Smart viruses that jump species: Covid-19, HIV, Ebola and others…


By Ricardo Ribas

Image from syaibatulhamdi,
Image from syaibatulhamdi,

Viruses are microscopic agents that infect living organisms and cause diseases. They are considered the most abundant biological entity on the planet, existing for over 1.5 billion years. Viruses have both life and non-life properties. They do not have cells and cannot turn food into energy, but have genetic material (either DNA or RNA). Without a host cell, viruses are inert containers of chemicals so they need to infect cells in order to reproduce, evolve and survive. Hosts can be humans, animals, plants, fungi and bacteria. Some viruses are harmless whilst others cause diseases, some of which leading to the death of the host. To date there are no drugs capable of killing viruses so the host is dependent on its own immune system to fight the infection. Nowadays, there are some antiviral drugs capable of inhibiting them from reproducing and developing, as well as vaccines able to prevent infections and control the spread of the disease.

There are many types of viruses, each one adapted to its own host, but at times, viruses can jump and infect different hosts through a process called “spillover”. This can happen as a result of increased contact between different species or due to mutations that allows the viruses to evolve and gain the capacity to spread more efficiency in order to survive and to become more dangerous. In recent years, we have heard more and more about viral diseases able to jump from animals to humans. Here are some examples:

Influeza: The Flu Viruses

In the last century, there have been many examples of flu-like diseases caused by viruses that jumped from animals to humans. Some are caused by influenza viruses, a family responsible for attacking the respiratory system and causing flu like symptoms in humans.

In 1918, a deadly flu-like pandemic (Spanish Flu) appeared and rapidly spread around the world, infecting 500 million people and killing an estimated of 50 million. There is still some controversy about where the virus was originated from since Europe, America and Asia were affected simultaneously, but recent studies tend to agree that the outbreak may have originated in the North of China, either from pigs or from domestic and wild birds.

But there are other more recent examples of influenza viruses that jump species, such as the ones responsible for the outbreaks of swine-flu and bird-flu.

Although pig’s influenza viruses are rarely transmitted to humans and are hardly spread between people, they were responsible for the worldwide outbreak of swine-flu in 2009-2010. The disease was firstly identified in 2009 when many cases of human respiratory illness were reported in Mexico. We now know that this virus is the result of a merge between genetic material from pigs, birds and human viruses. In animals, the disease is responsible for fever, coughing, nose and eyes discharge, sneezing, breathing difficulties and lack of appetite, however, some animals show no signs of illness. Humans show flu like symptoms and can be infected either by close contact with pigs through farming and fairs or by person-to-person contact during sneezing, coughing and by contaminated surfaces. Fortunately, the 2009 outbreak was not as serious as previously anticipated and only a relatively small number of cases lead to serious illnesses and deaths. Swine flu is now considered a normal type of seasonal flu and is included in the vaccination program.

Bird-flu is another infectious type of influenza that spreads among wild and domestic birds. The most common form of the disease is caused by H5N1, a deadly virus for birds. H5N1 was firstly identified in humans in Hong-Kong in 1997. Human cases of the disease were linked with the handling of faeces, nasal and mouth secretions of infected poultry, particularly in farms and markets. Bird symptoms include: sudden death, lack of coordination, purple discoloration of the wattles, combs and legs, misshapen eggs, diarrhoea, nasal discharge, coughing and sneezing. Humans generally suffer from fever, cough, sore throat, muscle ache but the disease can lead to pneumonia. The disease has high mortality rate and is responsible for causing the death of about 60% of those infected. The good news is that H5N1 only rarely infect humans and is not capable to spread from person to person. In spite of this, it is a fast mutating virus and if it gains the capacity to be transmissible between humans while retaining its capacity to cause severe disease, the consequences can be very serious.

Human Immunodeficiency Virus (HIV): one century with humans

Another example of a virus that crossed species is the one responsible for human immunodeficiency. Once infected, the virus attacks the immune system of the host, opening the door for other opportunistic diseases. This disease was first observed in 1981 in the USA, but scientists believe that humans got infected in the 1920’s in West-Central Africa, possibly in what is now the Democratic Republic of Congo. Scientists believe this happened when hunters consumed meat from non-human primates carrying a virus closely related to the HIV (Simian Immunodeficiency Virus or SIV), a virus that also attacks the immune system of these animals. It is suspected that the infection has reached the Caribbean islands in 1960s, New York City in the 1970’s and San Francisco a decade later, when it was finally discovered.

Ebola, the terrifying virus

The Ebola virus was first discovered in 1976 near the Ebola River in the Democratic Republic of Congo. Since then, the virus has been responsible for occasional outbreaks in human and primates in many African countries. Between 1976 and 2013, the world health organisation reported 24 human outbreaks of the disease with 1.600 deaths in total, but the largest outbreak occurred between 2013 and 2016 and was responsible for over 11.000 deaths. The disease is rare but very severe, often causing fever, sore throat, body aches, vomit, diarrhoea and sometimes bleeding inside and outside the body, with death occurring in 50% of the human infected. Scientist think that the Ebola virus may be carried by bats, because these animals don’t die of the disease. It is believed that humans get infected by contact with the infected animal’s body fluids, either directly from bats or during consumption of nonhuman primates. The virus spreads through human-to-human contact and it is also possible via blood or the body fluids of the infected person.

