Would dogs survive in a human free planet?

By Ricardo Ribas

Image from AnnalisaArt, pixabay.com
Image from AnnalisaArt, pixabay.com

How did dogs become domesticated?

Dogs have long been man’s best friends but this was not always the case. Dogs are descendants from wolves and up until domestication, they were considered wild animals. It is believed that humans, as solitary hunters, needed help hunting and herding, as well as companionship and protection, so they would have captured wolf pups, kept them as pets and gradually domesticated them. Alternatively, dogs benefited from this process by obtaining protection, love, food and shelter from humans.

Recent studies comparing genomes from several breeds of dogs and wolves showed that the genetic divergence between both species has occurred around 20.000-40.000 years ago, which is the same time that the domestication process is believed to have happened. Besides that, archaeological reports have found remains of domestic dogs buried besides humans, the oldest of which dating back 14.000 years ago in Germany.

The geographic location where domestication has occurred is still controversial. Some studies suggest East Asia, whilst others the Middle East and Europe. More recent data indicates that dog’s domestication may actually have occurred twice in both Europe and Asia.

Image from mohamed_hassan, pixabay.com
Image from mohamed_hassan, pixabay.com

And what about other species?

After dogs, other species have also gone through the process of domestication. Cats, for instance, became domesticated around 8.000 years ago in the Middle East to control mice and rats that use to attack crops and farms. Other animals were domesticated for food, such as goats around 10.000 years ago in Iran and pigs/cattle approximately 8.500 years ago in Western Asia. But many other animals have become domesticated around the world. Examples include horses, camels, donkeys, llamas, sheep, guinea pigs and many birds used either for work, food, wool, transportation or for company.

But would dogs be able to survive in a world free of humans???

The domestication process made the dogs very dependent upon humans for food, love and protection, so how would our best friends behave and learn to survive without humans?

There are many examples of free-range dogs being able to live in the absence of humans as well as several reports of family dogs that survived after disappearing from home for several months. As a matter of fact, it is believed that around 80% of the dogs in the world are already living without humans. Certainly, family dogs would struggle in an initial phase, but with the time they would learn to go back to their natural instincts, to adjust and become independent. To do that, dogs would need to learn survival skills such as forming packs in a similar manner to the wolves, create new relationships with other species, become independent and more willing to take risks, adapt quickly to the changing conditions and find shelter to protect themselves from predators. With time, they probably would also need to breed with other species such as wolves and coyotes to be able to produce fertile offspring to propagate survival genes to future generations.

But not all breeds would survive in the same way. Some believe that small animals would be more vulnerable whilst others think they would be at an advantage as they required less food and would easily hide from predators. On the contrary, large animals would be more visible to predators, but would be stronger at fighting them back. Hunting dogs, such as Foxhound, Pointer, Retrievers and Irish Setter would have the advantage to run quicker and easily catch preys, but some breeds such as Pugs, Pekingeses and Bulldogs would struggle to survive due to their breathing issues. Weather conditions would also influence dog’s survival capacities. Huskies, for instance, would have a better chance of survival in cold climates, whilst dogs with short hair would be more resistant to hot conditions.

But not only the animal’s size, gender and breed would influence its survival. Individual characteristics such a personality and social skills would also be of extreme importance. Street dogs, which are more independent and risk-taking, would likely be at more of an advantage compared with house-dogs who are less adventurous and not used to co-habit with other animals.

It is difficult to predict which breeds of dogs would be more likely to survive in a world without humans or indeed ‘how’ they might survive, but one thing is for sure, our best friends will be here to stay for a long time to come yet.

By Ricardo Ribas

Veterinary doctor, doctorate in veterinary sciences and Researcher in the field of oncology


Rabies is a rare but very serious viral infection affecting the nervous system. It is generally present in the saliva of the infected animals and transmitted to humans through their bite. Whilst currently eradicated from the United Kingdom and Western Europe, rabies still exists in over 150 countries around the world, particularly in Asia, Africa as well as Central and South America and is responsible for thousands of human deaths each year, half of which involving children under the age of 15.

Image from PDPics pixabay.com
Image from PDPics pixabay.com

Get to know a little more about one of the oldest diseases of mankind.

