Defects of Hides and Skins

DEFECTS OF HIDES AND SKINS

 
Defects due to disease and insects
  • The animals in tropics fall a prey to a number of parasitic, bacterial and viral conditions affecting the hide and skin.
  • The damage that results depends on the duration of the infection and its severity, and may range from slight marring of the grain to destruction of the corium itself.
  • Such damage is often attributable not so much to the disease itself, as to secondary infection, rubbing and scratching because most skin diseases are accompanied by severe itching.
  • Starvation during excessive drought and lack of green fodder, combined with heavy internal parasitic infestation, aggravate skin diseases.
  • Tick damage and damage due to strong concentration of tick killing drugs are some of the causes of defects of hides and skins due to disease and insects.
  • Follicular or demodectic mange
    • One of the most commonly seen disease defects is made by a mite called Demodex folliculorum, a parasite burrowing deep into the hair follicle, where it establishes its nest; this disease is called follicular or demodectic mange.
    • The damage is clearly visible on the flesh side of the hide or skin, in the form of raised whitish spots.
    • These lesions are erroneously called pox marks by the trade.
    • True pox is caused by a virus and leaves very slight marks only, located mostly on the udder and on the inner surface of the thighs.
    • When a vesicle bursts, the lesion may occasionally become infected, because of the severe irritation and the subsequent scratching by the animal.
  • Sarcoptic and soroptic mange
    • Sarcoptic and soroptic mange (commonly called scab) are widespread because of the warm climate and primitive management.
    • As these parasites tunnel between the fibres of the corium of the skin, the result is rough pitted leather with damaged grain.
  • Streptothricosis
    • Streptothricosis is another widespread disease caused by a microorganism of the genus Actinomyces.
    • It is known in tropical countries by various local names such as Krichi in Nigeria, Senkobo in Northern Rhodesia (Zimbabwe) and Uasin Gishu in Kenya.
    • The lesions made by this disease vary from slight inflammation of the skin, resulting in leather damage on the grain side only, to large areas deeply affected; in severely damaged areas, scar tissue is formed and there may be general thickening of the hide, giving it the appearance of elephant or rhino hide and making it quite unsuitable for leather.
  • Nodular dermatitis
    • Nodular dermatitis is a disease most probably caused by a virus and principally affects goats.
    • It causes lesions similar to those made by Demodex.
    • Other minor skin lesions may be caused by a fungal infection of ringworm of the Tricophyton genus.
    • Ringworm itself does not produce heavy damage to the skin, as the pathological changes are restricted to round, bald patches.
    • However, due to rubbing and secondary infections, deeper lesions may appear, affecting the resulting leather.
  • Lumpy skin disease
    • Lumpy skin disease, which occurs widely in the continent of Africa south of Sahara, also contributes to damage on cattle hides.
    • This appears in the form of lumps and nodules or round patches, deprived of grain, or as button-like defects reaching deep into the corium.
  • Photosensitization
    • The ingestion of certain plants or drugs may sensitize the skin to sunlight; this is known as photosensitization.
    • The areas usually affected are those where the actual skin is unpigmented; these are generally covered by white hair, and therefore known as white-haired animals.
    • Particular breeds such as Ayrshire and Friesian, imported from the temperate zones, suffer the most.
  • Dermatitis
    • Dermatitis is caused by strong concentration of tick-killing drugs or by their improper use, also contributes to the list of lesions to be found in hides and skins derived from territories where tick control is practiced.
    • In addition to the diseases mentioned above, certain insects (as mentioned below) attack the living animal and damage the skin.
  • Warble Fly (Heel Fly or Grub)
    • Warble flies cause very great losses in the temperate zones than in tropical and subtropical zones, since, these insects do not live in the true tropics.
    • The fly belongs to the family Hypodermidae and atleast three, namely, Hypoderma bovis, H.lineatum and H.crossi, exist on the northern fringe of subtropical countries.
    • The ova deposited by the fly on the hair of an animal hatch into very small larvae, which penetrate the skin and, after migrating through the body, settle on the back in the subcutaneous tissue, causing visible lumps, often referred to as Grub.
    • The parasite breathes through small openings, and after one or two molts, emerges as a whole warble, falls to the ground, molts again and appears as the mature parasite, starting the cycle again.
    • The damage to the hide skins depends on the stage of this cycle when the animal is slaughtered.
    • Open grubs are unhealed places where the grub was imbedded or from where the warble emerged, resulting in holes, while wounds leave scarred tissue.
  • Tick damage
    • Tick damage is extremely frequent.
    • Ticks leave the hides and skins doted with pinhole spots at each site where they were attached.
    • Tick-eating birds often cause damage to the deeper layers, especially if bacterial infection of the wound occurs.
      • Lice damage, biting flies and other stinging insects may leave spots on the grain, but these are of minor importance.
      • Insects may cause extensive damage to hides and skins after they have been removed from the animals. Of these insects, the hide beetle (Dermestes) is responsible for tremendous losses to hides and skins, which have not been properly protected. The beetle itself and its voracious larvae are able to consume a large part of the entire hide in a very short period.
  • Treatment
    • In the past, the only drugs suitable for destroying skin parasites were nicotine, derris root, rotenone, lime, sulphur and creolin.
    • Now modern chlorinated hydrocarbon insecticides such as DDT, lindane, BHC, toxaphane and chlordane, which allow mass control of the parasite, are used.
    • Thus give great hope for the reduction of damage to the hides and skins due to parasitic infestation. 
Last modified: Friday, 17 September 2010, 4:54 AM