Adverse Consequences of Vaccination (Part I)

Vaccination continues to be a safe, reliable and effective way of protecting animals against major infectious diseases.
Neverthless, the use of vaccines is not free risk.

Residual virulence and toxicity, allergic responses, disease in immunodeficient hosts, neurological complications and harmful effects on the fetus are the most significant risks associated with the use of vaccines.

Before using a vaccine, the veterinarian should consider both  the likelihood that an adverse event will happen, as well as the possible consequences or severity of this event.

Now in the next image you can see how we can classify the several consequences of vaccination, of course we will take one by one, and we won't extend to much on them, so let's see.

Normal Toxicity

The most common reactions to vaccines are local ones. For example, an immediate form of toxicity is the sting produced by some inactivating agents such as formaldehyde. This can present problems, not only to the animal being vaccinated but also, if the animal reacts in a violent way towards the vaccinator or Veterinarian, like biting or scratching (as most cats do),it can turn into a stressful situation for all parties involved in the consultation room.

More commonly, local swellings may develop at the reaction site. These may be firm or edematous and may be warm to the touch. They appear about one day after vaccination and can last for about a week. Unless an injection site abscess develops, these swellings leave little trace.

Vaccines containing gram-negative organisms (such as bordetella bronchiseptica), may be intrinsically toxic, owing to the presence of endotoxins that can cause cytokine release, leading to shock, fever, and leukopenia.

Even when the reaction is usually temporary, it may be enough to provoke abortion in pregnant females.

Inappropriate Responses

Vaccines may cause allergic reactions, for example: Type I hypersensitivity can occur in response not only to the immunizing antigen but also to other antigens found in vaccines, such as egg antigens from tissue culture cells.

Type I Hypersensitivity is an immediate response to an antigen and occurs within a few minutes or hours after exposure to an antigen. Reactions occurring more than 2 or 3 hours after administration of a vaccine are likely not type I hypersensitivity reactions.

Type III Hypersensitivity reactions are also potential hazards, they can cause intense local inflammation, or they may present generalized vascular disturbance such as purpura. They can occur in the eyes of dogs vaccinated against infectious canine hepatitis. Some rabies vaccines may induce a local complement-mediated vasculitis leading to ischemic dermatitis and local alopecia (this is more often seen in small dogs).

A common Type IV Hypersensitivity reaction is granuloma formation at the site of inoculation. This may be a response to depot adjuvants containing alum or oil. Vaccines containing a water-in-oil adjuvant produce larger and more persistent lesions at injection sites than vaccines containing alum and aluminum hydroxide. These lesions can be granulomas or sterile abscesses. If the skin is dirty at the injection site, these abscesses may become infected.

So of course we as Veterinarians have to be very careful with not only the handle we give the animals at the time of the vaccinations, but also we have to be very careful on what kind of vaccines shall we give the animals, keep them under observation, and of course the safety rule I will always apply, never put more than 2 vaccines in one visit, and never place them in the same site, specially on puppies and kittens.

So what are your thoughts on the vaccines? Has any of your patients ever had a vaccine reaction?
We will continue going through these vaccine consequences soon!




MVZ Carolina Pruneda

Failures in Vaccination

Hello Colleagues and friends!
A lot of people are wondering why vaccines don't work at protecting animals and providing them the immunity desired. Some people blame the Vets, some people blame the labs who produced the vaccines, well here are a couple of things to keep in mind so we can perhaps avoid them and keep our furry patients with high levels of immunity, check it out!

Some times the failure comes within something as simple as the incorrect administration of the vaccines.
For example: a live vaccines may have died as a result of poor storage (under the wrong temperature, or a lot of temperature changes along the transportation), the use of antibiotics in conjunction with live bacterial vaccines, the use of chemicals to sterilize srynges, or the excessive use of alcohol when swabbing the skin.
Sometimes, animals given vaccines by nonconventional routes may not be protected. When large flocks of poultry or mink are to be vaccinated, it is common to administer the vaccine either as an aerosol or in drinking water. If the aerosol is not evenly distributed throughout a building, or if some animals do not drink, they may recieve an insufficient vaccine dosage. 
Animals that subsequently develop disease may be interpreted as cases of vaccine failure.

However, sometimes there is a correct administration, but a failure to the response. This means that the vaccine may actually be ineffective, the method of production may have destroyed the protective epitopes, or there may simply be insufficient antigen in the vaccine. 
Anyhow, this type of problems are not that common, we can always avoid them by using vaccines from reputable labs and manufacturers.

More commonly, an animal may simply fail to set an immune response. Let's not forget that the immune response is a biological process, and it never guarantees absolute protection, and it is never equal in all members or a vaccinated population.

