‘One health’ and the economics of the human animal bond.

Companion Animal Economics Cropped
One of a series of blogs  written by CABI editors for One Health Day November 3rd 2016

The term ‘One health’ was created to emphasise the fact that health of humans and animals were inter-linked and that the control of zoonotic diseases is best achieved by breaking down the barriers between human and veterinary medicine, developing an holistic approach. The disaster of BSE and the emergence of a new human disease, variant-CJD, and the risk of another pandemic of avian influenza, strengthened the case for One-health, and it has been adopted by the WHO, OIE, and many other relevant organizations.

Within the area of One-health, interest has been growing on the modern phenomenon of companion animals. In many parts of the world, particularly in developed countries, pets – mainly dogs and cats, are kept as companions, and are treated as one of the family. They are pampered and treated to expensive veterinary treatments when they become ill, whereas in earlier times, a sick pet would be destroyed and replaced. This attitude to animals is particularly well established in the UK, a nation of animal lovers, with an estimated 12 million (46%) households incorporating about 65 million companion animals, and  where it is not unusual to see a sign on the door of a pub saying “No children, dogs welcomed”.

The beneficial health effects that animals can have on people has been recognised with such schemes as riding for the disabled and therapy dogs that are trained to provide affection and comfort to people in hospitals, retirement homes, nursing homes, schools, hospices, disaster areas, and to people with autism. The term ‘human animal bond’ was coined to describe this mutually beneficial and dynamic relationship between people and animals that is influenced by behaviours that are essential to the health and well-being of both.  

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The risks and benefits of neutering pets: what is the evidence?

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Veterinarians and animal health organizations usually recommend that owners should have their cats and dogs neuter. But what is the evidence that this is a benefit to the owner, the animal and society?

Having pets It is estimated that in the USA there are 30-40 million stray or feral dogs and cats roaming the cities, suburbs and countryside, which is a problem for the welfare of these animals and a threat to public health, and to the health of pets. In the year 2000 4.5 million cats and dogs were destroyed in shelters. This figure was much lower than 20 years before when 23.4 million were put down; though it still represents a large welfare problem and a significant cost. Reducing the number of unwanted puppies and kittens is an important way to control this problem, and best way to achieve this is to encourage neutering in the pet population.

 Measuring the benefits and risks of neutering dogs and cats is the subject of an excellent review by Brennan McKenzie published in CAB Reviews, which aims to take an ‘evidenced-based’ approach to looking at this complex issue. Neutering is beneficial to the population on welfare grounds and on risks to public health, but there are also benefits to the individual animal from being neutered. Reproduction itself has a number of risks including sexually transmitted diseases, pregnancy complications, and problems with parturition such as dystocia. There are diseases that are far more likely to affect intact animals than neutered ones, such as mammary cancers, pyometra (bacterial infection of the uterus), ovarian and testicular neoplasms, and prostate diseases. For example, benign prostate hyperplasia affects 60-100% of intact dogs over 7 years old and prostatitis  can occur in up to 28% of intact dogs, whereas they are both are rare in castrated dogs. There are other diseases that appear to be more common in intact dogs, such as perineal hernias, and perianal fistulas. Why intact dogs are more susceptible to these diseases is not known, although a link with sex hormones seems most likely.

One of the main benefits of neutering is in controlling problem behaviour such as aggression and roaming. Difficult behaviour is one of the main reasons for people abandoning their pets or taking them to shelters, to be destroyed. Castration of male cats greatly reduces fighting, urine spraying and roaming. Neutered animals may also live longer than intact ones, but the evidence on this is not really conclusive.

As for the risks associated with neutering, all surgical procedures carry some risk of surgical complications, although the risks associated with castration are small and the complications are usually minor. There are some behavioural risks linked with neutering. Aggression is much lower in castrated animals; however, more spayed females are referred for behavioural problems, including aggression, than intact females. Some dog breeds also seem to show more aggression after neutering than before. Neutered dogs also appear to be more susceptible to cognitive dysfunction (dementia) when older than are intact dogs.

