Interpretación de Laboratorio: Química Sanguínea (27 elementos)

Buen día amigos y colegas, en la publicación de hoy nos enfocaremos en los tipos de exámenes de laboratorio, comenzaremos con un examen general para analizar a nuestros pacientes metabólicamente. El examen de química sanguínea básica, o también denominado como análisis metabólico básico es un grupo de 27 pruebas químicas realizadas en el suero, la porción de la sangre sin células, o el plasma. Debemos recordar que tenemos otras pruebas de análisis metabólico o química sanguínea que incluyen solo 5, 6, 12 y 24 elementos, sin embargo, la más completa es la de 27 elementos, y en ellos se incluyen:

1-Glucosa (azúcar)

2-Nitrogeno Ureico (BUN/Urea)

3-Creatinina

4-Acido Úrico

5-Colesterol

6-Trigliceridos

7-Bilirrubina

8-Transaminasas (Aminotransferasas)

9-Fosfatasa Alcalina (ALP)

10-Albumina

11-Globulinas

12-Relacion A/G (albuminas/Globulinas en sangre)

13-Proteinas totales

14-Gamma-glutamil-transpeptidasa (GGT)

15-Deshidrogenasa láctica (DHL)

16-Amilasa

17-Lipasa

18-Creatinkinasa (CK)

19-Calcio Iónico y Sérico en suero

20-Cloro Sanguíneo

21-Sodio (Na)

22-Potasio (K)

23-Fosforo (P)

24-Magnesio

25-Osmolaridad Sérica

26-Hierro Sérico

27- Dióxido de Carbono (CO2)

Como Medico Veterinarios, es importante repasar estos elementos, ya que su interpretación es muy variable si solo unos cuantos están elevados y otros bajos, en ocasiones los elementos conjuntos o inclusive unitarios pueden hacer diagnósticos completamente distintos.

Ahora veremos algunos de nuestros elementos de este análisis sanguíneo.

1-Glucosa: es el principal tipo de azúcar que contiene la sangre. Procede de los alimentos que se ingieren, y es la principal fuente de energía necesaria para desempeñar las distintas funciones corporales.

En perros no es muy común, pero cuando se encuentra aumentada se podría pensar en una posible diabetes mellitus. La glucosa elevada también nos puede indicar una Pancreatitis, desordenes endocrinos (acromegalia, síndrome de Cushing, tirocoxicosis, feocromocitoma, etc), o inclusive insuficiencia renal crónica. 
También debemos tomar en cuenta si la extracción de la muestra de nuestro paciente fue en ayunas, pues si el propietario le dio alimento esto también podría elevar los niveles de glucosa sin ser un indicador de algun padecimiento relevante. En algunos gatos se puede ver reflejado el nivel de la glucosa como elevado debido al estrés generado al momento de extraer la muestra, por eso es muy importante que la muestra se extraiga de la vena yugular, ya que de la región yugular el flujo sanguíneo es mas fácil de captar.

Si los niveles de glucosa se reflejan disminuidos podría indicarnos una insuficiencia adrenocortical, hipopituitarismo, insulinoma, neoplasma extra pancreático, enfermedad hepática severa, ingestión de etanol, o hipo glicemia reactiva (funcional, pre diabética o alimenticia). Nuevamente debemos prestar atención al rango de niveles: normal, bajo y alto, pues en pacientes diabéticos la glicemia en ayunas está por encima de la cifra máxima del rango establecido.

2-Nitrogeno Ureico (BUN): La Urea es el producto final del metabolismo proteico. Es sintetizada por el hígado, pasa al torrente sanguíneo y se excreta por el riñón.

Su aumento puede indicarnos una función renal disminuida aguda o crónica (común en gatos), azotemia pre-renal (hemorragia gastrointestinal, shock, deshidratación, insuficiencia cardiaca congestiva, sepsis, acidosis, quemaduras, síndrome hepatorrenal, etc), azotemia post-renal (uropatias obstructivas -comunes en gatos adultos y geriátricos-), Enfermedad de Addison, dieta alta en proteínas, uso de corticosteroides (común en perros de criadero) y tetraciclinas.

Podemos sugerir insuficiencia hepática, sobre hidratación, desnutrición y nefrosis lapida al notar urea en niveles bajos. En algunos casos, las perritas en etapa final de preñez también pueden presentar niveles bajos de urea.

3-Creatinina (Relación BUN-Creatinina): La creatinina se forma en los músculos como resultado del metabolismo. Es excretada principalmente por los riñones y una pequeña parte con las heces. Es un producto constante y depende de la masa muscular y de su eliminación por el riñón. Es una prueba muy específica y sensible a posibles fallas de función renal, y es mejor indicador que el BUN inclusive en enfermedades renales crónicas. Sin embargo ambas deben solicitarse para evaluar problemas renales, porque la relación BUN-Creatinina provee mas información.

