Cyanobacterial Intoxication in a Terrier Dog

Edited by Autumn Berlied

Fig. 1. Swirling Green Algae Blooms in Baltic Sea Viewed from Space (Photo taken by European Space Agency, 2019)

Cyanobacteria, also known as blue-green algae, are photosynthetic, microscopic organisms found naturally in all types of water. These single-celled organisms live in fresh, brackish, and marine water. In warm, nutrient-rich environments, cyanobacteria can multiply quickly, creating blooms that spread across the water’s surface (CDC).  

Massive summer blooms of nitrogen‐fixing cyanobacteria have been documented in the Baltic Sea since the 19th century, but are reported to have increased in frequency, biomass, and duration in recent decades (Bianchi et al., 2000). Blooming of blue-green algae, especially the toxigenic species Nodularia spumigena, occurs annually in the Baltic Sea region, presenting a threat for animals exposed to contaminated water (Simola et al., 2012).  

Cyanobacterial Blooms 

Cyanobacteria form dense and occasionally toxic blooms in freshwater and marine environments, which threaten ecosystem functioning and degrade water quality for recreation, drinking water, fisheries, and human health (Huisman et al., 2018). Cyanobacteria blooms are not always easy to identify. Some blooms have the potential to cover only a small portion of the water surface whereas some have the potential to cover the entire water surface (Fig. 1). Cyanobacteria blooms produce several toxins, such as hepatotoxins, neurotoxins, and dermatoxins, that can be poisonous to humans and animals when exposed in drinking waters or if exposed to dermal contact.  

Fig. 2. A sick manatee is treated at Lowry Park Zoo Manatee Hospital in Tampa, Florida. 

(Photo taken by Skip O’Rourke) 

 Algal blooms are becoming more common and severe in many parts of the oceans, harming wildlife, and posing potentially dangerous health impacts for local communities (Hance, 2020). There are at least 40 species of cyanobacteria, with worldwide distribution. For example, the state of Florida is experiencing the ‘red tide’, which is a common name for harmful algal blooms occurring along coastal regions. The red tide algal blooms are pumping poison into the air, known as brevetoxin, which may be harmful to humans if inhaled. Anyone breathing it in can suffer from uncontrollable coughing and a sore throat (Hance, 2020). The red tide not only is a posing threat to humans but has already killed many manatees (Fig. 2), sea lions, and sea turtles near the Florida coast.  

Impact of Eutrophication and Climate Change  

Eutrophication is the process by which a body of water becomes enriched with minerals and nutrients, such as phosphorus and nitrogen. Blue green algae increase in distribution by an increase of nutrients such as phosphorus and nitrogen. Rising temperatures, and intermittent exposure to high light intensity also led to eutrophication (Carney, 2020). The main source of nitrogen pollutants is runoff from agricultural land, mainly from fertilizers. Whereas most phosphorus pollution comes from households and industries, mainly from phosphorus-based detergents. These nutrients enter aquatic ecosystems by air, surface water, or groundwater. 

Climate change contributes to excess cyanobacterial blooms by creating ideal conditions for cyanobacteria to grow because as global temperatures rise, the global water temperatures also increase. Cyanobacteria will not only grow rapidly in warm water from increased temperatures but having warmer waters will make it more difficult for the surface water to mix with the rest of the water. This accounts for why cyanobacteria grow more successfully and are more commonly spotted on the surface of the water. This is also disadvantageous for humans and animals because growing a thick cover on the surface of the water means that this photosynthetic organism can absorb sunlight easily, and grow even more rapidly (Bennettis, 2017). If the blooms grow more rapidly, covering more surface area of the water, the organisms living below the cyanobacteria bloom will be negatively affected as well. Since the cyanobacterial bloom is covering more of the water’s surface as they increase in growth, they are preventing sunlight from reaching the deeper waters and are absorbing most of the water’s oxygen. The increased global temperatures are allowing the cyanobacterial blooms to thrive, while infecting and killing animals, humans, and marine organisms.  