By Ricardo Ribas

Rabies is a serious and almost always fatal zoonosis that affect mammals. The term “rabies” was originated during Roman times, meaning rage/madness down to the disease’s frightening symptoms. As a matter of fact, humans have always been terrorised from catching this disease, and it was already the subjected of myths in the Mesopotamian civilization over 4,500 years ago.


Rabies is a disease that is currently spread all over the world. However, some countries have achieved disease eradication, such as Australia, New Zealand and many Scandinavian and Western European countries.

By the early twentieth century, rabies was eradicated from all Europe, however, in 1935, it was re-entered via Russia, and since the virus is transported through wildlife, its progression was difficult to control and the disease spread to Western countries. Nowadays and thanks to efficient preventive measures, rabies is currently eradicated from most Western and Scandinavian European countries. The United Kingdom has been free of rabies for 100 years with the exception of a rabies-like virus that is still existent in a small number of wild bats.

Whilst dog vaccination is not necessary in the UK, some European countries still require a compulsory annual vaccination for all dogs to avoid serious public health problems in the event of an outbreak. If you’re planning on taking your pet abroad to another European country, remember that your animal will need to be at least 12 weeks-old and already microchipped to have the rabies jab.

According to the world health organisation, there are currently 3 billion people in the world at risk of contracting this disease and an estimate of 59,000 deaths every year. This means that rabies kills one person every 9 minutes. Unfortunately, when the signs and symptoms start to manifest, the disease is almost always lethal.


The rabies agent is a bullet-shaped virus belonging to the family of the Rhabdoviridae. Carnivores such as foxes, wolves, bats, monkeys, racoons and coyotes are wildlife hosts of the virus. Domestic animals are usually contaminated by other domestic or wild animals, whilst humans are mainly contaminated through the bites of domestic animals (dogs and cats). Dogs contribute to 99% of all rabies transmissions to humans.

The virus lives in the saliva of the diseased animals and is usually transmittable through a bite, however, in rare cases, contamination is also possible via sneezing, coughing or through superficial wounds.


Upon entering the host wound, the virus multiplies in their local muscle cells for several weeks or months before migrating to their central nervous system (brain and spinal cord), causing inflammation (encephalomyelitis) and leading to changes in the host behaviour. In animals, the incubation period (period from the entry in the body to the appearance of the first symptoms) is on average one to two months. In humans, the incubation period can range from four days to as long as 19 years, but in the majority of the cases it takes around 20 to 90 days for the first symptoms to appear.


At the early stages of the disease, the animal exhibits increased nervousness and activity, difficulties breathing, fever and changes in vocalisation and sexual behaviour. Subsequently, two forms of the disease are possible: the furious and the silent forms. In the furious form, the animal becomes very alert and aggressive with dilated pupils, loss of appetite and changing in barking. Contrary, in the silent form, the animal becomes lethargic, paralysed, with muscle tremors and cries persistently. Cats present similar symptomatology with lack of mobility particularly in the chewing and swallowing muscles.


Humans affected by the disease show slightly different symptoms from the animals. Infected individuals, initially have flu-like symptoms, such as general weakness, headache and fever but with time those progress to neurological/behaviour symptoms. These include confusion, hallucinations, muscle spasms, bizarre beating and biting behaviours, fear of water (hydrophobia) and general deterioration of mental state, often culminating in death by cardiac or respiratory arrest.


In order to keep control of rabies and to provide prompt actions to eradicate the disease in the event of the outbreak, several countries are implementing measures such as:

– Compulsory annual vaccination for all dogs aged four months old and older.

– Registration and compulsory licensing of dogs.

– Slaughter of all animals that are angry or have been bitten by animals infected with rabies.

– Veterinary examination and compulsory quarantine for all pets coming from countries with rabies.

– Wildlife vaccination by releasing oral vaccines into the ground to prevent the spread of the disease.


It is recommended that people travelling to rabies endemic areas are vaccinated and avoid contact with domestic and/or wild animals, particularly dogs and cats.

Unfortunately, no treatment is available. Infected animals are usually slaughtered and humans rarely survive from the disease. For humans exposed to rabies, post-exposure treatments such as a course of rabies vaccine or a specific immunoglobulin can be effective in preventing the disease from developing particularly if given before the start of the symptoms. Washing the bite sites and scratches with soaped water or detergent may also reduce the number of virus entering the skin and may be somewhat effective at preventing transmission.

As of 2016, only fourteen people had survived rabies infection after starting of the symptoms.

