GENÉTICA



Dogs Likely Originated in the Middle East, New Genetic Data Indicate

Dogs likely originated in the Middle East, not Asia or Europe, according to a new genetic analysis by an international team of scientists led by UCLA biologists.

"Dogs seem to share more genetic similarity with Middle Eastern gray wolves than with any other wolf population worldwide," said Robert Wayne, UCLA professor of ecology and evolutionary biology and senior author of the Nature paper. "Genome-wide analysis now directly suggests a Middle East origin for modern dogs. We have found that a dominant proportion of modern dogs' ancestry derives from Middle Eastern wolves, and this finding is consistent with the hypothesis that dogs originated in the Middle East.

"This is the same area where domestic cats and many of our livestock originated and where agriculture first developed," Wayne noted.

Previous genetic research suggested an East Asian origin for dogs, "which was unexpected," Wayne said, "because there was never a hint in the archaeological record that dogs evolved there."

"We were able to study a broader sampling of wolves globally than has ever been done before, including Middle Eastern wolves," said the paper's lead author, Bridgett vonHoldt, a UCLA graduate student of ecology and evolutionary biology in Wayne's laboratory who studies the genetics of dog domestication. "In our analysis of the entire genome, we found that dogs share more unique markers with Middle Eastern wolves than with East Asian wolves. We used a genome-wide approach, which avoids the bias of single genome region."

The biologists report genetic data from more than 900 dogs from 85 breeds (including all the major ones) and more than 200 wild gray wolves (the ancestor of domestic dogs) worldwide, including populations from North America, Europe, the Middle East and East Asia. They used molecular genetic techniques to analyze more than 48,000 genetic markers. No previous study has ever analyzed anywhere near that many markers.
The biologists have samples from Israel, Saudi Arabia and Iran -- but they have not pinpointed a specific location in the Middle East where dogs originated.

"This study is unique in using a particular technology called a single nucleotide polymorphism, or SNP, genotyping chip; these chips interrogate the nucleotides at 48,000 locations in the genome," said John Novembre, UCLA assistant professor of ecology and evolutionary biology and a member of UCLA's Interdepartmental Program in Bioinformatics. "We are able to compare dogs looking at not just one small part of the genome, but at 48,000 different locations. That gives us the fine-scale resolution to analyze how these breeds are related to one another and how they are related to wolves."


Previous genetic research had suggested an East Asian origin based on the higher diversity of mitochondrial sequences in East Asia and China than anywhere else in the world. (Mitochondria are tiny cellular structures outside the nucleus that produce energy and have their own small genome.) However, that research was based on only one sequence, a small part of the mitochondrial genome, Wayne noted.

"That research made extrapolations about how the domestic dog has evolved from examination of one region in the mitochondrial genome," Wayne said. "This new Nature paper is a much more comprehensive analysis because we have analyzed 48,000 markers distributed throughout the nuclear genome to try to conclude where the most likely ancestral population is.

"What we found is much more consistent with the archaeological record," he said. "We found strong kinship to Middle Eastern gray wolves and, to some extent, European gray wolves -- but much less so to any wolves from East Asia. Our findings strongly contradict the conclusions based on earlier mitochondrial DNA sequence data."

Eighty percent of dog breeds are modern breeds that evolved in the last few hundred years, Wayne said. But some dog breeds have ancient histories that go back thousands of years.

"We sampled both groups, the modern explosion of dog breeds and some of the ancient lineages," he said. "Our data were aimed at resolving questions about the origin of domestic dogs, the evolution of dog breeds, and the history of dog breeds and relationships to their closest wild progenitor, the gray wolf."

The first dogs that appeared in the Middle Eastern archaeological record date back some 12,000 to 13,000 years, Wayne said. Wolves have been in the Old World for hundreds of thousands of years. The oldest dogs from the archaeological record come from Europe and Western Russia. A dog from Belgium dates back 31,000 years, and a group of dogs from Western Russia is approximately 15,000 years old, Wayne said.
"We know that dogs from the Middle East were closely associated with humans because they were found in ancient human burial sites," Wayne said. "In one case, a puppy is curled up in the arms of a buried human."

