Veterinary Articles and Case Examples

What age to spay or neuter my dog?

Posted on in Canine Cruciate Ligament Rupture, Dog Hip Dysplasia, Prevention, Puppy Care 3 Comments

What age to spay or neuter my dog?

(Part 1)

 

Sometimes I yearn for the ‘good ol’ days’.  Back then, if a client wanted to know when or at what age to spay or neuter their dog, the dialogue went like this:

Client: “What age should I spay (or neuter) my dog?”

Me: “At six to seven months.”

Client: “Ok.”

… and then we would talk about something else.  It was a quick and easy conversation that required very little thought.

Now when a client poses that same question, my answer starts with “Well, that depends…”, and then devolves into a ten minute lecture full of conflicting information.  It is no longer a simple question with a simple answer*, and my advice differs depending on who I’m talking to.

The incidence of orthopedic conditions such as cruciate ligament rupture or hip dysplasia are affected by the age that the dog has been spayed or neutered

Orthopedic conditions such as cruciate ligament rupture or hip dysplasia are affected by the age that the dog has been spayed or neutered

*Ironically, I had first started writing this blog on the flight back from the WAO worlds in Spain just a few months ago, and since that time more information has come forward that complicates the issue even further.  Now the question isn’t just “At what age should I spay or neuter my dog?” but also “Instead of a spay or neuter, should I consider a vasectomy or tubal ligation for my dog?”

 I was originally going to incorporate both questions into the same blog, but that just made my long rambling explanation even longer, so I decided to tackle the vasectomy/tubal ligation question in part #2.  So for now, let’s just address the question of what age to spay or neuter your dog.

 So, where was I?  Oh ya….

The reason why this question is so much more complicated to answer these days is because now we know a lot more than we used to about the effects of spaying or neutering at an early age.  There are benefits and there are drawbacks. We’ve known about the benefits for some time but have only learned about the drawbacks more recently.  Here is an overview of the many factors to be considered:

 Mammary Tumours

Exiting the tunnel at the BC/Yukon regional agility championships

Exiting the tunnel at the BC/Yukon regional agility championships

Mammary tumours are the single most common type of tumour found in in-tact female dogs.  Although most dog mammary tumours are benign, as many as 1 in 5 in-tact female dogs will develop malignant breast cancer in their lifetime.1,2  Other research has shown that the risk of breast cancer is almost non-existent in dogs that have never gone through heat.  By spaying your dog before the 1st heat, you reduce the chance of breast cancer by 99.5% compared to intact dogs.  By spaying after the 1st heat but before the second heat, you reduce the chance of breast cancer by 92%.  If you fail to spay your dog before 2.5 years of age, or before they have gone through 2 heats, your dog is just as likely to develop malignant breast cancer as a dog that has not been spayed at all3. However, spaying after the 2nd heat may still reduce the chance of benign mammary tumours from forming4.

 Bottom Line: Spaying before your dog’s 1st heat, and especially before the 2nd heat greatly reduces the chance of developing malignant mammary tumours during their lifetime.  Spaying after the second heat won’t reduce the incidence of malignant cancer but may reduce the chance of benign cancer (and the surgery that goes with it).

 Urinary Incontinence

Urinary incontinence is uncommon in intact female dogs, but relatively common in spayed females.  The incidence of urinary incontinence due to spaying is estimated to range from 3 to 21%, depending on the researcher5-18.

Other factors are at play as well, including breed genetics and size of the dog. One study of boxers found that 71% were likely to develop urinary incontinence if they were spayed after their 1st heat, but if they were spayed shortly before their 1st heat, that risk could be cut in half19-21.

Another study found that dogs spayed before 3 months of age were more likely to develop urinary incontinence22.

 Bottom Line:  Spaying your dog increases the chance of urinary incontinence.  It would appear that to minimize this risk (in boxers anyway), the best time to spay your dog is shortly before her 1st heat.

 Musculoskeletal Effects

This patient received a TPLO to repair a ruptured cruciate some time ago

This patient received a TPLO to repair a ruptured cruciate some time ago

It has been demonstrated that spaying or neutering before your pet is fully grown won’t change the rate of growth, but it will delay the closure of growth plates23,24.  This results in a longer leg length when compared to intact dogs.