Este elemento es clave en gatos adultos, pues si se encuentra elevado, nos indica insuficiencia renal, insuficiencia circulatoria y obstrucciones urinarias. En razas como persas y/o exoticos es mucho mas comun encontrar algun tipo de patologia renal en gatos adultos/geriatricos.

4-Acido Úrico: Es el producto del catabolismo de las purinas (compuestos orgánicos). Su mayor parte se excreta por el riñón y una proporción menor por el tracto intestinal. Su fuente principal son las proteinas (carnes).

Debido a que los felinos son 100% y estrictamente carnívoros, el aumento de este elemento nos indica enfermedades renales, trastornos hematológicos como leucemias, linfomas, anemias hemolíticas, anemias megaloblasticas, etc. En Perros que no consumen suficiente fibra se puede  llegar a acumular y puede indicar gota. Cuando se tratan pacientes con diuréticos también se debe tener cuidado, pues los diuréticos también pueden alzar los valores.  

Ahora, también debemos considerar en los perros el envenenamiento con plomo, para lo cual podemos realizar una placa de rayos X para descartar, pues nuestros pacientes caninos tienden a comer y masticar objetos que los pueden afectar.

En gatos debemos examinarlos bien en el consultorio para descartar alguna necrosis de algún tejido de algún traumatismo viejo.

También podemos encontrar el ácido úrico disminuido en pacientes cuales han recibido tratamiento con cortisonas recientemente, o en pacientes con daños en los túbulos renales.

5-Colesterol: Es un elemento indispensable en la producción de esteroides, síntesis de hormonas femeninas (estrógenos), principal componente de la bilis, catalizador activo de intercambios celulares, etc.

El colesterol está integrado por 3 lipoproteínas denominadas según la densidad:

-VLDL (Very Low Density Lipoprotein – Lipoproteína De Muy Baja Densidad) en un 13 %,

-LDL (Low Density Lipoprotein – Lipoproteína de Baja Densidad) en un 70% y

-HDL (High Density Lipoprotein – Lipoproteína de Alta Densidad) en un 17%

Las VLDL forman los triglicéridos y son materia prima para fabricar las LDL, las cuales, por su baja densidad se depositan muy fácilmente en las capas íntimas arteriales y son las que forman la ateroesclerosis (arterias tapadas).

Las HDL intervienen para remover las LDL de las arterias, su formación se estimula con el ejercicio y poca ingesta de grasas animales.

En pacientes con tendencia a la obesidad o con patologías cardiacas se debe realizar un perfil lipídico y dosificación de colesterol, ya que el primer factor desencadenante del infarto cardiaco es el colesterol elevado.

Ahora existe una formula muy sencilla para poder evaluar el colesterol total:

VLDL + LDL + HDL = Colesterol Total

Valores Normales para VLDL en perros: p<0.05 - p>1.7 y en gatos: p<0.2 - p>1.1

El aumento de colesterol se presenta en casos de Ictericia obstructiva, colelitiasis, síndrome nefrótico, diabetes, xantomatosis cutánea, hipotiroidismo, queratopatías lipídicas, pancreatitis necrótica aguda, lipidosis en el humor acuoso, lipemia retinalis, distrofia estromal, anorexia; entre otras.

La hipercolesterolemia tiene relación con la aterosclerosis, aunque puede estar ausente en algunos casos.

6- Triglicéridos: Forman Parte de las lipoproteínas y se dividen en exógenos (son los que se ingieren por medio de alimentos con grasas saturadas), y endógenos (los que fabrica el hígado en su proceso fisiológico al degradar los exógenos). Los triglicéridos también son materia prima para las LDL.

Los valores normales de triglicéridos tanto en perros como en gatos son de: 25 – 120 mg/dl

Debemos recordar que los perros pueden presentar hiperlipidemia después de comer, por lo que no necesariamente es signo de alguna alteración más severa como alguna enfermedad renal degenerativa o un bajo funcionamiento de la glándula tiroides.

7. Bilirrubina: Es el resultado de la ruptura de la hemoglobin por la destruccion de los globulos rojos, removida por el higado y excretada por la bilis. Se encuentra en dos formas: conjugada (directa) y no conjugada (indirecta).

Valores normales en perros y gatos son:

Bilirrubina Total: 0-0,8 mg/dl

Bilirrubina Directa: 0-0,4 mg/dl

Bilirrubina Indirecta: 0-0,4 mg/dl

Se encuentra aumentada en colestasis intra y extra hepática, enfermedad hepática, procesos hemolíticos, hiperbilirrubinemia congénita (Síndrome de Crigler-Najjar).

En gatos se presentan las bilirrubinas elevadas en gatos que presentan cuadros como: Síndrome Ictérico felino, ulceras gastrointestinales, lipidosis hepáticas en felinos, pancreatitis, parasitosis, Colangitis-Colangiohepatitis felina.

En perros, las bilirruinas pueden verse aumentadas debido a enfermedades hepáticas como hepatitis crónica congestiva (en especial en los doberman), lipidosis hepática, Lipemia,  Inanicion, Fiebre o Sepsis, alteraciones en el metabolismo de la bilis, necrosis hepatocelular o colestsis.

