Is Adenovirus Endemic In UK Foxes?

 

(c)2021 Chris Bertram

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Apart from my studying the introduction of mange into the United Kingdom I have also had to look at the possibility of other diseases and viruses affecting Vulpes vulpes such as rabies and babesia. I have twice been told by fox rescues that “adenovirus is probably widespread in UK foxes.” When I asked if these rescues could give me the contact details of the vet involved in (I assumed) the post mortems of these foxes I was told there were none. The assumption was just that.

It is a matter of record that none of the rescues I spoke to which claimed to have jaundiced looking dead foxes had submitted any of them for post mortem examination which would have cost them nothing.

I have to make it very clear that I am not a veterinarian. I have had to look at fox health issues as a matter of course in my fox work. With rabies I have had some experience as it was endemic in the part of Germany where I lived (Lippe, in Westphalia) and I will admit that walking through a forest when virtually everything flying or walking in it has been shot (as a precaution) and still lying on the ground is very nightmarish. You learnt pretty fast about rabies and its treatment. The last rabies outbreak in the UK was in the 1920s.

With the Fox Deaths Project run by Zoe Webber and myself the finding of two cases of babesia in foxes separated by some distance led to a very swift learning curve. But when it came to adenovirus it seemed to be stated as being widespread in UK foxes with no actual scientific back-up. I have asked and looked around and found a number of technical papers on adenovirus and if I have made any errors I welcome correction.

As far as I am aware the only Europe based study on adenovirus in foxes was in Germany and the paper, Detection of canine adenovirus 1 in red foxes (Vulpes vulpes) and raccoons (Procyon lotor) in Germany with a TaqMan real-time PCR assay by Silke Hechinger, Svenja Scheffold, Hans-Peter Hamann, Michael Zschöckm, was published in the Journal of Veterinary Diagnostic Investigation 2017, Vol. 29(5) 741–746 and the study was funded by the The Hessian State Laboratory (Hessisches Landeslabor), supported by the Hessian Ministry for the Environment, Climate Protection, Agriculture and Consumer Protection (HMUKLV). The paper was then published in English in the UK by SAGE (Scientific Advisory Group for Emergencies).

Adenovirus (c)2021 PetMed

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To date I am not aware of any UK study that is ongoing and in point of fact the British Fox Study with its Fox Deaths Project seems to be likely to discover it if adenovirus is present.

This leads to the question; “What is Adenovirus?” Well, there is adenovirus 1 and adenovirus 2. While adenovirus 2 creates minor respiratory problems type 1 is more serious.

Adenoviruses are a large group of structurally similar viruses containing a single molecule of unenclosed DNA. Adenovirus 1 causes infectious hepatitis in dogs, a serious liver disease which can be fatal in about 10-30% of cases. The virus is spread via faeces and contaminated fluids from infected dogs and may also be present in a recovered dog for a period of at least six months. It is more common and more severe among young dogs who have not yet been vaccinated. The vaccines are effective at preventing the disease.

I should point out that the data states that adenovirus 1 is rare among regularly vaccinated household dogs, however, it is seen as a threat from wild canids and other related carnivores –raccoons, raccoon dogs etc.

Adenovirus 1 can have symptoms of severe liver failure which may result in death – called infectious hepatitis. Vaccines against adenovirus 1 are commonly administered along with the canine distemper vaccine. The first, most common, sign of the disease is a low fever (above 104 degrees) which may drop and rise again; if this fever persists it will lead to leukopenia (which is a drop in white blood cells) and more severe symptoms. Infectious hepatitis can range from a mild, barely noticeable illness to a life-threatening condition. The following symptoms in your dog may indicate Adenovirus 1 and a vet should be consulted:

Fever

Congestion

Depression or apathy

Thick discharge from eyes and nose

Milky or blue appearance to eyes

Thirst

Lack of appetite and weight loss

Tender abdomen

Vomiting

Diarrhea

Elevated heart rate

Increased blood coagulation

Bleeding in the mouth and gums

Convulsions

One or more paralyzed limbs

What is known as canine adenovirus belongs to the genus Mastadenovirus which includes viruses that affect mammals rather than, say, birds though other types of adenovirus also infect horses and other farm animals. There are two commonly recognized types of adenovirus which can cause disease in dogs:

Adenovirus 1 - causes infectious liver disease.

Adenovirus 2 - causes respiratory infection (Infectious Tracheobronchitis) and is commonly also used in vaccines against both diseases.

