Can you count the dogs?
Recently social media presented me with a graph that showed the number of dogs in the UK, from 2011 to 2013. According to this graph, the number goes up, steadily, from 7.6 to 9 million over 2011 to 2020, but then a clear jump to 12.5–13 million in 2021 and 2022. In 2023 the number dropped again to 12 million. The story that some people told with this graph was that (1) many people bought dogs during the pandemic, and (2) after 2022 a million of these dogs were killed. We will come back to those claims later.
It is important to state that there is no way of knowing precisely the number of dogs in the UK. There is no official register, and while microchipping is required by law, the companies who keep the register for the chips don’t give out their data. That means, every estimate of the number of dogs in the UK is based on survey work with much smaller samples.
Let’s look at the numbers I quoted a bit more in detail. The graph I mentioned doesn’t have errorbars, but from the fact that most of the numbers are full or half million, it seems that the numbers can’t be much more accurate than plus/minus one million. The source and methodology are hidden behind a paywall, but it states that it’s based on a sample of 8901 respondents. This means, the 12 million or whatever is not the actual number (as expected), it’s an extrapolation from a (hopefully) representative sample of respondents to 67 million people. Just with basic statistics follows that the uncertainty of that extrapolation has to be at least in the order of 0.5-1 million.
The number of respondents actually may point us to the source of the graph, an online survey comissioned by a pet food manufacturer association. The same organisation conducted a similar study in 2024 and found that the UK has 13.5 million dogs in 2024. So, the drop-off reported in 2023 must have been temporary, or a fluke, or just a result of the methodological uncertainty. They also state that the survey moved online during the pandemic. As a consequence, and they are clear about this, it is not possible to compare current data with data sourced prior to 2021.
It is easy to find similar studies, run by various pet-related organisations, with various degrees of rigour and transparency. The one published by PDSA, a veterinary charity, is pleasantly open about its methodology. According to their findings, the dog population stayed between 8 and 9 million from 2015 to 2021, and then rose to 10.2 million in 2022 and 11 million in 2023. In the latest report, PDSA reports a drop-off to 10.6 million. That’s in the ballpark of the results mentioned at the top, and it shows again the increase in numbers during the pandemic years. But notably, it does not show a sharp dropoff in 2023.
How does the PDSA study work? They collaborate with YouGov to conduct two surveys, one for a representative sample taken from the general population (sample size 10000), and one for pet owners (sample size 5258). Note that the second sample includes cat and rabbit owners, not just dogs. It also uses demographic data from the ONS, for example, to assess the size of households. The exact calculation to get the total population is not described, but from the sample size alone it seems clear that the error has to be quite substantial.
What have we learned? Well, for one, there is no evidence for a drop-off in dog numbers in 2023 compared to 2022. Taken all data together, from 2022 to 2024 the number of dogs seems to be somewhere between 11 and 13 million, depending on source. Broadly the number is going up, but the change in methodology around the pandemic makes it difficult to ascertain that the increase was particularly steep in 2020–2021.
There are a few peer-reviewed studies on total dog numbers in the UK, but they don’t help us for the post-pandemic years. A paper from 2010 shows that the number of dogs in the year 2006 was 10.5 million (with a 95% confidence interval from 9.6 to 11.4 million). For 2007, a follow-up study gave 11.6 million dogs in the UK (10.7–12.5). In 2011 a study found that the total number of pet dogs in the UK is 9.4 (8.1–11.5). All these numbers come with caveats and issues which are discussed in the literature. Comparing those historic, peer-reviewed results with current numbers, it seems fair to say that the dog population has probably increased somewhat over the last decade. But it is worth noting that the confidence interval for the numbers from 2006, 2007 and 2011 include numbers reported for 2022 and 2023. So, the increase in the dog population, if it is real, cannot be as huge as it is often claimed. These are just pet dogs, by the way. In addition there are perhaps 100000 dogs in shelters, plus an unknown number of strays. Both of these, unfortunately, seem to go up in recent years, but, as you might guess, we don’t have good data on this.
Coming back to the graph I started with: The usual story — lots of people bought dogs during the pandemic, only to discard them shortly afterwards — is just that, a story. There is some marginal evidence for the first part of it, but the second part is completely without factual basis, as unsatisfactory as the data is. The number of dogs stays at a high level, and there is no evidence that millions of people just euthanise their dogs when they can’t cope with it anymore. But maybe that is not the story people want to tell.
It may not be surprising at this point, but it’s worth mentioning that we do not know how many healthy dogs actually get euthanised every year in the UK. Euthanasia is the predominant cause of death for dogs in the UK, but most of these dogs are old, seriously ill, or injured. For shelter dogs, the figures I can find are around 10000 per year, with lots of uncertainty. But that’s only a part of it. Vets are regularly asked to euthanis healthy dogs, mostly due to behavioural issues. This is actually the leading cause of death in young dogs under the age of 3. However, of course, very few dogs die when they are young, maybe 1% or less. Absolute numbers are not reported anywhere, but let’s do a bit of approximate scaling, with a lot of caveats: Assuming a life expectancy of 12 years, about one million dogs die every year in the UK, and maybe 10000 of those will be under the age of 3. With the numbers from the studies quoted above, about a third of these would be euthanised due to undesired behaviour, so, a few thousand. This is a tragedy of course — these thousands of dogs should not have to die.
But it’s not the mass murder that some people read into the overall dog numbers. Because those don’t tell you that.
This doesn’t answer the question why people want to believe that a million dogs are killed in a year, just in the UK. That half of those who got a dog during the pandemic discarded their dogs shortly after. Why is that horror story so attractive? Part of that is probably confirmation bias — someone who deals with lots of problem dogs every day, like a vet or a dog trainer, finds this graph, confirmation bias kicks in, and bang. But this doesn’t explain why so many people who are not dog professionals seem to like that story as well. Perhaps people seem to want to believe that humans are horrible. They drive too fast, they don’t pick up after their dogs, and they are quick to discard their dogs when they don’t want them anymore. It’s always the others, an unseen, unsourced mass of evil. Humans have their issues of course, and it’s quite obvious that dogs often have to bear the consequences. But it’s important to keep all that in perspective.