Una bilirrubinuria persistente o bilirrubina en una muestra de orina diluída, es indicativo de alteración del metabolismo de la bilis.

La bilirrubinuria es debida siempre a bilirrubina conjugada dado que la bilirrubina no conjugada no es soluble en agua y estando ligada a albúmina, no es filtrada por el riñón.

La determinación de la concentración en suero de bilirrubina conjugada y no conjugada, pude ocasionalmente ayudar a determinar el origen de la ictericia. Si hay ictericia sin anemia, entonces corresponde a una patología hepática o post–hepática. La hemolisis severa, suficiente para producir ictericia, siempre resulta en una anemia importante.

8. Transaminasas (Aminotransferasas): Son una serie de enzimas que se almacenan en: músculos, Corazón, cerebro y en el hígado. Esto se debe a que son producidas por las células del hígado. La función más importante que realizan, es en el metabolismo. Son el resultado de la acción de las enzimas sobre sustratos especiales y que genera como productos, aminoácidos como alanina, glutamato o aspartato, originando dos transaminasas importantes: glutamato-oxalacetica (TGO), también llamada aspartato amino transferasa (AST)y la glutámico-pirúvica (TGP) o alanino-aminotransferasa (ALT). En el suero la aminotransferasa que más abunda es la TGO (AST).

El aumento de estas enzimas se puede dar debido a alguna dieta pobre en nutrientes o enfermedades como:

-Pancreatitis (debido a que la enzima gamma-glutamil o GGT se encuentra principalmente en el páncreas y los riñones y es resultado de una obstrucción en el conducto biliar).

-Hepatitis infecciosa (esta es una enfermedad contagiosa de los perros causada por un virus de DNA conocido como Adenovirus Canino 1/CAV-1).

-Enfermedad de Cushing (Hiperadrenocorticismo, que causa un aumento en la producción de la hormona adrenal en el cuerpo. En estos perros la enzima ALT puede ser elevado ya que el hígado está tratando de purgar el exceso de cortisol del sistema).

Generalmente las enzimas elevadas del hígado en perros pueden ser causadas por problemas del hígado o incluso debido a la muerte natural de las células en el hígado.

En los gatos podemos encontrar similitudes al notar estas enzimas elevadas, por ejemplo:

-Hígado graso (la elevación de la aminotransferasa alanina y la aminotrasferasa aspartato se utilizan para valorar en lipidosis hepática, sin embargo, la enzima más importante es la de la fosfatasa alcalina).

-Hepatitis (las transaminasas o enzimas TGO y TGP normalmente están en el interior de las células hepáticas, cuando se detectan en la sangre, indican daño celular hepático o muerte celular).

-Enfermedades del páncreas

-Tumores de hígado

-Cáncer de hígado

-Quistes (sobre todo en gatas)

-Deficiencia alimenticia (El hígado del felino tiene una alta actividad de las transaminasas para poder producir glucosa a partir de las proteínas, por eso es que la vitamina B6, piroxidina, es fundamental para las transaminasas, pues los gatos requieren 4 veces que los perros).

Y bien, queridos amigos y colegas, en nuestras siguientes publicaciones veremos poco a poco el resto de los elementos y su interpretación. Esperemos les hayan gustado, y que ustedes tanto como nosotros hayan aprendido y recordado los elementos de un examen de química sanguínea, saludos cordiales!

MVZ Carolina Pruneda

Flea Allergies Dermatitits

Flea allergy dermatitis is the most common cause of pruritus in both dogs and cats. Symptoms can either be non-seasonal or seasonal, depending on the climate. Addressing fleas is not only important for the well-being of the animal but also for owners, as fleas can transmit zoonotic diseases. Diagnosis of flea allergy dermatitis is usually based on clinical signs. Treatment may include palliative therapy with antihistamines or steroids, but the best treatment option is preventing flea bites and eliminating fleas from the household. Proper treatment of all animals in the household as well as the environment will lead to resolution of clinical signs within 6-8 weeks.

Introduction

 • Ctenocephalides felis felis: Most common flea for both dogs and cats 

- Potentially carries pathogens: Bartonella henselae, Dipylidium caninum, and Yersina Pestis 

- Produce an average of 27 eggs/day 

- Lay eggs within 24-36 hours 

- Other flea species: C. canis, Pulex simulans, Echidnophaga gallinacea (sticktight flea) 

• Life Cycle 

- Adult à eggs à larva à cocoon àpupa à hatch 

- Average time to complete lifecycle = 3 weeks 

 Perfect conditions = 16 days 

 Can take months if conditions are not met 

• Dermatological conditions 

 Flea infestation: skin disease with mild to moderate pruritus caused by biting of the flea 

 Flea allergy dermatitis (FAD) (flea bite hypersensitivity): Allergic reaction to flea saliva 

 Type 1, type 4, and basophil hypersensitivities 

 Salivary enzymes contain proteolytic enzymes, histamine-like compounds, anti-coagulants, haptens and antigens

Clinical Signs 

• Intense Pruritus 

• Lesions: erythema, alopecia, papules, pustules, excoriations, crusts, and moist dermatitis. Hyperpigmentation and lichenification may develop in more chronic lesions. 

