The sow appeared healthy, suckling her piglets to the full but even an untrained eye could see the neck had a problem.
There was an area measuring about 10cm across with the top margin almost touching the midline on the back.
Medically, it is called a lesion. This refers to a disruption in the structure of tissue or organ due to disease or injury.
I encountered this case in Ruai last month. Muthithi, the farm manager, called to say that the sow had a wound that kept growing in all directions but it did not appear to affect the health and reproduction of the animal. The pig had farrowed 16 piglets while still having the wound.
He added that the wound started off from a bite by another sow about five months before. Five sows had been mixed after weaning their piglets but two could not tolerate each other.
Initially, the wound appeared to be healing but later kept growing above the skin and sideways. Attempts at using antibiotics and wound spray only appeared to stimulate more growth.
Some animal health service providers had even attempted surgical excision but the tissues had regrown with more vigour. “Could this be cancer” Murithi asked.
I restrained the pig with a catcher and closely examined it. The temperature, breathing and heart rate were normal, save for an elevation occasioned by handling.
I had seen ugly fight wounds in pigs before but never a massive one that just kept growing. I palpated the skin surface and deeply around the wound margins. It was a ball of growing tissue full of healing cells called granulation tissue.
It also contained fibrous or scar tissue, making it a hard mass. There was slight bleeding in areas the wound had been rubbed against the wall or floor. The wound surface was raised about half a centimetre above the skin at its highest point.
EXPOSED TO PHYSICAL INJURY
The lower parts of the wound shielded from abrasion had healed with thick scar tissue. However, tissue that was exposed to physical injury kept growing with every trauma. The wound did not appear infected as it had no puss, smell or rotting tissue.
It was now time to answer Murithi. His sow did not have cancer. It was a case of exuberant fibroproliferative disorder commonly termed “proud flesh”.
The wound keeps growing by producing healing tissue that turns into scar fibres. Proud flesh is common in humans and horses but rare in other animals.
In humans, it is called keloid and is responsible for the excessive scar tissue formation above the skin. It may occur on any part of the skin in sensitive individuals.
In horses, proud flesh is seen mainly in wounds on legs where the skin is tight. The cause of proud flesh is not known but may be genetic.
Offspring of one or more parents who had cases of proud flesh are known to be likely to develop the condition. There is a gene that has been associated with proud flesh in horses.
Proud flesh in animals and humans does not directly affect the health of the patient but impairs looks and exposes one to injuries.
Proud flesh is sensitive. Once injured, it grows more, exposing the scar to infections. The scars can be itchy or painful, thereby causing the animal to scratch, stimulating more growth.
Surgical removal of proud flesh is not an option because the tissue regrows more aggressively in many cases.
Christine Theoret, a Canadian professor of veterinary surgery, has studied wound healing and proud flesh in horses extensively.
SOFT PLASTIC MATTRESSES
She has also been researching the role of the horse as a model for studying wound healing and keloid formation in humans.
There is no effective way of treating proud flesh in animals because the methods used in humans require sustained follow-up, are expensive and not readily available to vets.
I told Murithi that he could retain the sow and keep treating the wound with antibiotic spray until the scar forms over the whole wound surface. The problem here is that the wound had been active for five months and was still growing.
It was unlikely the situation would change because the objects causing trauma were the floor and the walls.
The second option was to treat the sow in a special way and keep it in a room with soft padded internal wall surfaces.
The floor could be fitted with a soft plastic mattress. He would also need to keep the sow alone and breed it only with artificial insemination. I made this suggestion because the sow was one of his best producers and weaned 14 to 16
The option would, however, be expensive and still not guarantee complete freedom from injury.
Lastly, he could come to terms with the reality that he could not prevent repeated injury. Consequently, he should take care of the pig with its current litter and cull the sow after weaning the piglets.
He agreed to my recommendation but his dilemma was whether he should select breeding stock from the offsprings of the sow since they could also be carrying the proud flesh genes.
I advised that he could select some breeding stock but ensure he only used pigs on the farm.