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Tuesday, 31 October 2017

Toxoplasmosis in the Red Fox

From the National Fox Welfare Society. Please be aware and contact them if you know of a fox that might be affected. These foxes are NOT dangerous.

Toxoplasmosis in the Red Fox (Vulpes vulpes)

These oocysts often occur in parts of the brain. Studies in rats have shown that rats infected with Toxoplasmosis do not fear cat pheromones even though Rodents instinctively shy away from the smells of a cat. So it would seem that for the parasite to complete its life cycle the infected rat would have to be caught by a cat. What better way than to infect the part of the brain that would normally shy away from this and make life harder for the cat to catch the rat! So the cat catches and kills the rat and eats it and the life cycle is complete and ready to start again when the cat goes toilet. 

But what happens if it is a fox that catches the rat. It would seem that the Toxoplasmosis goes through the same stages and infects the part of the brain that is usually associated with fear and the fight or flight instinct. Whilst the fox can't pass on this disease, it is left with the condition none the less. However some foxes in good health and with a good immune system can fight this successfully.

Symptoms we have noticed in Toxo positive foxes are as follows: No fear and no real signs of aggression, circling, head pressing, food dangling from the foxes mouth whilst the fox seems completely unaware of this. Walking up to an object and then just standing there, seemingly unaware of the fact that if it moved to the left or right it could pass the object in the way. Following feet but unaware of things going on above knee level, teeth grinding and in extreme cases fitting. With all the Toxo infected foxes we have dealt with over the years however none were suitable for release back to the wild as the condition left them almost like a domestic dog. 
Toxoplasmosis: Is a Parasitic Disease caused by the Protozoan Toxoplasmosis gondi. Protozoan being a single-celled microscopic animal. The disease can be found in almost all warm blooded birds and animals, but the only animal that Toxoplasmosis oocysts (A cyst containing a cell) can reproduce is the domestic cat. The oocysts are released in the cat's faeces. 

Determining Toxoplasmosis: Whilst signs and behaviour traits may give an insight as to whether a fox is suffering from this condition, to be sure, blood tests need to be done specifically for Toxoplasmosis, as even normal bloods will show up no real abnormalities. The blood test is done and if a toxo count is present another test needs to be done two weeks later. The reason for this is to see as to whether the count has gone down, stabilised or is rising. If the count has gone down or stabilised it means the condition has been successfully treated. If it has risen obviously the opposite is true, the infection is active.

Treatment: Along with a good diet, Antirobe is used to treat Toxoplasmosis and whilst the treatment is often successful, obviously any brain damage can't be reversed

Locations: For whatever reasons we have found that more Toxoplasmosis positive foxes come from the South of the Country, and Essex, at least this year 2015, seems to be a hot spot. 

We are learning almost by the day with regards to foxes with this condition as initially we thought it would be impossible to pair up two foxes for companionship, if one or both was suffering from the effects. Our reasons for this was in the fact we didn't think a fox suffering Toxoplasmosis would be able to communicate with other foxes, so could therefore be attacked. We also noted a fox after successful treatment would always be very sleepy and you could often move the sleeping fox to another sleeping area without the fox even waking. Although a Toxoplasmosis fox could never be released back into the wild we wondered as to whether we could give a good home to them. They were ideal for this as they were so friendly and seemed to love companionship, and would sit for hours being groomed, never attempting to bite. In an attempt to make their lives better we thought we should really try to see how a toxo fox would get on with another resident fox. Our first attempts with this was with a fox called Pellow, he went in with a healthy adult but deaf dog fox. The results were that they seemed to get on fine, as they almost seemed to ignore each other. Our second Toxo fox Lewie went in with a vixen that couldn't be released back to the wild as she was too friendly. Again the pairing seemed to work, although at first, the vixen was a little frightened of her new companion. Lewie was also able to jump up on boxes and became quite agile. Sadly Lewie died of Kidney failure may be as a result of the Toxoplasmosis.

Our third pairing was quite by chance as Aphrodite (Pictured and her story can be read in her album) was exercised each day in one of our enclosures and once she had a walk around she would be taken back to the hospital unit and Dotty, another Toxo positive fox, would then be given a run in the enclosure. Quite by chance I tried both together so they could both have more exercise time whilst I was at hand to step in if needed.
The results were amazing. For the two hours that followed, the two vixens played chase, with tails up and displaying usual fox behaviour. First Aphrodite chased Dotty, then the tables would turn and Dotty would chase Aphrodite. After two hours they were exhausted and both curled up next to each other and slept. In the weeks and months that have followed, they have been observed grooming each other and have got really close. They eat together and there is never any aggression and both will cache food. Dotty who had a lower count than Aphrodite walks up a blank to the next level in the enclosure and will sometimes sleep in the higher box. Both have hunting instincts and will chase an object or investigate an object if it is moving. Over the course of the months both Aphrodite and Dotty will hide from me at the start but will come out but no longer like me grooming them, preferring it seems, their own company and this is brilliant to see. 

Our fourth pairing was with Rupert from North London, who had the highest count of all the one's we tested. He was placed in with Ruby from Coventry and instantly they bonded and have become inseparable, laying together in their bedding area and following each other around.

What this proves to us is a fox with Toxoplasmosis that will often be put to sleep by other organisations, can be given a new lease of life in captivity and will often go from a sleeping almost dazed fox to a near normal fox when placed in an enclosure with a companion. 
Aphrodite and Dotty, five minutes after meeting each other for the first time

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