It is also believed that this may contribute to a steeper slope of the tibial plateau, which has been identified as a cause of cruciate ligament rupture.  Spayed or neutered dogs are two to three times as likely to rupture their cruciate ligaments as intact dogs are25,26.  Spaying females before six months of age makes them 1.6 times as likely to rupture their cruciate ligaments26. At this time, there is no reason to believe that spaying or neutering a dog after it is fully grown predisposes it to cruciate disease.  One school of thought is that the later you delay the age of spaying/neutering, the less the chance of developing cruciate disease, up to 17 months of age.  This theory is supported by the data that will be discussed in part 2 of this blog.

One study found that 6.7% of dogs neutered before 5.5 months of age developed hip dysplasia, whereas dogs neutered between 5.5 and 12 months of age only had a 4.7% incidence27.

 Bottom Line: Delaying spay and neutering until after your dog is fully grown will reduce the chance of rupturing the cruciate ligament down the road.  Waiting until your dog is at least 6 months of age will reduce the chance of developing hip dysplasia.

  Behavioural issues

The increased incidence of aggression and other undesirable behaviours in intact males is well documented28-32.  Neutering before the onset of puberty is one way to decrease the chance of these behaviours from manifesting.  Researchers concluded that neutering decreases inter-dog aggression by 62%, and roaming by 75%.  Dogs neutered earlier in life tend to be less reactionary33,34.

 Bottom Line: To avoid aggression and other undesirable behaviours, neuter male dogs before puberty.

 So what do you recommend?

Again, the bottom line answer is “Depends”.  It depends on who the client is, and who the dog is.

 Shelter Dogs

If the client represents an animal shelter, whose primary concern is to not contribute to the pet overpopulation problem, I recommend spaying or neutering all dogs before they get adopted out, from 7 weeks of age upward.

 Non-Shelter Dogs

 Female Dogs

For the owners of female dogs, one has to weigh the risks of malignant mammary cancer against those of potential cruciate ligament rupture or hip dysplasia.  If I had to choose between the two, I would rather have a ruptured cruciate ligament than malignant cancer.  For that reason I generally recommend spaying as late as possible before the first heat – 7 months of age in smaller dogs, but closer to 10 months in very large dogs.  That is what I would do if it were my dog, except of course this issue gets more complicated with part 2 of this blog.

However, for working, or competition, or otherwise very athletic dogs, cruciate ligament rupture is not something to be taken lightly.  For that reason, some owners take the opposite approach and make it a priority to minimize cruciate disease by not spaying their dog before 17 months of age, and cross their fingers that she doesn’t go through a second heat before then.  Others choose to split the difference and spay their dog at 17 months of age, or 5 months after her first heat, whichever comes 1st.  In doing so, they still maintain a 92% reduction in the likelihood of breast cancer, and minimize the risk of cruciate ligament rupture at the same time.

 Male Dogs

Other factors can also play a role in the decision of when to spay or neuter – these two testicles came from the same patient, but one was cryptorchid or “retained” inside the body wall, so never grew to a normal size. Retained testicles are more likely to develop testicular cancer.

Other factors can also play a role in the decision of when to spay or neuter – these two testicles came from the same patient, but one was cryptorchid or “retained” inside the body wall, so never grew to a normal size. Retained testicles are 13 times more likely to develop testicular cancer.

Male dogs don’t face the same risk for malignant breast cancer as a result of not being neutered before puberty.  However, the onset of puberty can lead to undesirable behavioural issues.

For routine family situations, I recommend neutering male dogs before puberty.

For working, or competition, or otherwise very athletic dogs, many owners elect to delay neutering until 17 months of age.  They monitor their dog for behaviour changes, and respond by neutering earlier if they see unwanted changes following the onset of puberty.

All owners who delay spaying or neutering until after puberty need to remain hyper diligent about preventing unwanted puppies.  The only way to guarantee that a sexually mature dog cannot reproduce is to have a vasectomy or tubal ligation performed.