• Distribution 

- Dogs: Caudal-dorsal distribution 

 Base of tail, posterior/lateral aspect of rear legs and ventral abdomen 

- Cats: Often neck and face 

 Common cause of miliary dermatitis and eosinophilic plaques 

 Can also see similar distribution as the dog 

- Secondary infections are common.

 Diagnosis 

• Clinical signs 

- In dogs, a diagnosis is mainly based on distribution of lesions; however, often dogs that have FAD also have concurrent food and/or environmental allergies which may complicate the diagnosis. Therefore; ensuring proper flea control is crucial to rule out flea allergic dermatitis before working up other causes of allergies. 

- In cats, distribution is more difficult to rely upon for diagnosis and response to treatment may be more helpful 

• Fleas and flea excrement (flea dirt) 

 Majority of FAD patients will not have fleas or flea dirt 

 Using a wet paper towel and collecting excrement can help determine if it is truly flea feces. Flea excrement is mainly digested blood and the “dirt” should dissolve with water and cause a reddish hue on the paper towel 

• Intradermal testing (IDT) and serological testing can aid in diagnosis of FAD 

- IDT is highly specific but not very sensitive 

 If positive, then can help support your diagnosis of FAD 

- Immunotherapy is unreliable.

Treatments 

• Symptomatic and palliative therapy 

- Short term glucocorticoids 

- Antihistamines: generally not effective 

• Approach to flea control 

- Treat each animal in the house 

- Treat the home environment to eliminate the environmental reservoir 

• Adulticides 

- Eliminates fleas present on animal but does not prevent re-infestation 

- Speed of kill: Depending on the product, may take minutes to 48 hours 

 Dependent on concentration which declines over time 

 Speed at which new fleas are killed is important for FAD 

• Important to use products that kill before eggs are laid 

- Repellency 

 Two forms 

• Fleas deterred by vapor phase: Affect is unclear in animals and should not be used for sole purpose 

- DEET (N,N,diethyl-m-toluamide) 

- Citrus oil 

• Fleas repelled by physical contact 

- Permethrin.

• Insect Growth Regulators: Disrupt developmental process 

- Juvenile Hormone Analogues: mimics hormone and prevents progression through juvenile stages  Methoprene: UV light sensitive: Not for use outside 

 Pyriproxifen: Stable in UV light 

- Insect Development Inhibitors: Inhibit chitin synthesis 

 Disrupt formation of cuticle, mouthparts and other chitinous structures 

 Ex. Lufenuron.

Adulticides 

• Afoxalaner 

• Dinotefuron 

• Etofenprox 

• Fipronil: Toxic to rabbits 

• Flumethrin 

• Imidacloprid 

• Indoxacarb 

• Nitenpyram 

• Selamectin 

• Spinetoram 

• Spinosad: Do not use in conjunction with ivermectin. Caution in neurological patients 

• Fluralaner.

Adulticides and Repellants 

• Cyphenorthrin 

• Deltamethrin 

• Permethrin: Toxic to cats 

• Pyrethrin 

Repellants 

• Amitraz 

Insect Growth Regulators 

• Lufenuron 

• Pyriproxifen 

• S-methoprene

Font: VetPrep.com 

WHY VETERINARIANS SUICIDE

Good day dear friends and colleagues, it has moved my heart in the past few months with some news, that are not so new actually, but every day they become more frequent. Each time there are more and more Veterinarians taking a dangerous step, and I would like to take a little space in this blog to talk about this issue that is not only in the USA, but also worldwide.

Some studies have identified a relationship between suicide and occupation, including Health Care and Veterinary profession.

The rate of suicide in the Veterinary profession has been pegged as close to twice that of the Dental profession, more than twice that of the Medical profession, and 4 times the rate in the general population.

The 2012 CVMA National Survey Results on the Wellness of Veterinarians found that 19% of respondents had seriously thought about suicide and 9% previously attempted suicide. Of those who had seriously thought about it, 49% felt they were still at risk to repeat. The risk is real. The numbers are compelling.

Suicidal talk is a major warning sign for suicidal risk and should always be taken seriously. The myth suggests that suicidal talk is just attention-seeking behavior, while in truth it is an invitation to help the person to live. If help isn’t forthcoming, especially after they’ve made themselves vulnerable by having disclosed sensitive thoughts and feelings, they may feel it will never come. Without appropriate response, suicidal talk — which begins with suicidal thoughts — can escalate to suicidal acts.

Anecdotally it may seem that pet ownership is protective, but research has not demonstrated an association between pet ownership and suicide. In fact, the loss of a beloved pet can be a risk factor for suicide.

