Mike, depending on the kinds and levels of the chemicals in your pool, much water could be toxic. Throwing up later isn't fast enough... chemicals absorb. While he may seem better, it's always best to let the vet run tests. That he was lethargic and threw up hours later is an indication he did more than a little drinking... or that the levels are very high for his body weight.
Do not let your dog drink from chlorinated pools. Pool water contains a high level of a variety of chemicals such as chlorine. When a dog drinks pool water, he or she ingests more chlorine than is healthy and might also be ingesting other chemicals. There also might be algae, insects, bacteria growth, and other harmful substances in the pool. A small sip of pool water will not put your dog in the emergency vet's office. Try to keep your pet from drinking pool water whenever possible.<< Vetinfo.com
This one a bit more dire:
I just shocked my pool using chlorine yesterday. My dog went
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I just shocked my pool using chlorine yesterday. My dog went swimming in it and drank some of the water. Not an inordinate amount, however there may still have been small undissolved particles of the chlorine floating in the water when she did it. Later, I noticed that she seemed unable to get comfortable. She isn't eating her food, but will eat crunchy dog treats. She seems completely disinterested in water, however. I cannot get her to drink. Overnight, she would not settle for long sleeps all night. She whimpers when I try to massage her tummy area. She is lethargic, but will run and trot outside nearly as normal. If I assume that excess chlorine ingestion is the diagnosis, what is the recommended treatment at this point? It's too late to try to induce vomiting, it's been well over 18 hours since she drank the water. She just looks uncomfortable; she may well just need to let this get through her system but I need to get her drinking again or I'm going to have to put her on a drip! What can I do?
Expert: Dr. Andy replied 5 years ago.
Absolutely, get her into a vet for supportive care.
She is going to need aggressive stomach protectants and anti-nausea medication.
Products like Sucralfate (carafate) should be started to heal any ulcers in the esophagus or stomach.
Often, although barium is used to help diagnose an obstruction, you could ask your vet about giving some barium for its "therapeutic" beneift and soothing of the digestive tract.
Also, anti-nausea medication like Cerenia would be invaluable.
The system also needs to be flushed out, and considering how ill she is feeling, intravenous fluids should be strongly considered.
Sorry to hear what happened.