Some very old strains of dogs, with a history dating back more than several thousand years, may be mixed with modern breeds, enhancing their diversity in certain areas such as East Asia, Wayne said, interpreting the higher mitochondrial DNA diversity in that area of the globe.

There is one small set of East Asian breeds that does not indicate a strong Middle East origin, showing instead a high level of genetic sharing with Chinese wolves. This finding suggests there was some intermixing between East Asian dog breeds and East Asian wolves; the data do not make clear how long ago this occurred.

"However, the vast majority of dogs that we studied show significant levels of sharing with Middle Eastern wolves," said Novembre, a population geneticist who studies genetic diversity and the lessons that can be learned from it.

Co-authors on the Nature paper include a group of researchers from the National Institutes of Health/National Human Genome Research Institute led by Elaine Ostrander; a group led by Carlos Bustamante, formerly of the Cornell University Department of Biological Statistics and Computational Biology and now a professor of genetics at the Stanford University School of Medicine; and scientists from China, Israel, Australia, Europe and Canada.

UCLA co-authors include Eunjung Han, a UCLA graduate student of Novembre's in biostatistics; John Pollinger, director of UCLA's Conservation Genetics Resource Center and associate director of the Center for Tropical Research at UCLA's Institute of the Environment; and James Knowles, a graduate student from Canada's University of Alberta working in Wayne's laboratory. Wayne and Novembre's research is federally funded by the National Science Foundation. Novembre's research is also funded by the Searle Scholars Program.

"By analyzing a sea of scientific data, Bob Wayne and John Novembre are at the forefront of the 'new life sciences' -- which represents new ways to make discovery," said Victoria Sork, dean of the UCLA Division of Life Sciences. "Their integration of genomic data with bioinformatic approaches illustrates how integration has enhanced our ability to analyze biological systems. Integration of knowledge is changing how we think about how life works. We are no longer limited to studying just one piece of a puzzle."



Toy dogs and an evolutionary framework for dog domestication

The biologists have also found that when one looks at a relationship tree of modern and ancient dog breeds, there is surprising structure to it, and the structure mimics the classifications of dogs by breeders into herding dogs, retrievers, sight hounds, small terriers and others.

"We found there is a surprising genetic structure that accords with functional classifications -- suggesting that new breeds are developed from crosses within specific breed groups that share particular traits," Wayne said. "If they want a new sight hound, they tend to cross sight hounds with each other, and the same with herding dogs and retrieving dogs. That may not seem so surprising, but we had no reason to think beforehand that these groups would be strongly genealogical.

"There are some notable exceptions, such as 'toy dogs.' In this grouping, there are many different kinds of lineages represented, including traces of herding dogs and retrievers. When it comes to miniaturizing a dog, breeders start with a larger breed and cross that with a miniature dog to make a dwarfed breed on a new genetic background, causing the mixing of various lineages. It's a mix-and-match approach for some of these breed groupings. But in other cases, new breeds have been based on combinations of breeds that have specific traits."

New insights into the evolution of dogs have emerged from this Nature paper and several other recent studies by biologists, including Wayne and his colleagues.

"A framework about dog evolution is emerging," Wayne said. "Even though dogs have an almost infinite variety of forms, geneticists have been discovering that much of this diversity has a simple genetic basis. Short-legged dogs -- there are at least 19 such breeds, including dachshunds, corgis and basset hounds -- have short legs due to the appearance of just one unique gene, a mutant growth-factor gene."
Recent research by Wayne and his colleagues has identified genes responsible for short legs, small size, different fur types and different coat patterns and colors.

"It seems that in dogs, unlike other domesticated species, many of these different phenotypes distill to just a handful of genes," Wayne said. "These genes have been mixed with retrievers, herding dogs and sight hounds to create new breeds."

In humans, by contrast, most differences in height and weight involve many genes, each of which has only a small effect; most of the genes account for only about 1 or 2 percent of variability. Even in agricultural plants, most genes have only a small influence on a single trait.