Although folklore includes tales of suicide among animals, modern naturalistic studies of thousands of animal species in field situations have not identified suicide in nonhuman species. Death by suicide is strictly a human phenomenon.

The widely acknowledged risk factors for suicide in the general population include personality factors, depression (as well as other forms of mental illness), alcohol and drug abuse, inherited factors, and environmental factors (including chronic major difficulties and undesirable life events). Although the specific factors contributing to the increased rate of suicide in the veterinary profession have not yet been determined. The following factors may contribute to the increased risk of suicide in our profession: personality factors, undergraduate training, professional isolation, work-related stressors, attitudes to death and euthanasia, access to and knowledge of means, psychiatric conditions, stigma around mental illness, and suicide contagion.

Veterinarians tend to be high achievers, and high achievers have tendencies to perfectionism, conscientiousness, and neuroticism, all of which can be risk factors for mental illness. Similarly, veterinarians with a preference for working with animals rather than people, may have a higher risk of depression as a result of relative social isolation.

Many veterinarians in private practice work in relative isolation where there is often little supervision and access to assistance from veterinary colleagues, an environment ripe with the potential for professional mistakes. The considerable emotional impact of such mistakes may contribute to the development of suicidal thoughts.

Inadequate professional support and professional mistakes, along with other work-related stressors such as long working hours; after hours on-call duties; conflictual relationships with peers, managers, and clients; high client expectations; unexpected clinical outcomes; emotional exhaustion (compassion fatigue); lack of resources; limited personal finances; concerns about maintaining skills; and the possibility of client complaints and litigation can all contribute to anxiety and depression, which increase vulnerability. Long-term exhaustion (burnout), characterized by disillusionment and demoralization, may also increase vulnerability.

Veterinarians in private practice are commonly required to engage in the active ending of life, with strong beliefs in quality of life and humane euthanasia to alleviate suffering. Likewise, those in food production are required to end the lives of animals via the slaughter of livestock. Active participation in the ending of animal life may alter views on death and the sanctity of human life, and in the face of life’s challenges, enable self-justification and reduce inhibitions towards suicide, making suicide seem a rational solution.

Veterinarians have access to and knowledge of prescription medications (including drugs for anesthesia and euthanasia), increasing the potential for misuse. With ready access and knowledge, such substances could be used not only as a (maladaptive) means of coping, but also as a means to suicide, potentially being a key factor in the high rate of suicide in the profession 

Just as mental illnesses such as depression and substance misuse and dependence are associated with suicide in doctors, by extension, they may also be a factor in suicide by veterinarians. Two-thirds of people who die by suicide suffer from a depressive illness.

Now I would like to say something that perhaps could sound a little rare, specially for all of those who have known me for less than 5 years long. About 11 years ago I had attempted suicide, perhaps more than 4 times by then, from which I had been taken to the hospital for substances abuse, I was not a Veterinarian yet, although I know the feeling. About 8 years ago somebody talked to me about Christ, and before you begin to judge or say that this is a religious comment, maybe you should stop right there and open up your mind and read this.
I was going through the hardest times of my life, I knew what rejection was, I knew what the feeling of not being able to do things right was, but let me tell you something, Christ changed me completely.
I was never the same after I took Him in my life. I started the Veterinarian career, I finished it, and to be honest, even with all the pressure, Christ held me, comforted me, and loved me when nobody else did, if you are a Veterinarian, or just a person that likes animals and their care, this is also for you, Christ is more powerful than we could even imagine, movies are quite short, stories are nothing compared to what He really is. But you know what, the most important thing is that Christ loves you no matter what, and He will strength you and hold you as long as you let Him do so.

So for all my Veterinarian colleagues out there, hold on, and pray, just stop right there, Christ will change things completely, even when He's silent, He will turn things in your favor just because He can and because He loves you!
And think about your four paw patients, those who can't speak but surely are much more thankful than humans, think of how you can help the creations of God, and how humble and beautiful our profession surely is!
If you need any kind of help with depression, or have any suicidal thoughts, don't hesitate, contact me, or talk to someone you feel trust in, but please just stop right there, and talk about it, you are a very valuable person, unique, and definitely important!

Thank you for taking your valuable time to read this until the end.

MVZ Carolina Pruneda

References:
http://www.bostonglobe.com/lifestyle/2016/09/18/why-many-veterinarians-commit-suicide/iCCgr46bIJpgEeesPHTe2L/story.html?event=event25
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266064/
http://stevedalepetworld.com/depression-suicide-veterinary-medicine/
https://www.businessinsider.com.au/most-suicidal-occupations-2011-10#4-veterinarians-are-154-times-more-likely-to-commit-suicide-16
http://www.care2.com/causes/why-is-the-suicide-rate-for-veterinarians-so-high.html#15048451623692&action=expand_widget&id=0&data=
http://www.startribune.com/veterinarians-at-high-risk-for-suicide-and-the-job-could-play-a-role/392775791/

CHROMOSOMES IN OUR PETS!

Have you ever wonder how many chromosomes do cats and dogs have compared to humans?

