Vet Check

Vet Check Breeding, Timing and

Cycling in the BitchArticle by Dr Jasmin Hyatt BVSc (Hons) DipACT MANZCVS (reproduction) Veterinary Reproduction Consultancy Pty Ltd (02) 6301 9550, Orange, NSW

Determining the optimal time for breeding of a bitch in heat is not as simple as one might think! There is significant variation in the behaviour each bitch shows on her most fertile days, meaning we cannot rely on behavioural and anatomical changes to give us the best chance for conception. This is especially important when you are using stud dogs that may have poor fertility (be it because of old age, previous injury or infection), or when performing Artificial Insemination with fresh or frozen semen.

Thankfully we have additional tools available that, in combination, enable us to ensure breeding occurs during the bitch’s period of maximum fertility.

Physical and Behavioural Changes (Low accuracy)

The following table shows the changes you will see externally and behaviourally in bitch’s in heat. Usually those found in mid-late heat indicate increased fertility. It is important to remember that these changes can be used as a guide only. Many bitches will show receptive behaviour and bleeding changes at times OTHER THAN their fertile periods and reliance on these changes alone significantly reduces her chance of pregnancy.

Early in ‘heat’ (proestrus) Mid to late ‘heat’ (estrus)

Behaviour Attractive to male

But not receptive to mating Receptive to mating (including backing up, standing for male)

‘Flagging’ (lifting tail up & waving side-to-side) Vulva Swollen, turgid (firm) Softens, reduces in size, becomes wrinkly Vulval Discharge Bloody, red Lightens in colour and eventually becomes clear

Vaginal Cytology (Moderate Accuracy)

A veterinarian taking a cotton swab of the top layer of cells in the vagina tells us a lot about where the bitch is in her cycle. It is a simple, cheap and instant procedure which many vets can interpret. If confidence is lacking here at VRC we can interpret microscopic images remotely if your vets send images through. When a bitch gets closer to her peak fertile period she begins to build up layers of cells in her vagina. These function to protect the bitch both from the physicality of mating and entry of bacteria at the time of mating. As cell layers build up, the top layer of cells becomes further from the blood supply, changing the appearance of the top layer cells seen under the microscope from healthy ‘poached eggs’ (round, large central circle) to dying ‘fried eggs’ (flat, irregular shape), telling us she is nearing her peak fertile period. At the time of fresh insemination or natural mating we want to see >80% of the cells looking like fried eggs.

Progesterone Hormone Testing

At the beginning of a bitch’s ‘heat’, or estrus cycle, the hormone ‘Estrogen’ increases. Estrogen functions to prepare the reproductive tract for breeding and we can visualise these changes externally (like the swelling of the vulva, and the bleeding).

Then in the middle of their ‘heat’ when they are closing in on their most fertile time, estrogen levels start reducing and the hormone ‘‘Progesterone’ (P4) begins to rise. Progesterone hormone is measured by a blood test. Specific levels of Progesterone correlate with when the bitch ovulates her eggs. Following the subsequent rise in the hormone confirms she has indeed ovulated and then determines when the eggs are ready for fertilisation. This continual monitoring relative to P4 rising is the reason why we rely on the trend of P4 rising over a few blood tests, rather than one specific reading to determine best day for insemination. Due to their unique hormonal cycling, unfortunately we cannot ‘short cycle’ heat cycles in dogs like we can in other species like cattle, sheep and horses! However, it is important record the time between heats for each bitch as it can influence likelihood of conception: 1. SHORT time between heats (<5.5 months): The uterus in the bitch undergoes a lot of stress during the ‘heat’ and it needs 6 months to recover, regardless of if she becomes pregnant or not. For this reason, we know that intervals of <5.5 months between heats are associated with reduced conception and fertility, by about 30100%. If this is occurring frequently in individuals there are medications we can prescribe to lengthen the interval between heat cycles however you will need to contact us at VRC or a reproduction veterinarian to discuss.

2. LONG time between heats (>10 months): Whilst this has no impact on the bitch’s fertility as such, bitches that have a long time in between heat cycles can cause frustration if you are wanting to breed from them!

There are methods that we can use if the interval since her last heat has been confirmed as >10 months that will induce estrus in these girls; again you will need to contact us at VRC or a reproduction veterinarian to discuss.

Optimal breeding timing requires all the above tools to be used in combination and assessed by a veterinarian with accurate knowledge and experience. At VRC we use specialist knowledge, skills and vast experience in canine breeding to determine the optimal time for breeding for all inseminations performed at VRC. We also offer an Ovulation Timing consultation service for breedings (natural matings or vaginal AI) performed externally, assessing progesterone levels and cytology to determine the best day for breeding. Please contact us for more informa

A National Registery for pure bred working border collies, our aim is to maintain the stud book and promote the responsible breeding of the working border collie within Australia.

Offering members access to the online stud book, provenance in bloodlines and pedigrees.

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CANINE BREEDING SOLUTIONS TAS SERVICES

include: • Storage of semen under liquid nitrogen. • Ability to do site visits within Tasmania. • In house Progesterone testing. • Preparing chilled semen for transport. • Semen collection and evaluation. • Artificial Inseminations.

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GRAEME WRIGHT – HISTORY

• 40yrs+ breeding and exhibiting bull terriers. • Imported bull terrier semen from USA in 2002 to improve lineage and health. • 2007 Completed the world known Camelot Farms freezing system course. • Accredited Greyhounds Australasia. • Accredited ANKC (Australian National Kennel Control). • Accredited Dogs Tasmania. • Accreditation in Microchipping (Animal Industries Resource Centre). • Invited to Judge at the Dutch Bull Terrier Intercountry Competition.