Is Leptospirosis Helping To Kill Off UK Foxes?

 These posts are designed as updates and NOT technical papers!

   

video (c)2024 Sarah Mills/Bristol Fox Lady

 We are currently looking at some unusual fox cub deaths. In the last few weeks we have had seven cases of 8-10 weeks old cubs found having seizures. One or two you can put down to "natural"  causes but when you get 3-4 then 7 you need to wake up and see what is going on.

Sarah Mills, the Bristol Fox Lady, responded to a call of a cub seen fitting not far from where she lives. On arriving at the scene the cub did fit and one more seizure again on getting to the vet.  Again an 8-10 weeks old cub.

On arriving at the vet it was found that nystagmus was present, a stiff body and minimal jaundice. On this occasion the vet suggested that we submit the cub for post mortem -vets generally do not suggest that. 

As it is important that the average person understands the terms use (otherwise it is all gobbledegook); Nystagmus in dogs refers to the flickering or twitching of the eyes. In most cases, flickering eye movements are entirely normal. But they can become concerning if the movements happen when your dog's head is still. The primary cause of nystagmus is vestibular disease, which is a disturbance in the pet's body balance.

The vet suggested we submit this cub for PM as the only thing he could suggest was distemper which is worrying enough. The signs of distemper include: Discharge from the eyes and nose. Fever. Coughing. Lethargy. Reduced appetite. Vomiting and Diarrhea. For this reason we are submitting the cub for post mortem examination, however. In my previous post I made it clear that I was not calling it distemper or anything else until we had a PM report and test results and for a good reason:

 Neither parvovirus nor distemper have ever been conclusively recorded in UK foxes, and I must also point out that there is virtually no possibility of serious health problems arising from the presence of foxes.

It could be a false alarm and we have had vets wrong in the past and I suspect that this is why the vet involved suggested submitting for post mortem.  It will take a while to get tests, etc. but we are keeping an eye open.  I know people from rescues do read this blog and I will also be contacting them in the next day or so but if they have similar cases and the cub dies or is put to sleep PLEASE submit it to the Animal Plant Health Advisory who can point you to the nearest PM centre. Every scrap of knowledge help0s.

I have been in contact with two rescues who had similar fox cubs and I asked that they submit the cubs for post mortem. There was an outright refusal and the cubs were buried on the grounds.

I was also told by another wildlife rescue that they see this all the time and that it was ICH (Canine hepatitis) . I was further told that IF they thought a death was unusual they would decide to submit it for post mortem. Firstly, I lost my respect for that well known rescue. 1. ICH was unlikely and they should have known that but 2) ICH was a good way to dismiss deaths. 3) that is irresponsible behaviour to not have checks carried out and ignoring something that is happening "all the time" is turning a blind eye to something that is affecting the fox population.

Some rescues and even two veterinary groups have now passed the word along on what to look out for. In the meantime the tests on the foxes submitted all came back positive for...leptospirosis. Not distemper or parvo and certainly not ICH.  Lepto was something I suspected but without the testing not something I would put out there.

The term leptospirosis has cropped up a few times in fox post mortem reports. An explanation might ease any confusion and as dogs and foxes are canids this from the American Veterinary Medical Association explains things https://www.avma.org/resources/pet-owners/petcare/leptospirosis#:~:text=Dogs%20can%20become%20infected%20and,or%20carcasses%3B%20and%20rarely%2C%20through

"Dogs can become infected and develop leptospirosis if their mucous membranes (or skin with any wound, such as a cut or scrape) come into contact with infected urine, urine-contaminated soil, water, food or bedding; through a bite from an infected animal; by eating infected tissues or carcasses; and rarely, through breeding. It can also be passed through the placenta from the mother dog to the puppies."