Coronaviruses repeated stories

Recent history also showed us how coronaviruses can jump from animals to cause a large number of human deaths. Coronaviruses are a large family of viruses known to exist for over 10.000 years. Its name derives from the latin word “corona”, that means crown due to the presence of crown-like spikes in their surface.

Coronaviruses are responsible for respiratory and intestinal diseases in mammals and birds, but the symptoms vary according to the host animal and the type of virus. For instance, in chickens, coronavirus attacks the respiratory and urogenital tracts, whilst in dogs, cats, ferret, rabbits, turkeys, pigs and cows the virus tends to affect the animal’s intestine leading to diarrhoea.

Humans, can only be infected by seven types of coronaviruses. Four of these are very common and responsible for mild respiratory infections with symptoms similar to the ones observed with a cold, but the remaining three viruses can lead to serious and sometimes lethal respiratory infections, such as pneumonia. These include the viruses responsible for the Severe Acute Respiratory Syndrome (SARS), the Middle East Respiratory Syndrome (MERS) and the most recent outbreak in China in 2019-2020 (Covid-19).

SARS was first identified in Southern China during the outbreak of the disease in 2003. Scientists believe that bats are the reservoir of the virus and that the disease was transmitted to humans through consumption of civet cats meat infected by the bats. Once in humans, the disease can spread from person to person. By the end of the outbreak, over 8000 people have been infected and approximately 10% of those died (774 people). Fortunately, no cases of SARS have been reported since 2004.

MERS was reported for the first time in 2012 in Saudi Arabia. It is known that the virus was firstly transmitted to humans by dromedary camels in the earlier 2010s, possibly during consumption of camel meat. This virus has also been found in bats and is believed that it may have infected camels in Africa in the 1990s. Even though the possibility of human to human transmission is very low, the mortality of the disease is quite high standing above 35%. So far, MERS killed 858 out of the 2494 reported cases since it appeared in 2012.

Very recently a new outbreak of coronavirus has emerged in Wuhan, China (Covid-19). Similarly to SARS and MERS, this infection is also responsible for severe acute respiratory infection that can lead to severe organ failure, septic shock, blood clots symptoms and eventually death. Since this is a very recent virus, not much is known about it yet. To date scientists haven’t yet identified which animal the reservoir for the virus is, however, it appears that the contamination to humans may have occurred in a wildlife market, possible during consumption of wild animals. Despite the fact that the rate of transmission between humans is high, the mortality rate seems low. Since it’s origin, the disease has spread all over the world.

When human viruses infect animals?

Sometimes viruses can jump the opposite way. There are also examples of human viruses that alter and adapt to infect animals. This is the case of the human respiratory syncytial virus (HRSV) and the human metapneumovirus (HMPV) that have jumped from humans to chimpanzees. It is believed that this has occurred between 1999 and 2006 in West Africa possibly through tourists visiting the area. Whilst these viruses rarely cause severe disease in healthy adult humans, they are responsible for outbreaks of respiratory diseases among African chimpanzees leading to the death of entire populations.

Why are animal-derived outbreaks getting more frequent?

The fast-growing world population and the development of large metropolis are incentives to the expansion of wildlife trade, which favoured diseases to spill over from animals to humans. Additionally, environment and climate changes are shifting animal habitats, altering their life-styles, their geographic locations and their eating habits (who eat whom). Finally, in an era of international travel means that diseases can spread very quickly.

But a question remains. In a world more vulnerable than ever to new animal-borne diseases, what do you think can be done to prevent future outbreaks?

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

Reference Sources

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4. Sharp PM & Hahn BH. Origins of HIV and the AIDS Pandemic. Cold Spring Harb Perspect Med. 2011 Sep; 1(1): a006841. doi: 10.1101/cshperspect.a006841

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The subjects and ideas discussed on this article are for informational purposes only. For more information consult a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.

The astonishing reproductive life of the animals

The animal kingdom is extremely diverse consisting of a wide-range of anatomies and behaviours. In this article, we will explore the scientific reasons for some of the mind-blowing strategies developed by some species to court, reproduce and produce offspring. Some will leave you speechless!

By Ricardo Ribas

Image from Pexels,
Image from Pexels,

1. Males that get pregnant!!

Seahorses, pipefishes and seadragons have a very peculiar and different reproductive strategy, as they are the only fishes to undergo male pregnancy. Depending on the specie, the males have a pouch located in the abdomen or in the tail where the females deposit the eggs during mating. It is in the male’s pouch that the sperm fertilise the eggs and it is the male’s responsibility to carry and develop the fertilised eggs for a period between 9 and 45 days. The male pouch functions similarly to the mammal’s and human’s placenta, providing protection, the nutrients and the oxygen necessary for the fish development as well as the structure necessary to get rid of the waste products. By the end of the pregnancy, the males can deliver between 5 and 2000 young fish.

