Veterinary Nursing: Immunity, Vaccination, Microchipping and Neutering

  • Non-Specific Defenses: These defenses offer broad protection against pathogens. They include physical barriers such as skin, mucous membranes, and chemical barriers like enzymes in tears and saliva. Processes like phagocytosis, inflammation, and fever also contribute to non-specific defense by creating a hostile environment for pathogens.

  • Specific Defenses: These defenses are tailored to target specific pathogens. They involve T cells and B cells, which recognize and respond to specific antigens. This system creates immunological memory, allowing for a quicker, more effective response upon subsequent exposure to the same pathogen.

  • Antigen Recognition: The immune system distinguishes 'self' from 'non-self' by identifying antigens on cells. Antigens are molecules, usually proteins or polysaccharides, found on the surface of cells. Immune cells that mistakenly attack 'self' cells are eliminated through apoptosis (programmed cell death) to prevent autoimmune reactions.

  • Phagocytes: As the first line of defense, phagocytes ingest and destroy pathogens using phagocytosis. The pathogen is engulfed, forming a phagosome, which then merges with lysosomes. Lysosomes contain enzymes that break down the pathogen via hydrolysis. Different types of phagocytes include neutrophils, macrophages, and dendritic cells, each playing a specific role in the immune response.

  • T Cells: T cells are specific immune cells that mature in the thymus gland. They recognize infected cells by detecting antigens displayed on their surface via major histocompatibility complex (MHC) molecules. There are several types of T cells, including T helper cells, cytotoxic T cells, and regulatory T cells, each with distinct functions.

    • T helper cells (CD4+ T cells) bind to these antigens, triggering rapid division (mitosis) into memory cells. These cells stimulate phagocytes, B cells, and cytotoxic T cells by releasing cytokines.

  • Cytotoxic T Cells (CD8+ T cells) identify and kill infected or abnormal body cells by producing Perfornin, which creates holes in the cell membrane, and granzymes, which induce apoptosis.

  • B Cells: B cells produce specific antibodies that correspond to specific antigens. When an antibody attaches to an antigen, the pathogen is internalized via endocytosis, and the antigen is presented on the B cell surface in complex with MHC class II molecules. This complex activates T helper cells, which stimulate B cells to proliferate and differentiate into plasma cells and memory B cells.

  • Clonal Selection: T helper cells stimulate B cell division via mitosis. Plasma cells, which are short-lived antibody-secreting cells, can release up to 2,000 antibodies per second. Memory cells circulate in the body and, upon re-encountering the same pathogen, rapidly differentiate into plasma and memory cells, providing a faster and more robust secondary immune response. This process is crucial for long-term immunity.

Vaccinations

  • Vaccine Development Phases: The development of vaccines involves several critical phases to ensure safety and efficacy.

    • Preclinical Phase: Focuses on antigen selection to elicit the best immune response. This involves extensive in vitro and in vivo research to identify the most promising antigen candidates and optimize vaccine formulations.

    • Animal Testing: The selected vaccine is tested on animals to assess its safety profile and evaluate the immune response it generates. This phase helps identify potential adverse effects and refine dosage.

    • Phase One: A small group of healthy adult volunteers receives the vaccine to check for adverse effects and determine the appropriate dosage. This phase primarily focuses on safety.

    • Phase Two: A larger population, including both control and variable groups, is tested to evaluate the vaccine's efficacy, identify potential side effects, and further assess safety.

    • Phase Three: Large-scale, randomized, controlled trials are conducted across multiple countries. These trials are often 'blinded' to minimize bias and provide a comprehensive assessment of the vaccine's efficacy and safety in diverse populations.

    • Efficacy and Peer Review: The results of clinical trials are rigorously reviewed by organizations such as the WHO and governmental health departments. The vaccine is licensed based on a thorough evaluation of its benefits versus risks.

  • Successful Vaccine Program Requirements: A successful vaccine program must be economically viable, easy to store and transport, have minimal side effects, and be accessible to the majority of patients. Additionally, it should be culturally acceptable and ethically sound.

  • Herd Immunity: Herd immunity is achieved when a sufficiently high proportion of the population is vaccinated, thereby protecting those who cannot be vaccinated due to medical reasons, age, or weakened immune systems. The threshold for herd immunity varies depending on the disease's transmission rate.