Obesity, which is a big problem in both dogs and cats, is a risk factor associated with neutering, and some conditions linked to obesity, such as diabetes are also higher in neutered animals. The risk of some orthopaedic diseases can be increased by neutering, but other risk factors such as breed and family history have a much bigger association.

Examining the evidence on the optimum age for neutering showed no clear advantage of neutering dogs before 5-6 months, so no strong recommendation can be made from it. Spaying female dogs before their first heat does however reduce the impact of mammary neoplasms.

In conclusion Dr McKenzie emphasises the complexity of the picture of risks and returns associated with neutering, and that this picture should be made clear to veterinarians and through them to their owners. He states that it is critical to integrate relevant research evidence with the unique circumstances of each pet and owner when making recommendations concerning neutering. Having more and better data would certainly help when establishing establish causal relationships between neutering and specific risks and benefits.  

Evaluating the benefits and risks of neutering dogs and catsback, by B. McKenzie

CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2010, 5, No. 045, 18 pp.

 

Raisin questions.

Recently I read in an abstract in the CAB Abstracts Database that “Dog poisoning caused by grape or raisin consumption has been increasing recently. The first cases of poisoning were documented around 1989, several tens cases have been registered yearly in the world since 2003”. The author writing in a Czech veterinary journal is correct in saying that the first report of
raisin poisoning in dogs was fairly recent, and there appears to be no recorded cases before 1989. 

Raisin poisoning can be very serious with most affected dogs developing vomiting and/or diarrhoea within 6-12 hr of eating the grapes or raisins. Other signs include lethargy, anorexia, abdominal pain, weakness, dehydration, polydipsia, and tremors (shivering). Oliguric or anuric renal failure
can develop within 24-72 hr after eating the raisins, and once anuric renal failure develops, most dogs die or are destroyed. Some dogs develop transient elevations in serum glucose, liver enzymes, pancreatic enzymes, serum calcium, or serum phosphorus develop in some dogs.

The Merck veterinary manual recommends that affected dogs should be given an emetic as soon as possible to try and eliminate the fruit, followed by
doses of activated charcoal. With large ingestions or in cases where vomiting and/or
diarrhoea has spontaneously developed within 12 hr of ingestion of grapes or raisins, aggressive fluid diuresis for 48 hr is recommended. Renal function and fluid balance should be monitored during fluid administration. For oliguric dogs, urine production may be stimulated by using dopamine and/or furosemide. Anuric dogs are unlikely to survive unless peritoneal dialysis or haemodialysis is performed, and even then the prognosis is guarded.

The interesting thing about raisin/grape poisoning is why it has only been reported in recent years? Dogs have not suddenly become more greedy and less discerning in what they choose to eat. Also the availability of raisins in
houses would have been greater in the past when more people baked fruit cakes and their own Christmas puddings at home. I far as I know, dogs (some breeds in particular) have always been great opportunists when it comes to raiding the
larder, so its hard to belief that they never had the chance to eat raisins
before 1989. Could it be that raisins have changed in some way? Or is it just that cases
of raisin poisoning did occur in the past and were just not reported? Some authors have suggested that a mycotoxin
contaminating the raisins may be to blame for the poisonings. Would some change
in the processing of raisin and grapes be responsible? If the toxin can cause
kidney failure in dogs does it have an adverse effect in humans? As yet no toxin has been identified, so
suggesting a mycotoxin is just speculation. So, looking at the literature on a particular topic, like raisin poisoning, may not provide all the answers we would like, but it does help to us to ask the right questions.

A new deadly virus

As the world’s attention has been focussed on the global financial crisis,
little notice has been taken of the emergence of  a new deadly disease in
southern Africa. In September a woman tourist guide living near Lusaka, Zambia
was evacuated to South Africa in a critical state. Her symptoms included fever
myalgia, vomiting, diarrhoea, followed by rash, liver dysfunction and
convulsions. Within a few weeks she died of acute respiratory distress syndrome.
A paramedic who had cared for the patient during the evacuation developed
similar symptoms and died, as did an intensive care nurse who treated the
patient. A fourth person also fell ill.

