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Infectious diseases in the Algarve

In southern Portugal there are many diseases that your pet can contract from insect bites.  Left untreated, all the diseases are potentially fatal.  It is important for you to be aware of the dangers posed to your pet, so that you can offer it the best possible protection.

Many infectious canine diseases and parasites in the Algarve are rare in most of Europe, especially non-Mediterranean countries.

When people move to areas where there are endemic diseases they must take precautions (e.g. malaria).  The same goes for your dog.  Because of the various different vectors which can infect your dog, there are certain combinations of products which are most economical whilst remaining comprehensive in their cover.

Speak to our staff about parasite prevention as part of your dog's health.  Summer and spring are beautiful times to be in the Algarve for people and our pets.  We want you all to enjoy it with peace of mind and joy in the sunshine.  Don't be scared... be aware.

The blood borne parasites are spread by mosquitoes, sand flies, fleas and ticks as they feed.



Ticks and Fleas Diseases




Ticks and Fleas Diseases



Ticks and Fleas Diseases

Ticks and Fleas Diseases

Ticks and Fleas Diseases




Enter the Mosquito!

He (actually she) is the vector of transmission of heartworm.  The larvae are spread by mosquitoes as they feed.

Heartworms are just as nasty as the name suggests.  It is indeed a worm that grows inside the dog's heart and pulmonary blood vessels

They grow to 17-30cms long.  That is 6-12 inches! All this inside the dog's heart, and the arteries of the lungs.  In the post-mortem photo below you can see some of the adult worms extending from the right ventricle into the pulmonary arteries.

The adult worms cause irritation to the blood vessels and heart muscle.  This causes pressure to build up in the pulmonary (lung) circulation.  Eventually fluid on the lung and damage to it causes lethargy and coughing, which are often the first clinical signs of heartworm infection.

Left unchecked the disease is certainly fatal

Treatment of an infected patient is dangerous and can also be fatal as the dying worms cause blockages in the blood vessels of the lungs.  Patients need to be hospitalised for treatment because of these risks.

Even if successfully treated, badly affected dogs can retain permanent damage to their blood vessel walls heart muscle and lung tissue.

The diseases has been shown to occur in cats, however feline heartworm disease is not prevalent in Portugal.


Heartworm is the most preventable of our transmissible diseases here in the Algarve.


You can protect your dog by giving it monthly treatments.  These can be:

  1. Oral - tablets or ‘chews'… of which there are a number of licensed ones to ‘choose' from. ha ha!
  2. Monthly spot-on treatments, working in combination with flea treatments.

These monthly medications are very suitable for people holidaying here.

It is important to know that the monthly (tablet) will prevent heartworm infection for the previous month, not the following month, i.e. a tablet given on the 1st of June will protect for the month of May.


There is an injection available to prevent against heartworm which will protect your dog for 12 months.  Many people (your Lagos Vets, for instance) chose to synchronise this with their dog's yearly vaccinations.  This aids in not forgetting to administer this important prophylactic medication.

A blood test is strongly recommended prior to starting preventative medicine, as some of these drugs can cause reactions in infected dogs, and also to avoid the dangers of a false sense of security regarding this terrible disease.



An incurable disease transmitted to dogs by sand flies.

It causes a range of problems throughout the body.  Clinical signs mainly involve weight loss, poor coat condition and hair loss.  It doesn't sound like much but it causes a chronic debilitating disease that the immune system can never get rid of.

In some cases the infection will cause death from kidney failure soon after diagnosis, irrespective of the treatments given.

There is no cure for Leishmaniasis once established.  We can manage the disease (to an extent) with daily medications which extend throughout the course of the dogs life.  Even with these drugs, infected dogs do have a compromised life-span and remain susceptible to other diseases.

Clinical signs of infection are often vague.  Non-healing, non-responsive skin lesions anywhere on the body (especially the ears, head, legs, back and tail).  Chronic weight loss, bleeding (e.g. from the nose) and pale gums are a more serious syndromes of the disease.

Certain breeds such as Rottweilers, Boxers, Cocker Spaniels, Huskeys, Labrador Retrievers and German Shepherds are more susceptible to the serious illness from infection.

This is also a disease than humans can contract.  Not directly from animals, but infected dogs do act as a reservoir of the organism for sand flies.  Human disease is more common in other continents, such as South America and Africa.


Protection against this awful disease is strongly advised.  We recommend a vaccine and a spot on for this.


There are two vaccines now available.  One called Letifend® and one called Canileish®.  Both involve yearly boosters, like the normal vaccines.

You can start vaccines from 6 months of age.


Leishguard®.  This is an oral liquid to be used daily on the dog's food.

The liquid is used daily for 30 days.  This confers a total of 4 months protection.

To give a full year of protection, Leishguard® needs to be used every 4 months (i.e. 3 times in a year).

The drug works by increasing the production of a hormone called prolactin.  Initially thought to only affect milk production in the mammary glands, prolactin has recently been shown to have many properties, one of them being to drive the immune system forwards along the ‘cell-mediated' pathway, the one needed for Leish resistance… if you were curious.

This medication is also used in the treatment of dogs infected by Leish, by helping the immune system achieve the appropriate response to the Leish organism.


