The Cork branch of Dog Action Welfare Group (DAWG) is urging people who come across distressed dogs during the warm weather to report the incidents to the gardaí or Irish Society for Prevention of Cruelty to Animals (ISPCA).
With temperatures now exceeding 25 degrees in some parts of the county, and with the rest of the week set to be even hotter, DAWG say they have been getting numerous calls from concerned members of the public about dogs "in awful conditions".
"We posted photos we received a couple of winters ago about dogs in horrific conditions and chained in the snow," a spokesperson for the group said.
"We are now getting calls about dogs locked in wooden sheds in this heat and dogs on chains with no water.
"Please call the guards and the ISPCA urgently if you know of dogs suffering in this heat."
A spokesperson for the Department of Agriculture, Food and the Marine said because dogs can be susceptible to heatstroke, they should always have access to fresh water both indoors and outdoors, as well as a shaded area away from direct sunlight.
"Dogs should also never be left unattended in a car, even if it has been parked in the shade with the windows open.
"The temperature inside the car may rise rapidly."
Regular grooming, particularly breeds with long or thick hair, can help them regulate their body temperature during periods of hot weather.
If dogs become too hot, this may lead to heat stroke, a serious condition which can be fatal.
Signs of heat stroke include heavy panting, drooling, lethargy, confusion, vomiting, diarrhoea, weakness or seizures.
Any owner who suspects their dog has heat exhaustion or heat stroke, should seek immediate veterinary attention and try to cool the dog down by moving to a cooler location, preferably indoors. Owners should also wet their dog's body, ears and paws with cool, but not very cold, water.
Dogs can get also get sunburnt, especially if they are of a breed with thin coats and/or white hair. Such pets should only have limited exposure to direct sunlight, and owners should consider applying sunscreen to the companion's ear tips and bridge of their nose, if necessary.
While not all sunscreens are not suitable for dogs, vets can advise on suitable brands.
As regards walking, the department spokesperson said it is preferable to exercise dogs in the morning or evening, when the temperatures are cooler than in the middle of the day.
On longer walks, owners should bring water for their dog to drink.
Surfaces that heat up in the sun, such as tarmac, pavements and sand, may be painful on a dog’s paws. The spokesperson said that if the surface is too hot for the owner to touch, dogs should be walked on grass or shaded areas instead.