By Ricardo Ribas, Veterinary Doctor, doctorate in veterinary sciences and researcher in the area of oncology in London

Parvovirus, a killer of young dogs

Learn more about the disease that is responsible for a high mortality among puppies.

By Ricardo Ribas

Canine parvovirosis is a common and highly contagious disease affecting dogs. It is caused by a virus that attacks the cells of the intestine stopping them to absorb essential nutrients and liquids, what leads to vomit and diarrhoea and subsequent weakness and dehydration. Unfortunately, many animals diagnosed with the disease will die, particularly young dogs and puppies. The good news is that it exists a vaccine to prevent the disease.

Learn more about this disease…

Image from kim_hester, pixabay.com
Image from kim_hester, pixabay.com


This disease is caused by a virus (CPV2) that belongs to the family of the parvovirus, one of the smallest type of virus know to date. Canine parvovirosis is a relative new disease, firstly discovered in late 1970’s. It is believed to be the result of a mutation in a very similar virus responsible for feline panleukopenia, a disease that affects cats. In spite of this, CPV2 does not cause pathology in cats and only mildly affects minks as raccoons, given that is a virus that exclusively infect canines. In addition, it is very resistant to a wide range of pHs, temperatures and the majority of disinfectants, allowing it to survive in ground soil for up to a year. Commercial bleach is the only disinfectant able to kills this virus.

There are two types of parvovirus that can infect the dogs: the type 1 or non-pathogenic and type 2, responsible for this intestinal disease.


This is a canine-only disease, with the dogs being the most affected species. For unknown reasons, some breeds are more predisposed to the disease, such as Doberman Pinschers, Labrador Retrievers, German Sheperds, Springer Spaniels, Rottweilers and Pit Bull. Young dogs and puppies particularly between six weeks and five months old are more vulnerable. This is because it is around the sixth week that puppies stop breastfeeding, thus losing the protection given by the mothers breast milk. In turn, the parvovirus vaccination schedule is not completed until around five months, at which time the likelihood of infection decreases.


Heavy concentration of the virus are found in the infected dog’s stool. Transmission can occur directly through contact with another dog, or indirectly, through contaminated objects such as cages, shoe soles, hands, clothing, etc. The virus can survive for up to one year outside the host, thus the man plays an important role in the indirectly transmission of the disease through the transport of contaminated faeces. The most dangerous places are those where there is a large concentration of animals, such as public parks, kennels, pet shops and dog shows.

Image from qimono, pixabay.com
Image from qimono, pixabay.com


After ingestion, the virus multiplies in the tonsils before spreading through the bloodstream, to reach its favourite organs: intestines, bone marrow and lymphatic system, time which the first symptoms appear. This takes in average five to seven days. Generally, the intestinal signs, such as diarrhoea, are the most apparent. Rarely, in newborns, the virus can also lodge in the heart triggering cardiac arrest and subsequent death.


After an incubation period of five to seven days, the animal starts losing the appetite and shows signs of severe vomiting and diarrhoea, sometime accompanied by blood and foul odour. If treatment is not started quickly, the animal will start losing weight, will get lethargic and dehydrated what can rapidly lead to death. In some rare cases, the virus can also reach the heart causing cardiac arrest and death, or trigger heart failure that can persist a life time, leading to exercise intolerance, coughing and difficulty breathing.


Since there are no antiviral drugs to combat parvovirus, the treatment aims to target and reduce the symptoms of the disease, avoiding unnecessary discomfort to the animal and ultimately prevent its death. Most deaths of parvovirus occur between 48 to 72 hours after the appearance of the symptoms, reason why the treatment should start rapidly. This involve administration of intravenous fluid to prevent dehydration caused by the lost of liquids during vomiting and diarrhoea. The administration of antibiotics is also advised to prevent secondary bacterial infections. Furthermore, food should be withdrawn until vomiting ceases and, in more severe cases, anti-vomiting products are advised to prevent dehydration. In cases of diarrhoea with blood, blood transfusions may be required. It is very important to keep in mind that early detection of this condition is the key for the successful treatment.

The survival rate of animals treated in the hospital is about 70% and the majority of death are as a result of dehydration, secondary bacterial infections, production of toxins or severe loss of blood during diarrhoea.