In dogs, however, one gene that is responsible for differences in size accounts for more than 50 percent of the variation in body size, Wayne said. A small number of genes, he said, have been moved around in dogs to create the appearance of amazing diversity.

"Because we analyzed 48,000 locations in the genome, we can ask which regions are the most different between dogs and wolves," said Novembre, whose research group investigated whether specific regions of the genome have changed under domestication. "We identified a few regions that are exceptionally different between dogs and wolves; these might be places in the genome where some of the changes occurred that make dogs and wolves different from each other today. These are good candidate regions for follow-up research."

In a separate paper, Melissa Gray, who earned her Ph.D. from UCLA in Wayne's laboratory, reported in February, along with Wayne and colleagues, on an important gene known as IGF1, which is responsible for small size in dogs, and analyzed which wolf populations are closest evolutionarily to this gene. The findings, published in the journal BMC Biology show that the gene appears to have arisen in Middle Eastern wolves, giving further support to the major claim in the new Nature paper.


Overview

It is by now generally accepted that the dog is a wolf modified through 15,000 or more years of sometimes intensive breeding to live in human society. In Darwin's terms, the dog is a product of artificial selection, or "selection under domestication," while the wild wolf is subject to the laws of natural selection. Much about the origin and early development of the dog — the first domesticated animal — remains a mystery, with scientists still puzzling over how, when, where and why wolves and people first got together. Was it the dog's prowess in the hunt, its alertness as a camp guard, its companionship or a combination of those and other qualities that made it so valuable? Did the dog have religious significance as a guardian and guide for the dead? Did wolf become dog in the Middle East, East China, Europe or all of them? Was it 15,000 or 40,000 or 135,000 years ago that the transformation occurred?

 In recent years, scientists around the world have engaged in spirited debate over these questions, their research aided by sequencing of the dog genome in 2005. That has allowed researchers to examine the evolutionary history of the dog and probe the genetic relationships within and between breeds of dogs. Researchers are also able to use purebred dogs with their array of inherited diseases and extensive pedigrees to search for the genetic roots of diseases common to dogs and humans. Relying on the most comprehensive and largest survey to date of dogs and wolves, the most recent study by an international group of scientists places the origins of the dog in the Middle East, where cats and livestock were later domesticated and where agriculture began. Led by Bridgett M. vonHoldt and Robert K. Wayne of the University of California, Los Angeles, the international team analyzed 48,000 glitches or single letter changes in long stretches of DNA, called single-nucleotide polymorphisms, SNPs, and pronounced "snips," from 912 dogs representing 85 breeds and 225 wolves from 11 different populations. They looked for matches in those haplotypes, as they are known, indicating genetic relationships.


The survey showed that dogs were closest genetically to Middle Eastern wolves, but that for a short period of time after domestication, dogs apparently were bred to wolves from other areas, perhaps as they migrated with people into previously unoccupied lands where there were no dogs.

Without fixing a date for the transformation of wolf to dog, the researchers observed that their findings were consistent with an archaeological record that locates early dogs in Goyet Cave in Belgium, 31,7000 years ago; western Russia, 15,000 years ago; Germany,14,000 years ago; and the Middle East,12,000 years ago.
The researchers also identified genetic sequences shared by dogs within specific breeds that could be used to examine their development through the formation of modern breeds beginning in the late 18th century. To their surprise, breeds with similar phenotypes and functions grouped together, indicating a shared genetic heritage for herding dogs, mastiff-like dogs, sight hounds, scent hounds, small terriers, spaniels, toy dogs, retrievers, working dogs and a group containing ancient and spitz-like dogs. The survey by Dr. Wayne, Dr. vonHoldt and their collaborators was published just months after a 2009 study suggesting that dog domestication occurred in Eastern China, south of the Yangtze River, less than 16,000 years ago. These dogs were probably initially raised as food, reported Peter Savolainen of the Royal Institute of Technology in Stockholm. He argued that the dog resulted from a single domestication event and then quickly spread with people around the world. Dr. Savolainen and his team studied mitochondrial DNA, inherited only from the mother, while Dr. Wayne's team surveyed the entire genome, a more comprehensive approach because it includes contributions from both parents.