  • Problems with Vaccinating: Various factors can hinder vaccination efforts, including misconceptions, misinformation, disease mutations, pathogens evading the immune system, and defective immune systems. Addressing these challenges requires effective communication strategies, continuous monitoring of pathogen evolution, and research into novel vaccine technologies.

  • Ethical Concerns: Ethical considerations in vaccination include informed consent, addressing moral stances of owners, and managing the risk of zoonotic disease transmission. Respecting individual autonomy and promoting public health are key ethical principles in vaccination programs.

Common Vaccines

  • Dogs: Common vaccines for dogs include those against Parvo, Distemper, Hepatitis, L2, L4, Kennel Cough, and Rabies. These vaccines protect against highly contagious and potentially fatal diseases.

  • Cats: Common vaccines for cats include those against Feline leukemia virus (FeLV), Rabies, Cat flu (calici virus), Feline herpes virus/Rhinotracheitis, and Feline infectious enteritis/panleucopenia. These vaccines are essential for maintaining the health and well-being of cats.

Vaccine Protocols - Dogs

  • 6 Weeks: Parvo-virus only

  • 8 Weeks: Distemper, hepatitis and Parvo-virus as well as Leptospirosis

  • 10 Weeks: Distemper, Hepatitis and Parvo-virus (if over 10 weeks only need one dose) Kennel cough vaccine*

  • 12 Weeks: Leptospirosis top up, Rabies

  • 15 Months (1st year booster): DHP + Lepto + KC (after 1st year booster DHP is every 3 years)

  • 27 Months (2nd year booster): Lepto + KC

Vaccine Protocols - Cats

  • 9 Weeks: FeLv, cat flu, panleucopenia and herpes

  • 12 Weeks: Rabies (not standard protocol in the UK).

  • 11- 13 Weeks: FeLv, cat flu, panleucopenia and herpes

  • 14 Months: FeLv, cat flu, panleucopenia (liscenced for every 3 years), herpes

  • 26 Months: FeLv, cat flu, herpes

Microchipping

  • Legislation: Microchipping has become a legal requirement in many regions to improve pet identification and traceability.

    • Dogs: Since April 2016, all dogs must be microchipped by law in certain regions. Puppies must be microchipped before leaving the breeder, and owners are responsible for keeping their contact details up to date. Non-compliance can result in fines up to £500.

    • Cats: As of June 10, 2024, microchipping is a legal requirement for cats in England. Cats must be microchipped before 20 weeks old, with contact details stored and updated on a database. This legislation aims to ensure cats can be easily reunited with their owners if lost or stolen.

  • Risks: While microchipping is generally safe, potential risks include injury if the procedure is performed improperly, deactivation of the microchip, and the possibility of database information leaks. However, these risks are relatively low compared to the benefits.

  • Benefits: The benefits of microchipping include improved traceability, increased owner accountability, a one-off injection, and a higher likelihood of reuniting lost pets with their owners. Microchips provide a permanent form of identification that cannot be easily removed or altered.

  • Animals That Can Be Chipped: Microchipping is suitable for a wide range of animals, including dogs, cats, horses, rabbits, guinea pigs, and birds.

  • Chip Types: Two main types of microchips are available: mini and standard. Mini chips are recommended for small animals and cats due to their smaller size and ease of implantation.

  • Microchip Standards: To ensure international compatibility, microchips should adhere to ISO standards (10 digits long, readable internationally - codes 11784 and 11785).

Neutering

  • Neutering Timing Guidelines: The optimal timing for neutering varies depending on the species and individual animal.

    • Male dogs: 6 months +

    • Female dogs: Pre-first season or 3 months after the first season

    • Male cats: 4 months +

    • Female cats: 4 months +

    • Male rabbits/guinea pigs: 4 months +

    • Female rabbits: 4 months +

    • Female guinea pigs: Often not neutered due to high risks.

  • Pros: Neutering offers several health and behavioral benefits, including the prevention of mammary tumors and pyometra in females, prevention of testicular/prostatic disease in males, and reduction in sexually dimorphic behavior in male dogs.

  • Cons: There is an association with the development of joint disease, and recent studies suggest that the health benefits may be less marked than previously believed. Additionally, neutering can have metabolic effects, leading to weight gain in some animals.