Distemper is a highly infectious virus which affects dogs, ferrets and foxes. The virus can cause a number of syndromes from a mild lethargy and high temperature to severe respiratory disease or inflammation of the nervous system. The latter two syndromes are usually fatal. The effects are most profound in young puppies, old dogs or those with underlying conditions.
Fortunately in the UK, widespread vaccination has made distemper infection rare. A study of canine respiratory disease in 2020 found a low rate of canine distemper virus (CDV) causing infection in affected dogs (1). This is believed to be due to the use of an effective vaccine. The World Small Animal Veterinary Association (WSAVA) still consider distemper a core vaccine (2). A core vaccine is defined as ‘a vaccine that protects animals from severe life-threatening diseases that have a global distribution’. The WSAVA reappraises data regularly to assess disease risk and if a disease is no longer relevant in a specific locality it is deemed non-core. The fact that distemper is still a core vaccine reflects the possibility of fox infection spreading to dogs and the risk of spread from unvaccinated dogs.
The PDSA report a reduction in vaccine uptake in recent years.
This means that there is less herd immunity to distemper in the UK dog population. Vaccinating your own dog protects them against distemper but it also protects other dogs by virtue of herd immunity.
In the last 7 years, distemper has been reported sporadically in the UK.
However, reported cases often reflect more cases across the UK which are not written up in journals. A letter to the Veterinary Record in 2013 reported distemper in two poodle-cross puppies in the South-west of the UK. (3). Both pups presented with seizure and diarrhoea. Distemper virus was found in their nervous system. One pup died and the other had survived at the time of writing. The source of the infection was unknown in this case.
In 2014 a pregnant bitch imported from Bulgaria showed signs of distemper. Her litter of pups died after showing symptoms at two weeks of age and distemper was diagnosed on post-mortem (4). Distemper is common throughout Europe and dogs imported do not necessarily receive distemper vaccination before they enter the UK. Hence, there is a risk of them bringing infection. Puppies born from vaccinated female dogs have some immunity against distemper which often lasts until they are vaccinated at 6-8 weeks protecting them. Unvaccinated bitches do not confer immunity to their pups.
At present, the WSAVA recommendations state that an initial course of vaccination followed by a booster at one year of age then a three-yearly booster is appropriate.
The vaccine manufacturers have slightly different recommendations in regards to age and intervals between vaccines but this schema is generally used. Some vaccines such as Leptospirosis require annual vaccination but every three years is sufficient for distemper. All vets in the UK now follow these guidelines to prevent over vaccination.
Avoiding unnecessary vaccination is always a concern for vets and owners.
A small proportion of dogs can have vaccine reactions just like people. Rarely, dogs will have an allergic reaction or suffer from autoimmune disease where their body mounts an immune response against itself after a vaccine. Local reactions can occur where the injection site can become inflamed or a dog may have mild malaise after a vaccination. As vets only vaccinate against potentially fatal conditions, the rare cases of adverse reactions are usually outweighed by the benefit of the protection of the vaccine.
If vaccinating your dog is a concern, then your vet can take a blood sample to carry out a titre test to measure your dog’s antibody levels.
This is not an absolute guarantee of protection but can be used to lengthen vaccine intervals if they have sufficient antibodies. It is wise to retest regularly in case antibody levels fall rapidly. A study in 2004 showed that some dogs still had protective immunity after three years (5).
Distemper vaccination is still relevant and necessary.
There is a risk of distemper infection in the UK from the fox population and unvaccinated dogs whether imported or indigenous. Distemper is a catastrophic, usually fatal disease and there is no specific treatment. Some dogs recover with supportive treatment, but survival is rare. The virus is extremely contagious and spreads quickly between dogs. Dogs shed virus for many months if they recover. A now-rare chronic form can occur with hardened pads and nose (hardpad). The vaccine is extremely effective and has protected the UK dog population for many years. Continuing to vaccinate our dogs will prevent the recurrence of this horrible disease.
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References:
- Day MJ, Carey S, Clercx C, Kohn B, Marsilo F, Thiry E, Freyburger L, Schulz B, Walker DJ. Aetiology of canine infectious respiratory disease complex and prevalence of its pathogens in Europe. (2020). Journal of Comparative Pathology 176 :86-108
- Day M J, Horzinek M C, Schultz R D et al (2016) WSAVA Guidelines for the vaccination of dogs and cats. JSAP 57, E1-E45
- Adamantos S and Warman S. Diagnosis of canine distemper virus in puppies (2013) The Vet Record (letter) 174 (19)
- Walker D, Neard P, Sharp C and Philbey AW. Canine distemper imported into the UK. (2014) The Vet Record 175 (17)
- Bohm M, Herrtage ME, Thompson H, Weir A, Hasted AM and Maxwell NS. Serum antibody titres to canine parvovirus, adenovirus and distemper virus in dogs in the UK which had not been vaccinated for at least three years. (2004) The Veterinary Record 154 (15):457-63
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