The Cat Area 3: Chlamydia in Cats

Chlamydia in cats (Feline Chlamydia)

Good day colleagues and friends, so today we will talk a little bit about a respiratory infection in cats called Feline Chlamydia, also known as Feline Chlamydiosis.

The first thing we need to know about this disease is that it is caused by a bacteria called Chlamydia psitacci, this is an intracellular bacteria (a bacteria which lives inside the host's cells), The family Chlamydiae is now divided into two genera, Chlamydia and Chlamydophila. The genus Chlamydophila contains four species, including Chlamydophila felis, a causative agent for conjunctivitis in cats.

This is a zoonotic disease, this means that it is a transmissible disease to humans as well.

How does the infection takes place:

Transmission can take place even without direct contact with an infected animal, as the molecules from a cough or sneeze can travel across a room, a human caretaker can carry the bacteria and spread it by touch, or the cat may come into contact with a contaminated object, such as in a bedding or feeding area.

The bacteria attaches itself to the mucosal cells of the conjunctiva, gastrointestinal and genital tracts. The eyes become red, inflamed and develop a discharge, due to basic immune response.

There are 2 basic ways of infection:

Direct: Contact with an infected cat, such as nasal and ocular discharges. Kittens may become infected during the birth process.

Indirect: even though this bacteria doesn't survive well in the environment, contact with food bowls, bedding, litter trays, pet owner's hands etc. It is always advisable to exercise caution when dealing with infected cats and practice routine hand washing and disinfecting in order to minimize the risks of infecting other cats.

Clinical signs of Chlamydia in cats:

-sneezing

-watery eyes

-discharge from eyes

-coughing

-difficulty breathing

-runny nose

-anorexia (lack of appetite)

-fever

-pneumonia

-mucus enlargement

-nose lesions

We do have to consider, that all those signs are not always present altogether.  The predominant clinical sign of Chlamydia in cats is conjunctivitis; an abnormal eye discharge due to inflammation of the conjunctiva, the membrane lining the inside of the eyelid and the white part of the eye itself, (known as the sclera). The eyes initially develop a watery  discharge, as the infection progresses, the conjunctiva becomes reddened and swollen and the discharge becomes thicker. It may start out with discharge from one eye but usually, spreads to both eyes. Symptoms usually appear around 5 days after exposure.

It is possible for a cat to appear outwardly healthy but be shedding the bacteria which can be passed onto other cats via eye discharge.

Chlamydiosis can affect any cats but it is more often seen in kittens between 5 and 9 months of age and cats in overcrowded or stressful environments such as animal shelters.

In young kittens, chlamydiosis may cause pneumonia.


Now lets go to the part of how we know that it is actually chlamydiosis, the DIAGNOSE part...

Chlamydia can be diagnosed by ultimate and very complicated methods such as PCR (polymerase chain reaction), or Immunofluorescent assay (IFA), but the good news is that we don't really have to go that far, nor complicate ourselves, because we can also do a simple swap and send it to the lab for a bacterial culture. Sure it could take a couple of days to grow, but it is simple, cheap, and accurate, because really, chlamydiosis is not hard to diagnose with clinical signs, so mainly we do a bacterial culture just to confirm.

How do we treat chlamydiosis?

I'm pretty sure you all know the answer, antibiotics! yes, but what kind of antibiotics are the right suit for this bacteria...

As we know, Chlamydia psitacci is a respiratory tract bacteria, so we mainly want to go with respiratory antibiotics such as clindamicyn, tetracycline or doxycycline, but also we want to give oral antibiotics, or even topic antibiotics, this is so we don't give that bacteria a chance to flee to another organ and grow resistance. In to the eyes, we should give antibiotics as chloranphenicol or even terramycin(oxytetracycline), and let's not forget about the pain killers for the eyes, such as diclofenac (you must remember to give those in drops, and make sure to apply those drops as cold as just taken out of the fridge, because if you don't, trust me, the cat's eyes are going to feel in burning pain, yes diclofecnac burns the eyes).  

Feline Chlamydiosis is a disease that may take from 3 or 4 weeks, sometimes even up to 3 months if the treatment is not well given. 

Also I would like to add, that we can always prevent chlamydia infection among our patients, as most of you know, the best way is to keep them separate, often clean their areas (speacially with disinfectant), wash our hands before and after touching, holding, or lifting any of our patients and of course, vaccinating the healthy cats, we most keep our protocols for isolated patients. If the cats belong to a shelter, the best thing to do is to completely isolate the new, unvaccinated and sick cats from the normal, healthy ones, for at least 1-2 weeks (which is the regular time for incubation of a pathogen in a host's body to develop a disease).

I hope this is helpful for you, or at least of interest, if you have any questions feel free to ask them, have a great weekend!

