Why do some dogs scratch with their paws after they eliminate?

I recently read a discussion on Facebook about the meaning of this dog behavior. Some people’s speculations about the reasons for the behavior included:

• Avoiding something or another behavior (displacement)
• Expressing anxiety
• Expressing boredom
• Relieving stress
• Expressing frustration
• Calming oneself
• Calming another dog
• Expressing enjoyment of a previous activity
• Being stressed
• Expressing high arousal
• Marking (territorial)
• Marking by scent
• Marking visually

Note that all but the last three of these have to do with an emotion or internal state.

I was interested in particular in the conjecture that the behavior was linked to some kind of stress. My dog Summer is a “scratcher” and she does it with what I observe to be exuberance and satisfaction. (You’ll see in the movie.) Interestingly, she doesn’t scratch only after eliminating. She will also scratch where there were scents of another dog’s elimination. Summer also lifts her leg to mark with urine. More on that later.

What Does the Literature Say?

Dirt scratching or scraping has been studied by ethologists. These are mostly observational studies, where numbers of canids were observed performing various elimination, sniffing, and marking behaviors. The behaviors are counted and the surrounding circumstances recorded. Dr. Marc Bekoff points out that it hasn’t been studied all that much in dogs though, compared to the study of other animals.^[1]Bekoff, Marc. “The Significance of Ethological Studies: Playing and Peeing.”Domestic Dog Cognition and Behavior. Springer Berlin Heidelberg, 2014. 59-75.  He and others are gradually filling in the blanks, however.

Here are some of the functions for ground scratching that ethologists have proposed:

• Dispersing scent from the dog’s urine or feces^[2]Peters, R.P., Mech, D., 1975. “Scent-marking in wolves.” Am. Sci. 63, 628–637.^[3]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848.^[4]Bekoff, M., Wells, M.C., 1986. “Social ecology and behavior of coyotes.” Adv. Stud. Behav. 16, 251–338.^[5]Sprague, Randall H., and Joseph J. Anisko. “Elimination patterns in the laboratory beagle.” Behaviour (1973): 257-267.
• Dispersing scent from glands in the dog’s paws^[6]Peters, R.P., Mech, D., 1975. “Scent-marking in wolves.” Am. Sci. 63, 628–637.^[7]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848.^[8]Bekoff, M., Wells, M.C., 1986. “Social ecology and behavior of coyotes.” Adv. Stud. Behav. 16, 251–338.^[9]Sprague, Randall H., and Joseph J. Anisko. “Elimination patterns in the laboratory beagle.” Behaviour (1973): 257-267.^[10]Petak, Irena. “Patterns of carnivores’ communication and potential significance for domestic dogs.” Periodicum biologorum 112.2 (2010): 127-132.^[11]McClanahan, K., & Rosell, F. (2020). Conspecific recognition of pedal scent in domestic dogs. Scientific Reports, 10(1), 1-9.
• A visual demonstration in real time, in the presence of other dogs^[12]Kleiman, D., Eisenberg, J.F., 1973. “Comparisons of canid and felid social systems from an evolutionary perspective.” Anim. Behav. 21, 637–659.^[13]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848.^[14]Petak, Irena. “Patterns of carnivores’ communication and potential significance for domestic dogs.” Periodicum biologorum 112.2 (2010): 127-132.
• A visual demonstration in the form of leaving marks on the ground^[15]Kleiman, D., Eisenberg, J.F., 1973. “Comparisons of canid and felid social systems from an evolutionary perspective.” Anim. Behav. 21, 637–659.^[16]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848.^[17]Sprague, Randall H., and Joseph J. Anisko. “Elimination patterns in the laboratory beagle.” Behaviour (1973): 257-267.

Note that none of these hypotheses is linked to an emotion, although one source did note that ground scratching was seen more often “when the individual was aggressively aroused.”^[18]Petak, Irena. “Patterns of carnivores’ communication and potential significance for domestic dogs.” Periodicum biologorum 112.2 (2010): 127-132. The main discussion revolves around function, and even then, the conclusions are very circumspect. Dirt scratching may be communication to other dogs, but speculations by ethologists about the content of that communication are still very conservative.

This is a valuable reminder to me that as much as we would love to, we can never know exactly what is going on in our dogs’ minds.

What’s the Smelly Feet Thing About?

One of the hypotheses for the function of the behavior is that glands on the dogs’ paws may give off a scent, and that scratching may deposit and disperse it. What are these glands? Most sources mention sweat glands.

