Paralysis Tick Complications
Paralysis ticks produce a very powerful poison which can kill pets within a very short time. It affects nerves and muscles which then become paralysed.
Early symptoms include weak hindlegs, a grunting breathing sound, forceful breathing efforts and vomiting.
There are several complications associated with tick poisonings.
No Response to Therapy Due to Delay in Treatment
Anti Tick Serum (ATS) consists of large particles (antibodies) which are very good at collecting and destroying tick toxin while it is in the bloodstream.
After a while, tick toxin leaves the bloodstream and starts to run down the nerves towards the muscles where it causes paralysis.
This can start to happen during just a 10 minute delay in treatment
The pet does not look any sicker 10 minutes later, but the tick toxin has started on its way down the nerves. ATS antibodies are too big to go the same way after the tick toxin- they are left behind in the bloodstream.
Once the tick toxin starts moving down the nerves, it does not matter how much ATS is given, it just won't work.
So cases which don't look too bad to start with, can still go down over the next 24 hours despite the vet's best attempts at treatment. The delay means the ATS is not going to work.
- The national average of tick deaths for cases treated by general practice vets is 10%, and in specialist centres it is 8% (from a survey conducted by Prof Rick Atwell)
- For each year over 6 years of age, there is an additional 10% increase in the mortality
- Brachycephalic dogs (e.g. Bulldogs, Boxers) have a very high risk of sudden death early in the course of the illness despite all the best efforts
Slow Response to ATS
ATS can take up to 12-24 hours to neutralsie tick toxin.
As a result, cases often get worse in the first 12-24 hours until the ATS neutralises the tick toxin.
Reaction to the ATS itself
ATS is collected from the blood of specially looked after immune dogs on the mid north coast of NSW
When treating a case, we are basically giving a small blood transfusion. Recent studies have shown that if ATS is given too quickly to dogs, up to 80% of all cases will have a severe side reaction. It has been shown that giving ATS slowly over at least 1 hour avoids the majority of these reactions. For this reason, we connect dogs up to a drip and a special drip administration machine to give the serum slowly over an hour.
In cats, we are in effect giving them another species of blood- it would be equivalent to a human receiving pig blood.
The chances of a reaction are much more common. For this reason, we inject ATS into the abdomen of cats and pre- dose them with drugs to “knock out” their immune system so a reaction is minimized. The trade-off is that it takes longer for ATS to get absorbed into the body.
Effect on the oesophagus
The oesophagus (food tube connecting the mouth to the stomach) can become parlaysed by the tick poison.
It starts to relax and acts like a large wet sock as it can not contract in its normal way. Saliva, food and water build up inside the relaxed oesophagus (megaoesophagus) and is often vomited or regurgitated back up into the throat.
Effect on the throat
The tick poison can paralyse the vocal cords and swallowing mechanism at the back of the throat. Affected pets can choke on accumulated saliva or food/water that is vomited up from a megaoesophagus.
In cases with megaoesophagus and paralysis of the back of the throat, it is quite common for vomit to go down the wrong way i.e. the trachea (windpipe) and end up in the lungs. The vomit contains acid and bacteria and can cause a large amount of damage to the lungs leading to life threatening pneumonia.
If a case is slow to respond to treatment e.g. still can’t eat or swallow after 2 days, we have to consider fluid therapy to avoid dehydration. This will mean setting up an IV drip to slowly give fluids. This has to be monitored very closely in case there is secondary heart failure as even a small amount of IV fluids can end up as fluid in the lungs if badly affected.
Effect on the heart
1) Heart failure
In a small number of cases, the tick poison will also attack the muscles of the heart causing severe heart failure.
This effect on the heart is NOT reversed by ATS administration
We need to be on the alert for this which may mean taking chest x-rays and running blood tests to detect it early. The heart failure can cause sudden death whilst under treatment.
2) Irregular heart beat
A small number of cases have a problem with the toxin affecting the conduction of electrical impulses through the heart. These impulses cause the heart to contract, but in some tick cases, the impulses can suddenly become very erratic and cause sudden death. This can happen in hospital or in the first week or so back at home. It is very important to rest recovered pets for a few weeks following treatment for this reason.
Poor oxygen supply to the body
In many cases, the toxin paralyses muscles that are used to make the chest expand and suck in air to the lungs. These muscles of respiration are found in the diaphragm and between the ribs. In cases where these muscles are affected, the pet finds it very hard to get enough oxygen into the lungs and circulation. As a result, they can die suddenly.
We need to be regularly checking these pets by using a pulse oximeter on their tongue, ear or lip to measure the amount of oxygen circulating around in the blood. If it is low, then we need to supply these cases with oxygen.
This may mean an oxygen mask, intra-nasal or intra-tracheal oxygen tube insertion. Some cases can be on oxygen and intensive care for 2-3 days.
Despite our very best efforts in treating even mild tick poisoning cases,
serious life threatening complications and/or sudden death can occur
Affected cases that have been left in the cold outside and/or given tick rinses can often get a sub normal body temperature (hypothermia). A pet suffering from hypothermia alone can look very similar to paralysis tick poisoning and easily be mistaken for a tick case.
However, a tick case with hypothermia is in double trouble. We need to monitor body temperature to ensure there is no lowering of body temperature in affected cases. This may mean the use of heating pads and hot water bottles to keep their temperature up.
Effect on blood pressure
Until recently, it was thought that most tick cases had high blood pressure. With the use of Doppler measurement of blood pressure, it has been shown that this is not the case in most situations. In fact, blood pressure is often too low meaning poor blood supply to the muscles, heart, kidneys, brain etc.
Measuring blood pressure on affected cases is important to detect this problem.