• Thu
  • Aug 21, 2014
  • Updated: 5:05am

Urban Jungle

PUBLISHED : Friday, 25 July, 2008, 12:00am
UPDATED : Friday, 25 July, 2008, 12:00am

This week: tick fever

The worst cases we see as veterinarians are those that are totally preventable or caused by unfortunate accidents. Some have happy endings but many do not, with the animal succumbing to the Grim Reaper.

We have had some beautiful weather in the past week after the torrential onslaught of last month. But at work we have had an outbreak of a disease commonly called tick fever - and this pattern of weather is partially to blame.

Tick fever is a disease like malaria caused by ticks. Ticks are not transmitted from dog to dog, but breed and lay eggs in soil. Rain and increased soil temperature during the summer months cause ticks to thrive. During these ideal conditions, the eggs hatch and the ticks then climb to the tips of grass and wait for your unsuspecting dog to pass by. A batch of eggs can give rise to hundreds of hatchlings.

Ticks, unlike fleas, are not very mobile. Once on your dog they will find a suitable hiding spot and begin to feed on your dog's blood. They usually latch on to the top of your dog's head and neck, where the dog can't get at them with its mouth.

It is not uncommon to see stray mongrels roaming the streets with hundreds of ticks on their foreheads. Once they have had their fill of blood, the ticks fall back to the ground in search of a suitable breeding place.

It is certainly not nice to have insects suck blood from you until they are bloated and ready to mate, but it isn't the sucking of blood that causes the problem. The volume of blood taken by a tick isn't big. The problem is that during the process the tick can transfer a protozoa called babesia, which causes tick fever. It invades your dog's red blood cells and then proceeds to multiply.

The disease can lie dormant for months or years without causing any noticeable problems, but one day, seemingly randomly, your dog's immune system will recognise the infected red blood cells as abnormal and begin to produce antibodies against them. The antibodies will also attack uninfected red blood cells.

This will cause a precipitous drop in red blood cells, causing acute anaemia. If left untreated, the anaemia will become so severe that a blood transfusion may be necessary.

Ten years ago, this sort of disease caused by ticks was simple to treat. An inexpensive injection of a cheap antibiotic invariably killed the protozoa, but after repeated use of these drugs and poor public knowledge of tick prevention, the protozoa have changed and a more virulent form exists that is resistant to many drugs. About five years ago the situation was so bad that most dogs would die from the disease or from the use of progressively more dangerous drugs in a desperate attempt to save lives.

Since then, vets in Hong Kong and South Africa, where this disease is also common, have pioneered the use of human anti-malarial drugs in the fight against babesia with astounding success. My clinic has an 87 per cent remission rate with their use.

But there is a big downside to these new drugs - their exorbitant cost. It costs the owners thousands to treat a small dog, while a large dog could cost more than HK$10,000. And then there is the cost of a possible blood transfusion.

I fear the good news won't last long. This disease, like many have shown in the past, has an amazing propensity for adaptation and antibiotic resistance and it won't be long before these new 'super drugs' fail. So, as usual, prevention is the best medicine.

The trick to prevention lies in avoiding grass where ticks breed. Many owners mistakenly believe dogs only get this problem by going on hikes in bushy areas. This is untrue. Ticks are commonly found on your average urban pavement, because they can walk a couple of metres from soil on to concrete in search of food. It is prudent to examine your dog's skin after every walk for ticks.

It is important to note that ticks are very small to start with. The tip of a grass stalk can harbour hundreds, so you can imagine how small they are. On the day of contact, the tick may be so small you can easily miss it, so it is advisable to also examine your dog a day or two after taking it for a walk.

It is a good idea to talk to other owners where you walk your dog to see if they have discovered ticks, or their dogs have contracted tick fever. If you see a tick, just use your finger to scrape it off.

Evidence shows early removal of a tick from your dog will decrease its chances of getting the disease.

Lastly, there are chemicals that are vital for preventing tick infestation. There are spot-on topical products and tick collars that play a role in prevention. But it is important not to rely on chemical repellents because they are not 100 per cent reliable and vigilance is recommended.

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