“…paw pads in dogs are one of the few locations that contain eccrine sweat glands. In dogs, apocrine glands are the major type of sweat gland, and the distribution of eccrine sweat glands is limited to the footpads and nose.”  ^[19]Miller, William Howard, et al. Muller and Kirk’s Small Animal Dermatology 7: Muller and Kirk’s Small Animal Dermatology. Elsevier Health Sciences, 2013.

However, there are other glands that may be involved:

“…It has been suggested that the scratching action itself may leave scent in the environment produced by either interdigital glands, sweat glands on the foot pads, or sebaceous glands in the fur between the toes.” ^[20]Serpell, James, ed. The domestic dog: its evolution, behaviour and interactions with people. Cambridge University Press, 1995.

Since I first published this post, there has been a study of “pedal scent,” scent from the paw glands, in dogs. The researchers found that “dogs recognize scent taken from the pedal glands from other dogs, although the extent to which they use this information to determine the sex of the scent depositor remains unclear.”^[21]McClanahan, K., & Rosell, F. (2020). Conspecific recognition of pedal scent in domestic dogs. Scientific Reports, 10(1), 1-9. They found some differences in how male and female dogs sniff—different right and left nostril preference in females. I think I see Summer switching nostrils when sniffing poop in the movie below at about 1:35.

Male vs. Female Behaviors

Two studies by Marc Bekoff showed that approximately the same percentages of male and female dogs performed ground scratching (about 10%), but also that the males who ground scratched did so much more frequently than the females. ^[22]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848. ^[23]Bekoff, Marc. “Scent marking by free-ranging domestic dogs: Olfactory and visual components.” Biology of Behavior, 4, 123-139. Another study showed that among females, those who were spayed were more likely to scratch than those who were intact and not in estrous. (Females in estrous were not included in the study.) ^[24]Wirant, Sharon Cudd, and Betty McGuire. “Urinary behavior of female domestic dogs (Canis familiaris): influence of reproductive status, location, and age.” Applied Animal Behaviour … Continue reading

The same study also found that females four or more years old directed the majority of their urinations at objects in the environment (marked) and directed more of their urinations when walked off their home area than when walked within their home area. Both of these are true for Summer.

Raised leg urination such as many male dogs perform has also been theorized to have the function of visual display, since it is sometimes performed without urination.^[25]Bekoff, Marc. “Ground scratching by male domestic dogs: a composite signal.”Journal of Mammalogy (1979): 847-848.^[26]Cafazzo, Simona, Eugenia Natoli, and Paola Valsecchi. “Scent‐Marking Behaviour in a Pack of Free‐Ranging Domestic Dogs.” Ethology 118.10 (2012): 955-966. Male dogs have also been observed to raise their legs more frequently to urinate when in the presence of another dog.^[27]Bekoff, Marc. “The Significance of Ethological Studies: Playing and Peeing.”Domestic Dog Cognition and Behavior. Springer Berlin Heidelberg, 2014. 59-75. Some female dogs raise their legs as well, including Summer.

So What Does Summer Do?

The movie shows Summer enthusiastically scratching the ground in several different situations:

1. After squatting to pee;
2. After raising her leg to pee;
3. Immediately after entering an area with interesting smells and without eliminating at all; and
4. After smelling another dog’s droppings (also without eliminating).

If Summer’s behavior is functional, and not some kind of twisted evolutionary leftover, it may support the “dispersing odor from the paws” hypothesis. See what you think.

Link to the movie about ground scratching for email subscribers. 

Function vs. Emotional State

I’m not an ethologist; I’m a pet owner. So while I’m fascinated with the possible function of the behavior of scratching, I’m also interested in my dog’s emotional state when she does it. My observation is that she is enjoying performing a natural doggie activity. The prompts for her behavior seem to be scents, nothing more complex than that.

Summer is a primal sort of dog. Her breeding is so mixed that she resembles a village dog in all but her double coat (she could fit in well as a “northern” village dog, though). She has a strong prey drive and scavenger drive. And although our bond is strong and she loves doing things with me, her natural inclinations are very, very dog-y. In many ways she is more “wild” than my feral-born dog, Clara, who appears to have a wealth of “I like to partner with a human” genes. Go figure.

Clara has never scratched in her life, as far as I’ve seen, but she does lift her leg to mark when she pees. But Summer seems to love scratching the dirt. You could say she gets a real kick out of it.

How about your dogs? Males, females? When do they do it? What is their demeanor when doing so? Do tell!

 Related Post and Page

• On Dr. Patricia McConnell’s blog: Why Do Male Dogs Scent Mark So Much?
• Dog Body Language Posts and Videos

© Eileen Anderson 2014