The culprit of this deadly disease appears to be an Arenavirus (Family
Arenaviridae),.  These are enveloped viruses with a bi-segmented negative
strand RNA genome. The African and Old World arenaviruses (like Lassa fever virus)
differ from the New World viruses such as Junin virus in their use of primary
receptors.  The prototype Arenavirus is Lymphocytic Choriomeningitis virus
(LCMV) which can cause meningitis. Rodents such as mice and hamsters can harbour
the virus and pass it on to humans. It is a potential problem particularly for pregnant women
who should avoid handling pet (or laboratory) rodents. Other Arenaviruses cause
haemorrhagic fever, such as Lassa fever virus, Guanarito virus, and Machupo virus.
Lassa fever virus causes thousands of cases of disease each year throughout West
Africa, with estimates of around 500 deaths a year. As with LCMV, these other
viruses are also found in rodents, which act as reservoir hosts, and humans can
contract the disease by contact with faeces, urine, blood or saliva of infected
rodents.

The Arenavirus isolated from the recent South African cases of disease have
yet to be identified, but could be a new virus. In a brief news item in the New
Scientists there is a quote from Bob Swanepoel of the South African National
Institute for Communicable Disease saying "how little we know about the
viruses circulating in Africa". A look on the CAB Abstracts and Global
Health Databases show that there is more than 800 records on this viruses. Of
these over 200 are on Lassa fever virus. A brief look through these records
helps to create a picture of the effect that these viruses are having, what the
current state of knowledge is, and where the work is being done.

By looking through the records on CAB it appears that this outbreak in Africa
is not the only recent case of Arenaviruses emerging and causing fatalities. Earlier this year another new Arenavirus was reported in a cluster of fatal
cases associated with transplant complications in the USA. The virus in this
cluster was found to resemble the LCMV virus*. Most of the new viral diseases,
such as SARS, Nipah, and Hendra virus infection, that crop up in humans have
crossed the species barrier and come from other animals. This would reinforce
the importance of  information across the medical and the veterinary areas
in understanding and controlling these diseases. 

*Arenavirus in a cluster of fatal transplant-associated diseases. Palacios, G. (et. al), New
England Journal of Medicine, 2008, Vol. 358, No. 10, pp. 991-998.

A little more on Paget’s…

Just a week after finding out that Paget’s disease might be linked to distemper virus, I was surprised to see the disease mentioned in a story in the Guardian newspaper, in connection with a pianting I know well from visits to the National Gallery. The painting entitled ‘A Grotesque Old Woman’, is one of the most popular in the National Gallery, London, is commonly known as the ‘Ugly Duchess’. It was painted by the Flemish artist Quinten Massys, in 1513. The painting inspired illustrations for the Duchess (who owned the Cheshire cat) in Lewis Carroll’s Alice’s Adventures in Wonderland by Sir John Tenniel.

According to the Guardian story, the painting was studied by Michael Baum, Emeritus professor of Surgery at University College, and his student Christopher Cook who concluded that the subject was suffering from a rare form of Paget’s disease. Paget’s disease, osteitis deformans, is named after Sir James Paget, the British surgeon who first described it in the late 19th century The disease usually affects the lower body such as the pelvis and femur, and when it does affect the skull it is normally just the cranium so the woman was suffering from a particularly rare form. The condition most likely happened later in life so, according to Baum, she may even have been a beauty before the condition set in. Aside from the effect on her looks, she may have suffered no more than headaches and a damaged pituitary gland. Nothing else is known about the woman who was so meticulously portrayed, who she was, or why she was the subject of the painting. Baum speculates that she was a rich, powerful person who paid the artist handsomely to paint the picture.

The other interesting thing to emerge from research into the painting is that the theory that the painting was made from drawings by Leonardo Da Vinci is probably not true, and that it is more likely that Leonardo or his followers copied the Massys painting.

I am sure that we will never be know how she came to have Paget’s disease, or if there was any connection with distemper or dogs, but it is a thought, and one to ponder on the next visit to the National Gallery.

