WHY DOGS EXPERIENCE FEAR?

Good day colleagues and friends, about a few days ago a good friend of mine asked me if dogs actually felt fear and how does fear work in dogs. 

It is an undisputed fact that emotions drive behavior, moving the dogs towards comfort and pleasure, or away from discomfort and pain. 
Behavior is influenced by physiological processes including the activity of neurotransmitters and hormones. Neurotransmitters, such as serotonin and dopamine, transmit chemical messages in the brains and bodies of dogs and humans and as a result both have the same physiological reactions to behavioral states such as joy, fear, excitement and pain.

Fear often helps dogs (and pretty much any living being), with self-preservation. We feel fear, as well as related emotions, in order to protect ourselves from danger and to heighten our awareness.

Serotonin, for example, has a profound affect over emotions and is responsible for regulating mood, enhancing a positive feeling and inhibiting aggressive response. 
Dopamine helps to focus attention, promoting feelings of satisfaction. A lack of these neurotransmitters causes irritability, limited impulse control, over reactivity, anxiety and greater sensitivity to pain.

A dog’s nose dominates his brain; in fact the part of the brain dedicated to scent is forty times greater in a dog than in a human. The dog’s brain is literally built around the information it gets from scent and as smell is so closely linked to emotions(hippocampus), this provides even more evidence that the dog’s emotional experience might be even greater than we could ever imagine. 

The dog’s brain is literally built around the information it gets from scent and as smell is so closely linked to emotions.

When a dog is fearful, a number of changes happen in the body. The heart beats faster, blood pressure rises and blood flow is diverted to muscles that prepare for fight or flight. 

Stress from threat causes the dog to ‘shut down,’ effectively freezing him until the threat goes away. In this state of anxiety the dog ceases to learn and becomes more insecure, frightened and/or angry. If he cannot practice avoidance, the only other option left is to bite.

This awareness is thought to be controlled by a section of the brain known as the amygdale.

The amygdale is a section of the dog's brain's limbic system that is responsible for detecting fear and preparing for emergency events. It is surrounded by the pineal gland (gland that produces melatonin so the dog knows when it's time to sleep), and the hippocampus (part of the limbic system that stores memories).

The amygdale is an almond-shaped section of the nervous tissue located in the temporal(side) lobe of the brain. There are two amygdale per dog, one on each side of the brain. They are thought to be a part of the limbic system within the brain, which is responsible for emotions, survival instincts, and memory. However it has been debated with evidence that the amygdale functions independently of the limbic system. 

The hippocampus and the amygdale work in unison with the hypothalamic pituitary adrenal axis (HPA), which is responsible for the release of epinephrine (adrenalin), which provides the necessary fuel an animal needs to flee or fight. 

The amygdale is responsible for the perception of emotions such as anger, fear, and sadness, as well as the controlling of aggression.

The Amygdale is not really a thinking part of the brain, but it's actual job is to become alert from bad memories and just react, triggering the dog's hypothalamus to initiate the fight and flight response.

Sometimes the amygdale can also be an area for seizure activity. This is because a seizure focuses in the amygdale because it produces inexplicable and intense fear.

Also, one of the parts of the brain involved in this higher-order cognition is the prefrontal cortex (PFC). This region of the brain has direct connections to both the hippocampus and the amygdale and appears able to mediate some of the signals coming from those two regions. Functional MRI studies tell us that while fear acquisition involves the amygdala, fear extinction (learning to let go of a fear) involves the PFC as well. We also know that people who have thicker PFCs are better at extinguishing fear associations. This mediation by the PFC is what lets us take a deep breath and choose not to give in to our fears.

Despite of how bad we might think fear is, we ought to remember that fear can be good as well, because fear is important as it protects dogs (and other living being) allowing self-preservation and protection of the species.  So therefore being fearful is not always a bad thing, it's actually good if the dog is fearful of things that can actually pose a threat to his and wellbeing. 

So in a few words and to answer my friend's question, dogs can feel fear, and it works in the same physiological and chemical way as it does in humans.

I hope this post could get you out of doubt, or at least give you an idea of how fear works like in dogs. 

MVZ Carolina Pruneda

MASTICACION EN LOS PERROS (Y SUS PATOLOGIAS)

Buen día amigos y colegas, en este post vamos a repasar una lección de anatomía simple en los perros, la cual nos puede ser de mucha ayuda en algún caso clínico en el consultorio. Vamos a repasar los musculos de la masticación en los perros y vamos a ver en que situaciones o casos nos puede servir recordar este mecanismo.