2. Sexual Cannibalism

Some animals use reproductive strategies resembling horror movies. Take as an example the family of black and venous spiders, commonly named as black widows as a result of the females’ gruesome behaviour of killing and eating the males after mating. Scientists believe this form of sexual cannibalism appear to provide the females with an extra source of proteins increasing their chance for reproductive success and offspring survival. Studies have also shown that females who practice this type of cannibalism produce larger eggs and healthier offspring with a better chance of survival, than the females that don’t eat the males. Understandably, some males prefer to court females that have already eaten, even if they are less fertile and fruitful. Scientists believe the males are able to tell how hungry the females are by the presence of pheromone smells in the silk of their cob webs.

There are other examples of sexual cannibalism in nature, such as is the case of the mantises, where females also kill and eat the males during mating. Whilst the purpose for their behaviour is still unknown, studies shown that females with poor diets are more likely to eat their partners, and that, similarly to spiders, it appears to provide them with extra nutrients necessary to improve the chances of reproductive success.

3. Transsexual animals

Other species have the astonishing capacity to change sex throughout lifetime. All clownfish are born male but they carry both male and female reproductive systems. Their school is composed by one female, often the larger animal in the group; a dominant breeding male, usually the second biggest in the group; and several immature males. When the female dies or disappears, the dominant males starts a process of sex change taking about 45 days to be complete, during which the male hormones are inhibited and the female hormones are activated. At the same, one of the immature males becomes the dominant male. Scientists believe this sex-change capacity allows the clownfish to remain in their habitat, circumventing the need to travel and risk their life to find females to mate. Wrasses use the same sex-change strategy as clownfish but in the opposite way. In this case, is the larger female of the group that changes sex and transforms into a male, taking the role of the previous dominant male of the harem upon his death or disappearance.

4. Inflated balloons to attract females’ attention

Male dromedary camels have a very strange and peculiar way to attract females. They hold an organ located in their throat that once inflated turns into a giant pink balloon (often confused with the tongue) that hangs and dangles from one of the sides of the male’s mouth to show their dominance and to attract females. This organ is called dulaa, what means “soft-palate” in Arabic. Male seals have a similar organ also used for sexual attraction and territorial fights, however, in their case, this large pinkish inflated balloon-like sac appears from the animal’s nostrils.

5. Animals with multiple genitals

Some animals own more than one genital. Female marsupials, such as kangaroos, koalas and Tasmanian devils own three vaginas and two uteri, whilst the males have two pronged penises. The two-sided vaginas are used to transport the sperm to their two uteruses, whilst the middle vagina is used for birth. This process allows the females to be constantly pregnant by carrying a baby in their pouch, a foetus developing in one utero and a fertilised egg waiting to be released in the second utero. Marsupials also have the capacity to store sperm for long periods and even delay birth until the pouch becomes free, a great strategy particularly during harsh times of drought and starvation. Due to these reproductive tactics, the population of kangaroos can increase rapidly!!!

Snakes and the lizards are other examples of species carrying multiple genitals. Males own two penises (hemipenes) each one connected to a single testicle and the females have two clitorises (hemiclitoris). Scientists are still unsure why females require two clitorises, but they believe the reason for the two penises is to allow the males to be more flexible and able to mate with the female from either side, particularly during mating aggregations, where as many as 100 males can compete for the same female. Remarkably, female snakes can mate with several males and store their sperm for up to five years and have the capacity to choose which sperm to use to fertilise the eggs.

6. And some without genitals at all

Conversely, there are examples in nature of animals without genitals, such as the squids which lack vaginas. To reproduce, the males store their sperm in enclosed sacs called spermatophores and during mating, they use a special arm to transfer and implant the sacs into the female’s body, generally around her head or near her mouth, where the eggs are waiting to be fertilised. Once fertilised, the female releases the eggs from her mouth or funnel hiding them in the rocks or in holes until they are ready to hatch.

7. Strange Penises

Apart from the kangaroos, snakes and lizards, there are other examples of animals with strange penises. Both ducks and pigs have penis in a shape of a corkscrew or spiral-shaped, which are compatible with a corkscrew-shaped vagina. Boar’s half a meter penis rotates rhythmically during mating and can ejaculate more than half a litter of semen over a period of 15 minutes, whilst duck penises are equally not small, measuring in average about 20cm in length or even half a meter long in the case of the Argentine lake duck. Lucky Donald Duck and Daisy!!

Sea slug’s also use a strange reproductive strategy. They hold three penises and have the capacity to dispose and regenerate one of these penises every time it mates. And scientists seem to know the reason for this perplexing strategy. It appears the sea slugs use their first penis to remove any sperm left inside the female by other males. They then dispose this penis, before using the second penis to inject its own sperm, ensuring that it’s his genes that are passing to the next generation. Miraculously, a few hours later, the male is able to regenerate its first penis and to mate again. Similarly, orb-weaver spiders and other sea creatures also use very similar strategies as the sea slugs.