I hope this helps… It’s a complex issue with no clear best answer for all situations.  Hopefully though, by learning about the major pro’s and con’s, you are in a better position to decide what is best for your individual situation and for your pet.

As promised, part #2 of this blog will be posted soon.  It will discuss the concerns with spaying or neutering your dog vs. electing for a vasectomy or tubal ligation instead.

 Footnotes:

 

1 Dorn, C. R., et al. J Natl Cancer Inst 1968, 40, 307-318.

2 Moulton, J. E., et al. Vet Pathol 1986, 23, 741-749

3 Schneider, R., et al. J Natl Cancer Inst 1969, 43, 1249-1261

4 Phillips, B. S., Western Veterinary Conference, 2002

5 Angioletti, A., et al. Veterinary Research Communications 2004, 28 Suppl 1,

153-155

6 Arnold, S., et al. Schweizer Archiv für Tierheilkunde 1989, 131, 259-263.

7 B.S.A.V.A. Veterinary Record 1975, 96, 371-372.

8 Blendinger, C., et al. Tierarztliche Praxis 1995, 23, 291-299.

9 Holt, P. Journal of Small Animal Practice 1985, 26, 237-246.

10 Joshua, J. O. Veterinary Record 1965, 77, 642-646.

11 Okkens, A. C., et al. Journal of Reproduction and Fertility Supplement 1997, 51, 227-231.

12 Okkens, A. C., et al. Tijdschr Diergeneeskd 1981, 106, 1189-1198.

13 Osborne, C. A., et al. In Current Veterinary Therapy Kirk, RW., Ed.; WB Saunders:1980, 1128-36.

14 Reichler, I. M., et al. Theriogenology 2005, 63, 2164-2180.

15 Ruckstuhl, B. Schweizer Archiv für Tierheilkunde 1978, 120, 143-148.

16 Stöcklin-Gautschi, N. M. Dissertation Vet.-Med. Fakultät der Universität Zürich: Zürich, 2000.

17 Stocklin-Gautschi, N. M., et al. Journal of Reproduction and Fertility Suppl. 2001, 57, 233-236.

18 Thrusfield, M. V. Veterinary Record 1985, 116, 695.

19 Arnold, S., et al. Schweizer Archiv für Tierheilkunde 1989, 131, 259-263.

20 Stöcklin-Gautschi, N. M. Dissertation Vet.-Med. Fakultät der Universität Zürich: Zürich,

2000.

21 Reichler, I. M., et al. Theriogenology 2005, 63, 2164-2180

22 Spain, C. V., et al. J Am Vet Med Assoc 2004, 224, 380-387.

23 Root, M. V., et al. Vet Radiol Ultrasound 1997, 38, 42-47.

24 Salmeri, K. R., et al. J Am Vet Med Assoc 1991, 198, 1193-1203.

25 Slauterbeck,J. R., et al. Clinical Orthopaedics and Related Research 2004, 301-305.

26 Witsberger TH, Villamil JA, Schultz LG, Hahn AW, Cook JL, 008, Prevalence of, and risk factors for, hip dysplasia and cranial cruciate ligament deficiency in dogs. J Am Vet Med Assoc 232, 1818-1824

27 Barnes K, Baltzer W, Incidence of cranial cruciate ligament rupture in dogs ovariohysterectomized at less than six-months of age, Veterinary Orthopaedic Society 39th Annual Conference, Crested Butte Co, 2012

28 Spain, C. V., et al. J Am Vet Med Assoc 2004, 224, 380-387.

29 Borchelt PL. Aggressive behavior of dogs kept as companion animals: classification and influence of sex, reproductive status, and breed. Applied Animal Ethology 1983;10:45-61.

30 Write JC, Nesselrote MS. Classification of behavioral problems in dogs: distributions of age, breed, sex, and reproductive status. Applied Animal Behavior Science 1987;19:169-78.

31 Hopkins SG, Schubert TA, Hart BL. Castration of adult ale dogs: effects on roaming, aggression urine spraying, and mounting. Journal of the American Veterinary Medical Association 1976;168:1108-10.

32 Maarschalkerweerd RJ, Endenburg N, Kirpensteijn J, Knol BW. Influence of orchiectomy on canine behaviour. Veterinary Record 1997;140(24):617-69.

