17.4.2: Infertility in farm species

Question 1

What are the 3 broad presentations of infertility?

Answer 1

• Cycling animals do not conceive i.e. ovulating but not being fertilised
• Animals that are not/do not appear to be cycling at all
• Animals that conceive but do not maintain pregnancy

Question 2

What are the possible causes of cycling cows not conceiving?

Answer 2

• Improper/incorrect insemination
• Infectious causes
• Toxins
• Metabolic/nutritional causes
• Iatrogenic causes
• Sire choice

Question 3

What are some possible reasons why cows may not cycle?

Answer 3

• False anoestrus: oestrus not observed/recognised
• Metabolic/nutritional cause e.g. NEB
• Uterine infection
• Pregnancy
• Cystic ovarian disease
• Suckling calf at foot

Question 4

What are some possible viral causes of infectious infertility in cattle and sheep?

Answer 4

• BVD
• Border disease
• IBR (BoHV-1)

Question 5

What are some bacterial and protozoal infectious causes of infertility?

Answer 5

• Leptospira
• Brucella
• Campylobacter
• Tritrichomonas

Question 6

What are the effects and presentation of BVD with regard to fertility?

Answer 6

• Effects: early embryonic death and ovarian damage
• Presentation: long returns to service (25-35 days) and reduced conception rate
• This has a huge economic impact!

Question 7

What are the effects and presentation of Border Disease Virus in sheep and goats with regard to fertility?

Answer 7

• Effects: Poor fertility
• Presentation: Increased barren rate

Question 8

What are the effects and presentation of IBR with regards to infertility?

Answer 8

• Effects; temporary ovarian necrosis, follicular degeneration
• Presentation: reduced conception rate due to reduced ovulation capacity and reduced oocyte viability

Question 9

Describe the effects and presentation of Leptospira in cattle with regards to fertility

Answer 9

• Effects: poor fertility and EED, possibly due to endometrial inflammation but unknown
• Presentation: reduced conception rates and long returns to service (25-35d)

Question 10

Describe the effects and presentation of Brucella in cattle with regards to fertility

Answer 10

• Effects: poor fertility, epididymitis and orchitis
• Presentation: reduced concept rates in cattle / increased barren rates in sheep
• Notifiable and zoonotic!

Question 11

Describe the effects and presentation of Campylobacter with regards to fertility

Answer 11

• Effects: endometritis (cattle), failure to conceivem early embryonic death (cattle), abortion (sheep and cattke)
• Effects: irregular oestrus cycles, repeat breedings -> long calving intervals, long returns to service, high returns to oestrus. Visible abortion.

Question 12

Describe the effects and presentation of Tritrichomonas in cattle with regards to fertility

Answer 12

• Effects: early embryonic death, pyometra, endometritis
• Presentation: long returns to service (25-35d), identified on clinical exam
• Protozoal cause, more of an issue in herds using natural service

Question 13

If GnRH is given at the start of oestrus, what is the effect?

Answer 13

Ovulation in 24-48hrs
* GnRH stimulates the release of FSH and LH and so induces ovulation

Question 14

If GnRH is given 10-12 days post-oestrus, what is the effect?

Answer 14

• Reinforces CL action -> aids maintenance of pregnance
• Used to be used to help a cow keep a doubtful pregnancy - not done so much now

Question 15

When do prostaglandins have an effect on the ovary and how?

Answer 15

• Prostaglandins cause luteolysis of the CL
• The CL will only respond from day 5-15 of pregnancy
• CL will be over >17 mm on ultrasound

Question 16

What are prostaglandins used for?

Answer 16

• Synch protocols
• Treatment of luteal cysts
• Induce abortion or parturition
• Treat pyometra
• Control of breeding and oestrus timing

Question 17

What could you use to treat follicular cysts?

Answer 17

GnRH

Question 18

Buserelin

Answer 18

GnRH analogue

Question 19

Gonadorelin

Answer 19

synthetic GnRH

Question 20

Dinoprost

Answer 20

PGF2a

Question 21

Cloprostenol

Answer 21

Synthetic PGF2a analogue

Question 22

True/false: progesterone can be used to improve oocyte quality

Answer 22

True

Question 23

How can progesterone be used with relation to ovulation?

Answer 23

• Progesterone e.g. PRID, CIDR acts as exogenous CL
• This suppresses GnRH
• A dominant follicle may develop but will not ovulate
• When the progesterone-releasing device is removed, there is an LH surge which causes ovulation

Question 24

What complications can you see with progesterone devices?

Answer 24

• Necrosis at points of T where in contact with vaginal wall - tends to self-resolve
• Vaginitis, purulent discharge - self-resolves with removal and does not require treatment
• May need to cut device tail short in heifers who pull them out - take care to ensure the devices will not be left in accidentally

Question 25

How would you create a teaser bull?

Answer 25

• Epididymectomy is easier and safer than vasectomy because it can be done standing (compared to vasectomy which requires dorsal recumbency)
• Penile alterations not done in UK

Question 26

What is your diagnosis and what structure would you expect on the ovary? How will you treat this cow?

Answer 26

Diagnosis: pyometra
Expected ovarian structure: CL
Treatment: PGF2a; if a long standing pyo of 5-6+ months, will need to cull

Question 27

Diagnosis and treatment?

Answer 27

Follicular cyst
Can force ovulation with GnRH/ PRID/ both
Do not serve to this forced ovulation - the oocyte will be ancient and poor quality so conception rate likely to be poor

Question 28

Diagnosis?

Answer 28

• This cow has either just ovulated or may be in anoestrus
• There are tiny follicles less than 0.5cm in diameter
• There is no luteal tissue
• This ovary is not cycling but need to check the other one
• Need more history/ questions to work out if she has just ovulated or requires treatment e.g. GnRH / progesterone for anoestrus