8. Orphan species

Image from glucosala,
Image from glucosala,

Finally, some animals are orphans from the time they are born. Octopus only go through one single reproductive period and die before their offspring hatch. The males usually die after mating, sometimes killed by the females in an act of cannibalism, whilst the females tend to survive until the eggs are hatched. After fertilization, the female lay the eggs and stand close to them to protect them from intruders, but very soon they stop eating and wastes away starting a process known as programmed death. At later stages some females even go further and start self-mutilation, often slamming against surfaces, tearing off pieces of skin and eating the tips of their own tentacles. By the time the eggs hatch the mother is dead. Scientists are still uncertain why these intelligent animals undergo this process, but it appears it may be an effective strategy to ensure the female does not consume their youngster, particularly since these are remarkable cannibals. Other researchers believe that, since octopus can grow pretty much indefinitely, this may be a strategy to eliminate very big, old and hungry adults that could potential compromise hatchling and to maintain the ecosystem free of massive animals.

Squid use similar strategies during reproduction. Male squid die very soon after mating in order to provide food for the predators that otherwise would feed on the eggs, whilst the female die after releasing the eggs. Similarly, male salmons also die just after spawning but the females survive to guard the eggs, after which they die by exhaustion and the lack of capacity to travel thousands of miles back home to reinitiate their reproductive cycle.

Animals undergo astonish strategies and even ultimate sacrifices, to ensure propagation of their species and generation of viable and healthy offspring. Many more examples exist in nature and these will be part of a future article. Meanwhile, let’s keep observing the world around us and understand the reason behind their complex’s behaviours.  

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

Reference Sources


1. Foster, S.J.; Vincent, C.J. (2004). “Life history and ecology of seahorses: implications for conservation and management”. Journal of Fish Biology. 65: 1-61. doi:10.1111/j.0022-1112.2004.00429.x

2. Kawaguchi M, Okubo R, Harada A, Miyasaka K, Takada K, Hiroi J, Yasumasu S. Morphology of brood pouch formation in the pot-bellied seahorse Hippocampus abdominalis. Zoological Lett. 2017 Oct 17;3:19. doi: 10.1186/s40851-017-0080-9. eCollection 2017.

3. The biology of seahorses: Reproduction. The Seahorse Project.”The biology of seahorses: Reproduction” Retrieved July 2020

Black Widows

4. Welke, Klaas W.; Schneider, Jutta M. (January 2012). “Sexual cannibalism benefits offspring survival”. Animal Behaviour. 83 (1): 201–207. doi:10.1016/j.anbehav.2011.10.027

5. Johnson, J. Chadwick; Trubl, Patricia; Blackmore, Valerie; Miles, Lindsay (August 2011). “Male black widows court well-fed females more than starved females: silken cues indicate sexual cannibalism risk”. Animal Behaviour. 82 (2): 383–390. doi:10.1016/j.anbehav.2011.05.018

6. Baruffaldi, Luciana; Andrade, Maydianne C.B. (April 2015). “Contact pheromones mediate male preference in black-widow spiders: avoidance of hungry sexual cannibals?”. Animal Behaviour. 102: 25–32. doi:10.1016/j.anbehav.2015.01.007

Transsexual Animals

7. Iwata E, Mikami K, Manbo J, Moriya-Ito K, Sasaki H. Social interaction influences blood cortisol values and brain aromatase genes in the protandrous false clown anemonefish, Amphiprion ocellaris. Zoolog Sci. 2012;29(12):849-855. doi:10.2108/zsj.29.849. DOI: 10.2108/zsj.29.849

8. Godwin, J.; Thomas, P. (1993). Sex change and steroid profiles in the protandrous anemonefish Amphiprion melanopus (Pomacentridae, Teleostei). Gen Comp Endocrinol 91: 144-157.

9. Liu H, Todd EV, Lokman PM, Lamm MS, Godwin JR, Gemmell NJ. Sexual plasticity: A fishy tale. Mol Reprod Dev. 2017;84(2):171-194. doi:10.1002/mrd.22691

Camels and Seals

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Kangaroos multiple genitals

12. Ed Yong. Kangaroos have three vaginas. National Geograhic. kangaroos-have-three-vaginas/. April 17, 2012.

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14. Matt Hayes. 10 unexpected examples of animal genitalia. Listverse. 2012

Snakes and Lizards

15. Tina Deines. Why Do Snakes Have Two Penises and Why Are Alligators Always Erect? National Geographic. February, 2018

16. Friesen CR, Uhrig EJ, Squire MK, Mason RT, Brennan PL. Sexual conflict over mating in red-sided garter snakes (Thamnophis sirtalis) as indicated by experimental manipulation of genitalia. Proc Biol Sci. 2013;281(1774):20132694. Published 2013 Nov 13. doi:10.1098/rspb.2013.2694

17. King, RB.; Jadin, R.C.; Grue, M.; Walley, H.D. Behavioural correlates with hemipenis morphology in New World natricine snakes, Biological Journal of the Linnean Society, Volume 98, Issue 1, September 2009, Pages 110–120,


18. Morse P, Huffard CL. Tactical Tentacles: New Insights on the Processes of Sexual Selection Among the Cephalopoda. Front Physiol. 2019;10:1035. Published 2019 Aug 21. doi:10.3389/fphys.2019.01035

19. Pharyngula Friday Cephalopod: Undead Squid Penis. Science Blogs. August 2017

20. Stephanie Watson. How Squid Work. How stuff works.

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Weird Penises

22. McCracken KG, Wilson RE, McCracken PJ, Johnson KP. Sexual selection. Are ducks impressed by drakes’ display?. Nature. 2001;413(6852):128. doi:10.1038/35093160

23. Knox, RV. (2003). The Anatomy & Physiology of Sperm Production in Boars. Published in the internet. Department of Animal Sciences. University of Illinois.

