06 - Examples of Intersexuality in Domestic Animals (Horses, Pigs, Dogs)

Question 1

(Horses)

Several syndromes are described

1. What are the most common?
2. present for what?
3. Do these have streak gonads?
4. Some reports of cyclicity and pregnancies.. but these are likely to be what?

Answer 1

1. Turner’s syndrome (63, XO) mares with gonadal dysgenesis
2. failure to cycle or won’t stand for stallion (they also may have smaller stature and reduced athletic performance)
3. yes
4. mosaics (XX/XO)

Question 2

(Horses)

1. Kleinfelter’s syndrome also reported, will infertile stallion be cryptorchid?

Answer 2

1. maybe

Question 3

(Horses)

1. Both XX and XY sex-reversal have been reported in recent well documented cases….
2. so far all XX sex reversed horses haven been sry-negative… meaning what?
3. all XY reversals have been sry-negative… menaing what?
4. Most cases of “sex reversal” in the older literature were probably what?

Answer 3

2. downstream issue
3. lack of sry was the issue
4. complete or partial androgen insensitivity cases (may be the second most common syndrome in the horse)
   (though. .. as a species difference, most affected animals have fairly strong male behavior (probably via circulating testosterone acting directly on the brain after it is converted to extrogen… which does seem able to support good libido in stallions)

Question 4

(pigs)

1. How often is there evidence of vascular anastomosis in the developing placentas of early pig fetuses?
2. While abutment of membrances does occur at the tips they generally become what?
3. So…. is freemartinism rare?

Answer 4

1. raraely
2. necrotic
3. yes… obviously - a good thing onsidering all the mixed sex piglests

Question 5

(pigs)

(cont)

1. other forms of intersex are however not unusual in genetically female pigs
2. these generaly involve the presence of what?
3. incidence of intersex in pigs varies from what to what?

higher levels associated with what?

Answer 5

2. ovotestes or testes
3. from 0.1% to 4%

inbredding and use of particular boars

Question 6

(Dogs)

Many disorders of sexual development have been described in dogs, mostly affecting males. some examples include….

(Hypospadias)

1. In this condition there is partial failure of fusion of what?
2. thus… the urethra does not open at the end of the glans penis… but where?
3. is a mild form of what?
4. could be due to what four things?

Answer 6

1. the urogenital folds
2. further back, anywhere from the penile shaft to the perineal region
3. psuedohermaphroditism
4. inadequte T producntion

inadequte activity of 5a-reductase (to convert T to DHT)

androgen receptor problem

defects in downstream genes involved in epithelial-mesenchymal interactions

(maternal overexposure to estrogens or endocrine disruptors reported as a cause in humans)

Question 7

(Dogs)

(XX sex reversal)

1. Chromosomally female (78,XX), but most have what?
2. male or female externally? may have abnormalities of what?
3. Internally they also have what?

(another part of this syndrome is XX hermaphrodites)

1. these usually have what?
2. seen most oftn in what breed?

Answer 7

1. bilateral testes (usually cryptorchid), epididymis, vas deferens, and prostate
2. male; genitalia (hypospadias, other penile malformations)
3. small uterus (but no oviducts)
4. bilateral ovotestes and female genitalia that is variably masculinized

(masculinization in this syndrome is related to amount of testicular tissue)

2. cocker spaniels (autosomal recessive), seen in at least 18 breeds (all canines so far have been Sry negative)

Question 8

(Dogs)

(Persistent Mullerian Duct Syndrome (PMDS))

1. a form of what?
2. these dogs are 78 XY, have bilateral testes…. but 50% are what?
3. What do they have internally (in addition to male strucutres)?
4. The cranial uterine horns are attached to what?

Answer 8

1. male pseduohermaphroditism
2. bi or unilateral cryptorchids (otherwise are normal males externally)
3. oviducts, uterus, cervix, and cranial vagina
4. the testes (thus are probably mechanical cryptorchids)

Question 9

(Dogs)

(Persistent Mullerian Duct Syndrome (PMDS))

1. PMDS is inherited in what breed in US? in england?
2. transmitted as what?
3. due to what?
4. Do homozygous effected dogs have normal levels of MIS?

Answer 9

1. mini schnauzers, basset hounds
2. autosomal recessive
3. peripheral resistance (ie receptor defect)
4. yes

(Since they are phenotypically normal (except cryptorchidism) extrenally they may not be diagnosed till castrated or they present when older for signs assoicated with pyometra or Sertoli cells tumor

Question 10

(Cats)

1. The tortoiseshell cat is an example of X chromosome inactivateion - their coat is a patchwork of orange and black or tabby

2 black and tabby genes are autosomal while orange (O) is located where?

3. O is dominant over autosomal genes, so skin cells with an Xo will produce what?
4. Those without the O (X-) will produce what?
5. Given normal (XY) males only have 1 X chromosome, they can be what?
6. Female cats can receive one Xo and one X-. Random X-inactivation of cells early in development will result in clones of daughter cells where O is active in some but not in others, resulting in the patchwork coat
7. Since you need an XX to be this… males are rare… but possible

for example

some are XXY and sterile

some are chimeras with XX/XY or XY/XY and can be fertile

Answer 10

2. X
3. orange (irrespective of what is on autosome)
4. black or tabby
5. orange (XoY) or black and tabby (X-Y)