One medicine; in practice

The
‘One-medicine’ movement has been boosted by the launch of a new web site at http://www.onehealthinitiative.com.
It aims to promote the idea of ‘one
medicine’ throughout the world and provide information on this initiative for
the public, political and governmental leaders, news media, and all ‘One Health’
professionals, advocates, and supporters.

The concept of ‘one
medicine’ is now well established having been adopted by both the American
Veterinary Medical Association (AVMA) and the American Medical Association. It
seeks to enhance collaboration between veterinarians and physicians, and other
health professionals, to promote the health and well being of all species. More
recently, the health of the environment has been included in the ‘one medicine’
concept reflecting the facts that all three are interlinked. The term one medicine
was first used by the pioneering veterinary epidemiologist, Calvin Schwabe, who
sought to break down the barriers between human and veterinary medicine.
Professor Schwabe set up the Department of Epidemiology and Preventive Medicine
at the University of California, Davis, in 1966, which was the first veterinary epidemiology department in the world.
He developed his ideas from his experiences in researching into hydatid disease
and other parasitic zoonoses while he was teaching at the American University in Beirut.

The idea of ‘one
medicine’ sounds very worthy and laudable, but it is not always easy to
envisage how in practice to impact on the lives humans and animals and the
environment. If anyone wanted a really good example of how the ‘one
medicine’ approach can benefit all three, they would have done well to have
attended an excellent talk delivered by Dr Sarah Cleaveland on rabies control in
Africa, given at the British Veterinary Association Congress in London on Friday
26 September. Those of us who were fortunate to be there heard how the health of
livestock, wild animals and humans in the Serengeti are woven together in a
dynamic relationship, and how measures to control infectious diseases affect the
humans, livestock, wild animals and the environment. Dr Cleaveland has been
based at the veterinary school in Edinburgh, was awarded the Trevor Blackburn Award in recognition of her work on zoonotic,
livestock and wildlife diseases in East Africa and for her outstanding
contributions to animal and human health, wildlife conservation and animal
welfare in Africa and beyond. The talk covered the effects of
disease and its control in the Serengeti region of Tanzania, known to viewers of wildlife programmes as the site of spectacular wildebeest
migrations, followed by lions and other carnivores that live off them. Dr
Cleaveland spoke about the control of a number of zoonotic diseases such as
brucellosis, tuberculosis, and echinococcosis, but it was her account of the campaign
to control rabies which really showed the value of the ‘one medicine’ approach.
Rabies is a very serious problem in many parts of the world and it is
estimated that 55,000 people die from the disease each year. Most of the victims
are children, and poor children in remote areas are the most likely to die if
infected, because the cost of the post-exposure vaccine and time taken to reach
a clinic. We heard how epidemiological techniques were used to prove that dogs
were the reservoir host (and not the wild carnivores that were also affected),
and how a mass dog vaccination campaign that she directed and implemented, currently vaccinating
200,000 dogs annually, has prevented hundreds of human and animal rabies deaths.
We also learnt that one of the most difficult parts of the control programme was
persuading the Masai dog owners to wait in an orderly line to have their dogs
vaccinated, and that the commonest pet names for their dogs were ‘Osama’ and
‘Bush’. As well as saving at least 50 human lives saved each year, at a
fraction of the cost of post exposure vaccination, the measures have also
protected endangered wildlife species, such as the African wild dog.

We also learned how the wildebeest numbers, a dominant
feature of the ecology of the Serengeti, have grown since the control of
rinderpest in cattle in the 1960s, and that as reservoirs of malignant catarrhal
fever virus, the arrival of the wildebeest to the lush lowlands of the Serengeti
drives the Masai to take their herds, to higher more marginal grazing, which can
lead to environment problems from overgrazing.

A search of the CAB Abstracts database for information on
‘one medicine’ shows that not only is the concept helpful in improving the
lives of pastoralists in developing countries, but can also help deal with
global problems such as obesity and heart disease through the benefits of the
animal human bond.

Canine distemper and Paget’s disease: zoonotic?

