Warm, still water in September and October can grow blue-green algae that make toxins deadly to dogs. A dog only needs to swim, drink or lick its coat afterward to be exposed, and some toxins act within minutes. If the water looks scummy, discolored or smells bad, keep your dog out, and regard any exposure as urgent.
Why the risk lasts into fall in the Tri-Valley
Blue-green algae are not true algae but cyanobacteria, tiny organisms that live in fresh water everywhere. Most of the time they cause no trouble. When water is warm, shallow, slow-moving and rich in nutrients, they can multiply into a bloom, and some blooms produce toxins.
Livermore’s long, warm fall keeps those conditions going. By September, lakes, reservoirs, ponds and slow stretches of creek have been heating up for months, water levels are often low, and there has been little rain to stir things up. Blooms can persist until cooler weather and winter rain arrive.
What a bloom can look like
- Water that looks like pea soup or spilled green, blue-green or brown paint
- Scum, foam or a film on the surface, often pushed against the shoreline by the wind
- Floating mats or clumps, or mats on rocks and the bottom in shallow water
- A musty, earthy or rotten smell
The difficult part is that dangerous water does not always look dangerous. Toxins can be present when the water looks fairly clear, and a bloom can appear or move within a day. Posted advisories at a lake or reservoir are the best guide, and California also runs a statewide reporting portal for harmful algal blooms. If a sign says to keep dogs out of the water, it means it.
How dogs are exposed
- Swimming and playing in affected water, especially chasing balls where scum collects
- Drinking from lakes, ponds, puddles near the shore or slow creek pools
- Licking the coat after a swim, which is why a dog can become ill even after a short dip
- Eating mats or scum that have washed up or dried on the shore, which some dogs find interesting
Dogs are more at risk than people because they drink the water, swim through the scum and then groom it off. Livestock and wildlife can be affected too.
Two kinds of poisoning: minutes and days
Minutes to hours: nervous system signs
Some algal toxins act on the nerves and muscles, very quickly. Signs can include drooling, trembling, weakness, staggering, stiffness, difficulty breathing, seizures and collapse. These can progress fast and are an emergency.
Hours to days: liver signs
Other toxins damage the liver. Signs may appear over hours or even a day or two, including vomiting, diarrhea, lethargy, loss of appetite, pale gums, and later yellowing of the gums or eyes. A dog can seem fine at first and still be seriously affected.
There is no specific antidote for these toxins. The best outcomes come from getting help quickly, washing the toxins off the coat, and supportive hospital care from our medical services team. Bloodwork through our pet diagnostics service shows us how the liver is coping, and is often repeated over the following days.
If your dog has been in water you are unsure about
- Get your dog out of the water and away from the shore.
- Stop your dog from licking its coat. Rinse your dog thoroughly with clean water as soon as you can, wearing gloves if you have them, and wash your own hands afterward.
- Phone us right away, even if your dog seems normal, and head in. Do not wait for signs.
- Take a photo of the water and note where you were. It helps us, and it helps local authorities warn other owners.
- Do not induce vomiting yourself. Leave that decision to the veterinary team.
Our urgent care team is available during our open hours, which run into the evening every day. Once we have closed for the night, drive to the closest emergency hospital that is open and let them know you are on your way.
Safer water habits for fall
- Check posted signs and advisories before any swim, every time. Conditions change quickly.
- When in doubt, stay out. If the water is discolored, scummy or smelly, keep your dog on a leash and away from the edge.
- Carry fresh drinking water on hikes, so your dog is not tempted to drink from ponds and creeks.
- Rinse your dog with clean water after any swim in natural water.
- Keep dogs away from dried mats and crusts along the shoreline, which can still be toxic.
- If you have a pond or water trough on your property, watch for signs of a bloom in warm weather.
Fall in the Livermore Valley brings other seasonal hazards too, and our guide to grapes, raisins and the Livermore Valley harvest covers one that is right on our doorstep.
Frequently asked questions
Is it only green water that is dangerous?
No. Blooms can be green, blue-green, brown or even reddish, and toxins can be present in water that looks fairly clear. Posted advisories are more reliable than color.
My dog swam, but only for a minute. Could that be enough?
It can be, especially if your dog drank some water or licked its coat afterward. Rinse your dog with clean water, watch closely, and phone us if you have any reason to think the water was affected.
How quickly would I see signs?
Nerve-related signs can appear within minutes to a few hours. Liver-related signs may take hours or a day or two. That is why we would rather hear from you right away than wait to see what happens.
Can people be affected too?
Yes. People can get skin irritation or become ill from swallowing affected water. Follow posted advisories for yourself as well as your dog, and wash your hands after rinsing your dog.
Is flowing water safer than a pond?
Often, but not always. Blooms are most common in still, warm water, yet mats can grow on the bottom of shallow creeks and break loose. Slow pools along a creek deserve the same caution as a pond.
Are cats at risk?
Yes, but it is uncommon, because cats rarely swim in or drink from ponds. A cat who has been in or near affected water and seems unwell should still be seen right away.
Speak to the team at PetCura Animal Hospital
If your dog has been in water that might contain toxic algae, phone us now, or go to the nearest open emergency hospital after hours.
Published by the team at PetCura Animal Hospital.
This article is for general educational purposes only and is not a substitute for an in-person veterinary examination or advice about your individual pet. If you have an urgent concern about your pet, contact PetCura Animal Hospital or your nearest emergency veterinary hospital right away.
PetCura Animal Hospital
1817 Holmes St, Livermore, CA 94550
Phone: (925) 292-5153
Email: pcahlivermore@gmail.com
Hours: Monday to Saturday 8:00 AM to 9:00 PM; Sunday 9:00 AM to 8:00 PM