The Middle East and Beyond

Archaeologists insist that any date for the appearance of the dog backed by genetic evidence must also be supported by fossil remains to be credible. In an influential 2006 article in the Journal of Archaeological Science, Darcy Morey argued that first definitive proof of the dog — the fully domesticated wolf, as opposed to a tamed one — is found in dog burials, with the earliest confirmed one from Bonn-Oberkassel, Germany, 14,000 years ago. The earliest dog burial yet found in North America was uncovered in Illinois and dated to 8,500 years ago. In Dr. Morey’s view, the burials clearly signify the importance of dogs in people’s lives even at those early dates.  

But paleontologists and geneticists recently identified and dated the dog remains from Belgium's Goyet Cave to 31,700 years ago and from Eliseevichi in the Ukraine to around 15,000 years ago. While neither find is universally accepted, they once again have underscored the provisional nature of theories of dog domestication. A number of geneticists argue that genetic changes could have occurred in a population of wolves that effectively turned them into dogs before they looked the part. In other words, changes in phenotype, or appearance, followed some time after changes in genotype.

Dog Chose Man

Few relationships are so laden with mutual benefit as that between man and dog. No one knows the precise process by which certain wolves became dogs. Some experts claim that the dog evolved from wolves who lived by scavenging in and around human settlements, becoming tame in the process. Others argue for a more dynamic process involving wolves and humans. 

Despite their deep and fundamental disagreements, each group recognized that much of the credit for this unusual state of affairs may lie on the canine side of the equation. A study in the 2002 issue of Science Magazine probed the psychology of dogs, showing that although chimpanzees may have brain power of far greater wattage, there is one task at which dogs excel, that of picking up cues from human behavior. 

This interpretive skill was perhaps the ability for which they were selected.When two species live together for a long time, each usually influences the genetically conferred qualities of the other. People may have selected preferred abilities in the dog, but dogs too may have fostered their favorite qualities in people — not of course deliberately but simply by giving people who used dogs a better chance of surviving than people who did not.

Bad Dogs

These days dog experts have noticed signs of a growing concern over bad behavior by dogs, despite all the gourmet biscuits, educational toys and $70 dog sweaters lavished on them. (Perhaps because of that treatment, others argue.) Enrollment in obedience classes has escalated, veterinarians have seen an increasing demand for help with behavioral problems, and the ''Dog Whisperer,'' the National Geographic Channel's dog-behavior program, has become a hit. Figuring out the dog mind, it seems, has become a national obsession. 

The problem, some dog experts suspect, is not that there are more bad dogs, only more demanding owners. People expect their dogs to cooperate with their busier lives — to behave at cocktail parties, at real estate open houses and in cafes and shops and to respect their well-appointed homes. And in a culture that values achievement and excellence, they readily assume that dogs value the same things, especially when there are obstacle courses to master and social graces to display.

''This is the generation that invented the gifted and talented kid,'' said Jon Katz, the author of books on the human-dog relationship, ''so now you have the gifted and talented dog.''


Mr. Katz, who has written ''Katz on Dogs: A Commonsense Guide to Training and Living With Dogs'' (Villard, 2005) and ''The New Work of Dogs'' (Villard, 2003), which discusses the changing role of dogs from outdoor protectors and retrievers to indoor nurturers and soul mates, said there has been an explosion in the number of companion animals, almost a fivefold increase since the 1960s. Dogs are now expected to play the role of the best friend, confidant or child, who can be taken everywhere, including the mall and a friend's house.

Obedience Training

Annette Rauch, a research assistant professor at the Center for Animals and Public Policy at the Cummings School of Veterinary Medicine of Tufts University in North Grafton, Mass., cited a survey of new pet owners that showed 75 percent wanted counseling on behavior, and 85 percent said they intended to participate in a training course. Behavior problems, she said, are the leading reason people give their pets away.

