I thought I should mention that we've been seeing a real spike in tick fever cases lately, and have had four from the bayside area in the last few days. Interestingly, we're seeing the resurgence of a rarer, older form called Babesia canis. The good news is that Babesia canis is generally easier to treat than the more aggressive B. gibsoni species, but it's still a real nuisance and it can make dogs very sick. It's not a danger for cats or people.
Tick fever is caused by a parasite injected by a tick into the dog, and causes weakness, lethargy, pale gums, dark urine and loss of appetite.
As always prevention is better than cure - keep a watch out for ticks, especially around the head and neck, and give dogs a thorough check after walks. If you see a tick it's fine just to pull it out, there's no risk of leaving the head attached for these ones. And I'd recommend some kind of prevention like Seresto (8 month collar), Bravecto (3 month pill) or Frontline (monthly liquid applied to the neck - although we are seeing some Frontline resistance these days).
I hope that helps, David.