24. Rebecca Morelle. Sea slug’s ‘disposable penis’ surprises. BBC news. BBC. February 2013

25. Ed Yong. Sea Slug Amputates Its Disposable Penis, But Has Two Spares. National Geographic. February 2013

26. Sekizawa Ayami, Seki Satoko, Tokuzato Masakazu, Shiga Sakiko and Nakashima Yasuhiro. 2013. Disposable penis and its replenishment in a simultaneous hermaphrodite Biol. Lett.9. 2012.1150.

Animals who die after giving birth

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28. Z. Yan Wang, Clifton W. Ragsdale. Multiple optic gland signaling pathways implicated in octopus maternal behaviors and death. The Journal of Experimental Biology, 2018; jeb.185751 DOI: 10.1242/jeb.185751

29. Matt Wood. The grim, final days of a mother octopus. University of Chicago Medical Center. September 2018.

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The material discussed on this article are for informational purposes only. For more information consult a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.

Depression in the Animal Kingdom

Image from blende12,​
Image from blende12,

According to the World Health Organisation, depression is a common mental disorder affecting over 260 million people around the world. It is characterised by a persistent feeling of sadness, lack of pleasure in otherwise rewarding activities, often accompanied with lack of appetite, sleep and concentration and a constant feeling of tiredness. Depression is the result of an imbalance of hormones and chemicals in the brain often occurring during challenging times, but scientists have shown that it also has a genetic component in about 40-50% of the cases.

But, can animals also suffer from this condition? Every so often, animals look lethargic, with an appearance of sadness and lack of interest for activities that they otherwise would enjoy. Can this be the result of alterations on their mental state? If so, what is causing the animals to feel that way and how can help them improve?

By Ricardo Ribas

Whilst animals don’t have the same reasoning capacity as humans and don’t experience the same level of social and psychological complexities, scientists and behaviourists agree that animals can also feel stressed, sad and depressed.

What are the main reasons for depression in animals?

Many factors can trigger alterations in the animal’s mental state. Dogs and cats often develop anxiety and depression as a result of physical illnesses, fears or alterations in the animal’s environment, such as during fluctuations of the owner mood, new pet ownership, relocation to a new home, abandonment or confinement and whilst grieving after a loss of a close human or animal. Despite of being rare in the nature, wild animals can also develop suffer from these conditions, particularly throughout challenging times such changes in the environment, habitat or during death or loss of a close animal.

What are the symptoms in animals?

Researches have shown that mammals, and in particular primates, share anatomic, functional and chemical similarities with human brains, making them the most susceptible species to develop depression. However, since animals are unable to speak and transmit their feelings to humans, makes the diagnosis of these diseases very challenging. To better understand their mental state, scientists base their judgement on the animal’s mood and the changes in their normal behaviour. Primates are perhaps the most transparent of the species and the easiest to illustrate their feelings of sadness based on their facial expressions, but when this not possible, scientists and vets often look for other symptoms, such lethargy, lack of enthusiasm to pleasurable activities, loss of appetite, as well as changes in behaviour and in sleeping patterns. For instance, the majority of the dogs are comfortable when left alone at home for a few hours, whilst others develop obsessive behaviours such as constant barking and crying, repeatedly licking of parts of their body, biting furniture, defecating, urinating or showing changes in their normal behaviour such as aggressiveness, etc. Each animal has its different personality and is very important that the owners understand what is normal or not for each animal. It is also frequent to encounter signs of anxiety and depression in animals kept in captivity, often exhibiting repetitive and compulsory behaviours, such as the constant walking back and forward or in cycles.

Then how can we help the animals through these difficult times?

To start with, it is important to rule out that the changes in the animal’s behaviour are not the result of a simple underlying physical condition or disease. If the animal appears to be suffering from depression-like behaviour, there are a few things the owner can do. Here are some advices:

• Engage with the animal in fun activities, such as games, exercises, etc

• Increase the time spent with the animal and pay more attention to them

• Take your animal for longer walks and exercises

• Incentive the animal to play with other animals

• Limit the time the animal is left alone

• Take time to bond with them

Each animal has a different personality and is essential to understand the reason behind their sadness to better help them. If none of the advices work, consider taking the pet to a behaviourist or to the vet, which can ultimately prescribe antidepressant medications.

Depression can take time but often disappears with some changes in the animal day-to-day life. Nevertheless, it is crucial not to let the disease progress as it can deteriorate the animal’s health and be life threatening.