1. The main form of prevention is the vaccination. Thus, dogs should begin to be vaccinated at six to eight weeks of age, they are not complete resistant to the disease until they have received several boosters until the vaccination is complete. Boosters are given every three weeks until the animal reach six months of age. From that point, the dog should be revaccinated annually to strengthen its immunity.

2. Animals that are not yet fully vaccinated should avoid contact with other dogs, as well as contaminated objects and public places, especially those where other animals circulate.

3. In kennels and places where many dogs live, disinfection should be often perform using bleach to prevent the spread of the virus.

4. In the event of the death of a dog with parvovirus at home, bleach disinfection should be performed as the virus can survive for up to one year outside the host.

5. It is particularly important to be careful not to carry faeces in the shoes, specially when around animals that have not been yet vaccinated.

6. At the first suspicious of the disease, contact the veterinarian immediately since quick treatment is decisive for the animal’s survival.

7. If the animal successfully recovers from the disease, it can remain contagious for up to 3-6 weeks and the virus can survive in the ground soil for up to a year. It is therefore important that the animal remains isolated and that neighbours and family members with other dogs are informed so they make sure their animals are properly vaccinated.

By Ricardo Ribas, Veterinary Doctor, doctorate in veterinary sciences and researcher in the area of oncology in London.

Avoid a hot dog!!

During the summer months, animals suffer a lot with the heat. It is not easy to carry a “fur coat” around when thermometers are above 25° C. Here are some tips to help our pets enduring the hottest days.


Image from openClipart-Vectors, pixabay.com

By Ricardo Ribas


Imagine yourself in your pet’s skin performing the daily routines with high temperatures. How would you feel if you were left for a long time in a locked car on the sun with a fur coat. All this in midsummer! The idea itself is suffocating. But how many trips to the supermarket led to this situations? Dogs and cats are highly susceptible to the heat specially because they have few sweat glands, which are necessary to control and maintain body temperature. The majority of the dog’s sweat glands are located in their pads and tongue, reason why dogs often walk with the tongue hanging when they are tired or feeling hot.


Frequent problems during summer season

Ticks and flea infestations are very uncomfortable for the animal because of the itchiness and the skin irritation they produce. Additionally, both parasites are carriers of other diseases, reason why the importance of controlling and prevent their infestations. There are various products on the market in the form of sprays, shampoos, collars, tablets, etc. The veterinary can assist making the best choice. For instance, heartworm disease is a pathology caused by a parasite, which is transmitted to the dog or cat by the mosquito bite. Once infected the animal, it will lodge in the pulmonary arteries and heart, causing coughing, tiredness, wheezing, weight loss and if left untreated, can lead to death. The control of mosquitos is usually the best preventative measure.


Since pets do not sweat through the skin, extra baths during the summer months are not necessary or advised. The frequent use of shampoos and soaps – even those indicated for dogs and cats – remove the natural oiliness of their skin causing dermatological problems. In fact, the animals should only be bathed when they are really dirty and is important to keep the coat suitably dry. Wet hair attracts bacteria and fungi that can cause diseases called mycosis. If your dogs have long hair, the best option is to trim the hairs during the hot months. Seasonal trim provides a great relief ensuring a good hygiene.


Heat shock

Direct exposure to sunlight, especially when temperatures are high, should be avoided as much as possible. Often dogs suffer from heat shock, especially when they are left inside cars on hot days. The owners have the best intentions not to leave the animal at home alone, but as most stores do not allow dogs, and the most practical solution is to leave the animal “just a little” in the car. However, sometimes the time flies inside the shops particularly with air conditioning and the owner takes longer than normal… These distractions however can lead to serious problems that ultimately can cause the animal’s death. In hot days, the temperature inside the car can easily reach 60° C within few minutes? Exposure to heat causes initially an increase in the body temperature and dehydration. The animal will then show difficulty breathing, starts salivating, presents with anxiety, fever, dry skin, vomiting and bloody diarrhoea, and in extreme cases will suffer cardiac changes. If you notice these symptoms, remove the animal immediately from the sun and give him water to drink. Then try to lower his body temperature by wrapping him with moist towels or spraying him with warm water. Take all these precautions as calmly as possible. Avoid to pour cold water over his back as the shock created by different temperatures can be dangerous. Finally, take your pet to the veterinary immediately, since this is considerate an emergency.


