Your Beardie’s Battle Against Disease, part 2
Written by: Maryann Szalka
Intruder alert! Intruder alert! Some causative agent has gained entry to Beardieville, what now? No need to panic, your Beardie has other “weapons” in his or her arsenal in the battle against disease. Phagocytosis is the primary defense against disease. Shortly after the pathogens invade host cells, the inflammation process occurs. This is characterized by reddening of the affected area because of capillary dilation; swelling from the leakage of plasma through the capillary walls, which increases the fluid content of the tissue; heat/fever, which aid the destruction of some pathogens by increasing the action of white blood cells; and pain, indicating to the body that a problem is present. Phagocytes are cells that engulf and destroy microbes, other cells and foreign particles. The two primary ones are white blood cells called neutrophils and monocytes. During inflammation, the phagocytes leave the blood system and enter the tissues to destroy the pathogens. This is why your Beardie may have an elevated white blood cell count during a disease process.. If this process fails to destroy the pathogens possibly due to the the number and/or the character of the invading organism, the body must depend on its own immunity. Keep in mind there are many diseases for which one cannot be immune. Immunity results from the presence of an antibody that attacks a specific microorganism (disease agent). Immunity is divided into two categories according to how the body acquires it.
- Active immunity, in which the body of the user produces the antibodies. Active immunity can be acquired naturally or artificially. To have naturally acquired active immunity, the dog must have an infection (with or without symptoms) for which the body produces antibodies. To have artificially acquired active immunity, the dog must be vaccinated with live, weakened or dead pathogens, which stimulate antibody production usually without causing observable signs of disease.
- Passive immunity, is what happens when the acquired antibodies are not produced within the body that uses them, but are produced within another body. Passive immunity can be naturally or artificially acquired also. Naturally acquired passive immunity results from the transfer of antibodies across the placenta from the immune mother to the puppies, or via the mother’s colostrum when she nurses the puppies. Artificially acquired passive immunity occurs as the result of a blood tranfusion, or tube feeding newborn puppies with hyperimmune plasma.
The immune systems is a complex of organs, highly specialized cells and a circulatory system separate from blood vessels; all of which work together to clear infection from the body. The lymph system consists of lymph nodes, including the specialized lymphatic organs the spleen and thymus gland, connected by a series of lymphatic vessels that move lymph, a fluid extracted from the cells and rich in white cells, called lymphocytes, water and protein as well as cellular debris around the body. Lymph ultimately drains into the right side of the heart and enters the blood stream. Once in the bloodstream, lymphocytes are transported to tissues throughout the body, where they act as sentries to disable foreign antigens. The two major classes of lymphocytes are B cells produced in the bone marrow and T cells produced in the thymus organ in the neck. B cells produce pathogen specific antibodies that circulate in the blood and lymph systems and attach to foreign antigens to mark them for destruction by other immune cells. Once the B cells have produced antibodies these antibodies continue to exist in your Beardie’s body (memory). That means if the same antigen is presented to the immune system again, the antibodies are already there to do their job. The antibodies that B cells produce are basic templates with a special region that is highly specific to target a given antigen. Different antibodies are destined for different purposes. Some attach to the foreign invaders to make them attractive to the phagocytes (circulating scavenger cells), that will engulf the unwelcome intruder. T lymphocytewhich also patrol the blood and lymph, have two functions – first they assist the B cells in producing antibodies, and secondly they recognize and eliminate cells that seem foreign to the body. T cells are also responsible for eliminating otherwise normal cells that have been infected with a virus. As well as neutralizing toxins, antibodies can activate a group of proteins that assist in killing bacteria, viruses, or infected cells.
This may be a good place to discuss artificially acquired active immunity, or vaccination. It is certain that vaccines have saved a lot of lives. Before vaccination distemper wiped out thousands of puppies each year, for example. Only now that many of the diseases have been brought under control by vaccination can we begin to explore their possible downside. There are some dogs that cannot tolerate vaccines, and react violently to vaccination and sometimes die. While such reaction is uncommon, it is well to remember the power vaccination has for good and bad within the body, and not view vaccines as totally benign and innocuous. Often vaccines are multivalent, up to 8 different diseases may be “covered” by a single vaccine. Obviously this is far from natural. Dogs are unlikely to encounter 8 virulent diseases simultaneously, and it has been shown that such multivalent vaccines may overwhelm the immune system and are more likely to cause a problem than vaccinating against a single disease. Even in healthy dogs vaccination suppresses thyroid function as well as the function of the immune system for about 3 weeks. During that time, the dog is much more susceptible to other infections within the environment. Sick dogs should never be vaccinated as their resources are already under attack. Likewise, exposure to disease should be limited as well as other stresses to the immune system – travel, elective surgery, in this period. Finally, more is not better with vaccines. For vaccines against the big three core diseases – those it is recommended all dogs receive, distemper, parvovirus and adenovirus-2 – it has been shown that once the body has responded to the vaccine, the dog will have immunity to that disease for life. When vaccinating past 6 months of age a single vaccine will be good for life. The reason a series of puppy shots is given is because immunity acquired from the mother lasts for a variable time, and interferes with a vaccine acquired immunity. The pup’s body will only respond to the vaccine once maternal immunity has dispersed, which can happen anywhere between 8 weeks and 6 months. It is likely that this is also true of rabies, but for now we are waiting the results of a study to prove this. Vaccines are not the enemy, but they must be used carefully and in moderation. Do not vaccinate a sick, old, or stressed Beardie. You may want to postpone vaccinating dogs that have recently been to shows or trials, as you may assume that they may have been exposed to some pathogens, but are not showing signs of disease. (Remember if the immune system functions properly only in rare situations – when it is overwhelmed – does infection result in disease.) Raging hormones are also a stressor, so you want to wait before vaccinating your hormonally challenged Beardie. Senior Beardies have senior immune systems and you should exercise caution when introducing vaccines to them as well. Non core vaccines do not produce lifelong memory, and have a variable duration of protection that varies significantly from dog to dog. Often this can be less than 6 months, so assuming the dog is covered because it has been vaccinated is unwise and may delay diagnosis. Titering for core diseases need not be repeated. You can do it once 3 to 4 weeks after the final puppy shot to make sure the dog did indeed respond to the vaccine. After that you can assume he will mount a suitable response for the rest of his life if he encounters that disease.