Large studies are lacking in this field and a lot of research is still necessary to better understand the way the animal feel and how to help them fight the disease. However, many studies agree that animals often help humans improve from depression and that owning a pet can be very beneficial to fight this condition. It is now in our hands to help them too!!

By Ricardo Ribas, veterinary doctor, doctorate in veterinary sciences and scientist in London.

Reference Sources

1. Flint J., Kendler K.S. The genetics of major depression. Neuron. 2014;81:484–503. doi: 10.1016/j.neuron.2014.01.027.

2. Krista Mifflinm. Dogs and Depression. The SprucePets. Updated 28.05.20. Accessed on August 2020.

3. Depression. World Health Organisation

4. Sasha Ingber, Do animals get depressed? National Geographic News, National Geographic. Published 06.10.12. Accessed August 2020

5. Tibi Puiu. Can animals get depressed too? ZME Science. Published 22.09.16. Accessed August 2020.


The material, ideas and prevention measures discussed on this article are for informational purposes only. For more information consult a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.

Holiday Season: what to do with my pets?

With the holiday season approaching, it is time to decide whether to take your pets with you or to leave them at home. Here are some tips to help you make the right decision.

By Ricardo Ribas

Image from   Pexels,
Image from Pexels,

Taking your pet on holiday can turn out to be a very stressful experience for both your furry friend and your family, so it is essential to start planning it well in advance. Before deciding whether to take your furry friend on a trip, make sure you consult your vet to check their health condition and to advise you what is the best way to proceed. For instance, elderly, pregnant and very young animals as well as the ones with underlying health conditions, may require extra care and may be advised against going on longer trips. Bear in mind that some animals get very stressed whist travelling so it is important to take into account both the distance and the mode of transport before deciding whether to take them. Finally, remember to check the weather conditions at your destination to avoid exposing the animals to very hot temperatures and ensure the access to animal-friendly accommodations, restaurants and other attractions such as beaches, etc.


If you decide against taking your pets on holidays, make sure you plan in advance where to leave them. Like humans, each animal has a different personality and can react differently to the same situation. It is important to remember that a separation of the animal from its owner usually causes some degree of anxiety. Some animals respond well to separation, particularly if they stay with acquaintances and in familiar surroundings, whilst others may exhibit behavioural changes such as stopping eating, lethargy, sadness or even aggression. In order to minimize their anxiety, it is important that the you start adapting the animal to the place and the person who will be taking care of them during your absence. Ideally, leave your pet at your home and invite a friend or a family member to stay at your house, but if this is difficult, there are several kennels, hotels or animal sitters that are happy to take care of your pet during your absence. It is important to visit the facility well in advance to examine if it is good enough for your animal. Be aware of the hygiene, size, light, exercise area, food, veterinary assistance, employees, as well as the risk of your animal being infected by any potential diseases. Also remember that many places require an advanced reservation so plan well in advance. If you leave the animal at one of these places, it is a recommended that you bring some of the animal’s toys, as well as their bed or basket and a piece of the owner’s clothing with their scent so that the animal feels more comfortable. Make sure you instruct the carer about the animal’s habits as well as their food requirements. Finally, leave your contact details as well as your vet’s for any eventualities and ask for regular updates whilst you are away.

Never in any circumstances abandon your pet. An animal left without any human protection will feel lonely which can lead to extreme anxiety and psychological disturbances.


If you decide to take your animal on holidays, it is important to plan the trip well in advance and to choose the safest and most comfortable way of transportation, making the animal’s experience as comfortable as possible.

Travelling by car is usually the best option, but some precautions should be taken. Other easy options include train or boats/ferry where owners are usually allowed to take their pets with them, often with a charge attached to it. It is important to make sure owners prepare their animals for the long trip ahead by taking them for short test drives. During the trip, always carry cold water for the animal and never leave your animal inside the car, on its own, specially in hot weather. Make sure you stop regularly to allow for short exercises and keep in mind that some animals get very stressed on a trip, so avoid feeding them too much beforehand to prevent them from vomiting or having diarrhoea.

Travelling by air requires a lot of planning and should only be considered if there are no other alternatives. If travelling abroad, remember that each country has its own legislation regarding animal arrivals so check in advance with your airline, your vet and the country destination for the specific requirements and regulations. Animals often require to be microchipped and to show their documents confirming they are fit and healthy to travel and to enter the country. Some countries also required a pet-passport and a proof of vaccinations and in some instances quarantine measures may apply. It is also highly recommended to have a pet insurance covering trips abroad in case the animal gets sick whilst in a different country.

Always contact your airline well in advance, making sure you reserve a place for your pet and that you understand the animal transportation conditions. Each airline has its own policies and some flights may not be licensed to carry animals, whilst others may only accept a certain number of animals per flight. In some instances airlines may allow you to take small pets with you inside the plane under the seat, but often animals are required to go in the hold under the plane, generally in pressurised conditions similar to the ones in the cabin. If in the hold, the animal will need to be carried inside a special container or box with an adequate size to allow the animal to sit, stand and rotate inside. Assistance and guide dogs are usually allowed in the cabin and can travel for free, but make sure you inform and confirm this with your airline.

