Recent reports have suggested that dog bites may follow specific weather patterns… But is this a real effect? Do we really need to take extra care on sunny days? Or is something else going on here? Vet blogger Lily investigates…

Why do dog bites happen?

Dog bites are usually a result of miscommunication between human and dog. Often the dog is communicating discomfort in some way, whether it be due to injury or wanting to protect a space or resource. They are stressed, startled, threatened, protecting food, toys, or their puppies. It is when that communication is ignored until the dog is forced to escalate their communication to a bite. Read more about the dog aggression ladder escalation here

What are the possible contributing factors leading to a dog bite?

Environmental factors 

Humans are shown to be affected by UV rays and heat. Dogs are 11% more likely to bite due to high UV levels and 4% more likely to bite on sunny days and 3% more likely on days with higher Ozone levels. In contrast, dog bite incidence slightly decreased (by 1%) on days with higher levels of rainfall.


According to research, more violent crimes in humans occur during hot weather and increasing temperatures. Studies have shown that in-species aggression is linked to rising temperatures across the animal kingdom too, notably in rhesus monkeys, rats, and mice. Interactions between species i.e., between humans and dogs, have also been studied and links between increased aggression and rising temperatures are found here too. 

Just like people who may feel hot, bothered, and sluggish in the warmer temperatures, our dogs can experience the same type of discomfort leading them to be less than forthcoming with family interactions. This is why it is important to help your dog stay cool on hot days. And ensure they have ample opportunity to get out of the heat, stay hydrated and actively cool off. 

UV radiation 

Higher levels of UV radiation (that which contributes to sunburn) have been associated with a higher incidence of human aggression but have also been shown to have links with more frequent incidences of dog bites. It has been shown that 90% of UV rays penetrate cloud; so days that aren’t overtly sunny but stickier and more uncomfortable could still be a problem. Darker stormy clouds don’t let UV light through as well as white, wispy clouds do. So being aware of the environment and how it might make you and your dog feel is important. 

Ozone levels 

At high concentrations, ozone has a strong smell, is highly reactive and triggers oxidative stress in the airways and impairs pulmonary (lung) function leading to inflammation and impaired cognitive (brain) function. Higher levels of ozone in the environment have been linked to a higher incidence of aggressive behaviour in humans and also more frequent bite incidences in dogs. 

During COVID-19 lockdowns, air pollution (including ozone levels in hotspots) decreased, but paediatric emergency department visits for dog bites increased. This suggests that other factors, such as forced proximity and victim factors may be a larger determinant in dog-on-human aggression.

Dog Factors 


It has been hypothesised that some breeds have a higher protective instinct or a higher natural aggressive drive and so may be more prone to eliciting bites. It certainly is documented that some breeds are represented more frequently in the incidence of dog bites to humans. Breed is a factor to consider when risk-assessing bite incidences. 


Research demonstrates bites more commonly involve intact male dogs. 

Castration/ Spay status 

Bites were more common from intact dogs of both genders who had not been neutered. This can be explained by hormonal factors influencing territorial drives or protective drives such as a bitch protecting their litter or an entire male dog protecting their home. 

Victim factors 


The incidence of dog bites was highest for both children and older adults. Children have to learn to interact with dogs and be taught appropriate behaviour to keep themselves safe. Given the right support they can form an incredible, lasting bond of friendship but this hidden danger is why young children and dogs should never be left alone unsupervised. Older adults with impaired cognitive function, likewise, may not be able to understand the dog’s behaviour cues which puts them at risk. 


Males were more likely to be bitten by dogs than females. 

Familiarity with the dog 

Research has found dog bites involving humans are more likely when the victim already knows the dog, and when the human initiates an attempt to interact with the dog. 

According to hospital-based surveys, the majority of dog bites happen in familiar surroundings, involving a family member (mostly a young child) bitten by the family pet. Interactions triggered by the child towards the pet dog appear to account for 86% of the bites recorded. 55% of these injuries required medical attention. Only 20% of dog bites occur outside the private home. Of these, only 5% of these needed any medical intervention and most resulted in no injuries at all. 

This information highlights how important it is to supervise interactions between pets and at-risk family members in the home at all times. 

Victim behaviour 

Is the observed increase in dog bites a consequence of the dog’s behaviour in response to heat or in response to human behaviour?

Research has already determined that in hot weather, days with higher UV levels or with increased ozone levels, humans are more likely to be aggressive, and we know that dog bites are more common when humans initiate the interaction, so it is possible that the incidence of bites occurs due to inappropriate interaction initiated by the human. Certainly, with respect to children interacting with dogs, I think this could be a factor as young children with a lack of understanding about correct and appropriate behaviour interactions with a dog represent the majority of bite incidences. 

On hot days, house doors are often left open for children and animals to enjoy free play between the house and the garden, at which time children and animals may not be supervised as they would normally. Additionally, children’s behaviours are usually more excitable on warmer days with the addition of novel stimuli such as paddling pools and ice cream. Such circumstances are perhaps ironically the perfect storm for accident and injury when considering an overstimulated child and/or dog or perhaps an older, hot, and bothered dog looking to get out of the heat and avoid excessive noise or rough play. 

We should also consider the case of dogs coming into contact with strangers on their own. Dogs may be more likely to be left outside unattended during the summer months when their owners are away for the day enjoying the sunshine. Understandably a dog encountering a stranger in their perceived territory could elicit biting behaviour and aggression towards strangers.

So, are dog bites more common on sunny days?

It appears that they probably are! There is no one reason why dog bites may occur more frequently in the summer. We have considered several possible explanations including, environmental factors, dog factors and victim (human) factors. The important take home is to make sure everyone in the family is taking precautions to keep themselves and their furry companions safe, whatever the weather and whatever you’re doing that day. 

What can you do to prevent dog bites on at-risk days?

Whatever the weather, make sure you always supervise young children and dogs, but especially on hot days, even those without a history of aggression could become a danger in the right environmental conditions. If you’re hot, bothered, and short-tempered, it’s likely your dog will be too. 

Ensure dogs have a quiet, cool place to hang out on hot days, ensure they have plenty of water and check to see if they need help cooling down with fans or icy treats. 

If the family are being particularly excitable or you are enjoying a livelier activity, keep an eye on our furry friends encase they become overstimulated and dysregulated. Accidents can happen. Consider a time-out for overexcited pooches before it’s too late. 

If your dog’s behaviour changes it could be a sign something is wrong, they are injured, feeling unwell, or experiencing heatstroke. If you are worried about your dog’s behaviour, contact your veterinarian for advice. 


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