Investigators are exploring a possible link between dogs and the recent spike in cases of sudden onset hepatitis in UK children.
More than 160 cases have been recorded in the current outbreak but the reason for the increase is unclear.
Family questionnaires have shown "relatively high numbers of dog-owning families or other dog exposures", said the UK Health Security Agency, with 64 of 92 cases with available data mentioning dog exposure.
The UKHSA said "the significance of this finding is being explored" but that it could be a coincidental because dog ownership is common in the UK.
No one has died in the current outbreak, though 11 UK children have needed a liver transplant, and health authorities stress the risk of getting hepatitis is "extremely low".
Hepatitis is inflammation of the liver and is usually caused be a viral infection or liver damage from alcohol.
Jaundice (yellowing of the skin and eyes) and vomiting are the most common symptoms in the UK cases, which have mostly been in under-5s.
A common virus called adenovirus may be the cause of the surge and has been detected most often in the samples collected, said the UKHSA.
However, it's uncommon for adenovirus to cause hepatitis in previously well children and so investigators are looking for potential contributory factors.
Among these are previous COVID infection or a change in the adenovirus genome itself.
Another theory is that lockdown and social distancing may be factors, as children may not have been exposed to the usual common infections.
Good hygiene, including helping young children wash their hands, can help to prevent infections that can cause hepatitis, the NHS says.
"It's important that parents know the likelihood of their child developing hepatitis is extremely low," said Dr Meera Chand, the UKHSA's director of clinical and emerging infections.
"However, we continue to remind everyone to be alert to the signs of hepatitis - particularly jaundice, look for a yellow tinge in the whites of the eyes - and contact your doctor if you are concerned.
"Our investigations continue to suggest that there is an association with adenovirus and our studies are now testing this association rigorously."
Another 18 cases were recorded as of 3 May, bringing the total to 163, according to the latest UKHSA update.
The World Health Organisation (WHO) said this week nearly 300 probable cases of children with severe hepatitis had been detected in 20 countries, including Canada, Japan, the US and Israel.