To Understand this, we most remember what the DNA is.

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. 

DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. 

Each chromosome has a constriction point called the centromere, which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.” The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome.

Now moving on with the diferences between cat and dog's chromosome vs humans, first of all we find that the number is different.

Dogs have 39 pairs of chromosomes, for a total of 78. This works out to 76 autosomes and two sex chromosomes. As with other mammals, the karyotype of male dogs is XY whereas females' karyotype is XX

Although dogs have 39 pairs of chromosomes (compared to 23 pairs for humans), dogs have fewer genes overall. Researchers sequencing the canine genome have identified around 19,000 dog genes compared to the 25,000 or more genes in the human genome. Despite having 6,000 fewer genes than humans, dogs exhibit a diverse range of phenotypes, from animals as large as a Great Dane or St. Bernard to toy dogs weighing no more than a few pounds. Geneticists think the canine genome may be especially prone to gene duplications and chromosomal rearrangements compared to the genomes of humans and other mammals.

Most cats, including domestic breeds, have 19 pairs of chromosomes for a total of 38. Some types of cat in South America, however, have only 36 chromosomes, including ocelots, kotkots and margays. Dogs have more than double the number of chromosomes with 39 pairs.

Hopefully this information is somewhat useful, or at least fills in the curiosity of some of us.

MVZ Carolina Pruneda

FLEA CONTROL PRODUCTS AND THEIR MECHANISMS

Good day colleagues and friends, today we will talk about about some of the most important chemical products that we can use and prescribe for flea control and elimination.

1. Selamectine: this one contains Avermectins and derivatives (a group of macrocyclic lactones produced by soil bacterium Streptomyces avermitilisand derivatives). It can be topic applied, it hits all stages, especially larvae, and even eggs. Its efficiency is over 90%, residual protection for over 20 days. And the way it works is that it opens of chloride channels in muscle membranes of arthropods.

2. Fipronil (Front-Line): it contains phenylpyrazole insecticide. It can also be topic applied as a spot-on. It hits adult and off-host stages. This one it's very cool because it's efficiency is over 90%, residual protection for ~90 days. The way it works is by blocking (GABA)-gated chloride channels in central nervous system, paralyzing the fleas and ticks so eventually they will release the skin of the animal and fall and die.

3. Imidacloprid (Advantage): it's chemistry is pretty basic, it contains chloronicotinyl insecticide, and it is also topical. It also hits adult and off-host stages. It's efficiency goes by 90%, residual protection for ~20-40 days. It's mechanism it's a little more complex, because it competitive inhibits at nicotinic acetylcholine receptors of the nervous system, which may take a little while to work, but it does work!

4. Nitenpyram: this one it's similar to imidacloprid, it contains chloronicotinyl insecticide but this one goes by mouth, and it only affects the adult stages. However this is one within 8 hours, 100% of fleas are killed, remain active in the blood for 48 hours. It's mechanism is the sae as the Imidacloprid, but because it goes systemic it acts faster.

5. Pyrethroids: this one is similar to pyrethrins, natural compounds produced by the flowers ofChrysanthemum spp. It goes topical, it only hits adult stages. it is more than 90% effective  in number of cat fleas for 28 days. This one opens the sodium channels in the nervous system.

6. Pyriproxyfen: it goes topical, it hits larval and eggs stages, it has a significant reduction in flea numbers and almost 100% elimination over the period of six months. It releases juvenile-hormone analog (JHA), so the flea grows backwards and eventually can no longer live.

7. Lufenuron: it can be administered orally or by injections, it hits larval and eggs stages. We can observe a 90% decrease in number of adult fleas emerging from eggs for ~200 days after treatment. This one is an insect-growth regulator (IGR), which inhibits chitin synthesis.

8. Methoprene: because this one goes always as a flea collar, it's not very recommended, especially in kittens, because the kitten may bite it, chew it, or even worse eat it, so it may be toxic for them. It is somewhat effective because it hits larval and eggs stages and lasts for 4 to 6 months on a dog and up to a year on cats. 

9. Bravecto: it's main ingredient is Fluralaner, it goes topical, it affects all stages from egg to adult. It is over 95% effective and its effect last over 12 weeks. These compounds have activity against γ-aminobutyric acid- (GABA-) and glutamate-gated chloride channels with significant selectivity for insect neurons over mammalian neurons. This product is very effective, however, we as Veterinarians must be careful when prescribing it to cats, cats under the age of 6 months most not use this product due to high rates on neurological side effects.

Hopefully this post may be helpful and if you can also recommend any other your comments are welcomed!

MVZ Carolina Pruneda

The Cat Area 9 : Ctenocephalides felis

Good day colleagues and friends today we will talk about the most common ectoparasite in cats, yes we are talking about CTENOCEPHALIDES FELIS, a flea that gives all of us veterinarians headaches when we are at the consultation room, because they are stubborn and they jump not only to other patients but also to us veterinarians and owners.

