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May 2013
Contents / home
Disease research in cheetahs
Top awards for NZG research
Ragged-tooth shark released
Holiday fun at the zoo
Knysna seahorse pampering
Emma the lioness
11th ICEE comes to Africa
Exhibit draws large crowds
Scifest Africa 2013
A kiss from a seal
Farm programme fascinates
Rhino poaching update
Conservation Grapevine
 

The intriguing case of Emma the lioness

 
  Emma with a mane.
Male lions are well known for their long mane hair that covers the side of their head and neck, often extending onto their chests and ventral abdomen. Male lions start developing a mane when they reach puberty. This is mainly due to rising levels of the hormone testosterone.

Male lions that are castrated, will lose their mane hair because the testes are the main site of testosterone production. Similar to castrated males, female lions do not normally produce sufficient testosterone to produce any significant mane hair.

Emma grows a mane

In April 2011, Emma, a 13-year-old lioness at the National Zoo starting growing a mane of similar length to that of a sub-adult male. Initially we suspected that she may have some abnormalities of her reproductive tract, so an abdominal ultrasound evaluation was performed at the Onderstepoort Veterinary Academic Hospital.

However, all her reproductive organs appeared to be normal. Blood levels of various sex hormones were evaluated and as suspected, she had elevated levels of testosterone. We decided to remove her ovaries as these where most likely the cause of her elevated testosterone. This was done laparoscopically by Dr Marthinus Hartman at Onderstepoort in September 2011.

Skin biopsy samples were sent to Stellenbosch University for chromosome analysis to see if Emma had some sort of sex chromosome abnormality, but the results showed that she had normal female XX chromosomes.

The removed ovaries were evaluated by the NZG's own pathologist, Dr Emily Lane. Surprisingly, the "ovaries" that were removed, only contained cells normally seen in the testicles of males. This was obviously where the testosterone was being produced.

Did Emma's ovaries change into testes?

What makes this case remarkable, is that the zoo records show that Emma gave birth to four cubs in 2000. In order to give birth to cubs, she must have had normal ovaries at that time.

Genetic tests done on Emma and her cubs, so far also seem to confirm that she is the mother of those lions. Further genetic tests are currently being done on samples from the only other female that was present in the zoo at the time to ensure that no mistake was made in identifying the mother of the cubs. If Emma proves to be the mother, then this case seems to indicate that Emma's ovaries changed into testes. This is something that is virtually unheard of in mammals.

Other cases

Other cases have been documented in the popular literature of lionesses that have developed mane hair. These reports have come from both zoo and free-ranging animals, but so far the abnormality has not been described in the scientific literature. Currently Dr Adrian Tordiffe and other researchers are investigating individual cases reported in the Kruger National Park and in the Okavango Delta in Botswana.

After her ovaries were removed, Emma gradually lost her mane hair and returned to her normal female good looks.

A health evaluation conducted only a few days ago revealed that even at 15 and a half years of age, she is in excellent health.

By Dr Adrian Tordiffe, Clinical Veterinarian, NZG


 
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