Summer dangers: dog owners warned about toxic berries and algae

Dog owners are being urged to stay vigilant this summer as the New Zealand Veterinary Association warns of potential hazards posed by toxic karaka berries, algal blooms, and other seasonal risks.

NZVA Head of Veterinary Services Companion Animal Sally Cory said warmer weather means pets are spending more time outdoors, increasing their exposure to potentially harmful substances. “Unfortunately, dogs are attracted to karaka berries and toxic algae because of the strong smell,” she said. “Even small amounts can be dangerous, so if you think your dog has eaten karaka berries or toxic algae, call your veterinarian immediately.”

Karaka trees, which fruit from January to April, drop bright orange berries containing the alkaloid karakin, which is highly toxic to dogs. Consuming these berries can lead to neurological issues, respiratory failure, and even death. Symptoms may not appear immediately, with signs potentially delayed for up to a week.

Toxic algae, or cyanobacteria, is another common hazard during the summer months. Found in rivers and lakes, it appears as black, green, or brown slime on rocks or as brown or black mats. Symptoms of poisoning, such as panting, lethargy, muscle tremors, and convulsions, can appear within 30 minutes of exposure.

“When walking your dog near fresh water, be mindful of stagnant water during dry periods or algae mats dislodged after heavy rain,” Cory said. “Toxic algae has a strong, musty odour that attracts dogs, and reactions can occur quickly. If humans are advised not to swim somewhere, dogs shouldn’t swim there either.”

Cory also advised dog owners to check updates from local councils and Land Air Water Aotearoa for information on waterway risks, as signage may not always be present.

In addition to toxic berries and algae, Cory warned of rising cases of parvovirus, a highly contagious viral disease that often increases when dogs spend more time in public spaces. The virus, transmitted through contaminated faeces, surfaces, and objects, can cause severe symptoms such as bloody diarrhoea, vomiting, lethargy, and rapid dehydration. Vaccination is the best defence.

“We’ve started to see an increase in parvovirus cases already this season,” Cory said. “It’s preventable with appropriate vaccination.” Puppies aged six weeks to six months and unvaccinated dogs are most at risk.

Dog owners are also encouraged to ensure their pets’ vaccinations are up-to-date for canine cough (kennel cough), which spreads in areas where dogs gather, such as beaches, parks, and daycare facilities.

Other seasonal risks include bee stings, excessive saltwater ingestion, and grass seeds becoming lodged in dogs’ ears or between their toes.

Signs of karaka poisoning include:

•Vomiting or diarrhoea

•Abdominal pain

•Reduced appetite

•Paralysis of back legs

•Loss of balance

•Convulsions

•Slower breathing

Signs of toxic algae poisoning include:

•Panting

•Lethargy