This month Vet News Exotics Editor, Charlotte Hitch brings us a fascinating piece on the breeding of White Bengal Tigers.
Breeding White Bengal Tigers
Charlotte Hitch (Vet News Exotics Editor)
White tigers, which originate from South Asia, are becoming increasingly popular in zoos in the Western world. Despite the undeniable beauty of the sleek black and white coats and piercing blue eyes of the white tiger, much controversy has arisen about the ethics of breeding these animals.
Many people believe that the white tiger is a rare, separate species; one which is rapidly and alarmingly decreasing in numbers, and call for conservation programmes to be initiated in order to save the ‘Royal’ white tiger. However, this is a common misconception. The white tiger is not a species, but rather a genetic mutation of the normal orange and black Bengal tiger, caused by an abnormal recessive allele in a single gene, SLC45A2, which is only partially responsible for pigmentation of the animal. This explains the presence of black stripes on an otherwise colourless body – a condition called leucism (not albinism as some may think; which causes the whole coat to be white and the eyes to be pink).
For most zoo owners and directors, the primary reason for breeding white tigers is for profit. The scarcity of white tigers makes them a huge attraction in zoos, and one cub can make up to US$60,000 when sold.
The truth about the conservation of this ‘species’ is often hidden from the public – during the breeding process it is not uncommon for normal orange-coloured cubs to be born from a white tiger parent. In this case, the cubs are often sold or disposed of in ways which are far from humane because they do not show the rare colour desired by the breeder.
Since the white tiger is not a species on its own, and is caused by one mutated gene, until now the only way to produce white cubs was to extensively and continuously inbreed close relatives; e.g. daughter to father or brother to sister. In fact, it is thought that the whole population of white tigers originated from one single tiger.
A famous example of the problems that inbreeding may cause is the case of Kenny the tiger. Kenny was born with serious deformities, such as abnormally arranged teeth causing difficulty with eating and a ‘pug nose’ which prevents correct and efficient breathing.
Other white tigers may have bulging or crossed eyes due to incorrect routing of their visual pathways, club feet, hip dysplasia, cleft palates, immunological problems, scoliosis (curving of the spine), shortened tendons, or kidney problems. It has been reported that they also react abnormally to anaesthesia, and their blood coagulates at a slower rate than that of their orange counterparts, causing more severe bleeding. Consequently, treating the animals to correct some of the problems caused by inbreeding is therefore close to impossible.
Now that the gene which causes the white coat has been discovered, it may be possible to screen normal orange tigers to see if they are carriers of the recessive gene and selectively breed the carriers to produce non-inbred white tigers. However, even this has consequences; the white colouration of these animals means that they would be incapable of camouflaging themselves in the wild in order to catch prey. For this reason, all white tigers are bred for a life in captivity. Some may argue that we are simply causing suffering by wasting money and resources on animals which will never be able to survive in the wild, while the number of healthy wild Bengal tigers from a more varied gene pool dwindles at an ever increasing rate.