(c)2021 Conserve Ireland

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Adenovirus 1 is a contagious disease which is spread from one dog which is sick with or recently recovered and some may spread the virus without manifesting symptoms themselves. The virus is more commonly present where there are large populations of dogs congregated in one place such as kennels or even an animal rescue centre. The

common methods of transmission include the following:

1. Eating infected faeces.

2. Saliva or mucus transported through the air (a cough or sneeze from an infected dog)

3. Contact with contaminated urine.

4. Staying in a kennel where there are other infected dogs.

5. Spending time in a dog park or crowded dog walking area.

In a perfect world all rescues should check for signs of adenovirus before releasing rescued cubs and adult foxes but at the moment that involves more money than they can afford. The virus will survive for several months and so contaminated surfaces remain dangerous for quite some time. The most effective known method for preventing infection from contaminated surfaces is cleaning with a bleach solution.

Dogs who are far too young to receive vaccinations are the most susceptible to the disease.

For a diagnosis of adenovirus 1 in dogs making an appointment with your vet as soon as you notice symptoms of fever in your dog can result in the earliest possible diagnosis and the highest level of treatment. The veterinarian will suspect adenovirus 1 based on the symptoms although occasionally it can be confused with canine distemper or even parvovirus both of which create similar symptoms. Blood and urine tests will further indicate the presence of infectious hepatitis. If your dog has not received a vaccination and spends considerable time among large groups of other dogs, dog walker groups are becoming more of a thing now, this will increase the likelihood of the illness being related to adenovirus 1.

I have to note that, from everything I have read it is not known what causes more acute cases of infectious hepatitis but the degree of anti-body already present in the dog may be a factor as well as the combined infection with other diseases such as canine distemper or parvovirus. In general terms a more severe drop in the white blood cell count at the beginning of the disease will indicate more pronounced symptoms and a higher chance of fatal liver failure; however, this is something that will need to be diagnosed and evaluated by your veterinarian.

There is so far no cure for adenovirus 1 but treatment can decrease the severity of the symptoms. Antibiotics are given to eliminate the development of bacterial infection which can result from a weakened immune system and an IV is administered to balance fluids and electrolyte levels. In some cases blood transfusions will be needed if it is an extreme cases. Severely ill dogs will be kept for treatment and monitoring until their system has returned to normal; maintaining fluids and healthy blood levels can increase your dog’s chance of survival. However, recovery will also depend on the severity of the attack.

Hepatitis blue eyes (c)2021 https://wilmotveterinaryclinic.com/

Once a dog has recovered from adenovirus 1 it will be immune for life. Dogs which have survived severe forms of the disease will have lesions and tissue damage sometimes visible on the internal organs but these do not usually present a problem. Lesions are also often present on the cornea both during and after the disease and this can result in a clouded or blue appearance to the eyes (sometimes called “hepatitis blue eye”) and this will make your dog’s eyes more sensitive and so bright, direct lights should be avoided. Occasionally, a dog can suffer from short, sharp eye pain due to the corneal lesions and if your dog exhibits this condition don’t panic as the pain can be treated with medication. There are some dogs which have been vaccinated with weakened strains of adenovirus 1 that can develop the same clouded, blue-eyed appearance from corneal lesions and this means the same light sensitivity problems and pain. This is one of the reasons adenovirus 2 is used in most vaccines in the US. Both the MLV (modified live) and killed versions can create immunity to the two forms of the virus without negative side-effects.

Basically, I have not found anything specifically different in how UK vets would treat the virus but if anyone has links to any papers online –let me know.

(c)2021 dogtime.com: https://dogtime.com/dog-health/57449-adenovirus-1-dogs-symptoms-causes-treatments

Obviously in order to prevent adenovirus 1 young dogs should begin vaccination at around 6-8 weeks of age. Before this time, an antibody from the mother will prevent the vaccine from being effective which is why vets will tell you at what age your pet should have its first jab –none of the dogs I had ever exhibited negative side effects and to be honest the only one hurt by the jabs was me…or, rather, my wallet.

In the United States three doses are given at one-month intervals and when adult dogs are vaccinated they receive 1 or 2 doses depending on whether the MLV or killed vaccine is used. The vaccine is often combined with the canine distemper and parvovirus vaccines. Although yearly booster shots have been traditional studies show that dogs remain immune for at least 4 years after receiving the vaccine and some vets recommend a longer interval between vaccinations.

The concern has been that adenovirus (most rescues seem unaware or there being a type 1 and type 2) is foxes might lead to an outbreak amongst pets. It should be made very clear that there is no indication, as far as I know, that adenovirus is rampant in UK foxes and I suspect there are other factions who are anti-fox spreading this rumour. With the Fox Deaths Project we have only encountered babesia but the pathologist involved in performing the post mortem examinations is very experienced and extremely thorough and we are currently at Fox number 13 and no sign of adenovirus yet.

It should also be noted that a fox is just as likely to pick up adenovirus from a pet dog as a pet dog picking it up from a fox.