Food Care

During the summer the food intake should be similar to the rest of the year. However, due to the heating, it is important to take extra care as food spoils quickly. Avoid leaving meals on the sun and remove them from the plate ideally after 30 minutes. It is also important to keep moist foods refrigerated until served and dry foods in cool, dry and ventilated places. It is normal that during hot weather, the animals have less appetite and are less energetic. This is generally normal behaviour and not a reason for concerned.

Always have fresh and clean water available for the animal to drink, making sure is it is kept away from the sun and is changed regularly.


Pay attention to the walks

In hot days, go for walks at the cooler hours of the day to avoid sunburn or burning of the paw caused by scorching floors. It is important to be well prepared if taken the animal for long walks. Animals should be physically well prepared before beginning a rigid exercise program. Forcing animals to a strong exercise beyond their physical capacity, especially in warm weather, can led to exhaustion. These are characterized by a rise in body temperature, cardio-respiratory problems, dehydration and potentially death. When walking puppies, take extra care as young animals can get tired very quickly. Puppies need a lot of rest to be able to allocate a lot of their energies to their grow. Also, if you have an old or obese animal that walk slowly, spare them from too much effort.


Image from stylemotions, pixabay.com

Beaches and pools …

Both swimming pools and beaches are places to avoid taking your dog. Dogs are often infected by a parasite called Ancylostoma caninum, that is eliminated by their stools and easily spread to people, causing skin problems. Children are particularly affected. If you are still keen to take your pet with you to the beach, make sure you deworm him beforehand.

It is also important to be careful when taking the dogs to swim in the sea or in swimming pools. Often dogs with drooping ears – where ventilation is less effective – suffer from ear infections due to water accumulation. To avoid these problems, place cotton in the ears before take the animal to the water. After swimming in the sea, is also important to wash their hair with fresh water to remove the salt, avoiding skin irritation.

Finally, always keep in mind that swimming pools are very dangerous places for dogs, as only a few animals can make their way up the vertical stairs. The vast majority, when dropped too long in the water will drown themselves from exhaustion. Further attention should be payed when dogs are accompanied by children in the pool as the animals may try to lean on the children causing them to drown.


Burns and skin cancer

It is important to take in consideration that the animal’s fur will not protect them from sunlight. All animals are at risk of developing sun burns and skin cancer. It is important to protect the dog from the sun whenever you take him to the beach. Avoid lying in the sun and always take fresh water with you so that the animal can drink whenever feels the need.

White-haired animals are particularly more susceptible to these diseases and extra care should be taken.


Ricardo Ribas

Veterinary doctor, doctorate in veterinary sciences and researcher in the area of oncology in London

Your dog is pregnant? Learn how to prepare for the great moment…

Whilst is very important to take care with your pet during pregnancy, preparation for delivery is also crucial.

Photo from ulleo, pixabay.com

The day has arrived! Your dog is finally ready to give birth. Don’t know what to do? From gestation to delivery, learn all you need to make sure everything goes well.

The pregnancy in a dog lasts on average 63 days, but varies depending on the breed and the number of foetuses. If you have doubts about whether your dog is really pregnant, there are some signs that you should consider. As a rule, there is an increase in the volume of the belly and the breasts and the animal tends to becomes more docile and calmer, spending more time sleeping and resting. In addition, there is a gradual increase in appetite due to the higher demand of energy and nutrients necessary for the development of the embryos. From the second half of gestation, the dog starts showing a clear and viscous discharge.

During pregnancy

Once you suspect your dog is pregnant, you should take her to the vet to confirm the diagnosis and to make sure that everything is going well with the pregnancy. It is also important to keep an eye on the female throughout all this period and if she experiences any signs of sickness, vaginal bleeding or discharge, don’t wait to take her to the vet for advice.

Food is particularly essential during this period. Pregnant dogs need more calories and nutrients so it is important to make sure they ingest increasing amounts of protein as well as supplement in calcium, minerals and vitamins that are crucial for the embryo development. The veterinarian can recommend a good commercial food containing supplements specific for pregnant females. Also be aware that the total amount of food should increase gradually during pregnancy to the point that by the end of this period, the dog should be eating approximately 30 percent more food each day. It is also very important to have fresh and clean water always available. Finally, make sure the pregnant dog continues exercising, but avoiding strenuous or stressful activities particularly during the second half of the pregnancy.

