Understanding Semen Analysis
When looking at your stud dog’s semen analysis there are a number of things to consider regarding his fertility.
Volume – Depends on age, size but mostly on the prostate fraction. It varies from 1 ml to 40ml per ejaculate and volume alone is not very important.
Motility – Has very little correlation with fertility, but is commonly requested by owners. It is important to see there are live sperm and once upon a time a live / dead count was done but this has been replaced with morphology and motility percentages. Progressive forward motion is desirable with side to side motion or circling of individual sperm undesirable.
- Very good – rapid swirls – mass waves
- Good – slower swirls & eddies
- Fair – no swirls but prominent individual sperm motion
- Poor – little or no motion
- Dead sperm don’t move.
- Normal – opaque, cloudy/milky
- Brown or red – blood (from prostate or penis)
- Yellow – Urine or inflammation
- Green – pus
- Clear – no sperm
Any abnormality may affect the viability of the sperm. Blood, urine, and/or infection can all be toxic to sperm.
Concentration – This depends on the volume – measured in millions sperm/ml of ejaculate. This is important to measure, to ensure there are enough sperm – at least 100 million normal mobile sperm per insemination needed.
Sperm morphology – This has a clear correlation with fertility.
Primary abnormalities are most important. These occur during spermatogenesis within the testicle; examples are any abnormalities of spermatozoa head (acrosome or nucleus), heads with no tails or double heads or proximal droplets.
Secondary abnormalities are less important. They are problems of sperm maturation and occur in the epididymis. Examples are bent tails, kinked tails and distal droplets.
This ranges normally from 6.3 to 6.7 but depends mainly on the amount of prostatic fluid in the ejaculate and is not always tested unless a problem is suspected. Seminal alkaline phosphatise – is only tested if there is a fertility problem, such as no sperm, to help work out where the problem is.
As the ejaculate passes through the urethra there may be contamination with red blood cells, white blood cells, epithelial cells and/or urine. In small amounts this is not a problem but larger numbers are abnormal and may indicate infection, haemorrhage or inflammation (orchitis or prostatitis).
Good semen would have:
- greater then 70% motility
- less than 10% primary abnormalities sperm morphology
- no more than 30% secondary abnormalities
Semen evaluation is an important tool in evaluating fertility. Remember that not every ejaculate is the same. A single lousy sample may not be the end of your stud dog’s career. Often the first ejaculate is poor – often only dead sperm. The seminal tubules need to be emptied out and then a repeat semen evaluation done.
Factors that cause problems in sperm production are:
- Stress – cold climate, starvation, illness, injury, fever, neoplasia and pain
- Genetic – both chromosomal problems and breed related problems.
- Abnormal heat regulation – humidity, fever, local inflammation (often dermatitis), obesity, hot baths and cryptorchidism.
- Nutrition – deficiencies in phosphorus, calcium, manganese, zinc & vitamin B & E.
- Season – photoperiod, temperature, humidity.
- Drugs – cortisone, amphotericin, griseofulvin in particular but most drugs will have some effect.
- Age – The best age for a dog to have his semen frozen is 2 to 6 years, as there are age related changes.
Remember there is a period of time for production and maturation of sperm of about 3 weeks. Any change in your breeding management will take at least 3 weeks to take effect. If you treat a prostate infection with antibiotics, you may get resolution of the infection in the prostate itself within 10 days, but it may take another 3 weeks to get a good semen sample. If a hormone injection is given, for example cortisone, it will affect the sperm for at least 2 to 15 days afterwards.
Results after Artificial Insemination with frozen semen are variable and depend on:
- The semen quality
- The method used to freeze it
- Where the semen is placed (into vagina, through cervix, into uterus)
- The number of inseminations
- The timing of the insemination
Dr Kay Pitkeathly BVSc