Ask Dr. OES

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Dear Dr. OES,

I have a beautiful 6 month old female and have some questions about spaying: 

  • When will the OES breed, in general, be expected to reach puberty, and have her first heat?
  • What is the current clinical posture regarding spaying? Before or after the first heat? 
  • What are the pros and cons specific to this timing with regard to the OES breed?

 Wanting To Learn in Alden, IA


Dear Wanting To Learn,

Generally speaking, Old English Sheepdogs reach physically maturity by 18 months of age.  Some people think that maturity occurs with the bitch’s first heat cycle, but that is not true.  Growth stops when growth plates of the long bones close, although muscle development tends to continue at a lesser degree and the long bones may grow longer.

When Should I Expect Her First Heat?

Predicting the first heat cycle is difficult because it varies with individuals and occurs at different times.  For some, it may occur as early as 6 months.  For others, it could happen as late as 18 months of age.  Your breeder who knows his / her lines will have a better idea of when it may happen.  Bitches usually have heat cycles every 6 months, but that also varies by individual.  Marking on your calendar the time you first see vulvar swelling to the time it returns to normal will give you a good indication for the future.  Also, the cessation of bleeding does not mean that she is out of season.  The cycle lasts about 3 weeks with bleeding occurring during the 2nd week.

If and When Should I Spay?

If predicting the first heat cycle wasn’t hard enough, deciding if and when you should spay or neuter your Old English Sheepdog is even more difficult.  If you look in the literature, you will find pros and cons of spaying and neutering that contradict each other or that have little data to support the findings.  The studies often involve specific breeds that can’t be extrapolated to cover all breeds.  About the only thing that is clear is that a spayed or neutered dog cannot develop uterine or testicular cancer since those organs are removed, which is not very helpful information and is more common sense than scientific data.

The literature does have some generalized data that applies to most dogs but not all dogs.  Studies suggest that spayed and neutered dogs regardless of breed live longer than intact dogs, and the rate of urinary incontinence increases in spayed females due to decreased estrogen levels.  In some of the breeds studied, spaying or neutering increases the risk of certain cancers, while decreasing the risk of other types of cancers.  (In the Old English Sheepdog, increased risks of cancer associated with spaying or neutering have not been seen, as far as we know.)

Mammary Cancer Risks

The one cancer that has been well-researched and well-documented across all breeds is mammary cancer.  Studies show that spaying before the first heat cycle reduces the risk of mammary cancer to less than 1%.  Spaying after the second heat cycle results in a risk of about 25% of developing mammary tumors, although that risk does not continue to rise with the more heat cycles they have.  Approximately half of the mammary tumors seen in dogs are benign, and few of the malignant tumors are fatal.

Current Recommendations for Large Breeds

The current thinking regarding the timing of spaying or neutering a large breed dog is to wait until they are 18-24 months old to allow for physical maturity.  Veterinarians used to recommend spaying before the first heat cycle to avoid unwanted pregnancies, mammary tumors, etc., but waiting until the body has matured seems to be more beneficial in regard to bone and muscle development.  Both males and females need the hormones for proper growth, especially in large breed dogs.  Specific studies on spaying and neutering in the Old English Sheepdog have not been performed.



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