The birth day approaches…

Before giving birth, it is very important that the future mother becomes familiar with the place where delivery will occur. You should prepare a wood or cardboard box with sufficient space for the female to be comfortable, allowing her to lie down and to stretch her legs. You can cover it with newspapers, which must be changed every day. It is also important to keep the box in a warm and quiet place so that the animal can feel comfortable. When the delivery time approaches, the female will show some restlessness, loss of appetite, thirst, frequent urination, fast breathing, pain symptoms and she will be looking at hot and dark places. Usually, delivery is a natural event, and the animal should be able to perform it on its own.

The time has come!!

The birth begins with the first abdominal contractions and finishes with the birth of the puppies and placenta expulsion. It should be up to the dog to choose the right place to give birth, and if she refuses to do it in the box, do not contradict her. Moreover, some females demand full attention from the owner during delivery, while others prefer to be on their own. In the later case, make sure you are attentive and keep an eye on her without her noticing.

They were born…

Once puppies are out, generally the mother breaks the umbilical cords with her teeth. If this does not happen, you can cut the umbilical cord with disinfected scissors at a distance of two to three centimetres from the puppie’s belly. Also make a ligature with a thick wire about one centimetre of the belly. Finally, disinfect the animals navel. It is natural for the mother to lick the puppies after birth to make sure they are clean and to stimulate their breathing. If this does not happen, rub the animals with a soft towel. If the puppies still not breathe or cry, hold them upside down so they can release the mucus from the throat and nostrils allowing them to start breathing.

The best food for the puppies

As soon as the pups are born, they should start sucking the first milk from the mother. The milk produced immediately after delivery is called colostrum and is very rich in a type of proteins called antibodies, that helps protecting the new-borns against diseases. If the puppies are having trouble getting to the mother breasts you can help them to reach them. Similarly, if the puppy is having difficulty breastfeeding you can use a bottle of milk powder. Cow’s milk is not recommended since it has ccomponents that are not digested by dogs, leading to diarrhoea. It is also important to take in consideration that during breastfeeding, the mother is spending a lot more energy so the amount of food intake should be increased.

One step independence

After delivery, the mother will want to remain in the box, going out only to eat, drink water, defecate and urinate. Little by little, she will spend less time with the puppies. Intensive contact with the offspring finishes with weaning which occurs approximately 30 days after delivery and coincides with the growth of the teeth. At this point, the puppies can start eating their own commercial foods.

6 alerts to take into account:

• During and after birth, avoid the contact of the female with males, as sometimes males can kill the puppies due to jealousy.

• Make sure you take the mother and puppies to the vet 24 hours after delivery to certify that everything is normal.

• If needed, the tails should be cut around the third day after delivery.

• Wait at least 50 days after delivery to separate the puppies from the mother and between each other because only at this point they learn to relate to other animals.

• Do not get surprised if the puppies are born with their hind legs first.

• It is normal for the mothers to eat dead dogs and placentas.

Out of Curiosity

Pregnancy durations vary widely within the animal kingdom. Here are some examples:

Mouse21 days
Rabbit31 days
Dog63 days
Cat63 days
Pig115 days
Sheep151 days
Goat151 days
Monkey164 days
Chimpanzee240 days
Gorilla257 days
Human280 days
Cow283 days
Horse336 days
Giraffe430 days
Whale535 days
Elephant617-645 days

By Ricardo Ribas

Veterinary, Doctorate in veterinary sciences and Researcher in the field of oncology

Can animals help finding the cure for cancer?

Image from AnnaliseArt, pixabay.com

By Ricardo Ribas

What is Cancer?

Cancer is a group of pathologies characterized by the abnormal and uncontrolled multiplication of the cells. Under normal conditions, cells grow and divide in a controlled and organized fashion to produce new healthy daughter cells, allowing the growth and regeneration of the body tissues. However, occasionally cells undergo changes turning them abnormal and with carcinogenic properties. In the majority of the cases, organisms have mechanisms capable of destroying and controlling the reproduction of these cells, but in some circumstances these defences fail allowing their multiplication and the formation of tumour masses. Cancer cells also have the ability to separate from the tumour and travel to other parts of the body through the blood and lymphatic system giving rise to secondary tumours which are called metastasis.


Cancer in animals

Cancer is not a disease unique to humans. Animals can also be affected by the disease and in some species with incidence rates similar to those found in the humans. This is the case of dogs and cats, in which cancer affects approximately 1 in 4 animals, being one of the main causes of death in these pets. Despite the fact that the prevalence of the disease has recently increased due to the increase in life expectancy, cancer is a very old disease known to have affected dinosaurs millions of years ago.


