately in their quest, they cause misery to the animals, emotional stress to the owners and economic losses due to treatment costs, loss of production and sometimes deaths of the infected animals. Sometimes the infections in our animals also cross over to humans.
While some diseases are easy to treat, others can be difficult and frustrating. This brings me to a highly visible cattle skin disease that does not kill but frustrates farmers whose animals fall victim to it.

Benjamin, a farmer from Maseno, shared his frustrations in an e-mail two weeks ago. His one-year heifer had developed a strange rash with itchy swellings on the inside of the ear. He had slaughtered the heifer’s mother because of the same condition.

The condition was unsightly. His local animal health service provider tried to treat the cow with some injections of antibiotics and anti-inflammatories while at the same time washing with copper sulphate solution to no avail. The service provider said the animal had contracted Bovine Papillomavirus (BPV).

Benjamin was worried the heifer had been infected with the same disease and he might have to dispose it as well. Obviously having gone through a frustrating episode of the disease with the adult cow, he would probably choose to dispose the heifer before the disease spreads to the whole body. He was optimistic I could advise him on good treatment.

After reviewing the history of Benjamin’s cow and his photograph, I concurred with his service provider that the problem was BPV infection. The disease is common in cattle. It spreads in herds mainly among young animals below 15 months, once it establishes in the index or initial case.

Bovine papillomavirus is a group of viruses that infect the skin and sometimes internal body surfaces such as those of the digestive, reproductive and urinary systems in cattle. It is related to other papillomaviruses that affect humans and other animals. However, BPV is not known to infect humans. The virus may cause cancerous growth in cattle especially when it infects internal body surfaces.

BPV is classified into six species termed BPV 1 to BPV6. The virus resides in the environment and infects cattle through contact with breakages in the skin.

For some unknown reasons, the virus tends to start infections from around the head and neck and then spreads to the whole body. Calves and young animals are mainly affected possibly because their immune system is not well-developed.

Farm structures such as fences, poles and trees may habour the virus from where animals get infected when they brush against the structures. Direct animal-to-animal contact also transmits the disease from infected to clean animals.

This would explain why Benjamin’s heifer got infected even after the mother had been disposed of.

Once in the skin, BPV causes growth of cells above the skin surface. The disease manifestation, medically called a lesion, comprises raised skin growths that may be cauliflower-like, horny, flat, or round with a stock attaching to the point of infection. In layman’s terms, these are the lesions called warts. The skin warts are actually non-spreading tumours scientifically called benign growths. Left untreated, BPV usually heals on its own within 18 months because the animal develops immunity that clears it .

While a farmer could wait for the self-healing, the problem is that the infection will spread to other animals and also contaminate the farm structures. In addition, infected animals are scaring and consumers may avoid milk from such herds.

Fortunately, BPV can be treated with a vaccine prepared from the virus lesions on individual cows. It is called an autogenous vaccine. Commercial vaccines do not work because there are six species of the virus and it is difficult and expensive to determine the type of virus causing an infection at any one time.

To prepare an autogenous vaccine, a veterinary doctor collects an adequate sample of the lesion on an infected animal and submits to the laboratory. The sample should be collected from multiple lesions to ensure that all virus species are included in the vaccine. If more than one animal is infected in a herd, then a sample is taken from a number of animals.

The laboratory prepares a fresh vaccine from the samples submitted and returns it to the submitting veterinary doctor. The doctor will vaccinate the infected animals with the autogenous vaccine on the first, 10th and 30th day. The University of Nairobi has reported having prepared an autogenous BPV vaccine and successfully treated four 14-month-old heifers.

The warts on the animals started dying off three weeks after vaccination and completely cleared off by the seventh week. Veterinary scientists in other parts of world have reported similar successful treatments. The autogenous vaccine also works for goats infected with the papillomavirus.

Scientifically, the autogenous vaccine works by alerting the body’s immune system that there is a viral intruder residing in the animal’s skin.
The body produces antibodies in large numbers against the virus and deploys them at the point of infection where they kill the virus and its virus producing skin tissue, thereby drying off the warts.

Under normal circumstances, the outer surface of the skin which the virus infects is poorly supplied with blood. The body is therefore not able to detect the presence of the virus naturally until it has grown deeper into the skin layers. That is why it takes up to 18 months for the body to clear the warts naturally.

Farmers whose cattle is suffering from BPV infection may contact Dr Andrew Thaiya of the University of Nairobi’s Department of Clinical Studies on mobile 0701838301. They can conquer this stubborn virus and save their cattle from slaughter.