Primero que nada, vamos a recordar cuales son los músculos que ayudan a la masticación, los cuales son los siguientes: 

MÚSCULOS MASTICADORES

El músculo temporal, el músculo masetero y los músculos pterigoideos forman el grupo de músculos masticadores. Comparten origen embrionario, ya que derivan del I arco faríngeo, e inervación, ya que están inervados por el nervio mandibular. Todos ellos elevan la mandíbula e intervienen, por tanto, en el cierre de la boca. El músculo digástrico, aunque desde el punto de vista ontogénico no pertenece al grupo, colabora con los músculos masticadores.

1. M. temporal
Se origina en la fosa temporal y se inserta en la apófisis coronoides de la mandíbula.

Función: Eleva la mandíbula.

Inervación: Nervio mandibular.

2. M. masetero
Se origina en el arco cigomático y en la parte caudal del hueso maxilar y se inserta en la fosa masetérica de la mandíbula. En función de la dirección que toman sus fibras se distinguen las porciones superficial, que es la más grande, media y profunda.

Función: Eleva la mandíbula.

Inervación: Nervio mandibular.

3. Mm. pterigoideos
Los dos músculos pterigoideos se disponen medialmente a la mandíbula. El músculo pterigoideo medial es, con diferencia, el más grande, y también el más rostral de los dos. Se origina en la fosa pterigopalatina del cráneo y se inserta en la fosa pterigoidea de la mandíbula y en la cara medial de la apófisis angular. El músculo pterigoideo lateral es mucho más pequeño y se sitúa caudalmente al medial. Se origina en la cara lateral del hueso esfenoides y se inserta en la cara medial del cóndilo de la mandíbula.

Función: Ambos músculos elevan la mandíbula.

Inervación: Nervio mandibular.

4. M. digástrico
Se origina en la apófisis paracondilar del occipital y se inserta en el borde ventral de la mandíbula.

Función: Abre la boca.

Inervación: La doble inervación del músculo es una muestra de su doble origen ontogénico. El nervio facial inerva el vientre caudal (que deriva del II arco faríngeo). El nervio mandibular inerva el vientre rostral (que deriva del I arco faríngeo). Ambos vientres, en el caso del perro, están separados únicamente por una intersección tendinosa que no siempre es bien identificable.

Ahora vamos a revisar algunas  de las patologías o casos en los que pudiésemos necesitar esta información:

-miopatia inflamatoria mandibular/facial
-bruxismo (masticación rapida)
-incapacidad para abrir o cerrar la boca)
-dificultad para vocalizar, gemir mientras trata de comer
-el hueso mandibular puede estar fuera de lugar
-perdida del apetito / anorexia
-dolor al masticar los alimentos

Algunas de las causas de los transtornos de la articulacion temporomandibular en perros son:

-lesiones o traumas en la articulacion
-traumas en los musculos de la masticacion
-fractura de la articulacion
-estres en la articulacon despues de cargar objetos pesados por periodos prolongados de tiempo.
-labio leporino (congenito)
-fisura labiopalatina (congenito)
-hendidura palatina

Como podemos diagnosticar a nuestro(s) pacientes?

Nuestra primer herramienta es el examen físico, que incluye la observación, la palpación y revisión con herramientas simples como tal vez una linterna para ver con más detalle la parte de atrás del paladar o de la faringe y laringe, guantes para poder abrir bien el hocico del paciente y poder bien si hay alguna anormalidad.

Si notamos algo anormal en nuestro examen físico, también nos podemos apoyar en otras herramientas como los rayos X, en estas como ya sabemos, podemos ver hueso si sospechamos de alguna fractura, o inclusive con el kilo voltaje y mili amperaje adecuado se pueden apreciar también los músculos faciales en caso de alguna anomalía en el movimiento o en la palpación. 

Si bien tenemos acceso a la resonancia magnética de imagen (MRI), también se puede recurrir a esta, preguntando primeramente al propietario si el paciente tiene algún implante metálico/microchip de identificación/chip para localización/rastreador/marcapasos/clavos de alguna fractura previa o cualquier tipo de metal en su cuerpo. En la resonancia magnética de imagen podremos apreciar con mayor precisión si hay algún tejido anormal obstruyendo los músculos de la articulación temporo-mandibular, o inclusive podremos apreciar actividad calórica de las células en caso de alguna infección que no pueda verse a simple vista en el examen físico.

Dependiendo de nuestros hallazgos es el tipo de tratamiento hacia el cual nos debamos inclinar, siempre tomando muy en consideración la edad del paciente y la raza.

Esperemos que esta publicación les haya gustado, y  nos sirva de repaso para futuras ocasiones.

MVZ Carolina Pruneda

The Cat Area 8: Otodectes Cynotis

Good day friends and colleagues, today we will talk about the main source of ear mites not only in cats, but also in dogs.

Otodectes Cynotis, this mite has been proven to be found in dogs, ferrets, foxes, and of course, cats. It is found all around the world, America, Europe, Asia, Middle East and Australia.  