Both in humans and in animals, older cells are more prone to suffer alterations and to become cancerous, which is the reason why the incidence of the disease tends to increase with the age. For instance, in dogs and cats, cancer accounts for about 50% of deaths in animals over 10 years of age. However, other factors can also increase the risk of contracting the disease. For example, just like in humans, animals living with owners that smoke have a higher risk of developing certain types of nasal, oral, lung and lymphoma cancers, just as excessive sun exposure increases the risk of skin cancer. It is also known that animals exposed to certain chemical agents, radiation and some viral infections, as well as bad diet and sedentary lifestyle have an increased risk of developing the disease.


Genetics and Cancer

Not only environmental factors are responsible for cancer. Genetics also play a very important role, reason why different species and breeds of animals possess different predispositions for certain types of cancer. It is known that the Tasmanian demons are the only animals affected by a type of facial tumour that is transmissible through physical contact. On the other hand, elephants show a much lower incidence of cancer compared to other species and humans even although they have many more cells. This is because elephants have several copies of a gene responsible for fighting cancer. Similarly, Greenland whales also have certain genetic mechanisms to prevent the onset of cancer. Nevertheless, one of the most interesting species on the planet are the naked mole-rats. Despite the fact that they live much longer than other rodents (sometimes surviving up to thirty years), naked mole-rats are immune to cancer. And scientists have discovered the reason why. This is because these animals produce a protein called hyaluronic acid, but in a version much bigger than the one produced by other species and humans. The presence of this big protein makes it very hard for the cells to aggregate to each other, making it very difficult to form tumours.


What are the most common types of cancer in animals?

In both dogs and cats, lymphoma is the most common form of cancer. Lymphoma is a type of cancer that affect the blood particularly the white blood cells (lymphocytes) and the lymph nodes. In dogs, lymphomas have genetic origin affecting predominantly breeds such as Boxer, Basset Hound, German Shepherd, Poodle, Bulldog, Rottweiler, St Bernard and Beagle. Labrador is the most susceptible breed affecting 1 in 8 animals. Conversely, in cats, lymphomas are usually associated with previous infections by certain viruses, which leads to the increased risk of developing this disease by more than 60 times. In both animals, the symptoms can be varied according to the organs affected and may include: swollen lymph nodes, vomiting, diarrhoea, loss of appetite, weight loss, lethargy as well as increased thirst and urination. Recently, a group of scientists discovered a type of lymphoma in clams, affecting the cells of their hemolymph (a fluid equivalent to mammalian blood) and usually leading to the death of these molluscs.


Skin cancer is also common in dogs and cats. Although it can affect any part of the body, it is most commonly found in areas around the eyes, ears, nose and mouth as well as areas with little hair, particularly in light-skinned and hairless animals. Similar to the humans, the main cause of the disease is the exaggerated sun exposure. The animal initially presents irritation in the skin that progresses to crusts, loss of hair, difficulty in healing and reddish bumps on the skin. In more advanced states, it can lead to the development of bleeding ulcers, the destruction of nearby bone tissues and metastasis to the lymph nodes and lungs which may culminate in the death of the animal. However, not only mammals can suffer from skin cancer. Recently, scientists have observed the presence of melanomas in a population of coral trout that inhabit the great barrier off the Australian coast. This is the result of the increased exposure to high levels of ultraviolet radiation due to the large hole in the layer of ozone in this region.


Another type of cancer that commonly affects pets is breast cancer. This type of cancer affects predominantly elderly females that have not been castrated. In particular, Siamese cats are at high risk. It is important for the owner to be aware of signs of breast cancer such as the presence of hard lumps around the nipples, skin ulceration and the presence of swollen or inflamed nipples. The veterinarian can confirm the diagnosis by taking a biopsy.


Although less frequently, many other cancers can affect pets. Bone cancers are relatively common in dogs of large breeds and sometimes amputation is the only appropriate treatment. Also cancers located in the lungs, thyroid and liver are relatively common in older animals, but, any organ can be affected.


Future Prospects

The good news is that due to the great efforts and scientific developments of recent years, approximately half of all cancers diagnosed in pets are curable if they are identified early. Therefore, the awareness of the owners for this group of pathologies is essential to allow an early detection and appropriate treatment in order to prevent the progression and metastisation of the disease.