Distribution

But before we get started, it is important to know where this ectoparasite is most common at.

 Cat fleas are commonly found on both cats and dogs in North America, while dog fleas are found in Europe. The two species are distinguished by a slight morphological difference which is detectable only under high magnification. Although it exists worldwide, the cat flea is most commonly found in the United States and Mexico, in and around homes with pets.

Life and Cycle

The Ctenocephalides Felis or cat fleas are small pests measuring about 2mm in length. They are dark brown or reddish in color, typically wingless, but capable of jumping long distances. Their laterally compressed bodies are covered with hair. They have very strong hind legs which enable them to jump from one host to another. In the adult stage, the Ctenocephalides Felis also have mouthparts that allow them to suck blood from their host.

Now let's review this flea's stages and life cycle. Under optimal conditions, a cat flea can complete its entire lifecycle in just two weeks. In adverse conditions, the lifecycle of the cat flea can take upwards of one year. Cat fleas like warm, humid environments, so if they make it into your nice, warm home they can be hard to banish.

Cat fleas have four distinct stages in their lifecycle: eggs, larvae, pupae, and adult.  This cycle usually lasts 30 to 75 days, yet may vary due to external factors, such as temperature and humidity.

Adults: Adults are stimulated to emerge by vibration or an increase in carbon dioxide. They are about one to three mm in size, reddish-brown to black in color, wingless, and are laterally compressed. They possess powerful hind legs which allow them running and jumping through hair, fur, and feathers. Adult cat fleas require fresh blood to produce eggs. This is the only stage in the cat flea life cycle when the fleas live on the pet. Adults live from 4 to 25 days.

Adults feed directly from capillaries. Female fleas can ingest an average of 13.6 µl of blood daily, about 15 times their body weight.

Eggs: Cat flea eggs are laid at the rate of up to one egg per hour, and 20 to 50 eggs per day, which hatch in 2 to 5 days. They are oval, smooth, and about 0.5 mm in size. Due to their dry, smooth surface, the eggs easily fall out of the animal's hair. Though otherwise visible, the white eggs are nearly impossible to see against surfaces such as carpet, bedding, and lawn. It is here where the eggs will remain until the larvae emerge.

Larvae: Within two days of oviposition, wormlike larvae hatch from the eggs. They range from 1.5 to 5 mm in length. This stage lasts 5- 15 days. Larvae lack eyes, legs, are covered with few hairs, and possess dark guts, visible through their thin translucent exoskeleton. Larvae feed on almost any organic debris in the floor covering, but their main dietary component is dried adult cat flea fecal matter.

*Adult flea feces, also known as "flea dirt", consist of relatively undigested blood which dries and falls from the pet to serve as food for the newly hatched larvae. The larvae prefer to develop in areas protected from rainfall, irrigation, and sunlight, where the relative humidity is at least 75 percent and the temperature is 70 to 90°F.

Pupae: Before becoming adults, the larvae spin silk cocoons in which they will develop. Because of the sticky outer surface of the cocoons, dirt and debris are attracted to them and provide camouflage. The pupae remain in the cocoons until they have fully developed into adult fleas.

Signs of cat fleas infestation, control and treatment.

Cat fleas love the warm, moist, safe haven that’s provided in a cat’s furry coat. Two of the main ways to tell if fleas are making a meal out of our cat patients is to take note of whether they are scratching or biting their skin and fur.

Fleas regurgitate digestive juices onto the skin of a bite site while they suck blood from their prey, and sometimes cats and dogs can have serious allergies to this juice. This allergy is called fleabite allergic dermatitis and can be developed over the course of a dog, cat, or human’s lifetime.

Cats that are allergic to flea bites (flea allergy dermatitis) will exhibit excessive grooming and scratching from just a single bite. It’s also characterized by intense itching, hair loss, reddening of the skin, and secondary infections. The reaction and itching can persist for up to five days.

On the Examination we ought to check the skin around the base of its tail or under the armpits for tiny, moving black dots. There's another way we can tell if our patient has fleas by using a flea comb to comb our patient  and look for flea “dirt” (the feces of fleas) which can alert us to an infestation even without seeing live fleas. The fleas will get caught at the base of the comb’s teeth.

We most advise the owner to monitor the patient for scratching and biting on a regular basis. 

If we find any we must advise the owners to treat the patient as much as the home, indoors and outdoors.

When we advise the owner to treat the home, we should make emphasis on how to do so, inside they must vacuum the floor and carpets (specially carpets), and on the yards we can use pesticides that are garden friendly,

Some of the products we can recommend our patient's owners are: 

To treat the outdoors, pyrethroids may be sprayed in dry shaded areas which the animal frequents, as well as insect growth regulators such as pyriproxyfen and fenoxycarb, which are the most effective outdoor treatments. Methoprene is also commonly used outdoors, but is not stable in sunlight. Since larvae prefer shaded, dry areas, spraying the entire yard is wasteful and irresponsible. For outdoor areas which are difficult to treat (under decks), pet access should be restricted. Outdoor treatment is primarily used in severe cases of flea infestation and may not be necessary if fleas are controlled on the pet and in the home.

