Friday, March 4, 2016

How Do Dogs Recognize Other Dogs?

How do dogs recognize each other, especially when their shapes and sizes are so different? For instance, how do they know that all the animals at the dog park are dogs?

Afghan and Pug

Researchers says they use visual cues.

Dogs have the largest morphological variety among all animal species.  (If humans had as much size variation we would stand between 3 to 12 feet tall, and weigh between 30 to 500 pounds.)

Two hundred pound Great Dane and three pound Yorkie
The researchers wanted to know if the vast variety of shape and size presented a challenge to dogs trying to recognize their own species.

They found that dogs form a visual category of dog faces. And they group those pictures of very different dogs into a single category, despite diversity. In other words, from Pug to Greyhound, Chihuahua to Great Dane, dogs immediately know a dog when they see one.

Scientific American has a really good article about the research.

Or read the journal article:

Visual discrimination of species in dogs, Animal Cognition, July 2013, Vol 16, Issue 4, pp 637-651

Friday, February 19, 2016

Dogs Have 13 Blood Types

That's a lot considering that:

  • Humans - 4
  • Horses - 8
  • Cats -3
  • Pigs -3
  • Cows - 9

About 60% of dogs are either DEA 1.1 negative or DEA 1.1 positive.  In the other 40%, blood type varies greatly.

Is blood type breed specific? Yes and No. A majority of individuals within these breeds have the same blood type:

  • Doberman
  • German Shepherd
  • Rottweiler
  • Great Dane
  • Golden Retriever
  • Greyhound
  • Dalmatian

But other breeds have great variation.

Interestingly, even when blood type is breed-specific in one location, it may differ from country to country. For instance, one blood type exists only in dogs from Australia, primarily in the German Shepherd population.

Scientists don't have an explanation for the many different blood types in mammals, including dogs and humans. Blood types likely evolved more than once, probably as immunity to pathogens. Different blood types may protect us from different diseases.

I want to know more about blood types in the wolf, but I couldn't find anything.  If you know, please comment.

 For more information ask your veterinarian. Also, you can read about canine blood types here.

Monday, February 1, 2016

What Breed of Dog are You?

The best dog quiz ever

Take the Gone to the Dogs quiz to find out what breed you are.
When you get to the site, press MUTTSCOPE. Then on the right side you'll see an icon with the words Click here to play what dog are you.  Then press the start button and respond to the questions. 

Dr. Barkman is a Soft Coated Wheaten Terrier.

Tuesday, January 19, 2016

Why Small Dogs Have a Lower Incidence of Cancer

Cancer mortality varies across breeds, from under 10 percent to higher than 60 percent. In general, small dogs weighing less than 20 pounds are at very low risk. For instance, the chance that a Chihuahua, Maltese, Miniature Pinscher and Pomeranian will get cancer is less than 18 percent.
Breeds with the highest risk include the Bernese Mountain Dog and Golden Retriever - upwards of 60%. (The average cancer risk in dogs is 27%. In humans it's 23%.)
 
Only 10% of Chihuahuas get cancer.
Cancer rate in Golden Retrievers bred
in North America is higher than 60%. 













Why do miniaturized dogs have a lower incidence of cancer? Scientists suspect that one reason might be low levels of IGF-1, a hormone that, along with growth hormone, affects bone and tissue growth.  Dogs under 20 pounds are small because of a mutation that puts the brakes on IGF-1 production.    
Although there are many causes of cancer, each type starts with alterations in genes that tell cells how to function, which triggers accelerated and uncontrolled cell growth. A lower level of IGF-1 is related to shunting growth in small dogs, so maybe it does the same to cancer cells.  
This journal article addresses the possibility of the link between size and cancer in dogs: The Size-Life Span Trade-Off Decomposed: Why Large Dogs Die Young.

Tuesday, January 5, 2016

Eye-Gaze and the Human/Dog Bond

When dogs stare into their persons' eyes (and vice versa), the gaze activates a hormonal response that reinforces their bonding system.

It's well known that oxytocin, the so-called cuddle hormone, strengthens human social ties.  In new love relationships, people produce higher levels of oxytocin. It's why mothers are heads over heels in love with their babies. 

And now scientists say it's why people who make gaga eyes at their dogs have more oxytocin in their blood, and why their dogs do, too.


Mutual gazing has an intense effect on both the dog and the owner.  The researchers suggest that human-dog interactions elicit the same type of oxytocin positive feedback loop as seen between mothers and their infants.  
One caveat though. Don't try this at home with a wolf.
In wolves, eye gaze signals aggression.
Better to look at your feet.
Read more in The New York Times or check out the the scientific journal article, Oxytocin-gaze positive loop and coevolution of human-dog bonds.

