I have a male dog and I can’t help but notice his sexual organs look nothing like, well, mine. I really don’t want to google for “dog penis” - can anyone point me to an anatomical diagram of a male dog, or explain how things work down there? Some specific questions I have are:
[ul]
[li]How exactly does the neuter work? It looks like the scrotum is intact, and the incision is in front of it. Did they reach in from this incision to remove the testicles, or what?[/li][li]What are the two bulges that appear at the base of the penis when excited? It almost looks like he has two sets of balls.[/li][/ul]
The actual penis is normally housed within the dog’s sheath.
In most neuters , yes , the incision is made and the testes are removed . The scrotum usuallt shrinks back up .
The bulge is commonly called the bulb among breeders ; it swells within the bitch during breeding , and is what causes the tie after the dog ejaculates . Until the swelling goes down , it is almost impossible for the dog and bitch to break the tie . They will usually stand butt-to-butt during the tie , which , if you ask me , looks mighty uncomfortable for the dog . But I have never heard one complain 
.
Hope this helps .
As far as #2, when dogs mate, the base of the penis swells up and “ties” them together until after orgasm (which can last a while) is done. It’s entirely possible to spook a bitch during the act of mating and have her drag the male around by his penis. Now that’s instant wince for any men around…
A dog’s penis is very different from a humans. First of all, it contains a bone - the os penis. The whole thing lives in the prepuce (sort of a skin pocket) most of the time. For about 90%+ of a dog’s life, the penis stays in the prepuce and is not visiable. The smaller pink thing that sticks out sometimes is the end of the actual organ.
When dogs mate, the penis doesn’t become erect like a human’s (the bone keeps it straight). Although it does enlarge to some degree, it doesn’t get all that much bigger. There is an area towards the back that does enlarge a great deal (sorry, freshman anatomy is too long ago for me to remember the exact name of this part, and, like you, I can’t be bothered to look it up). As previous posters have mentioned - when this part enlarges inside the bitch’s vagina it essentially locks the dog and bitch together. Forced extraction at this point can seriously injur one or both of the animals. If rapid separation is desired, a bucket of cold water usually will cause the erection to go away quickly and voila.
The skin of the dog’s scrotum is extremely sensitive and heals quite poorly when incised - so it is avoided if all possible when dogs are castrated. Rather, the testicle is pushed up towards the inguinal ring from which it descended until it can be reached through an incision made in normal skin. Other animals don’t have the same scrotum skin issues, so they are cut directly when castrations are performed.
Other fun facts to know and tell:
One common veterinary term for castration is “brain surgery” - for obvious reasons.
The domestic animal with a penis most like a human’s (although it isn’t all that similar) is the horse. Like a person, the horse penis contains no bones, and erection is achieved through blood engourging the organ. Because of this, like a person, the erect horse penis is quite a bit larger than non-erect.
Thanks, very interesting. I assume it’s normal for neutered dogs to have swollen bulbs occasionally?
So when it comes out of the prepuce, it’s actually the prepuce retracting, not the penis enlarging?
And thanks on the info about scrotal skin. I’d seen my parents’ neutered cat so I was a bit surprised to see an intact scrotum on my neutered dog.
And I’m sure I (or the shelter) didn’t pay for neuticles.