The Kennel Club has confirmed it is looking into reports that up to six dogs were poisoned at this year's Crufts show.
It comes after an Irish setter called Jagger died after allegedly eating beef laced with poison at the prestigious dog show.
According to the Daily Telegraph, several other dogs including a West Highland white terrier, an Afghan hound and a Shih Tzu were also sick after the show at the Birmingham NEC.
The spate of illnesses has sparked concerns that one or more people may have been poisoning the dogs.
Mylee Thomas's Shetland sheepdog Myter Eye to Eye is thought to have been poisoned the day after the Irish setter was killed. She said she thought her dog was targeted by an expert whereas Jagger had been randomly targeted.
Mrs Thomas told the Daily Telegraph: "The setter was poisoned the day before my bitch, and I don't think there is a link between the two.
"I think that one (Jagger) was someone who had randomly targeted them because a lot of people don't agree with Crufts."
But the Kennel Club, which organises Crufts, said no other dog owners have contacted them to report suspicions of poisoning.
A spokeswoman said they are looking into the reports, but stressed that no formal investigation has been launched because they have not got any direct information to act upon.
She said: "The facts surrounding Jagger's sad death are still being established. With regards to speculation about any other incidents involving other dogs, we must stress that these are at this stage just rumours.
"There are any number of reasons why a dog may display symptoms such as sickness and should a dog fall sick there are vets at Crufts who will examine the dog in question and file a report."
She added: "As with any international competition rumours of sabotage do occasionally surface. This of course is not in the spirit of competition and will not be tolerated.
"Anyone caught attempting to deliberately sabotage another competitor's performance, particularly if a dog's welfare is put at risk, will face severe disciplinary action, which could include a ban on competing at all Kennel Club licensed events.
"Furthermore anyone who puts a dog's welfare at risk could face prosecution under the Animal Welfare Act."
No vets have raised concerns about poisoning and there have been no official complaints from any other owners at Crufts, she added.
Reports other dogs may have fallen victim to poisoning came as the co-owners of Jagger vowed to continue competing in the world famous dog show.
Dee Milligan-Bott and her husband Jeremy told reporters they wished to be left alone to grieve for Jagger but would return to Crufts next year.
Speaking outside their home near Wigston, Leicestershire, Mr Bott offered his congratulations to the winning Scottish terrier and the gun-dog group runner-up he competed against at this year's show.
Mr Bott said: "Both were worthy winners. What a shame this incident has marred this, the biggest success of their careers.
"Crufts is the best show in the world and we will certainly be back again next year competing. This one isolated incident will not spoil our enjoyment to show and compete with our lovely dogs."
The three-year-old Irish setter, whose pedigree name is Thendara Satisfaction, collapsed and died after returning to Belgium from the show at Birmingham's NEC.
Jagger, who came second in his class at the show on Thursday, is also part-owned by Belgian Aleksandra Lauwers.
The animal's joint owners have said that beef laced with unknown poisons was found during an autopsy, and West Midlands Police is liaising with Crufts officials and the NEC to secure potential evidence.
Mrs Milligan-Bott said Jagger's death was the result of a "heinous crime", but said she did not want dog shows "to become a ground of finger-pointing and suspicion".
She believes the suspected poisoning to have been a random attack.
West Midlands Police said officers had not received any complaint at this stage or been asked to investigate an allegation involving the death of a dog in Belgium.
The Kennel Club asked anybody who has any information about alleged poisoning at Crufts to email email@example.com.