MVZ Carolina Pruneda

Organs of the Immune System (Secondary Lymphoid Ogans)

Good day friends and colleagues, in this post we are going to continue talking about the lymphoid organs, but this time we will talk about the secondary lymphoid organs, what they do, and how they work.

So despite the primary lymphoid organs develop early in fetal life, the secondary lymphoid organs arise late in fetal life and even persist in adults, also they enlarge in response to antigenic stimulation.

Some of the secondary lymphoid organs include the spleen, the lymph nodes, the tonsils, and lymphoid tissues in the intestinal, urogenital and respiratory tracts.

The anatomical structure of these organs is therefore designed to facilitate antigen trapping because they contain dendritic cells that trap and process antigens and lymphocytes that mediate the immune responses.

Now let's see how the organs work:

Lymph nodes: they consist of a reticular network filled with lymphocytes, macrophages, and dendritic cells through which lymphatic sinuses penetrate. Lymph nodes are round or bean-shaped structures that are widely distributed throughout the body. 

Imbedded in connective tissue or fat, they are concentrated in the cervical, axillary, and inguinal regions – the neck, armpits, and groin, respectively. They are typically less than ½ inch in length, depending on the size of the animal.

Lymph nodes are enclosed by a capsule of connective tissue and comprised of several compartments called "lymph nodules." The nodules are masses of T-cells, B-cells, and macrophages. 

 Macrophages are specialized cells that ingest and destroy foreign material.

The nodules are separated by spaces called "lymph sinuses." The vessels that deliver unfiltered lymph are called "afferent vessels," and there are several per node. The lymph is then filtered for antigens and particulate matter, and an immune response is generated, if necessary. The filtered lymph leaves the node through one or two efferent vessels near an indentation called the "hilum." Blood vessels also enter and exit the node at the hilum.

In Lymph node that have been stimulated by antigen, some of the cells within these nodules expand to form foci of dividing cells called germinal centers. These germinal centers have 2 types of zones: light and dark.

the dark zones are sites where B cells proliferate and undergo a process called somatic mutation.

the light zones are sites where immunoglobulin class switching memory B-cell formation occur.

The lymphatic vessels: link together all of the secondary organs and also connect to the cardiovascular system. They provide a route for the one-way flow of lymph from the tissues of the body to the heart. Lymph is the clear, yellowish fluid that is collected from the interstitial spaces (the spaces between the cells of a tissue) into lymphatic capillaries.

The lymphatic vessels are structured similar to veins, with thin walls and valves to prevent backflow. They are not muscular vessels, and external forces such as limb movement regulate the flow of lymph. Once in the capillaries, the lymph moves into progressively larger vessels, passes through the lymph nodes and/or spleen, reaches the large ducts, and enters the blood circulation near the junctions of the jugular and subclavian veins in the upper chest. Thus, the fluid and proteins are eventually returned to the blood, which helps maintain the proper balance of fluid between the blood vessels and the tissues. All of the lymph from the lower body, left arm, and left thorax are drained through the thoracic duct into the junction of the left jugular and subclavian veins. The fluids from the neck, right arm, and right thorax empty into the right lymphatic duct which joins the venous system at the junction of the right jugular and subclavian veins.
Lymphatic capillaries: are interwoven with the blood capillaries. Fluid and proteins are forced out of the arterial end of the blood capillary and into the interstitial space. About 90% of the fluid is reabsorbed in the venous end of the blood capillary, but none of the proteins are able to reenter the blood vessels because they cannot fit through the tight junctions of the cells. The lymph capillaries have extremely loose cell junctions, however, and they are able to absorb the remaining 10% of the fluid along with the plasma proteins. Once inside of the lymph vessels, the fluid is then termed "lymph."

Lymphoid tissues in the intestinal tract: Near the small intestine, where fats are digested and absorbed, the lymphatic vessels have a special function and, therefore, a special name. They are involved in the absorption of digested fat from the small intestine, and are called "lacteals". After a meal the fluid within the lacteals generally has a fat content of 1-2%, and it appears cloudy. This cloudy lymph in the lacteals is called "chyle."

Hemolymph Nodes: are structurally similar to the lymph nodes found in association with the blood vessels of ruminants and other mammals. They differ from conventional lymph nodes in that their lymphatic sinuses contain numerous red cells. They have a cortex containing germinal centers and B cells as well. T cells predominate at the center in association with lymphatic sinuses. There are some differences, however, in the characteristics of these T cells are compared to conventional lymph nodes. They may combine features of both the spleen and lymph nodes.