Encouragement of scientific research is of paramount importance to continue to provide better knowledge of cancer prevention, diagnosis and treatment strategies in humans and animals. Possibly a better understanding of the defence mechanisms used by elephants, Greenland whales or naked mole-rats, may allow us to develop new strategies to combat the disease so that in the future no human or animal will die of cancer.


By Ricardo Ribas

Veterinary doctor, doctorate in veterinary sciences and Researcher in the field of oncology

When immunity goes wrong!

Image from mohamed_hassan (pixabay.com)

The immune system is the part of the body responsible for the defence and protection against diseases and infections. Under normal conditions, it is able to detect and attack external agents (such as bacteria, viruses, toxic substances, etc.) and to distinguish them from the healthy tissues of the organism. However, in certain cases, and for unknown reasons, the immune system does not recognize its own tissues and begins to attack healthy cells. This set of pathologies are called autoimmune diseases. Autoimmune diseases are characterized by a variety of symptoms depending on the organ affected but it is known that both environmental and genetic factors play a preponderant role in the origin of these diseases.


Allergies are another type of diseases that involve the immune system. These are characterized by an excessive and disproportionate response of the immune system to substances or particles normally harmless to the body, called allergens. Allergies have been increasing in prevalence in the last decades, particularly in industrialized countries, emphasizing the importance of scientific research to better help us understanding these diseases.


Similarly to the humans, both allergies and autoimmune diseases can also affect animals. In dogs and cats, allergies are extremely frequent and are usually caused by agents similar to those that cause allergies in humans, such as pollen, dust, plants, certain foods, insect bites or chemicals such as medicines, perfumes or cleaning products, etc. The symptoms can vary according to the allergen, often leading to itching; inflammation of the skin, ears or legs; watery eyes; sneezing; vomiting and diarrhoea; coughing and difficulty breathing. The best remedy for the allergies is to reduce exposure to the allergen, but there are also some medicines available in the market, such as antihistamines, to help reduce the symptoms. Even though any animal can suffer from allergies, some breeds of dogs are more susceptible, such as Terriers, Setters, Retrievers, Pugs and Bulldogs.


Autoimmune diseases are usually less frequent but more serious than allergies. The symptoms are diverse according to the part of the body that is attacked by the immune system. For instance, hypothyroidism is a condition in which immune cells attack the thyroid, the organ responsible for regulating the organism’s metabolism. Animals suffering from this condition appear lethargic, lazy and gain weight, and in certain cases, if it affects the muscles of the head and muzzle, it makes them shrink, giving the appearance of sadness. Autoimmune hemolytic anemia is another example of a devastating autoimmune disease, primarily affecting healthy animals. In this condition, the immune system destroy the blood cells and the animal have pale gums, lethargy and intense tiredness. In extreme cases, it is necessary to carry on blood transfusions or administer medicines to suppress the immune system. Female dogs from breeds such as Cocker Spaniels and Water-dogs are particularly susceptible to this pathology. Thrombocytopenia is an autoimmune disease that attacks platelets, the blood components that promote coagulation and stop bleeding. Initially, the symptoms are subtle such as presence of bruises in areas such as the gums, ears and belly, but if remained untreated with suppressors of the immune system, the disease can lead to severe haemorrhage in the lungs. Female from Water-dog breed are particularly vulnerable.

Other autoimmune diseases can affect the skin causing hair loss, whilst others can affect the muscles leading generalized and abnormal weakness and fatigue. Masticatory myopathy is a specific autoimmune disease that affect particularly the chewing muscles.


Like humans, dogs, cats and horses can also suffer from Lupus, a generalized autoimmune disease that affects several organs simultaneously. The symptoms are very diverse according to the organ affected but can include arthritis, alopecia, high temperature, anemia, loss of appetite and loss of weight. Shepherd Germans and Water-Dogs as well as cats from Siamese, Persian and Himalayan are among the most affected breeds.


Besides dogs and cats, also horses, pigs and cattle can suffer from allergies and autoimmune diseases, and even chickens can experience autoimmune hypothyroidism.


Awareness of the pet owners for this set of diseases is essential to enable early detection and appropriate treatment.


Dr. Ricardo Ribas, PhD

Veterinary doctor, doctorate in veterinary sciences and researcher in the area of oncology.