Photo from Clinicians Brief https://www.cliniciansbrief.com/article/leptospirosis-dogs

The natural question is what is leptospirosis and what can we do about it? Leptospirosis is caused by an infection with the spirochete bacterium Leptospira. It is most often spread through exposure to the urine of infected animals either from direct contact or from contact with soil or water contaminated by the urine.  We can do very little other than make sure that there is always a good supply of fresh water for wildlife but even then drinking from other sources will continue and to mark their territory foxes do also urinate on food and into water bowls.

In almost 70 fox post mortems we have not seen any sign of the "endemic in UK foxes" adenovirus.  We have found babesia and quite a few cases of lepto which makes it a common occurrence. I wrote about this a while ago:

Is Leptospirosis More "Endemic" in British Foxes Than Adenovirus? Wildlife Rescues Please Note  https://foxwildcatwolverineproject.blogspot.com/2023/08/is-leptospirosis-more-endemic-in.html

I give a link to a veterinary site explaining leptospirosis here : 

https://foxwildcatwolverineproject.blogspot.com/2023/06/what-is-leptospirosis.html

What needs to be asked is why this is going on in different parts of the UK -we see more in Bristol as our dead fox and badger reporting has improved each year, although it is quite clear we do not have all foxes reported to us. Last year due to no cold storage, etc. we lost six foxes that collapsed and were jaundiced.  Bristol is the only place where foxes meeting certain criteria are submitted for post mortems and what we learn here will, we hope, benefit rescues and vets across the country.

 

This old map of jaundice cases is now out of date within a month.

I have looked at all the old fox hunting and natural history books from the 18th-20th centuries and manger is the only health problem ever noted -mainly from foxes imported into the UK. No reports of jaundice, seizures, etc. This seems to be a modern "thing" from at least the early 2000s but very noticeable since the mid 2000s.

The problem is that, despite what you may think at times, we do not get as much rain in the UK as we used to and the weather is far warmer apart from an occasional short very cold period in some winters. Hedgehogs  tend to come out of hibernation, feed and then return to hibernation and in at least one winter there was no hibernation locally. Less rain to wash away bacteria in soil and water bodies and changes in the environment can all be possible combined factors in making lepto become more common. It may also be that people feeding foxes unhealthy foods are also contributing. Foxes are supposed to look lean; they are built to hunt (in the country and outskirts of towns) rabbits and (in towns) rats. They will also eat fruit, etc. but when people feed 'their' fox breakfast and supper and sometimes even an afternoon snack that is not natural.

"Oh it must be hungry as he came back for more" is showing that the fox is doing what they do naturally which is cache food. Every spring the same jokey comments appear on gardening sites asking how eggs are appearing in planters or under bushes. They are there because someone fed them to a fox who had way too much so buried it and because it was getting fresh every day it never went to the food caches.

I believe that this major change in diet is helping to weaken immune systems.  People insisting that someone feed an "emaciated" fox only add to the problem. The photographs of these 'emaciated' foxes show that they are trim and perfectly healthy.  I have seen so many photographs of what are obese foxes described as "looking healthy" that it is angering; the foxes are being killed because they are overweight, not hunting and their cubs are taught the same behaviour. 

Weakened immune systems as well as climate and environmental changes have all combined together to, in my opinion and it really needs to be studied, to make perfect conditions for leptospirosis to thrive and spread.  We need to do far more to look at wildlife health and particularly in foxes that have been ignored for so long.  With cases in Scotland, the North of England and other areas it seems that leptospirosis is taking its toll of the fox population and sadly we do not know how many are dying; rescues refusing to submit foxes for PM examination and some simply dismissing deaths as ICH are hiding the true picture of what is going on.  I also think that it may be possible that many deaths put down to adenovirus (no tests or post mortems it was just a "buzz word" that people latched on to)  and ICH are leptospirosis cases.  The attitude of "it's just foxes" does not help.

With 'fun' shooting across the UK every week killing large numbers of foxes and cars claiming thousands each year  I think with leptospirosis added in we can wee why the fox population has been steadily declining since the 1990s and why it is being suggested that the species need to be Red Listed.  

As we learn more I will post updates.