Dog share?

Bobby

“Can we have a pet for Christmas?” is something I hear a lot each December. The answer, much to my children’s disappointment, is always no.

In addition to the fact that we are often told that Christmas is not the best time to introduce a new animal into a household [e.g. see PetRescue.Com article: No Christmas Puppies, Please!], I can’t think of any pet that is both practical and fulfils the necessary fluffy/cute criteria that my kids are requesting. (Apparently the stick insects that we have are not ‘proper’ pets!). 

After listening to experts talk at CABI’s Human-Animal Bond Symposium last month, I can appreciate the benefits that introducing something cuddly into the family could bring. Professor Alan Beck, of Purdue University, described some of the ways that pets can benefit human health and welfare. For example, dog ownership generally results in increased exercise and greater social contact through talking with other dog owners; people with dogs or cats have been found to have lower blood pressure, heart rates and reduced cholesterol than those without; and even staring at a fish tank can provide enough of a distraction from our worries to induce a relaxation response. Animals can also help teach children about responsibility and compassion.

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Climate change – will it affect spread of vector borne diseases?

Climate change is going to mean mosquito-borne diseases
spread north out of the tropics right? That seems to be the story the news media are giving us. But it is really the case? Do we really need to start thinking about buying bednets to protect against mozzy bites?




Aedes mosquito(CDC)As editor of Global Health database I was invited to the ISNTD Bites
seminar in London, at the Natural History Museum where the issue was hotly debated. The session on climate change and disease vectors showed that
while biology of disease vectors like mosquitoes and sandflies is affected by temperature there are several other
factors that influence spread of disease vectors and the diseases they carry that may mean they don’t spread in the way straight climate maps predict.
Among these are land use, urbanisation and global trade. In fact, the
entomologists at the seminar were arguing that climate change issues are
distracting researchers from looking more into factors that are having drastic effects on the spread of disease vectors
and disease right now.

 

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He’s OK if you don’t get on the wrong side of him

Most of us have preferences such as left- or right-handedness, and tend to favour one eye over another to look down a telescope. These biases are the result of brain lateralisation, with a dominant left side of the brain leading to right handedness, and vice versa. Many animals show comparable biases. Lesley Rogers believes a better understanding of these biases could be used to improve animal welfare. Rogers, of the University of New England, Australia explains her ideas in an article in CAB Reviews.

Horse_profile

Horses, like many animals, show side bias  (Fir0002/Flagstaffotos, see License).

The left hemisphere of the brain deals with repeated stimuli, paying attention and learning rules, whilst the right is more concerned with emergency responses to threats. Given the switch over between brain side and the part of the body that it relates to, this means that domestic chickens prefer to look at potential predators with their left eyes (associated with the right hemisphere), but to use their right eyes (and left hemisphere) to search for food, having learned rules for what is and isn’t food. Many animals respond more strongly to predators that approach them from the left.


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It’s not just puppy fat

While it’s a well-known piece of perceived wisdom that owners look like their dogs, there is evidence that obese owners are more likely to have obese dogs. Writing in CAB Reviews, Ian Bland and Julian Hill discuss the importance of owner’s perceptions of exercise and diet in terms of controlling obesity in dogs.
It is hard to be sure what the level of dog obesity is, as there is no BMI equivalent, and estimates based on owner assessments are different to those conducted by vets, but the trend is upwards.

GermanShep1_wb 


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

Cat1 small 

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.

 

Please can I have some more?

Pets may be able to negotiate with their owners over what, when and how much they are fed. This is the view of Jon Day of the Waltham Centre for Pet Nutrition, based in part on evidence of how human babies “ask” for food before they can talk. Analysing these interactions may help avoid obesity in pets. The paper by Day and his colleagues appears in CABI’s broad-ranging reviews journal, CAB Reviews.

 

Both pets and babies use begging and finicky eating habits to control what they are given, in a push-pull relationship. Day and his colleagues say that behaviour before, during and after eating all influence the feeder. Cats can self-regulate their diet in the laboratory at a healthy level, suggesting that obesity in the home may be the result of the pet manipulating the feeder, whether intentionally or unintentionally.

 

Hungry 

cc schmollmolch

Evidence suggests that men are less able to judge levels of hunger in infants than women. There is also wide variation in the ability of pet owners to interpret the behaviour of pets in terms of appetite and “fullness”.

 

Food refusal is common in infants and is thought to make the caregiver more dependent on the infant, and gaining them more attention. Cats sometimes refuse a food that they have previously eaten without problems, and they too may use feed refusal as a strategy to influence what they are fed, but also more generally to dominate their relationship with their owners.  

 

While begging behaviour is influenced by an animal’s hunger, there may also be elements of conditioned routine and social interaction with the owner that affect how much an animal begs. For example, the extent which a dog will beg depends on whether it can see its owner’s face or eyes.  

While there is still more research to be done, it’s probable that at least eight out of ten owners know that their cats are manipulating them over what food they give them, and a better understanding of this may help keep their pets healthier.

 

The paper, “Do pets influence the quantity and choice of food offered to them by their owners: lessons from other animals and the pre-verbal human infant?” by Jon E.L. Day, Sophie Kergoat and Kurt Kotrschal appears in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 2009 4, No. 042.

http://www.cababstractsplus.org/CABReviews/Reviews.asp?action=display&openMenu=relatedItems&ReviewID=106612&Year=2009

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