By far the most popular dog in the country for the last 16 years has been the Labrador retriever, which had 137,867 American Kennel Club registrations in 2005, more than twice as many as the second most popular dog, the golden retriever, which had 48,509. Large dogs like these need more exercise than many owners realize. And if they don't get enough, they may chew the furniture or become aggressive.


Andrea Arden, the owner of Andrea Arden Dog Training, a Manhattan firm that does house calls, said small dogs present a different kind of trouble, which she calls small-dog syndrome. Many owners (especially those who think of themselves as parents to dogs) treat their Yorkies and Chihuahuas like babies, she explained, which leads to spoiling. 

Owners often fail to discipline small dogs when they relieve themselves on the carpet, for example. The lack of discipline can lead to aggressive snapping, biting, barking and chewing, Ms. Arden said. Pet owners tend to respond to bad behavior in two ways, said Prof. Nicholas Dodman, the director of the Animal Behavior Clinic at Cummings: by getting rid of the dog or by taking extreme measures to improve the behavior immediately. Dr. Dodman cautioned owners to be patient, to maintain realistic expectations and to aim to control their dogs without shouting or violence. Methods of training vary, but most favor rewards for good behavior over punishment for bad. 

Cesar Millan, who runs a dog psychology center in Los Angeles and is the host of the TV show ''Dog Whisperer,'' calls for asserting dominance, so that the dog learns that the owner is the leader. Mr. Millan preaches that dogs need exercise, discipline and affection, in that order.

The following information is adapted from "The New York Times Guide to Practically Everything"

Picking a Canine Companion

A dog’s breed is no guarantee that it will act according to the book.
Every dog has its own personality. But some breeds are better suited to being jostled by children than others, while the circumstances of other pet lovers may require quite different choices. Here, the veterinarian Sheldon L. Gerstenfeld suggests which dogs make good pets for families with children, owners with active lifestyles and people who are older and looking for easy pet companionship. Dr. Gerstenfeld is the author of numerous books about pet care, including the “A.S.P.C.A. Complete Guide to Dog.”

Dogs for Children

Collie: They’re gentle and predictable and won’t bite your kids. They’re easy to train and want to please. Adult collies weigh about 50 pounds and their long hair requires grooming. Lassie was a rough-coated collie. The smooth-coated collie is somewhat less popular.


Golden Retriever: Easygoing, active and alert, golden retrievers have the best temperaments. They love to interact with kids and to play ball. The adult female weighs 50 to 60 pounds; the adult male 70 to 90 pounds. They need to be groomed and fed, which teaches kids to be responsible.

Labrador Retriever: Black, yellow and chocolate Labs are known for being even-tempered and friendly. They are always ready to play, and kids can just lie on them. Adult dogs weigh 60 to 70 pounds. They need grooming, so they also teach children about responsibility. Avoid the Chesapeake Bay retriever (curlier coat) since it can be nasty and unpredictable (bites more readily than others). Labs are the most popular American Kennel Club breed.
Standard Poodle: A gentle dog that is very intelligent. A standard poodle will let a kid lie on it. You need to groom them, but a fancy haircut is not necessary. Because poodles are so popular, prospective owners have to watch out for puppy-mill degradation. Larger dogs require more exercise.

Dogs for Active People

Boxer: Animated, with outgoing personalities, boxers respond readily to playfulness. Caveat: they tend to drool and snore.


English Cocker Spaniel: These are sweet dogs, and they haven’t been inbred. They’re playful and alert at all times and great for children and active people.
Greyhound: They are a little aloof but also very gentle. Most are adopted from the racetrack. Greyhounds have a regal personality and don’t slobber with affection like a retriever. One caution: they are high-strung and at times easily upset by sudden movements.
Terrier: Terriers start out their morning as if they had eight cups of coffee, so they are good for an active person. The bull terrier get a recommendation since it is always ready to frolic. They need firm training but are also known for their sweet personalities.


Dogs for Older People

Chihuahua : If they are from a good breeder, they will have a good personality. Their short hair requires less grooming, which makes them a good choice for an older person living alone. They can be yappy and clannish at times.