Ahead of your flight, make sure you prepare everything for the animal’s comfort and safety, such as:

• Place an identification tag in the animal collar as well as in the container displaying your name, address at destination and your phone number.

• If the animal is travelling in the hold, make sure the details on their tickets are the same as the ones on your ticket and that the tag attached to the container is correct.

• Feed the animal earlier in the day and make sure they are relieved before putting them in the container. For animals that get very stressed during the trip and often vomit, consider withholding food for a minimum of 2-4 hours before the flight. Ask the vet for some medication to prevent it from happening.

• Make sure you include food and water packs within the container particularly for long flights

• Exercise the animals before the trip to tire them. The use of tranquilizers should be avoided because they affect the way dogs and cats control their body temperature.

• Place their blankets and toys inside the transport container.

• Make sure a container has a secure closure, but that allows for opening in an emergency.

Independent of the way you travel with your pet, always remember to take with you:

• Animal documentation such as the health documents and the vaccination certificates.

• The pet passport if you are travelling abroad

• A lead as well as a collar containing the complete identification.

• The animal’s bed or basket

• Bottle of cold water for the trip

• The animal’s toys, food, plates, poo bags and muzzle (if necessary).

Extra care in the summer:

• Like us, animals can suffer sunstroke, dehydration and sunburn – often on their pads – so walking in the street during peak hours should be avoided.

• Parasites such as fleas and ticks are more common in hot months, so make sure you deworm your animal to avoid discomfort and the possibility of catching infections.

• The beach must also be avoided if possible. Dogs can be vehicles of a worm called Ancylostoma caninum, which spreads through their faeces and can penetrate human skin, causing itching. If you take your dog to the beach, don’t forget to deworm him/her beforehand. Also be careful when taking your dog to the sea as water often penetrates the animal’s ears and can lead to infections, particularly in those animals with droopy ears. Cotton can be used to avoid water from entering. If you decide to take your dog to the beach, protect him/her from the sun to avoid sunburn and always carry a bottle of fresh water. Finally, remember to keep your pet on a lead to prevent them from escaping, becoming lost or bothering others.

Enjoy your holidays and love your pet in all seasons!!!

Ricardo Ribas

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

Reference Sources

1. Bring your pet to the UK: step by step. Accessed June 2020

2. Travelling abroad with dogs. Blue Cross for Pets. Accessed June 2020

3. Delaney Ross. How to fly with a pet on a plane. National Geographic. Accessed July 2020.

4. Travelling with Your Dog on a Plane. Purina. Accessed July 2020.


The material, ideas and recommendations discussed on this article are for informational purposes only. For more information consult a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.

Animals and the Covid-19 Pandemic

A virus pandemic has struck the world in 2020. Coronavirus disease 2019, or Covid-19, is an infectious respiratory disease firstly identified in Wuhan, China in December 2019 and has since spread to every corner of the world, killing many hundreds of thousands of people. A lot of research is still necessary to understand the disease and the virus that causes it, yet scientists believe it was originated in animals. But what do we know so far about the role of animals in the emergence of this disease and which animal is the most likely to have transmitted the virus to humans? Can animals also be affected by Covid-19 and how can they help us in fighting the disease? Discover some answers for these and other questions in the following article…

By Ricardo Ribas

Image from Fernandozhiminaicela,
Image from Fernandozhiminaicela,

Understanding Coronaviruses…

Coronaviruses are a large family of viruses that have existed for over 10,000 years. The name derives from the latin word “corona” that means crown due to the presence of crown-like spikes in the virus surface. Coronaviruses are often responsible for respiratory and intestinal diseases in mammals and birds but symptoms can vary according to the host as well as with the type of virus involved. For instance, in chickens, coronaviruses tend to attack predominantly the respiratory and urogenital tracts, whilst in dogs, cats, ferrets, rabbits, turkeys, pigs and cows it affects predominantly the intestines and digestive systems leading to diarrhoea.

Humans can also be infected by coronaviruses. So far there are seven types of coronaviruses known to infect humans, four of which are responsible for mild respiratory infections and three that lead to serious and sometimes lethal respiratory infections, such as pneumonia. These include the Severe Acute Respiratory Syndrome (SARS), a disease initially discovered in China in 2003; the Middle East Respiratory Syndrome (MERS), first found in Saudi Arabia in 2012; and the most recent outbreak that started in China in 2019-2020 (Covid-19), all of which believed to have been transmitted from animals to humans.

All the three coronaviruses responsible for serious infections (SARS, MERS and Covid-19) appear to be originated in bats, that is believed to be the natural reservoir. Bats are often reservoir organisms due to their tolerant immune systems, what allows the viruses to live and reproduce in their bodies without causing any disease. But to be able to reach and infect humans, these viruses generally need an intermediate host animal. In the case of SARS, it is believed that the disease has jumped to humans through the consumption of civet cats previously infected by bats, whilst in the MERS, it is though that the transmission has occurred through dromedary camel’s meat. Scientists are still trying to understand the intermediary specie for the Covid-19 virus but it appears to have happened in a wildlife market probably during consumption of animal products. To try to identify the intermediate animal, researchers have compared the genomic sequence of the human coronavirus responsible for Covid-19 and other coronaviruses that infect several animals and they have discovered large similarities with the virus that infect pangolins, indicating that this is the most likely intermediate host.

