Unwanted pregnancy TR Flashcards
What age do farmers typically put their heifers with a bull for the first time?
- 24months
- 60% adult body weight
Ideally, heifers should calve at about 24 months so are put in with the bulls around the age of 14 months.
You have now been in practice now for 2 years, working in a mixed practice based in Somerset.
In July, you attended Mr Jackson’s dairy farm to treat a bull for lameness. You explained that although the bull should be back on his feet very soon, you advised that the infection and possible associated pyrexia might mean that his breeding ability may be temporarily affected.
It is now the end of August and Mr Jackson is currently on hold to one of the receptionists. The receptionist summarises that he has called to speak to you at the practice to tell you that because of your advice he decided to leave the bull grazing next to his youngstock, as he thought the bull would not be interested in the heifers.
However, he has just seen the bull jump a dodgy fence and serve one of the heifers in the field (the heifers range from 8 to 10 months old). He is concerned the bull may have got her (and possibly other heifers) pregnant and wants to know what he should do. Apparently, he does not sound happy with you at all…
Why could these possible pregnancies affect the way the farmers runs his farm and why might they cause problems?
- Sets up for block calving and budgets for block calving
- Welfare concern for the heifers
- Dystocia
What are 3 potential options you could suggest to Mr Jackson to deal with these unwanted pregnancies?
- PD them in 28d time
- Oestrogen administration immediately
- <3m give prostaglandins: estrumate or lutalyse
- Bred >3m give prostaglandins and steroid and they will abort 5d later.
- Steroids mimic foetal cortisol at parturition therefore exogenous steroids results in abortion.
- Steroids given with prostaglandin to lyse the CL
Termination of pregnancy:
Which drug is commonly used in cattle to terminate pregnancies?
- PGF2a- estrumate or lutalyse
What is the mode of action for the drug to terminate a pregnancy?
Lyse CL so takes away support of conceptus
Termination of pregnancy: discuss the several options?
- Wait 7-14 days and inject all potentially pregnant heifers with prostaglandinF2a (why wait 7-14 days?).
- Because the CL is not responsive to prostaglandins.
- If takes 5-6days for the CL to form therefore it will not be responsive to PGF2a
- Observe all heifers for clear signs of oestrus over the next 25days - all not seen bulling are then given prostaglandinF2a
- Wait 30 days, scan for pregnancy and terminate with prostaglandin F2a if confirmed pregnant. The heifers may be too narrow/small to scan, a scanner with the probe on a stick or a vet with small hands/arms is useful here!
- In all of above options monitor for abortion/return to oestrus in 3-5 days post injection – if in doubt follow up with a rectal reproductive examination
One of the options is allowing the heifer to continue with the pregnancy.
How is pregnancy confirmed?
- Correct answer: Ultrasound >30d after breeding
- Balloting the animals does not definitely diagnose pregnancy
- Rectal ultrasound the sounds here an now and you may seem some changes with the CL but you cannot determine pregnancy
- Ultrasound <21d is too early for an ultrasound to be diagnostic for pregnancy.
List your top three potential issues that could arise from allowing young heifers to continue with the pregnancy?
- dystocia resulting from MFD
- welfare concerns for heifer
- Negative energy potential: weaker young/ calves, poor milk production
Feedback
- Consider genetic defects – in case bull is father of heifer; check with farmer as to whether the bull is related to the heifer in any way i.e. father especially if he keeps a closed herd and uses the heifers as replacement stock.
- Possible calving difficulty: Potential calf size is determined partly by genetics but the physical size of the dam plays a major part. However heifers as young as this will not have developed a pelvis of mature proportions by the time of calving and dystocia is a high risk. Consider careful monitoring near the time of parturition and induction of parturition aiming for about 2 weeks pre-term.
- Aim for maximum growth of the heifer in the first half of pregnancy, promote growth but do not allow the heifer to get overconditioned in the second half of pregnancy to reduce dystocia risk.
What happened next:
You advise Mr Jackson to remove the bull, wait for 7-14 days and then inject all the heifers over 3 and a half months old with prostaglandinF2a, with a follow up pregnancy check when the heifers are big enough for a rectal scan.
You book the visit but on the day of the visit Mr Jackson calls to say that he is too busy and will rebook the visit at a later date.
Nine months later, the practice receives a phone call from Mr Jackson with a request for you to attend a heifer calving.
You arrive at the farm and find a very small heifer straining in a loose box. The calf’s feet are not visible when she strains and a long length of afterbirth is hanging from the vulva. An unpleasant smell is noticeable from a metre away. Mr Jackson tells you that one of the other heifers calved on her own 3 days ago. He first saw this one straining 8hrs ago but has only just been able to get her in.