Miniature Poodle: These poodles are intelligent and good because they are small and don’t shed a lot. They love attention. All poodles are fast learners; the smaller they are the faster they learn.

Toy Poodle: These dogs love to be cuddled and are intelligent. They have to be groomed, but they don’t shed, so there is not much hair to clean up. It is the brightest of all the toys and will demand its owner’s continuous attention. Because of the dog’s popularity, inbreeding can be a problem.
Yorkshire Terrier: These dogs are small and easy to care for. They weigh about seven pounds and have silky, long draping hair. Their coats require grooming, which may not be good for an elderly person who lacks the energy or who has arthritis.

Buying a Pedigree Pup

More than 200,000 American households bought puppies online in 2004, according to the American Pet Product Manufacturers Association, a trade group. But not all Internet purchases have a happy ending. There were more than 30 cases where charges were filed by consumers who either received sick puppies that later died, or paid upward of $1,000 for a dog and never received it. The American Kennel Club — the largest registry of purebred dogs — says that more people are reporting health problems in dogs bought online.


To help buyers find the right breed and to choose responsible sellers, The A.K.C. has introduced a Web-based service called Breeder Classifieds, found under “Online Service” at www.akc.org. Only breeders in good standing can advertise.

Some people mistakenly think that A.K.C. papers alone guarantee that a puppy is healthy and of good quality. They prove only that a puppy is the offspring of a known sire and dam.
Prices for pedigree puppies vary by region, depending on the type of dog, its health-screening tests and whether the parents are champions. In the New York metropolitan area, for example, Rhodesian ridgebacks — large, athletic dogs with permanently raised hair along their backs — sell for around $1,500. In upstate New York, they go for half that price.

In general, buyers can usually expect to pay $500 to $2,000 for a pet-quality pedigree puppy — one that the breeder believes won’t be able to compete successfully in dog shows. Pedigree show dogs fetch a much higher price.

Many fans of purebreds say that you know it’s a good breeder if you can make sure of the following things:
* They are not in the business solely to make money. For many, it is a hobby, with the goal of improving the breed.
* They often specialize in one breed, and spend time educating buyers about its advantages and disadvantages.
* They raise puppies in a loving home environment, not in a kennel, since socialization to humans occurs between one and 18 weeks.
* They sell only healthy animals and guarantee them for reasonable periods. They have tested a puppy’s parents for hereditary diseases, and the puppy’s vaccinations should be up to date. They are willing to put you in contact with the veterinarian who has cared for the puppy.
* Their contracts stipulate that if the buyer does not meet specified conditions of care, or becomes unable to keep the puppy, they will take it back. (Most contracts for pet-quality dogs also have a clause that requires spaying or neutering of the dog.)
* They are willing to let you meet at least one of the puppy’s parents; the appearance and temperament of the parent can provide an idea of how the pup may turn out.
* They have a good reputation at the local breed club.

Smelling Like a Wet Dog

When it comes to baths, almost all dogs second the notion attributed to Elizabeth I: once a month would be just fine, whether she needs it or not. And most dog owners would subscribe to that view, too, given the fuss their charges make, if it weren’t for their habit of lolling in mud puddles and rolling ecstatically over dead fish on the beach.


Slowly, basic dog shampoo is disappearing, replaced by a bewildering array of “pet spa” products with names like Adventure Dog Suds, Earthbath Mediterranean Magic and so on. And that’s just the beginning. There are aromatherapy spritzers, between-bath splashes and even massage oils.
Some of the newest products come directly from the human beauty industry. Are they better than basic shampoo?

A dog with dry skin can benefit from shampoos made with extra fatty acids or oatmeal (which has anti-itch properties and helps moisturize). But pet owners should pay attention to ingredient lists; some products may contain steroids.

Because dogs’ skin has a pH level different from human skin, it’s wise to use a shampoo formulated for them. Some human shampoos may dry out their coats. Milder shampoos like Johnson’s Baby Shampoo are better, especially for dogs that are bathed frequently.