 Advise the owners not to leave their pets on the outside at least 4 hrs after using pesticides outside.

Now Let's talk about the patients treatment. By own experience, and other colleagues won't let me lie on this, but fleas and ticks control collars are simply not good at all, for some cats it won't matter, but the majority of the feline patients show skin irritation on the neck, some develop allergies to the chemicals used in those collars, some cats have even been intoxicated because of the owners don't place the collar tight enough or because the cat it's just to restless that start biting and chewing on the collar. The safest ways to treat a cat for ctenocephalides felis will always be fipronil or imidacloprid topical treatments. 

When using a pesticide, always consult the label. Insect growth regulators (IGR) and insect development inhibitors (IDI), administered as a daily or monthly dose, will disrupt egg and larval development but not kill adult fleas. Methoprene and pyriproxyfen are active ingredients of IGRs  and are safe to use on our patients, but also easy on the owners pockets.

We also have other options, as many of us know we also can prescribe shampoos. Insecticidal shampoos contain certain pesticides such as pyrethrins, carbamates, and citrus peel derivatives. Pennyroyal oil, another natural products, are also available in shampoos. However, pulegone, the active ingredient in the oil has dose related toxicity to mammals and may induce lethargy, vomiting, diarrhea, nose bleeds, seizures and possibly death due to liver failure.

Now, it is also important to treat the patient's wounds done by the flea bites, because as we know, fleas can transmit bacteria that may result in an infection, therefore we ought to treat the skin of our patients also with antibiotics, our best option of course is Neosporin antibacterial ointment or by mouth. In case of severe FDA (flea dermatitis allergy), we can also prescribe corticosteroids, personally, I would definitely rather to leave those as a last resource, not only because it may be hard to discontinue them, but also because it could cause undesirable side effects if the condition it's chronic or becomes chronic.

Associated diseases

And just like ticks, fleas also can bring diseases to our patients along with them, some of those diseases are:

Flea allergy dermatitis (FAD) The cat flea is primarily responsible for flea allergy dermatitis (FAD) in both dogs and cats. FAD is a hyper sensitization to antigenic components contained in the saliva of fleas. Cats and dogs that have flea allergies will bite at the base of their tail and rump frequently. Animal become nervous and sleepless, sometimes, they vocalize (yelp or meow) sharply from a single flea bite. Even a few fleas can lead to prolonged itching that causes animal to groom extensively sometimes biting and scratching their skin, which can result in painful lesions.

Dog tapeworm Cat fleas are the primary intermediate host of Dipylidium caninum(cucumber tapeworm or the double-pore tapeworm), the common intestinal cestode of dogs and cats that also rarely occurs in children after accidental ingestion of infected flea. 

Murine typhus Cat fleas are able to transmit murine typhus, also called flea-borne typhus or endemic typhus, a rickettsial disease caused by the organism Rickettsia typhi, which usually is associated with rat fleas (Xenopsylla cheopis).

Flea-borne spotted fever Cat fleas are most common vectors of Rickettsia felis, relatively recently described pathogen, causative agent of flea-borne spotted fever (also called cat flea typhus). In 1994, the first human case of infection was reported in United States. Because the disease has similar clinical manifestation as murine typhus (including high fever, myalgia, and rash) and other febrile illnesses such as dengue, the infection in humans is likely underestimated.

Cat scratch disease (CSD) Cat fleas have recently been implicated in the transmission of Bartonella henselae, the etiologic agent of cat scratch disease (CSD). In immunocompetent humans this infectious disease usually is not serious and associated with papule or blister at the site of injury (scratch or bite) and malaise. Cat scratch disease is a common cause of chronic lymph node swelling (lymphadenopathy) in children. It has been suggested that Bartonella spp. may be responsible for numerous chronic inflammatory conditions of the cat. It was shown that as many as 58% of stray cats can be Bartonella spp. carriers and up to 90% of fleas are infected. The prevalence of the infection is much lower in pet cats (~3%).

Cat anemia Over 50% of cat fleas collected from stray cats were shown to be infected with Mycoplasma haemominutum or Mycoplasma haemofelis associated with infections in cats, which can range from subclinical and subtle anemia to severe hemolytic anemia.

Plague Cat flea was shown to be a competent vector for transmission of plague(causative agent Yersinia pestis). Although not as efficient as rat fleas (Xenopsylla cheopis) C. felis is the most common flea in human habitations in many African countries and threat posed by the ectoparasite cannot be dismissed. Plague transmission is carried out by infected fleas that become "blocked" - a clot of microorganisms hinders flea's feeding forcing the flea to regurgitate overwhelming doses of the pathogen into the host and to seek the next available host.

We hope you like this post and most important that you find it useful. On our next post we will talk about the products that we can use for flea management and their mechanisms.

Cheers and happy holidays!

MVZ Carolina Pruneda