The Northland SPCA is pleading with dog owners to ensure their pets are vaccinated against the parvovirus disease following the death of 17 animals admitted to its Whangarei centre in a week.Whangarei SPCA inspector team leader Michelle Potter said 15 cases were from Otangarei, adding canine parvovirus could be prevented with a vaccine that costs under $100.\"It\'s only happening on unvaccinated dogs. Parvovirus is very, very virulent and causes terrible pain and suffering and death,\" Ms Potter said.She said owners should keep stray dogs off their properties because they could spread the disease. Parvovirus could remain in soil for up to a year.\"Any unvaccinated puppy will be at particular risk. It\'s mainly carried in dogs\' vomit or faeces, but it can also be carried and spread on people\'s shoes,\" Ms Potter said.\"Most disinfectants won\'t kill parvovirus. Bleach and viricides like Virkon will kill it, but you\'re wasting your time with normal disinfectant.\"She said the first symptoms were the dog going off its food then becoming lethargic and inactive. \"Then will come the vomiting and diarrhoea, with the diarrhoea possibly having blood in it, and there\'s a very strong, distinctive smell. It basically destroys all the lining of their stomach and it\'s a horrible, painful death for them and not nice at all.\"\"It\'s parvo season at the moment and we normally get three or four cases a week at this time, so to have 17 in one week is unprecedented,\" she said.\"It\'s quite devastating to see all these dogs that are just so sick and dying.\"