Salt water: Many dogs just love playing in the waves—and when they do they can drink a lot of salt water in a short time. Because of the salinity, hypernatremia can occur. Clinical signs may include vomiting, polydipsia, ataxia, depression, tremors and seizures.
Ocean creatures: Starfish, jellyfish, sea urchins, squid—there are a lot of creatures in the water that can cause harm. Fortunately most of them live far enough out in the water that most pets won’t come in contact with them. Pets often find sea creatures dead on the shore when they are likely to pose less of a problem.
Red tide: This is a common name for an algal bloom caused by certain species of dinoflagellates; they are recognizable by their red-brown color. Not all red tides produce toxins, however when they do regional differences are noted.
Brevetoxins are primarily isolated from blooms in the Gulf of Mexico and the Gulf of California. Concerns may include ocular and respiratory irritation, gastroenteritis, disorientation, ataxia and possible seizures. Pets can become ill from drinking the water, eating dead fish (mainly bivalves), or inhalation.
On the northern Atlantic and Pacific coasts, paralytic shellfish poisoning may occur and is often noted by ataxia, restlessness, paralysis, tachycardia and potentially respiratory distress. Pets generally become ill by eating contaminated shellfish, particularly bivalve shellfish.
Blue green algae: Salt water has its red tides and fresh water has its blue green algae. The latter is a phylum of bacteria that gets the name from its color. Large accumulations or “blooms” of these organisms can be found in lakes, ponds and rivers. These bacteria can produce several types of very nasty toxins with microcystin (hepatotoxic syndrome) and anatoxin–a (neurological signs) being the most notable.
Fugu: One little considered danger is pufferfish, or fugu, which is considered a delicacy in Japan and rarely imported to the United States. However, they’re also found in the Atlantic Ocean, and sometimes wash up on shore, where pets ingest them. Pets are also sometimes fed them by humans having the dish.
The skin, gonads, liver and viscera of fugu can contain tetrodotoxin, a neurotoxin that blocks sodium channels. Clinical signs include perioral numbness, GI upset, weakness, ataxia (with normal reflexes), generalized flaccid paralysis, respiratory failure, hypotension, bradycardia and cardia arrhythmias.
There is no antidote for fugu intoxication, and decontamination is typically not possible, as signs are often seen within minutes post exposure and the numbing effects make both emesis and activated charcoal high risk for aspiration. Treatment is largely symptomatic and supportive, including IV fluids, atropine and up to 72 hours of ventilation needed in severe cases.