Dieting

More and more dogs and cats are adopting the habits of their human companions, and like them, they are increasingly overweight. Between 25 percent and 40 percent of America’s pets are obese, according to George Fahey, a professor of nutrition at the University of Illinois Animal Sciences Department, a big jump in just the past decade.


There are two basic reasons: Too little exercise and too many treats, especially people food.
Pets are also suffering the same consequences as overweight people, including joint problems and diabetes, said John E. Bauer, a professor of veterinary nutrition at Texas A&M University, in College Station. Too many treats may even shorten their lives.

Pet supply companies have begun marketing weight loss supplements, including products like Canine Slim Results and Vetri-Lean. But these don’t work any better for pets than they do for people, veterinarians say.
Dozens of companies now sell low-fat or low-calorie pet foods. Researchers in France and Belgium who recently evaluated an Atkins-like high-protein, low-carbohydrate diet for obese dogs found that it worked, but not much better than diets that merely cut back on calories. Many veterinary experts say giving smaller portions of a balanced pet food is a healthier choice for weight loss.

According to Professor Fahey, the best — and simplest — approach is to buy pet food from a reputable manufacturer and follow the directions. “Feeding instructions are very reliable,” he says. “If the package says your dog should be eating a cup a day, that’s what they should get. A little less if your pet needs to lose weight.” Treats like “vanilla woofers” and carob-covered fire hydrants should be reserved for special occasions. Your dog may not like that idea. But the second part of Professor Fahey’s prescription — more exercise — should get tails wagging.

When a Dog Is Sick

Once your pet is weaned, the natural protection garnered from its mother’s milk eventually wears off, leaving it prey to a host of opportunistic viruses. As with humans, pets’ diseases often are highly contagious and, in cases such as rabies, pose a serious threat to humans as well. Here are some of the ailments pets may be subject to.


Common Diseases in Cats and Dogs: Rabies is a viral disease that can attack the central nervous system of all warm-blooded animals, including humans. It is fatal if not treated. Most states require dog and cat owners to vaccinate their pets against rabies. 

The disease is transmitted by saliva, which is usually transferred by a bite from an infected animal and is frequently found in wild animals, such as skunks, raccoons and bats.
There are two types of rabies — “dumb” and “furious.” Both cause a departure from normal behavior. Animals with furious rabies will have a period immediately prior to death in which they appear to be “mad,” frothing at the mouth and biting anything that gets in their way. Dumb rabies differs in that there is no mad period. Instead, paralysis spreads to limbs and vital organs and death quickly follows. Wild animals that are unusually friendly and appear to have no fear of man or domestic animals should be avoided and reported immediately to the police and animal control authorities.

Rabies is almost totally preventable by vaccination. Dogs and cats should receive an initial rabies vaccination by the age of three to four months. Protection lasts from one to three years. Regular boosters are required.
The diseases listed below are those that most commonly affect pets. Vaccines are available for all of these diseases, but not necessarily recommended for all pets.

Canine bordetellosis: Caused by bacteria in the respiratory tracts of many animals, it is the primary cause of kennel cough. Besides the cough, some dogs suffer from a purulent nasal discharge. Transmission usually occurs through contacts with other dogs’ nasal secretions. Vaccination is generally administered by nasal spray.

Canine distemper virus (CDV): A highly contagious viral disease, canine distemper is transmitted by direct or indirect contact with the discharges from an infected dog’s eyes and nose. Early signs are similar to those of a severe cold and often go unrecognized by the pet owner. The respiratory problems may be accompanied by vomiting and diarrhea. A nervous system disorder may also develop. The death rate from canine distemper is greater than 50 percent in adult dogs and higher in puppies. Even if the dog survives, distemper can cause permanent damage to its nervous system, sense of smell, hearing and sight. Partial or total paralysis is not uncommon.

Canine leptospirosis: A bacterial disease that harms the kidneys and can result in kidney failure. Vomiting, impaired vision and convulsions are signs. Transmission results from contact with the urine of infected animals, or contact with something tainted by such urine.