33 Neilson JC, Eckstein RA, Hart BL. Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior. Journal of the American Veterinary Medical Association 1997;211(2):180-82.

34 Hopkins SG, Schubert TA, Hart BL. Castration of adult ale dogs: effects on roaming, aggression urine spraying, and mounting. Journal of the American Veterinary Medical Association 1976;168:1108-10.

35 Maarschalkerweerd RJ, Endenburg N, Kirpensteijn J, Knol BW. Influence of orchiectomy on canine behaviour. Veterinary Record 1997;140(24):617-69.

 

 


Radiograph Abnormality

Posted on in Radiographs 3 Comments

Can you identify the radiograph abnormality:

What is your diagnosis?

hemivert bottle cap

Radiograph abnormality answer:

This dog has an abnormally short 7th lumbar vertebra.  Notice how much smaller the furthest vertebra on the right is when compared to it’s neighbours.  This is a genetic issue he was born with, and is more common in pugs, boston terriers, bulldogs etc.  There is also some degeneration of the lumbosacral joint.

Also, for some reason, this dog has been throwing up a lot.


How long does it take for a broken bone to heal?

Posted on in Broken bone, Case Reports, Radiographs 14 Comments

How long does it take for a broken bone to heal?

 

I’m frequently asked how long it takes for a broken bone to heal, especially by owners who are dreading the prospect of keeping their hyperactive dog on short leash walks.

Bone healing time varies depending on several factors including the age of the dog or cat, the location and complexity of the fracture, the amount of associated soft tissue damage, and the type of repair that was performed.

Wire in femur

Residual wire in old fracture: This was a dog who presented for evaluation of the cruciate ligament (notice the effusion and arthrtis in the knee joint). As an incidental finding it looks like this dog had a femoral fracture when it was quite young. The original repair was likely a pin and wire, with the pin being removed afterward. As the bone grew, it engulfed the wire, which is why the diameter of the wire loop is less than that of the adult bone.

Age: Younger dogs or cats heal faster. They are already producing new bone in order to grow, and the cellular /chemical processes for growing bone are the same as those needed to heal a fracture; enzymatic momentum is on their side. Juvenile pets heal broken bones 2-4 weeks faster than adult pets.

Fracture location: Regions with an abundant blood supply heal faster. Some regions are easier to immobilize than others and immobilization acclerates repair.

Fracture complexity: A simple two piece fracture with no displacement of the bone ends and no disruption of the surrounding soft tissue is going to heal much faster than a high energy fracture with many broken fragments that are widely displaced. Infection slows the healing process even further.

Associated soft tissue damage: Again, regions with an abundant blood supply heal faster. Soft tissue damage compromises blood supply during the initial healing stages. Extensive soft tissue damage in a region that already had minimal soft tissue (e.g.: the front leg just above the wrist) doubly complicates healing.

Healed Femoral Fracture

This is another view of the same dog. Notice that the associated hip dysplasia. Unilateral hip dysplasia can be the result of injury during puppyhood and failure to properly weight bear on the limb as the hip joint is developing. A comprehensive rehabilitation program that encourages early and full weight bearing after surgery may reduce the chance of this happening.

Type of repair: A perfect repair immobilizes the bone without disrupting any of the surrounding soft tissue. This is not always possible to achieve, but it is something that surgeons strive for. In developing a treatment plan and/or discussing your therapeutic options (e.g.: casting or splinting vs. surgical repair), your surgeon will automatically gravitate toward the therapy that will offer the most rapid healing.

For most adult dogs or cats, broken bone healing time is 8 to 12 weeks.  In puppies or kittens, broken bone healing time is 6 to 9 weeks.  Complicated fractures can take as much as 16 weeks.

Delayed Union and Non-Union Fractures.

If a fracture is not healing as fast as expected, it is called a “delayed union” and may just need more time. If that same fracture is given more time and nothing changes, it is called a Non-Union.

Non-Unions require further intervention, which usually means more surgery. Supplementing or changing the type of repair, stimulating blood flow by debriding tissue, and/or adding a bone graft are typical treatments.