Spleen: is an organ located in the upper left portion of the abdominal cavity along the outside curve of the stomach that filters blood. The filtering process removes both antigenic particles and aged blood cells. Also stores red cells and platelets and undertakes red cell production in the fetus. It is therefore divided into two compartments: one for antigen trapping and for red cell storage, called red pulp, and one rich in lymphocytes where immune responses occur, called the white pulp.

So generally there is lymphoid tissue also in other organs such as the lungs, the liver and throughout the body. Later we can discuss a little more about how some of theese immune process occurs, such as the simple inflammation or even a bruise.
For now this is in a few words how the lymphoid organs work.
Have a great week everyone!

MVZ Carolina Pruneda

Organs of the Immune System (Lymphoid Organs)

Good day colleagues and friends, so a couple of days ago, a friend of mine asked me what are the lymphoid organs, and well, that's what we are going to talk about today: the lymphoid organs and how they work!

First of all, we ought to know that the lymphocytes are cells that help protect the body of all animals (well yes, including humans!). The lymphocytes fall into 2 major populations called T cells and B cells based on the organs in which they mature. So therefore the organs that regulate the growth and maturation of these cells are called the primary lymphoid organs.

These include the bursa of Fabricius in birds only, the bone marrow in primates and rodents, and intestinal lymphoid tissues in rabbit, ruminants, and pigs.

The primary Lymphoid organs all develop early in fetal life. As animals develop, newly produced, immature lymphocytes migrate from the bone marrow to the primary lymphoid organs where they mature.

It is very important to remember that the primary lymphoid organs are not sites where lymphocytes encounter antigens and so they do not enlarge in response to antigenic stimulation.

Ok now we are going to mention the Primary Lymphoid organs and what their functions are:

Thymus: is located in the thoracic cavity in front of and below the heart. In horses, cattle, sheep, pigs, and chickens it also extends up the neck as far as the thyroid gland. The size of the Thymus varies, it's relative size being greatest in newborn animals and it's absolute size being greatest at pubrty. It may be very small and difficult to find in adult animals.The main function of the thymus is to produce a development in the immune system's cells called: lymphocytes T (which defend the body by responding to antigens).
There are three types of Lymphocytes T: lymphocytes T cytotoxic,  lymphocytes T auxillaires. and lymphocytes T regulator. And of course we shall talk about theese cells later on.
Back to the thymus, this organ is mainly responsible for the hormons production that helps regulate the growth and the definition of the lymphocytes in their characteristics.
Some of the hormones that are produced by the thymus are peptides such as: thymosins, thymopoietins, thymic humoral factor, thymulin and thymostimulins. The thymulin is especially

Bursa of Fabricius:This organ is only found in birds, it is a round sac located just above the

cloaca. The bursa reaches its greatest size in the chickens about 1 to 2 weeks after hatching and then shrinks as the bird ages. The main function of this organ is maturating and causing the differentiation of B lymphocytes (antibody-forming system), it also produces the hormone bursin, which activates B lymphocytes.
The bursa acts like the thymus insofar as immature cells produced in the bone marrow migrate to the bursa. These cells then proliferate rapidly but 90-95% of these B cells die by apoptosis (physiological cell death or cell suicide mediated by normal body processes).

Peyer Patches: also known as PPs, are lymphoid organs located in the walls of the small intestine. Depending on the specie they can be found in several areas in the intestine walls.
They are divided in two groups: group I includes ruminants, pigs, horses, dogs and humans. Group II includes other mammals such as cats, rabbits and rodents.
In group I, 80-90% of the Peyer's Patches are found in the ileum where they form a single continuous structure that extends forward from the ileocecal junction. Ileal PPs consist of densely packed lymphoid follicles, each separated by a connective tissue sheath, and contain only B cells.
In group II, all PP's are located at random intervals in the ileum and jejunum. In these mamals, the PPs do not develop until 2 to 4 weeks after birth and persist into old age.
The main function of the PPs are to grow and proliferate B cells, althoughmost cells undergo apoptosis (cellular death), the survivors are released into the circulation, then they produce antibodies.

Lymphoglandular complexes: they are submucosal masses of lymphoid tissue penetrated by radially branching extensions of mucosal glands.These glands penetrate both the submucosa and the lymphoid nodule. Their function is unknwon in full, but contain plasma cells, and are sites of antibody production, they may be antigen-sampling sites.

Bone Marrow: Lymphoid cells developing and maturing here are referred to as B cells (B for Bursa or for Bone marrow). This is the site for proliferation for stem cells and for the origin of pre-B cells and their maturation to become immunoglobulin-producing lymphocites. Like thymic selection durng T-cells process withing the bone marrow eliminates B cells with self reactive antibody receptor.
There is no exclusive  B-cell development site in the bone marrow, although it is suggested that precursor B cells develop at the outer edge of the marrow and migrate to the center as they multiply.




