QUESTIONS

1. On a vaginal smear, what does a sudden decrease in the # of cornified cells indicate?
    
2. How long do canine sperm live in the female tract?
    
3. Regarding Brucella Canis:
   
   a) does B. Canis cause infertility?
   
   b) If you test a bitch & her serology is negative, how confident are you that she is truly negative?
   
   c)  What are the screening tests?
   
   d)  What are the confirmatory tests?
    
4. Bitches with short (like 4 month) interestrous periods tend to be infertile. Why?
    
5. What is happening in a "split heat?"
    
6. List a differential diagnosis list for prolonged (>  1 year) interestrous period.
    
7. List a differential diagnosis list for estrus lasting > 6 weeks
    
8. What is "Sex Reversal?"
    
9. What is "Androgen Sensitivity" also called "testicular feminization?"
   
   
   
   
    

ANSWERS

1. A sudden decrease in cornified cells signifies DIESTRUS.
   
   
   
   
    
2. Canine sperm live 7 days in the female tract (I was actually taught 5 days in school but the point is that this is an unusually long time relative to other species).
   
   
   
   
    
3. a) Depends on your definition of infertility.  B. Canis causes fetal resorption which can appear as  failure to conceive.
   
   b) It can take up to 8 weeks to seroconvert so the recommendation is to retest in 30 days before saying she is really negative.  Breeding bitches should have a negative test that is less than 30 days old when they are bred. Stud dogs should be tested at least every 6 months.
   
   c) Screening tests are tube agglutination & rapid slide agglutination tests (many false +'s and there is still the issue that it can take up to 8 weeks  post infection to be able to generate a positive test). Cornell uses a modified RAST that cuts down the number of false positives. Both tube agglutination and RAST measure cell wall antigen.  By the time an abortion has occured, you can probably figure the RAST test is going to be positive.
   
   d) confirmatory tests = Gel diffusion (AGID) or blood culture (bacteremia levels are generally low which makes culturing the organism very difficult) Cornell uses an AGID for cytoplasmic antigen (rather than cell wall antigen). It is run with the modified RAST. It can take up to 12 weeks post infection for this test to turn positive and antigen persists for months after bacteremia fades out.
   
   Remember that Brucella organisms can be transmitted across mucous membranes and that doesn't necessarily mean sexual contact (ie a dog that  is housed in a group of dogs could get infected)
   
   Treatment is streptomycin for the first week followed by doxycycline or tetracycline for a couple of months (if you dont' have any streptomycin lying around you may have to smuggle it in from Mexico)
    
4. The answer may not be known for sure but the theory is that frequent stimulation of the uterus leads  to cystic endometrial hyperplasia. German Shepherds & Rottweilers tend to have shorter cycles than other breeds & it may be normal.
   
   
   
   
    
5. "Split heat" occurs in a young female usually but could occur at any age. A follicular phase yields proestrus but instead of going into a luteal phase, the follicles regress & there is no estrus.  In a few weeks or in a couple of months she will try again to go into heat but she may split again.
   
   
   
   
    
6. DDX for long interestrous interval:
   
   * could be normal (wolf hybrids & basenjis tend to have long interestrous periods)
   
   * silent heat
   
   * metabolic disease (esp. hypothyroidism )
   
   * aging (one study showed 50% conception failure in beagles > age 5!)
   
   * Progesterone secreting ovarian cyst (dx by progesterone assay after diestrous period should be well finished. Treatment = PGF2-alpha or surgical removal of the cyst. 
   
   * Ovarian neoplasia
   
   
   
   
    
7. DDX for heat> 6 week duration
   
   * estrogen producing follicular cyst (causes behavioral nymphomania)
   
   * Rule out vaginitis (the discharge may look like heat)
   
   * Neoplasia
   
   * Hepatic disease/shunt leading to reduced hormone clearance.
   
   
   
   
    
8. Sex Reversal. Hmm. Could be fun. Just kidding.  As you recall, the development of the male gonads results when the Y chromosome codes for the H-Y antigen. This antigen leads to the undifferentiated gonad to become a testis. If there is no antigen, the gonad becomes an ovary.  In Sex Reversal, a very confused autosome codes for an H-Y like protein which causes testes or ovotestes to develop in an XX animal.  The usual breed is the cocker spaniel.  This condition is an inherited autosomal recessive condition in this breed.
   
   
   
   
    
9. Androgen insensitivity: an embryonic testis produces anti-Mullerian hormone which leads to the development of a male reproductive tract. Without anti-mullerian hormone, the Wolffian ducts regress & the tract becomes female.  In Androgen insensitivity, there is some kind of receptor deficiency leading to the development of an internally male set of gonads with an externally female tract in an XY individual.  The vagina ends in a blind sac & there are normal testes where the ovaries are supposed to be.