Briefly discuss your approach to the examination of this heifer, what key parameters do you assess to help your decide on your management of this case?
- Restrain the heifer appropratiely.Is she standing up?
- Is she clinically well or unwell?
- Try an assess whether the calf is alive- the smell probably indicates that it is not.
- Is an Epidural required to stop straining or provide oxytocin to encourage straining?
- Perform vaginal exam: is there indications of uterine torsion? Hence why the legs are not visible?
- If the calf is dead then a C-section is not possible.
- If the calf is dead then a foetotomy is indicated.
Investigation of the case
You perform a brief clinical examination followed by a sterile vaginal exam.
Look at these results.
List 3 treatment options in priority order, including pros and cons of each –
-
Forced extraction
- You start to attempt an extraction but the calf is far too big. If anything you might have damaged the cow trying to remove this calf.
- The farmer is getting frustrated with you so you decide to proceed with a c-section instead.
-
Complete fetotomy
- This could be an option and requires appropriate equipment and skill.
- Partial fetotomies are more common than complete fetotomies in the UK, but are unlikely to be sufficient in this case of a swollen emphysematous fetus in normal presention/posture/position with a clear indication of fetomaternal oversize.
- Aside from experience it is even more important to consider the status of the animal; she is down, clinically ill, the uterus is tightly wrapped around the emphysematous fetus. The condition of the calf and heifer suggests that bacterial invasion of the uterine cavity has already taken place. The described condition of the heifer does not bode well for the prognosis, even if the procedure can be performed successfully with a cost of approximately £250…
-
Caesarian section
- With difficulty, you perform the c-section, you are a little worried the infected uterine fluids may cause a peritonitis.
- (A low paramedian incision is often used to reduce the chance of contamination when extracting the emphysematous fetus via a caesarean section.)
-
Euthanasia
- Very likely the best option in this case, considering the state of the heifer as described in the clinical findings. It requires a clear and reasoned discussion with Mr Jackson where you explain the options, prognosis, animal welfare and balance this with his goals and expectations
-
Do nothing?
- The heifer is systemically ill and will not survive without adequate intervention. Is this acceptable welfare?
Discuss treatment plans further?
Call your boss:”Nahh… better put it to sleep, will cost a load to sort out and will likely get a septic peritonitis if you try and caesar it… a fetotomy would be ok… have you done one before…? No…? alright don’t worry then.”
Euthanasia: Very likely the best option in this case, considering the state of the heifer as described in the clinical findings. It requires a clear and reasoned discussion with Mr Jackson where you explain the options, prognosis, animal welfare and balance this with his goals and expectations.
Mr Jackson is now more concerned about the other heifers in the group. What do you advise?
Keep bull further away with better fencing. Induce the other heifers two weeks before parturition i.e. now! Chunk and check information when you next visit the farm so he completely understands everything that you have said and make it clear the bull will still be interested in females its just his sperm might not be as functional.
Herd level treatment and prevention
Arrange to pregnancy check the rest of the heifers asap; consider induction of calving of pregnant heifers using PGF2a and dexamethasone.
Inducing the heifers in the last weeks of gestation may not reduce the incidence of dystocia but it will concentrate the calvings into a short time period and enable Mr Jackson to monitor them more closely; awareness of difficulties will result in earlier intervention, and an assisted calving/caesarean will help the remaining heifers towards a brighter future.
Be aware of the consequences of inducing dairy heifers/cows; when using a short acting corticosteroid such as dexamethasone, the heifer will often not ‘bag up’ and milk production may not increase enough postcalving to keep her in the milking herd; make sure you manage expectations with Mr Jackson by clarifying the consequences of each option.
Prevention concentrates around heifer and youngstock management; review fencing and other options to prevent this from happening again. Discuss the ethical aspects of aborting heifers; how would this reflect on the farming industry if the general public was aware that vets and farmers consider this an acceptable management option?
What was the case outcome?
You’ve learned to be really clear in the future about explaining the possible effects of disease on breeding ability in bulls, including the fact that although disease may affect spermatogenesis and therefore fertility for about 6 weeks, they may be fertile much earlier on.
You return the following day and PD the other heifers. Two heifers are heavily in calf and you induce parturition with dexamethasone and PGF2a. Mr Jackson monitored both heifers closely and called you in respectively 48hrs and 72hrs after injection when calving started. Both heifers required a caesarean. In both cases a live calf was delivered and the heifers made an uneventful recovery.