The mites live in the ear canal of the cat. Most times there can be over a thousand mites present in the ear without any apparent mites appearing on the surface of the feline host.

Now we must remember the life cycle of these mites. First of all, the female mite secretes a fluid that helps her eggs to be glued onto the cat's ear canal. The eggs typically require 4 days of incubation prior to hatching. The life cycle includes a larva, a protonymph, and a deutonymph. Each stage takes a minimum of 3 to 5 days to develop, and the development is followed by a quiescent period of about 24 hours during which time the mites molt and shed their cuticles. As soon as the adult emerges from duetonymph cuticle, it will seek out and form a pair with a deutonymph. The complete egg to egg cycle took aproximately 18 to 28 days (about 3 weeks).

Transmission between hosts is by direct contact. The mites seem to require a relatively high humidity for survival and seem to rapidly dessicate at typical room humidities.

As for the clinical signs and pathogenesis, most cats tend to scratch a lot, however, some cats vary in their abilities to serve as hosts for Otodectes cynotis. If we observe close enough we can see that most cats can have severe lesions with significant quantities of dark cerumen and sometimes even blood present in their ears but one or two mites, other cats will have very clean ear canals, almost devoid of cerumen and detritus but have lots of mites. Still other cats can host huge numbers of mites in their ears and still have shown very little in the way of outward signs of infection. Ears of cats with very large numbers of mites tend to contain a dry waxy parchment-like material that occurs as sheets throughout the ear canal. These layers of sheets will contain mites throughout and consist in part of rafts of eggs that are embedded in the material. These ears tend to not contain large quantities of wax.

The easiest way to diagnose Otodectes cynotis is with an otoscopic examination, by observing movement. Another way to diagnose is with a swab in the ear with a cotton tipped applicator and to place the swab in a glass vial serum vial with a small drop of water or even baby oil. After about an hour, the mites will begin to migrate out of the cerumen and dentritis and can be observed walking on the walls of the glass vial or on the applicator stick. Smearing the ear swab onto a glass slide and examining under 400 X magnification usually reveals the mites too.

The Identification is relatively simple, no other non-burrowing mites of large size are typically found in the ears of the cat. The living mites appear as small white organisms that can be seen moving about within the ears or on swabs of deteritus removed from the ears. An examination of the distal portions, pretarsi, of the anterior pairs of legs will reveal the 'wine glass' shaped caruncle on a short pedicel.  The eggs are white, oval, slightly flattened on one side, and are 166 to 206 µm long.

As Veterinarians we have now days multiple options regarding treatment for otodectes cynotis, and of course as we know, not all patients can react properly to a certain treatment, and that is why, it is our job to test and provide the best treatment for each patient.

Our best chance on treatment can be Pyrethrin, there are several presentations containing different type of compounds, such as Otomite Allerder by Virbac, Nolvamite by FortDodge, Eradimite by Solvay, Aurimite by Schering Plough. Also we can use Rotenone containing compounds such as Er Miticeby Phoenix, Ear Mite Lotion by Durvet, Ear Miticide by Vedco.

If we want to go beyond, because our patient has a greater infection we can also use Otomax, which is a mineral-oil based otic ointment containing gentamicin sultate, betamethasone valerate, and clotrimazile.

However, if our patient is not too infected, or if the patient has shown in previous ocasions to be picky on the meds, we can also do a test using natural products such as 2ml of mineral oil based and 30 seconds of external massage of the base of the ear of the cat, and we can see if after 2 treatments one week apart we are able to see a difference. Of course if we decide to go all natural with the mineral oil, we might notice that this oil might tend to leak from the ear, and the hair on the head of the cat might appear oiled for the first day or so after treatment.

And of course as we all know, when it's about a fiery cat we can always go with shots, Ivermectin injectable, even if is not officially approved in cats, ivermectin has been used to treat feline infestations with otodectes cynotis. The most typical dosages are 0.2 to 0.225 mg/kg injected on one occasion or on two occasions with a 3 week interval between injections.

As Veterinarians we most be aware of the toxicity of Ivermectin when used not just in cats but in dogs too, 0.5mg / kg body might just be the limit of this medication, any more than this and it can become extremely toxic. However, Ivermectin can be used safely into the ear canals in drop presentation, it really is highly effective!

Also, we most remember, that one dosage of medication, which ever we choose for our patient may not be enough, and we most tell the owner that they need to return within 2-3 weeks for a follow up visit, and then we most check our patient again and see if there's been improvement.

Now let's talk about the hazzard towards humans, there is a slightly chance for this mite to be transferred to humans, since 1978, there haven't been any reports, so in few words, it can be hazzard towards humans, however is very rare.