Sometimes the pathogen is too strong for the body to overcome, and this is the time you need to seek medical attention. Your veterinarian is armed with tools to help diagnose (blood/urine tests, cultures, x-rays, biopsies, ultrasounds, electrocardiograms, CT scans, MRIs) and treat (medication and surgery) your Beardie. Let’s say you notice your Beardie has a red and painful ear canal. Certain bacteria produce chemicals that damage or disable parts of the body. In an ear infection, for example, pathogenic bacteria have become established in the depths of the ear canal. Your Beardie’s body is working to fight the bacteria, but the immune system’s natural processes produce inflammation. Inflammation in the ear is painful. So your veterinarian will prescribe an antibiotic to kill the bacteria and eliminate the inflammation. Not all antibiotics work in the same way. Some will kill bacteria; these are known as bacteriocidal antibiotics. Others just prevent the bacteria from reproducing, these are known as bacteriostatic. Different classes of antibiotics have different action on bacteria.
- Some will interfere with the making of the bacterial cell wall. All bacteria have a cell wall that protects them from the outside environment and helps contain the cell contents. Whent the bacteria multiplies it divides into two, if the cell wall is damaged the bacterial cell will burst.
- Some antibiotics stop bacteria from making important chemicals they need to survive.
- Others interfere with the genetic material in a bacterial cell and cause it to stop the cell from dividing and multiplying.
Just as antibiotics act in different ways, they also act on different bacteria. Some will selectively act on a few, specific bacteria, these are known as narrow spectrum antibiotics. Others will target a wider range of bacteria and these are known as broad spectrum antibiotics. If your Beardie has a bacterial infection, it is important to know which bacteria are causing it, so that the appropriate antibiotic is used. This is done by obtaining a specimen and performing a culture (growing the bacteria) to determine the type of bacteria causing the infection. A sensitivity test will show which antibiotics – at least outside the animal, can kill or inactivate the bacteria. Before prescribing antibiotics it is essential that your veterinarian determines that the cause of the ear infection is indeed bacterial and not fungal – for which antifungal drugs would be required, fungus – such as yeast, may colonize an ear that has been cleared out by antibiotics, so finding the cause of the ear infection is especially important in cases of recurrent infection. It’s also important that the antibiotics get to the bacteria, so ear drops may work better than those taken by mouth, especially if the infection hasn’t crossed the eardrum and entered the middle ear. Antibiotics do not work on viruses because viruses are not alive. A bacterium is a living, reproducing life form. A virus is just a piece of DNA (or RNA). A virus injects its DNA into a living cell and has that cell reproduce more of the viral DNA. With a virus there is nothing to “kill,” so antibiotics don’t work on it. (The word antibiotic comes from Latin; anti meaning against, and bio meaning life.) A final word on antibiotics, although it applies to other medicines too. Increasingly we are finding bacteria that are resistant to antibiotics. We have grown to rely on this class of drugs since Fleming first discovered penicillin. It is unimaginable to many of us that less than a hundred years ago people died regularly from diseases that this class of drug easily cures. We may be faced with this situation again, resistance tends to piggy-back, and a bacterium that resists one antibiotic may also prove resistant to several other classes. As we or our animals improve we tend to stop the drug, but in fact some bacteria may still be alive and stopping the drug prematurely fosters survival or the very bacteria which the antibiotic has most trouble killing. We foster the generation of these resistant Superbugs. Choosing the right antibiotic and using it per your veterinarians directions, rather than randomly giving a drug while your Beardie acts sick is our best course of action if we want to continue to be able to fight bacterial infection effectively.
In addition, there is an ever growing list of medications your veterinarian can use to treat other conditions caused by allergies, internal and external parasites, and fungi. Some conditions may require more invasive treatment such as surgery. Modern medicine has developed to such an extent that a disease can be treated successfully in many cases.
As you now know, there are many weapons to help your Beardie fight disease. But the most important is prevention! Here are three things you can do to help prevent disease.
- Provide a safe environment (inside and outside).A little prevention may be just enough to avoid a pet tragedy from happening in your home or yard.
- Make sure your Beardie gets a regular medical exam. “A regular physical is the most overlooked pet health need today,” says Dr. Bill Swartz, an AAHA veterinarian. “Most people only take their pet to a veterinarian when a health problem already exists or for routine vaccinations. Preventive vaccinations and early detection of diseases are the keys to successfully treating your pet,” he added. Your veterinarian can conduct a comprehensive exam that includes appropriate lab analyses, heart organ system check, and dental exam.
- Design a diet and exercise plan to meet your dog’s specific needs. Obesity leads to serious health problems. The right kind of food and activity can add to the quality of your Beardie’s life.
Learn as much as you can about your Beardie’s health and become a champion for one of the many Bearded Collie health organizations. Knowledge is power.