I came across a brief report in a local Michigan paper (thanks to the internet) of an outbreak of distemper in Manistee County, Michigan. The short report said that “Police said they’ve recently shot at least a dozen foxes and raccoons wandering around backyards and golf courses. A local veterinarian was reported to have said that “household pets could become infected if exposed to bodily fluids of animals with distemper”. The versatility of the law enforcers in dealing with this wildlife reservoir of disease is impressive. This prompted me to check up on the research on this well known dog disease, and I was surprised to discover that the virus may be linked to human disease, and that keeping up the dog’s vaccinations could be important to the owner’s health as well as to the dog’s.

Canine distemper is viral disease caused by a Morbillivirus (similar to the measles virus – in fact the measles vaccine can protect pups against distemper). The disease can affect all Canidae (dogs, wolves and foxes), as well as Mustelidae (such as ferrets, mink, and skunk), most Procyonidae (including raccoons), and some Viveridae. It is highly infectious in dogs and other susceptible species and symptoms can range from being mild to severe, and can be fatal in some cases. Young puppies and dogs that have not been vaccinated are most susceptible.

The virus is relatively labile and unstable outside of the host. Distemper can be endemic in urban areas, and the infection is transmitted by inhalation and by direct contact and via fomites. Infected animals shed large numbers of viral particles in secretions and excretions during the active stage of the disease. The presence of maternal antibody can result in many infections being sub-clinical. The incubation period for the virus is 3 to 7 days but may be as long as 4 weeks.

The disease usually causes nasal and eye discharge, twitching, coughing, diarrhoea, vomiting and seizures. The infected dog often refuses its food. Signs of the disease usually include fever, respiratory and gastrointestinal signs, encephalomyelitis, and hyperkeratosis of the footpads (which is why it is sometimes called hardpad disease), and neurological signs. The neurological signs can include muscle twitching, paralysis and ataxia, and convulsions. A chronic course of the disease called old-dog encephalitis usually includes ataxia and compulsive movements, with the neurological signs being progressive.

A number of vaccines are available including modified live vaccine, recombinant vaccines. The 2006 American Animal Hospital Guidelines (2006) recommend that puppies should be given 3 doses of vaccine between 6-16 weeks of age, with a booster dose one year after the end of the first series of injections with revaccination at intervals of 3 years or longer. There is no specific treatment of the disease but is easily prevented by vaccination.

There are more than 2000 records on canine distemper on the CAB Abstracts database and these can be found using the keyword descriptor canine distemper:su.

Canine distemper is not usually thought of as a disease of humans, however there is some evidence to link the canine distemper virus with Paget’s disease of bone. Paget’s disease of bone (osteitis deformans) is a chronic condition that affects bone growth, causing the bones to expand and become deformed. The deformed bones then weaken and are more likely to fracture. The spine, the pelvis, the legs, the skull (head) and the collarbone are most often affected. There are 11 references on the CAB Abstracts Database on Paget’s disease and distemper. One reference concludes that there is conclusive proof that canine distemper virus "can infect and replicate in human osteoclast precursors, raising possible zoonotic implications for CDV. This study provides further evidence for the possible role of paramyxoviruses in the pathogenesis of Paget’s disease.

More work would need to be done on the epidemiology of the Paget’s disease and canine distemper virus, before any conclusions can be made on whether it is a zoonotic disease, but it might be wise to keep the dog’s vaccinations up to date.

References:

A comparison of in situ hybridisation, reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ-RT-PCR for the detection of canine distemper virus RNA in Paget’s disease. Hoyland, J. A.; Dixon, J. A.; Berry, J. L.; Davies, M.; Selby, P. L.; Mee, A. P. Journal of Virological Methods, 109, (2) 2003, 253-259

Canine distemper virus induces human osteoclastogenesis through NF-κB and sequestosome 1/P62 activation. Selby, P. L.;Davies, M.; Mee, A. P. Journal of Bone and Mineral Research, 2006, 21, (11). 1750-1756

Other useful sources of online information on the canine distemper disease are:

Merck Veterinary Manual

and

UC Davis Koret Shelter Medicine Program. Information sheet