It is very important to remind the owner of our patient, that if they have any other pets at home, they should treat all of them, since ear mites can be easily transmitted among them, even if it's a dog or a rabbit, or a ferret, even a parrot.

We hope that this post is of some sort of help for you, or as a kind reminder since ear mites are very common among cats and dogs.
Cheers!




MVZ Carolina Pruneda

RABBIT BREEDS

Good day dear friends and colleagues, today we will review some of the most common rabbit breeds, and some general information about them, we hope you like it!

Developed in Pasadena California, USA, in 1917.

Also called Hollander or Brabander. Developed in England in 1830.

Developped in San Gabriel, California, USA, in 1924.

Developped in Missoula, Montana, USA, in 1962.

Developped in Beveren, Belgium in 1898.

Developed in Belgium in 1882.

Developped first in France, then in the USA in 1919.

Developped in the UK.

Developped in Holland inthe 20th Century.

Developped in Paris, France in the 1880s.

Developped in Germany in 1970s.

Developped in High Bridge, New Jersey, in 1984.

Developped in Southern California, USA, in 1920.

First developped in Belgium, in the 1980s.

Developped in England, in the 19th Century.

Developped in Flanders, Belgium, in the 16th Century.

Fisrt discovered at Essen, Germany, in the 1970s.

Originated in France, in the 1920s.

Developped in France in 1850.

Fist Developped in England in 1860.

First Bred in France in late 19th Century.

Originally from France, recognized by the British Rabbit Council in the 1920s.

Developped in England in the 19th Century.

First bred in Washington State, USA, in 1952.

The third breed to be developped in the USA, in North Canton, OH. Officially recognized by the ARBA in 1925.

This is a mutation between several european breeds, finally developped in 1755.

First bred in England in the late 1800s.

Originally from Ankara, Turkey, in late 1930s.

Different from other angora rabbits, the french one has a clear head and sometimes also clear front feet.

First appeared in the Holland in 1898, the name came from the colour of the Cuban cigars.

Developped in Ontario, Canada in late 1970s.

First developped in New Zealand in 1910.

So, these are the most important and common rabbit breeds, and we hope you enjoyed it as much as we did also.

MVZ Carolina Pruneda


References:

https://www.arba.net/breeds.htm

The Cat Area 7: Oniquectomia / desgarre en felinos

Buen dia queridos amigos y colegas, en el blog de hoy hablaremos sobre un tema del que muchas personas tal vez no estén completamente informadas, sin embargo es de gran importancia. Hoy hablaremos sobre la extracción de las garras de los felinos, desgarre en felinos u oniquectomía. Esta es una practica que muchas personas realizan a sus mascotas para que estas no arañen o destruyan muebles o paredes o lugares en sus hogares, sin embargo, que es realmente lo que implica el desgarre en felinos?
El desgarre en felinos se refiere a la amputación de la última falange de los dedos de los felinos, desmembramiento. La CFA (Cat Fancier’s Association of America)  declara respecto al desgarre en gatos que “El hecho de que los gatos rasquen cosas y lugares es un comportamiento natural, y que los gatos pueden llegar a estar indefensos sin el completo uso de sus garras, y que el daño hacia muebles por rasguños puede minimizarse o inclusive evitarse al cortar las uñas de los gatos rutinariamente, o utilizando garras de plástico protectoras, y lo más importante redirigir a los gatos hacia áreas aceptables como posters rascadores o alfombras”.

La AAFP (American Association of Feline Practitioners) ha declarado que “El procedimiento para desgarre en felinos no es medicamente necesario”.

De hecho una publicación reciente (Associated Press-Petside.com) menciona que solo en los Estados Unidos de Norte America cerca del 60% de propietarios de mascotas (incluyendo 55% de los propietarios de gatos) mencionan que está bien tener un gato sin garras.

Sin embargo, estamos en total desacuerdo con este procedimiento, pues no es de ninguna manera ético, es medicamente in-necesario, cambia la posición y la manera de caminar de la mascota, cambia la anatomía de la mascota, y está comprobado inclusive medicamente que las mascotas cambian su carácter, se vuelven gatos con miedo.

Esto también repercute en el hecho de que no puedan defenderse contra algún extraño o depredador, y se vuelven presa fácil para estos.

Así que ya lo saben amigos, en lugar de pensar en la remoción de garras en sus amigos felinos, la mejor opción es el corte rutinario de uñas y el uso de alfombras o rascadores para gatos. Evitemos el trauma en nuestros amigos felinos por amor a la naturaleza.

Si tienen cualquier duda respecto a este procedimiento, contáctennos, y con gusto aclararemos sus dudas. Que tengan un excelente fin de semana!



MVZ Carolina Pruneda

Referencias:

• “The Cat Bible”, Tracie Hotchner, Gothambooks, New York, Octubre 2007.
• cfa.org
• Press-Petside.com