Your dog is dying from water intoxication.
Either get him to the vet or dig a hole.
HYPONATREMIA AND DOGS
I post this only in hope to help someone or their dog from suffering what I have suffered with my 1 year old Papillon, Lexie.
Lexie decided to join my daughter and her friend for a swim during our heat wave. You would think she was part otter the way she kept launching herself in over and over again. After about 15 minutes, she left the kids in the pool and started to whimper, tried to walk and then collapsed in the shrubs. After trying to stand up a couple of times, she kept on collapsing. My daughter scooped her up in a towel and ran her into the house. By the time I got to her she had already vomited quite a bit of water, had a vacant look and had shallow, labored breathing. Her gums were pale. We rushed her into the emergency vet. On the way there she started convulsing. She arrived in critical condition and stopped breathing within minutes of getting in the exam room. Quick responses, CPR, stat blood panels, oxygen, and IV treatment for electrolyte imbalances, had saved her. Lexie was discharged from the hospital after 48 hours mentally alert but unable to use her limbs. The extent of damage to her brain due to oxygen deprivation was unknown.
She apparently drank so much water while swimming in the pool that her electrolytes dropped to the point of causing hyponatremia (water toxicity) causing her blood plasma to thin and her brain and other organs to swell.
HYPONATREMIA* -- Water Toxicity:
Any activity or situation...can lead to water intoxication when water is consumed to replace lost fluids. Anyone working in extreme heat and/or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. Overexertion, heavy perspiration, and drinking large amounts of water to rehydrate, can lead to electrolyte imbalance and water intoxication. Even those who are resting quietly in extreme heat or humidity may run the risk of water intoxication if they drink large amounts of water over short periods for rehydration. If water enters the body more quickly than it can be removed, body fluids are diluted and a potentially dangerous shift in electrolyte balance occurs (particularly sodium compounds, such as sodium chloride). This causes cells to swell as a result of changes in osmotic pressure from within. When this occurs in the cells of the central nervous system and brain, water intoxication is the result. Initial symptoms typically include light-headedness, sometimes accompanied by nausea, vomiting, headache and/or malaise. Plasma sodium levels below 100 mmol/L (2.3g/L) frequently result in cerebral edema, seizures, coma, and death within a few hours of drinking the excess water. As with an alcohol poisoning, the progression from mild to severe symptoms may occur rapidly as the water continues to enter the body from the stomach or intravenously. This can effect human or dog and care should be taken when engaging in any strenuous activity especially during the hot seasons.