Sunday, December 20, 2015

Tail Wagging Side Dominance

"You might think a wagging tail is a wagging tail, but for dogs there is more to it than that.  Dogs recognize and respond differently when their fellow canines wag to the right than they do when they wag to the left. The findings show that dogs, like humans, have asymmetrically organized brains, with the left and right sides playing different roles."
Read the entire article at  Science Daily or see the October 31, 2015 issue of the Cell Press journal.





Monday, December 14, 2015

Canine Microbiome -

I published an article in the summer issue of The Bark magazine on the canine microbiome.  In summary - Kiss your dog. It's good for you in more ways than one.

Here's an excerpt:
"Affected by age, environment, ancestry, evolution, genetics and diet, microbial communities vary widely between species and across individuals within a species. A recent study suggests that our housemates—including the family dog—may also affect the composition of our personal microbial signature. 
If you and your significant other kiss, hug and/or share a bed with your dog, the three of you have more in common than you think. A study conducted by researchers at the University of Colorado, Boulder,  revealed several similarities: Adults who share a dog have more similar mouth microbes than those who don’t. Dog-owning families have more diverse and different microbial colonies than dogless households
Parents tend to share more kinds of mouth bacteria with their dog than they do their children. And children raised with dogs have a wider variety of microbes than dogless kids (Song et al. 2013). 
Whether these spit-swapped microbes serve a purpose or are just passing through is not clear. But research shows that children raised with dogs are less likely to be afflicted by eczema (Epstein et al. 2010) and asthma (American Society for Microbiology 2012)."
Read the entire article in this issue-
 canine microbiome.





Thursday, December 10, 2015

Identical Twin Dogs? It's Rare but Possible

I posted this originally in October of 2013, saying that identical twin puppies delivered in a single amniotic sac rarely if ever occur.  Well… I stand corrected. Several people have responded to the post describing identical twin pups in one of their litters.  This is what they said:

"I  have to say that until it happened to my dog, I never knew it could happen. 2 puppies, one sac with umbilical cord going from puppy to puppy and a 3rd cord going to mom. It looked like a Y or T. I just buried the babies as they did not survive. I could seal them up and send them to you if you wanted to see this yourself. Shocked the heck out of me - a seasoned and experienced breeder. My vet says this does happen just not very often."Anonymous 4-25-2015

"My dog had a litter of 15 on 11/12/15. She had a set of twins at 7:57am. 2 pups, one male on female, come out the same sac attached to the same placenta. So yes, it is possible! I couldn't get a picture as the mother quickly tended to them. The female twin is very tiny about a third her twin brothers size but she is doing well and is definitely a fighter."Samantha S 11-15-2015


"My dog just had identical twin girls, she had a couple of hours after birth of first pup, then delivery of second was much more of a struggle. When it finally came out she got straight in and began cleaning the sack away so I never got a good look immediately, but the slimy blob definitely seemed bigger than the first. When I lifted her leg to make sure she was getting the membrane off it's face, I realised it was actually 2 pups in the same sack, one laying on top of the other, both head first. They were identical, both cream, both females and even both exactly the same weight, at 174g each, whereas the first pup only weighed 145g also a female, but pure white".Mandy 12- 9- 2015

The original post is below:

Can dogs be identical twins, meaning two animals developed from the same fertilized egg, having the same genetic material and delivered in a single amniotic sac? The answer is somewhere between not likely and probably never.
That's just your reflection Bud, not your twin.
Puppies in a litter are usually fraternal twins or triplets and so on, no closer than you and your siblings, having the same mom and dad.

They can also be half sibs meaning they have the same mom, but different dads.


But monozygotic twins? The only foolproof way to identify identical twins is to use a DNA test, and no reports exist. Sometimes breeders report two pups in one placenta, but more likely the placentas grew together during the pregnancy.

Identical twinning in cats is
 fairly common.
What about pups with identical markings?  Random cell divisions that occur after the fertilized egg splits determine spot placement, along with where the fetus develops in the womb.  So two pups may look the same, but that doesn't mean they are identical.
Are these Aussie twin pups? Not likely.

Twin cows aren't unusual


Baby armadillos are  identical quadruplets.
Identical twins are fairly common in sheep cattle, cats, ferrets, deer, and humans, but identical twinning in dog just doesn't happen.


Just a band of brothers (and sisters)

Monday, November 9, 2015

Best Antique Dog Photographs

If you're charmed by antique photos with dogs in the picture, don't miss The Antique Dog Photograph Gallery.

The Pug with Bells
Blogger Lauren Goode has been collecting period dog photographs since 2009. She posts regularly and includes information about the breed, photographer and history behind the image. You can index her photos based on context, breed, photographer, and location.

The Greyhound in Durban

See all of Lauren's photos at

The Dalmatian and the Donkey