But, can animals also get sick from Covid-19?

A lot of research is still necessary to better understand this virus, but the good news is that it looks like animals are not playing a significant role in the spread of the human disease and the risks of animals spreading Covid-19 to humans is low. To date, only a few but very exceptional cases have been reported of humans contaminating animals and one case in which animals have transmitted the virus back to humans. The Netherlands government reported in April 2020 that several minks suffering from respiratory symptoms tested positive for Covid-19 in four different farms possibly infected by humans. More recently, it was announced that two farm workers have now been infected from one of those animals, in what appears to be the first European case of transmission from animals to human. Similarly, several tigers and lions in the New York Zoo also tested positive for the disease after showing symptoms of a cough and loss of appetite. Scientists believe these animals may have been infected by a member of staff carrying the virus, however investigations are still ongoing. Similarly, there have been a small number of cases of confirmed Covid-19 reported in dogs and cats suffering from diarrhoea, vomiting and shortness of breath after being in close contact with people infected by the virus.

Several studies are underway in laboratories to understand which species can or cannot be infected by the disease. Preliminary data in a small number of animals have shown that cats, ferrets and hamsters can be easily infected by the virus and transmit it to other animals of the same species, but that dogs appear to be less sensitive to infection, whilst pigs, chickens and ducks failed to become infected.

As we learn more about this disease and the way it can affect animals, governments around the world are recommending to treat pets in the same way as we would treat other members of our household, to wash the hands frequently before and after handling animals and their food, and to contact the vet if have any questions.

How can animals help scientists fighting and understanding the disease?

Many efforts are ongoing to develop new methods of diagnosis and to discover new treatments and vaccines. To achieve that, scientists are taking advantage of animals to help them answer some of these questions.

It is already known that some dogs can efficiently detect the odour of many human diseases such as cancer, Parkinson’s diseases, diabetes and malaria. Scientists in the UK (at the London School of Hygiene and Tropical Medicine and Durham University) and around the world are now trying to find out if trained sniffer dogs can also be able to reliably detect Covid-19 infections in people even before symptoms appear. So far, preliminary studies seem promising and if successful, this could unleash a new non-invasive tool and a potent early warning measure to detect coronavirus and to help control the spread of the disease.

Some other studies and trials are underway to learn if llamas can help protect humans against this virus. Humans produce antibodies, proteins that recognise the virus and attach to their surface to help in destroying it, but scientists have found that camels, llamas and alpacas produce a small version of these antibodies, called nanobodies. Due of their smaller size, nanobodies are more stable and capable of attaching and sneak into certain pockets of the virus surface, that otherwise human antibodies would struggle. Studies in Belgium have previously shown that nanobodies derived from llamas are efficient in fighting SARS and MERS and scientists are now working towards clinical trials to understand if this is also possible against Covid-19.

Apart from dogs and llamas, scientists also take advantage of other species to help study the disease and to develop vaccines and new treatments. Mice are often used to test the safety of vaccines and therapies before testing in humans. Due to its close proximity with humans, non-human primates such as monkeys are used to help understand how the virus work inside the body, as well as to test the safety and the efficacy of new treatments or if people can be repeatedly infected by the virus. Finally, researchers are taking advantage of other species, such as ferrets, hamsters and cats, because they are good models of the disease or because they can be easily genetically modified to become susceptible to Covid-19 infection.

But, why are animal-derived diseases getting more frequent nowadays?

In the last century, we have witnessed a rapid emergence of new infectious diseases transmitted from animals to humans (zoonosis), such as Ebola, HIV, Swine-Flu, Bird-Flu and several coronavirus infections like SARS, MERS and now Covid-19. But why are these outbreaks becoming more frequent? The fast-growing world population and the development of large metropolis are pushing animals away from their natural habitat, allowing humans to intermingle with wildlife and encouraging the trade of isolated groups of animals often carrying microorganisms to which humans have never been in contact with. Additionally, environmental and climatic changes are causing alterations in temperature and rainfalls therefore shifting animal habitats and ecosystems, altering life-styles, geographic locations and eating habits (who eat whom). The increasing consumption of animal meat is another important factor contributing to the rise of zoonosis as a result of the increased consumption of wild animals, the intensification of greenhouse gas emissions and the deforestation of massive areas for farming and the animal food industry. Finally, and to worsen the situation, the escalation of international travel further contributes to the rapid spread of these diseases.

History has repeated itself and humans are once again suffering the consequences of altering Earth’s habitats and environments. Hopefully lessons will be learned from this pandemic, helping reshape human’s future decisions.

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


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The material and ideas discussed in this article are for informational purposes only. For more information consult a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.