Cairn Terrier Cyanobacteria Case Study 

A three-year-old female Cairn Terrier became acutely lethargic with vomiting and inappetence after being in contact with the Baltic Sea, which contained blue-green algal blooms. One of the common algal blooms that occur in the Baltic Sea are a species of nitrogen-fixing cyanobacteria called N. spumigena. N. spumigena produces nodularin, a tumor promoter hepatotoxin known to have killed wild and domestic animals by seriously affecting the liver (Teater, 2010). Nodularins are known for attributing to gastroenteritis, allergic irritation reactions, and liver diseases. 

Within five days of experiencing clinical signs, the owner elected euthanasia for the terrier as it seemed that the general condition of the terrier would continue to deteriorate. Based on the clinical history and the pathologic findings, cyanobacterial intoxication was suspected (Simola et.al, 2012). At necropsy, samples of liver and several other organs and tissues were examined. During gross examination, the liver (Fig. 3) was brownish red, swollen, and fragile with a prominent lobular pattern and moderately dark areas (Simola et al., 2012).  

Fig. 3 Liver; dog (Simola et.al, 2012) 

Fig. 4 Product ion spectra of protonated molecular ions of nodularin (m/z 825) from liver, kidney, and the reference Nodularia spumigena AV1 are almost identical (Simola et.al, 2012). 

As a result of the analysis, a protonated molecular ion of nodularin (m/z 825) was detected in all samples as seen in Figure 4. There is a common spike that occurs across the two organs and in the cyanobacteria species. It can be confirmed that nodularin, the main toxin produced by N. spumigena, was the cause of hepatic injury in the three-year-old Cairn Terrier. 

Call to Attention 

Unlike humans, dogs cannot descriptively notice the alarming scent or appearance of what algal blooms may look like. Cyanobacteria blooms, like the nodularin bloom, can be very toxic, poisonous, and even lethal. By being aware of your surroundings such as paying attention to any unusual scents or by observing the appearance of swimming waters, we can prevent any possible cyanobacterial intoxication in ourselves and our furry friends.  

To help prevent cyanobacteria blooms, as humans we must reduce eutrophication. We can do this by reducing our nutrient usage of nitrate and phosphate fertilizers. This will decrease the runoff of fertilizers into bodies of water, which will deprive the cyanobacteria in the waters from gaining any source of nutrient that they need to reproduce.  

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Sources 

CDC. “CYANOBACTERIA (BLUE-GREEN ALGAE) BLOOMS When in Doubt, It’s Best to Keep out!”  https://www.cdc.gov/habs/pdf/cyanobacteria_faq.pdf  

Bennett, Lauren. (2017) “Agea, Cyanobacteria Blooms, and Climate Change” Climate Institute. http://climate.org/algae-cyanobacteria-blooms-and-climate-change.  

Bianchi, Thomas S., et al. “Cyanobacterial Blooms in the Baltic Sea: Natural or Human‐Induced?” ASLO, John Wiley & Sons, Ltd, 26 Apr. 2000, aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2000.45.3.0716.   

Carney, Miranda. “Blue-Green Algae Poisoning in Dogs: Symptoms and Prevention.” American Kennel Club, American Kennel Club, 26 May 2020, www.akc.org/expert-advice/news/blue-green-algae-symptoms-tips/.  

Hance, Jeremy. “Lethal Algae Blooms – an Ecosystem out of Balance.” The Guardian, Guardian News and Media, 4 Jan. 2020, www.theguardian.com/environment/2020/jan/04/lethal-algae-blooms-an-ecosystem-out-of-balance.  

Huisman, Jef, et al. “Cyanobacterial Blooms.” Nature News, Nature Publishing Group, 26 June 2018, www.nature.com/articles/s41579-018-0040-1. 

Simola, O., et al. (2012). “Pathologic Findings and Toxin Identification in Cyanobacterial (Nodularia spumigena) Intoxication in a Dog.” Veterinary Pathology, 49(5): 755-759.  

Skulberg, Olav M., et al. “Nodularia Spumigena- Taxonomy of Toxic Cyanophyceae (Cyanobacteria).” Nodularia Spumigena - an Overview | ScienceDirect Topics, 1993, www.sciencedirect.com/topics/agricultural-and-biological-sciences/nodularia-spumigena.  

Teater, Charlie. “Nodularia Spumigena.” Microbewiki, 2010, microbewiki.kenyon.edu/index.php/Nodularia_Spumigena.