More and more pedigreed animals continue to pour in to my hospital with the same type of diseases. When we check we find that several dogs suffering from the same disease – like hip dysplasia – have come from the same breeder. I have him raided. We find three females all pregnant by their brother. Inbreeding or incest is defined as the use of close relations for breeding such as mother to son, father to daughter, brother to sister. It is taboo in most cultures for good reason. Genes carry the map of who you will be and what diseases you will suffer from. Let us suppose you carry the ‘bad” gene of a disease. You mate with someone who does not have the disease. Bad genes are usually recessive – which means they are weaker than good genes. So when the bad gene is mixed with a good gene it has less than a 50 % chance of affecting your child. But if you were to mate your brother, your child would have a much stronger bad gene as both of you are carrying it.
Which communities have the most physical problems? Parsis, Muslims, those small sects and clans that marry first cousins. One group that has been intensively studied is the Ashkenazim, or Eastern-European Jews in whom exist a large number of genetic diseases especially of a neurological nature. In Finns, 39 genetic diseases unique to the nation have been identified. These are known as the Finnish Disease Heritage (FDH) and most commonly affect the eyes and nervous system. A close relationship between parents increases the risk of miscarriage, stillbirth and early death of children as a result of weakened immunity against disease.
The same thing applies to animals. Inbred animals lose their ability to produce antibodies to fight diseases. Suddenly whole species can be lost to infections that would have little effect on a normal animal. Scientists have produced laboratory animals, strains of mice, rats, and other animals that are so inbred as to be genetically identical. Each animal in one of these strains is the identical twin (aside from sex) of every other animal of that strain. These animals must be kept in a nearly sterile environment, because their immune systems are not capable of fighting off any diseases. The cheetah was reduced by habitat restriction, overhunting to a very small number of individuals. All cheetahs now come from this very small gene pool. A virus can take them to extinction as they have no resistance and currently they are being decimated by feline infectious peritonitis, which has a disease rate in domestic cats from 1%–5% but 50-60% in cheetahs. Asiatic lions in Gir have the same problem. The population is a few hundred and there is no mechanism for preventing inbreeding.
In the prides, most lionesses are related to one another. The alpha males of two neighbouring prides can be from the same litter; one brother may come to acquire leadership over another's pride, and subsequently mate with his 'nieces' or cousins. Wolf packs and Giant Pandas suffer from the effects of inbreeding. This has led to poor fertility and high infant mortality. As Panda populations become more isolated from one another (due to humans blocking the routes which Pandas once used to move from one area to another), they have greater difficulty in finding a mate with different genes. The worst inbreeding problems exist in the animals that humans “ use”.
Animal breeders have a set goal in mind: to make the animal bigger, fatter or smaller, a colour, one that gives more milk etc. So they repeatedly breed animals with each other and kill those that do not have these traits till they get what they want. Dogs, cats, cows, pigs, geese, chickens – practically all the animals that are used by man have been tampered with in this way. The result is much weakened species’ with a host of diseases. (Now you know why 60 % of the world’s antibiotics are fed to animals.)
Till today, attempts to produce highly productive inbred lines of domestic livestock have met with little success. Although occasional high performance animals are produced, inbreeding generally results in an overall reduction in performance. This reduction shows in many ways. The most obvious effects of inbreeding are poorer reproductive efficiency including higher mortality rates, lower growth rates and a higher frequency of hereditary abnormalities. This has been shown by numerous studies with cattle, horses, sheep, swine and laboratory animals. The greater the degree of inbreeding, the greater the reduction in performance.
What happens when cows are inbred? While intensive inbreeding of Holstein cows led to higher yields of milk in twenty years, the cows themselves became more and more delicate and had much higher health costs. Studies done on cattle Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey, and Milking Shorthorn showed that for every increase of 1% level of inbreeding those animals gave 65 less pounds of milk, 2 pounds less of butterfat, and 2 pounds less of protein. When Dexter cows were inbred severely deformed, dead foetuses were typical and often necessitated surgical intervention to save the cow. Research with swine shows that for each 10 percent increase in inbreeding, there is a decrease in the number of pigs born per litter. The most experimented on species has been the dog.
Dogs have been bred for diverse purposes as hunting big game, retrieving small game, guarding homes, herding sheep, racing, dog-fighting, finding criminals, sniffing out drugs, guiding the blind, fishing, rat hunting, keeping humans company, drawing sleds and even for food, fur and as living hot-water bottles. They have been adapted to the needs of the elderly, solitary apartment dwellers, large families, farmers and fashion conscious socialites. From a base of two breeds , they are now more than 300, and ranging in size from 90 kg in weight and 90 cm high at the shoulder down to a height of 15 cm and a weight of 1 kg. Now dogs suffer from a number of genetic diseases common in particular breeds. Rottweilers suffer from a neurological disease known as neuroaxonal dystrophy, while ceroid lipofuscinosis, hereditary myelomalacia, hound ataxia and spongiform leukodystrophy are neurological diseases seen in cocker spaniels, Afghans, beagles and Labradors . Bred for size, big dogs have shorter life spans than small dogs because their size tends to put strain on their cardiovascular and skeletal systems. Problems such as hip dysplasia and achalasia in the German Shepherd and patella luxation are more common in certain breeds. The flat faces of bulldogs and boxers cause breathing difficulties, and breeding for round heads has resulted in pugs requiring surgical intervention when birthing. Pure-bred dogs, having less variety in genes are generally less resistant to disease than mixed-breed dogs.
How can you tell if a breed or line is inbred? Reduced fertility in both sexes. Small litter sizes and high puppy mortality. The loss of a large proportion of dogs to one disease. Highly inbred dogs also display abnormalities on a regular basis ranging from simple misaligned jaws to blindness and cancer. Many species disappear. For the 300 species of dogs that you see today, thousands of breeds have died out because they were malformed and sick. Many, like the Alsatian are on their way out. Dog breeders are motivated by short term profit rather than the health of the animal.
In cats inbreeding has given rise to domestic breeds such as the Manx which is tailless. Its problems are small litters, stillbirths and spinal abnormalities. Other cat problems are many toes on each foot; dwarfism. One breed which was almost lost because of inbreeding is the American Bobtail. Breeders tried to produce a bobtailed cat with white boots and white blaze, but only succeeded in producing unhealthy cats with poor temperaments. The rules governing colour and pattern which had turned large, robust cats into small, delicate creatures had to be abandoned.
Most animals have evolved mechanisms to avoid inbreeding of any sort. Pack animals like lions, monkeys and dogs, kick young males out to prevent them from mating with female relatives. Even fruit-flies have a sensing mechanism to avoid too close inbreeding. Unfortunately man discovered artificial insemination and created a Pandora’s Box of disease and suffering in the animal kingdom.
Maneka Gandhi
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