This is because the immune reponse is influenced by a large number of genetic and enviromental factors, the range of immune responses in a large random population of animals tends to follow a normal distribution. This means that most animals respond to antigens by setting an average immune response, whereas a few will set an excellent response and a small proportion will set a poor immune response. 
This group of poor responders may not be protected against infection in spite of having received an efective vaccine. Therefore, it is impossible to protect 100% of a random population of animals by vaccination.
The significance of the unreactive portion of this population will depend on the nature of the disease.
For highly infectious diseases against which herd immunity is poor and in which infection is rapidly and efficently transmitted such as foot-and-mouth disease, the presence of unprotected animals could allow the spread of the disease and would thus disrupt control programs. Likewise, problems can arise if the unprotected animals are individually important; for example, pets.

In contrast, for diseases that are inefficiently spread, like rabies, 70% protection may be sufficient to effectively block disease transmission within a population and may therefore be quite satisfactory.
Another type of vaccine failure occurs when the normal immune response is suppresed. For example: heavily parasitized or malnourished animals may be immunosuppressed and should not be vaccinated. 
Some virus infections induce deep immunosuppression. 
So that is why animals with a major illness or high fever should not be vaccinated unless for a compelling reason. 
Animals that are stressed may have a reduced normal immune response, probably because of increased steroid production; some examples of such stress include pregnancy, fatigue, malnutrition, and extremes of cold or heat.

But guess what, those are not the only cases, sometimes everthing can function properly, sometimes we use the correct administration and there is a correct response, however, even animals in adecuate dose of an effective vaccine may fail to be protected because maybe the vaccinated animal had been incubating the disease before the inoculation. 
That's right, some times the vaccine may be given too late to affect the course of the disease.
In other scenarios, the vaccine contains the wrong strain of organisms or even the wrong antigens (non protective).

So this is why, always in consultation, before you take an animal to give the due shots, first ask how long has the owner had it, if it has had contact with other animals, and if it's been less than 15 days, the animal should not recieve it's shots, just to make sure you know...

So what are your thoughts on this? Have you had any situation where the vaccines didn't work as expected? Has it ever happened to you that you vaccinated an animal and it gets sick right away?
This are just common failures, and we can always keep on learning.
So if you liked this post, share it with your colleagues!


MVZ Carolina Pruneda

Hurones

Buen día Colegas y amigos, en este post, hablaremos sobre el origen e historia de los Hurones!

Los primeros datos que se tienen sobre los hurones indican que comenzarían a ser domesticados por los egipcios alrededor de los 1500 a 1400 años antes de la era cristina, para ser utilizados como mascotas y para la caza de ratones.

También se conoce que fueron usados por los griegos en los años 450 A. C., y por los romanos para combatir la plaga de conejos en el año 6 antes de Cristo.

Posteriormente, se dedicaron a eliminar plagas en Alemania, Inglaterra y España.

Durante el renacimiento, las familias de pocos recursos utilizaban a los hurones para la caza y de esta manera, sus familias contaban con un medio para conseguir más alimento.

Estos animalitos adquirieron popularidad cuando en el último tercio del Siglo XIX, la reina Victoria de la Gran Bretaña adopto como mascota a un hurón albino.

Se cree que fue España el puente para que los hurones llegaran a América en el siglo XIX.

Los hurones también fueron utilizados en América para cazar roedores. Este uso fue declinado poco a poco cuando se comenzaron a comercializar los venenos para ratas, y entonces, su función giro hasta convertirse en animales de investigación y creación de medicamentos que son utilizados durante el embarazo, vacunas contra el moquillo canino, para el estudio de la influenza humana, para la peletería o para la cestrería.

En la actualidad podemos encontrar asociaciones de propietarios de hurones que proveen a sus integrantes de publicaciones mensuales, asesoría medica para sus mascotas y exposiciones. 

Hoy se tienen reglamentadas las características de la especie, para poder presentar estándares.

Que opinas? Te gustan los hurones? Si tienes algun huron, como se llama? mandanos una foto para conocerlo!

MVZ Carolina Pruneda

Welcome to the Vets blog!!

Welcome to our Veterinary Blog,  let me introduce myself to you, my name is Carolina Pruneda, I am an MVZ (Medico Veterinario Zootecnista/ Veterinary Medicine And Animal Handle Certified) in Mexico. I'm from Mexico. 

I own a dwarf Dalmatian and an American red short haired cat. Manchita(the dog), and Timon (the cat)

I've been working with cats and dogs since even before I started my professional career, and I have to say it, I love it!

I'm pretty much doing this for fun, and also to learn more,

Some of my colegues, are also participating in this blog because this is a place to learn! 

In this blog you can learn about veterinary practice, care tips for your pets, and more, whether you are an owner or a veterinarian, you can comment, ask questions, and even suggest topics or clinical management in specific circumstances, etc.  Your opinion matters, because this blog is to learn!

In this space we will learn a lot, you can even suggest a topic, from basics in pet care, to specialized science topics, medicine it's exciting of course, but veterinary medicine it's exciting, and fun!

So what is your favorite animal? What would you like to read about?

Please leave a comment, or send me an email about your thoughts and ideas we can use in this learning space!

Have a good one!

MVZ Carolina Pruneda