Canine parainfluenza: A viral infection of the respiratory tract, it is frequently accompanied by other respiratory viruses and is usually spread through contact with the nasal secretions of other dogs.
Canine parvovirus (CPV): A serious problem because the virus withstands extreme temperature changes and even exposure to most disinfectants. The source of infection is usually dog feces, which can contaminate cages and shoes and can be carried on the feet and hair of infected animals.

CPV attacks the intestinal tract, white blood cells and heart. Symptoms include vomiting, severe diarrhea, a loss of appetite, depression and high fever. Most deaths occur within 48 to 72 hours after the onset of clinical signs. Infected pups may act depressed or collapse, gasping for breath. Death may follow immediately. Pups that survive are likely to have permanently damaged hearts.

Infectious canine hepatitis: Caused by a virus that can infect many tissues, the disease usually attacks the liver, causing hepatitis. In some instances, a whiteness or cloudiness of the eye may accompany the disease. Another strain of the same virus can cause respiratory tract infections. These viruses are transmitted by contact with objects that have been contaminated with the urine from infected dogs. Infected canine hepatitis is different from the human type.

 High Tech for Pets

The pet care business offers medical and technological advances that are helping pets live longer and healthier lives. Because many of these procedures are costly, it may be worth the money to invest in pet insurance.


Farewell to fleas. The most radical changes in veterinary medicine have occurred in flea control. Until recently, pet owners had few choices: use flea powders and collars on their pets and spray the yard with chemicals.

Today, new options include pills and topical spot-on solutions. The pills prevent flea eggs from hatching, and the skin treatments kill fleas on contact for 30 days. Both are available at the vet’s office.

New advances in outdoor flea control are available that contain nematodes, live organisms that feed on flea larvae. These products reduce harm to the environment, as well as to humans, animals and insects.
Computer I.D. A new way to identify your pet involves implanting a tiny microchip — about 1/4 to 1/3 inch long — under the skin of just about any animal. The chip is injected by a vet with a device that looks like a syringe and needle. The result is a lifetime I.D. that can’t be lost or removed. The information can be read by scanners now used by animal control centers and humane societies. So if your dog strays and ends up at one of these centers, the scanner reads the identification number that traces the pet back to you.
Patching up pain. The new patch technology that’s so popular for humans — estrogen patches for women, nicotine patches for smokers — is now used on animals. If an animal is in pain after an accident, or is having a major dental procedure, a time-release patch can steadily relieve the pain, rather than having to wait until the animal needs another dose of painkiller. Time-release patches are a bit expensive but they last several days. At the vet’s office, an owner can choose between the patch technology and standard medication. Most owners pick patches because they don’t have to get up in the middle of the night or come home from work to re-dose their pets.

Modifying your pet’s behavior. Shelters and humane groups destroy millions of dogs and cats each year because of the animals’ behavior problems. That’s more than the number killed each year by any disease. But behavior problems like aggression, digging, barking, biting and house-soiling can now be resolved through behavior-counseling programs. The earlier in a puppy or kitten’s life that behavior problems are picked up, the greater the success in resolving them. Pets can get behavior counseling at special clinics or through veterinarians or specialists that your vet can recommend. Many counselors will even come to your home.

A pet’s behavior can also be modified with drugs. Until a few years ago, information on treating animals with drugs was limited, but now we can treat disorders such as car sickness, aggression and separation anxiety with a combination of behavior training and drug treatments.

Diagnosis and surgery. Ultrasound and endoscopy have been around for humans for many years, but they are now becoming affordable and more routinely used to diagnose and treat animal problems. They have revolutionized exploratory surgery. If an animal has a serious heart problem or cancer, for example, it can be diagnosed without having to make any incisions. The result is lower costs and less stress for owners.
Pet surgery has also come a long way. Dogs no longer need to go blind from cataracts. Cataracts can be removed surgically and artificial lenses can be implanted. And pets that suffer from chronic hip and knee deformities can have their joints replaced surgically.

Por: Erik Farina. Psicolmascot