Spot-ons and collars are the best way to help repel the sand flies.

They are recommended by the makers of the Letfiend® and the CaniLeish® vaccine, as well as the Leishguard® liquid.  Manufacturers request owners to still use an insect repellent whilst using their medicines.

Less sand fly bites decreases potential Leishmania load and is part of a comprehensive preventative protocol.

Prior testing for the Leish disease is recommended to ensure your dog does not have it before starting protection.

Ticks and Fleas


Here in the Algarve there are several infectious parasites that are spread by ticks, which cause disease in dogs, cats and horses.  All of them are debilitating and all of them can be fatal.  Some can also cause disease in humans.

Ticks are more prevalent in the warmer months, especially after a period of rain.  But the tick fevers can remain latent and present at any time of year.  We have diagnosed the diseases through the winter.

Clinical signs are very diverse. From inappetence to nose bleeds to anaemia and collapse.


Ticks can also carry more than of these parasites at the same time.

Animals which are infected with more than one of these organisms at the same time are in much greater danger than those with single infections.  All aspects of the disease process are worse and the immune system is seriously compromised.  This decreases the chances of survival in the animal and complicates treatment protocols.


Ticks are stubborn and unfortunately none of the treatments will give you 100% guarantee of your dog of being tick-resistant.

The options are:


These last from 4-6 months, depending on the collar (despite what it says on the packet).

We advise you to take collars off every month, clean off the oily residue and twist them to release the chemicals again.


Make sure you part the hair and place it in a line along the middle of the animal – directly onto the skin.

Skin should not be wet and no swimming for 48 hours, whilst the product spreads around the body in the oily layer on the skin.  Most of them are water resistant but shampooing takes off the oily layer and the product.


Some of these are monthly, and some last for 3 months, like Bravecto®.

Below are the author's favourite preventatives.  Note, all the products below are effective against ticks, as well as 100% for flea control!

  • Advantix® spot-on (1 month per pipette)
  • Activyl® spot-on (1 month per pipette)
  • Seresto® collars (6 months+ per collar)
  • Bravecto® tablets (3 months per tablet)

Daily checking of your pet is the third arm of defence against ticks and it is a very important role that you can play in your dog's health, especially in the high-risk period of spring and summer.  Focus on the head-chest region and between all the toes.

It takes 48 hours for these diseases to spread from tick to host, so if you check your pet daily then you maximise his or her protection.

Below we have described the main parasites that cause the infections.  All of these we often ‘lump' together under the umbrella term ‘tick fever'.


This blood borne parasite is spread by infected ticks when they feed.  

The parasites invade red blood cells (RBC's) and start to multiply rapidly inside them, you can see in the microscope photo below. These RBC's soon die and burst, releasing even more numbers of Babesia into the circulation.  In some ways this is similar to malaria.  It is the burst RBC's that cause the first clinical signs of Babesiosis, most commonly anaemia and jaundice.


Owners will notice lethargy, weakness, depression and vomiting.  As the disease progresses the animal will get breathing difficulties and may collapse.  Bruises are often seen on the gums, as well as the anaemia and jaundice noted above.

Treatment is usually successful if the disease is diagnosed early, though the treatment course extends to one month.  Occasional relapses do occur.

Babesia species infect dogs and horses.

This is the only ‘tick fever' disease for which there is a canine vaccine.  This involves a yearly booster.  Although the vaccination against Babesiosis is not 100% effective, a vaccinated dog will stand a much better chance of surviving the infection.


Ehrlichiosis is the most aggressive and acutely fatal of the tick-borne diseases.  It can cause coma and rapid mortality soon after infection.

Ehrlichiae are also transmitted by ticks when they attach themselves to your pet.  They can survive in their tick hosts for 5 months.  So, immature ticks that are infected in autumn act as a reservoir for infection in the following spring.

Clinical signs start with bleeding from the gums, nose or other mucous membranes. They quickly advance to lethargy, depression, anorexia, anaemia and worse. 

Dogs, cats and horses can also be infected by Ehrlichia in Portugal.

Early diagnosis and treatment is imperative for a good outcome with Ehrlichiosis.  Treatment is similar to that of Babesiosis. 

Borreliosis (Lyme's disease)

The Borrelia parasite is also transmitted by feeding ticks, and (it too) can remain in a developing tick throughout the winter.  BUT, a tick must be attached for 48hrs for transmission to occur.

When the body's immune system attacks this organism a reaction follows which causes damage to the body itself.  Because of this a number of different clinical signs can appear, such as lameness, weakness, seizures, anaemia.

Borreliosis can be treated by a long course of antibiotics, but damage to organs like joints or the kidney can be permanent.

Lyme's disease can be contracted by people as well.  Though they can only be infected from tick bites directly (NOT an infected dog).

Rickettsia and Haemobartonella

The organisms invade the bloodstream damaging the red blood cells and the lining of blood vessels.  This causes damage to any number of organs.

Clinical signs are again non-specific with lethargy, weakness, depression and anorexia being seen early on. Bruising to the gums is sometimes seen here as well.

Dogs and cats are affected by both of these organisms.

Early treatment is usually effective, though relapses occur commonly.