Now that we have mentioned the primary lymphoid organs, we can go ahead and mention the secondary Lymphoid organs, which are: lymph nodes, hemolymph node, and the spleen.
 There are other secondary Lymphoid organs, however, these are the most important, and we will get into details with theese in our next post.

Thank you all for your support, and let's keep learning! 
Have a great week everyone.


MVZ Carolina Pruneda

The Cat Area 2: Sustancias Toxicas para los Gatos (Parte VI)

Chocolate

Hola queridos colegas y amigos, en esta ocasión, hablaremos particularmente sobre los efectos del chocolate, no solo en nuestros pacientes felinos, sino también en los caninos.

Es bien sabido entre los veterinarios que el chocolate es malo para nuestros pacientes, pero, de qué manera? como podemos reconocer que es el chocolate la sustancia que esta dañando a nuestros pacientes? que tratamientos podemos utilizar?

Primero que nada el chocolate que es generalmente a base del cacao, contiene una sustancia que lo hace toxico, la teobromina. La teobromina, en pequeñas especies (sobre todo en el gato), se elimina muy difícilmente de su organismo, por lo que se acumula en la sangre y comienza a producir deshidratación en las células, por lo cual el paciente experimentara sed excesiva.

Además, la teobromina produce alteraciones en el sistema nervioso, por lo cual, el paciente desarrollara una hiperactividad, aceleración del ritmo cardiaco, vómitos, fallos sistémicos, coma, y si pasan más de 24 hrs después de que el paciente lo haya consumido sin recibir atención medica, es muy probable que el paciente pueda fallecer de un ataque cardiaco (claro que estos son casos extremadamente aislados, y dependerán en gran manera en si el paciente fue atendido a tiempo o no y de la cantidad ingerida de chocolate).

Pero, la teobromina no es la única sustancia toxica en el chocolate, dependiendo

de si es un chocolate a base de leche o un chocolate negro, también depende la cantidad de cafeína, la cual también es una sustancia en cierta forma toxica para los gatos y los perros.  Ya que la cafeína, es una sustancia altamente estimulante, tanto del sistema nervioso como del corazón, en raras ocasiones puede también estimular la actividad renal y causar incontinencia urinaria, la cual libera mayor cantidad de fluidos fuera del organismo, lo cual conlleva a una deshidratación aun mayor.

Otros signos comunes de intoxicación por chocolate:

agitación (debido a la estimulación cardiaca por la cafeína)

espasmos musculares (debido al daño en el sistema nervioso)

disfunción renal (debido a la estimulación de la actividad renal)

Cual es la dosis letal de chocolate?

de 80 – 100 gr. de chocolate ingerido por kilo del animal

Que otras sustancias contiene el chocolate que pudiesen ser dañinas en los gatos y perros?

La leche, hay chocolates que con el objetivo de hacerlos más cremosos o suaves al gusto contienen una buena cantidad de leche. A medida en que los gatos van madurando su intestino, la mayoría se vuelven intolerantes a la lactosa, algunos la toleran poco, sin embargo, en su gran mayoría la leche se vuelve un alimento que no deben ingerir pues puede ocasionarles vómitos, diarreas, y otros problemas digestivos. Los cuales, cuando se tiene un gato que tiene acceso a la calle, es muy difícil detectarlos, pues el instinto natural del gato, es salir y hacer sus necesidades fisiológicas en tierra, y enterrar sus heces, pues su instinto le determina que debe protegerse de otros depredadores más grandes.

Como podemos tratar a un perro o a un gato que ha ingerido chocolate y presente signos de intoxicación?

No existe antídoto específico.

Inducir el vómito (hasta 6-8 horas tras la ingestión).

Realizar lavado gástrico.

Administrar carbón activado 1g/kg, repetir cada 2-6 horas, y un catártico salino.

Vigilar el equilibrio electrolítico y la hidratación. Administrar líquidos intravenosos.

Controlar la frecuencia cardíaca (ECG): Administrar atropina (0'02 mg/kg IV), si hay bradicardia, lidocaína.

Si hay contracciones ventriculares prematuras y b-bloqueantes si hay taquicardia (propanolol 0'04-0'06 mg/kg en inyección IV lenta).

Cateterizar la vejiga urinaria con objeto de evitar la reabsorción.

Sedación con diazepam(gatos), o fenobarbital.

Con esto concluimos el post de hoy sobre el chocolate en gatos (y en perros también), espero que les sea de ayuda. 

Y los esperamos en la próxima sección de The Cat Area todos los viernes recuerden es exclusivo de gatos!

Les mandamos un fuerte abrazo y que tengan un lindo fin de semana!

MVZ Carolina Pruneda