General Considerations
A preventive health plan should include regularly scheduled exams of an apparently healthy dog to maintain optimum health. The AAHA (American Animal Hospital Association) and the AVMA (American Veterinary Medical Association) gathered medical information from various specialty groups (American Heartworm Society, American Association of Feline Practitioners, Companion Animal Parasite Council to name a few) to standardize wellness plans.
The revised guidelines focused on preventive health care for cats and dogs reference includes history, physical examination, testing appropriate for age and findings, parasites (heartworm and intestinal), blood and urine (when indicated), dental care, immunizations, parasite and flea/tick prevention, weight maintenance, consideration of spaying/neutering.
Infectious disease and parasite and flea/tick prevention are a major focus for owners. Decision making involves knowing:
- How a carrier of a parasite, flea, or tick becomes infected place with a transmissible disease(s);what is the reservoir of the disease organism?
- How the carrier gets onto or into the dog
- How the disease(s) is (are) transmitted
- What diseases are present in the carrier’s geographic range
- The dog’s location and opportunities for exposure to the carrier
- Options for preventing the vector from getting to the dog. In some locations, preventives are recommended year-round
- Disease severity and treatment
Some may opt for natural or over the counter preventives rather than prescribed ones, depending on belief systems or preferences to minimize exposure to chemicals. Whatever choice is made, if your dog becomes ill and you see a veterinarian, be sure to tell them your method of preventive care. Dr. Douglas H Thamm notes in a short vetvine youtube that there is no evidence that vaccination, flea or tick preventives, or heartworm preventives have been associated with development of cancer.
More
Vaccination
Vaccination. All infectious disease organisms (viruses, bacteria, protozoa, fungi, etc.) have components called antigens, and each organism has unique antigens. These antigens will cause the body to respond by producing antibodies which are responsible for defeating the organism and removing it from the body. Immunity has memory, so that future exposure to the same antigen results in a much more rapid response.
A vaccine is a preparation of either killed or altered microorganisms that is administered into the body. The vaccine stimulates the immune system to learn how to fight a microorganism (i.e., have memory of) so that if the microorganism is encountered in the future, the individual will either not get sick or will have less severe illness.
In a modified-live or live-attenuated vaccine, the causative organism (virus, bacterium, etc.) has been weakened or altered so that it is no longer harmful or virulent but is still capable of stimulating protective immunity when injected or otherwise administered. With a killed vaccine, the causative organism has been killed or inactivated to render it harmless. Killed vaccines often need a helper or adjuvant included in the vaccine to stimulate a long-lasting immune response.
Some vaccines are given locally, for example into the nose (e.g, kennel cough), but most require injection so that maximum stimulation of the immune system is achieved. Some vaccines are injected subcutaneously or just under the skin, others are injected into the muscles or intramuscularly.
Newborn animals have not yet had a chance to make their own immunity so they need protection against infections present in their environment. They receive this immunity from their mother, as maternal antibodies. Part of this passive immunity is transferred across the placenta while the pup is still in the uterus, but most of it is transferred in the first milk or colostrum. This maternal immunity is only temporary. It declines steadily over the first few weeks of life and is largely gone by twelve weeks. The rate of decline is variable, depending on a number of factors. One reason for the series of initial vaccinations (rather than a single injection) is that it isn’t possible without antibody testing of a pup, to know when the maternal antibody level has dwindled to non-protective a level.
Core vaccines for all puppies and dogs include: distemper virus, parvovirus (+/- parainfluenza), adenovirus-2 (hepatitis), and rabies virus. Schedule for core vaccines is:
- Rabies: as required by law
- Others:
- Initial: < 16 wk, at least 3 doses of a combo vaccine between 6 and 16 wks and 2-4 wk apart; or > 16 wk, 2 doses of a combo vaccine 2-4 wk apart
- Revaccination: single dose of combo vaccine within 1 yr of the last initial series; thereafter every 3 years
Non-core vaccines are recommended for some dogs based on lifestyle, geographic location, and risk of exposure. These include leptospirosis, canine Lyme disease, Bordetella bronchiseptica & canine parainfluenza virus (intranasal) or Bordetella bronchiseptica only, canine influenza, Western diamondback rattlesnake toxoid (immunity is developed to the toxin).
It is important to discuss your puppy breeder’s suggestions with your veterinarian; they are the ones who know if there is history of adverse reactions to immunization in the puppy’s family that should be taken into account.
If for some reason an owner chooses to not vaccinate their puppy or maintain vaccination in an adult dog, there is risk of acquiring one of the preventable diseases and having mild-severe disease or even death, and to spreading the infection if they are amongst other dogs (e.g., dog shows, veterinarian’s office, dog parks) or if they bite an animal or person (specifically – rabies). Be aware that if a dog bites a person, the owner is legally liable when the dog is not up to date with rabies vaccination as required by law.
Routine “titer testing” to decide if it is necessary to revaccinate at currently recommended intervals can be done. The AAHA guidelines say this is not usually advised, except in cases in which dogs have a history of adverse responses to vaccination, there is a suspicion of vaccine-related autoimmune disease, or when owners express resistance or hesitancy to having their dogs vaccinated or boostered—in which case client communication and education may help overcome this hesitancy.
NEW. The Rabies Challenge Fund Charitable Trust supported a long term study to determine duration of immunity. Goals were to: 1) determine if one rabies vaccination is enough to protect a dog for many years, possibly even for life. That wasn’t proven, 2) Conduct studies that would meet USDA standards for vaccine licensing (i.e., the challenge was injection of the live rabies virus). The trial showed that fully vaccinated dogs who’ve had their first two initial rabies vaccinations should have solid protection for far longer than 3 years. Some rabies vaccines provided protection seven years out from the single dose given at 6 months, the point at which the study ended. Not all the vaccines were tested that far out; the one that worked for 7 years was BI’s IMRAB-3TF (Dodds, JA, et. al. Duration of immunity after rabies vaccination:
the Rabies Challenge Fund Research Study. Can J Vet Res. The updated veterinarian guidelines from the 2016 Compendium of Animal Rabies Prevention and Control say that if a dog exposed to rabies is overdue for his rabies vaccination, he can have a booster shot, followed by an observation period at home, instead of being euthanized or quarantined.
More
Heartworm
The entire section has been updated. Heartworm. The Heartworm Society of America is a source of information about the different stages of heartworm infection and recommendations for prevention. The latest update was in 2020; heartworm resource center has information searchable by topic, audience (e.g., pet owner, shelter), animal species, and language. The life cycle of parasite (Dirofilaria immitis) dictates when heartworm testing is done after a heartworm preventive was started. Heartworm disease has the greatest morbidity and mortality of any vector-borne disease affecting dogs in the United States, and despite the excellent products available to prevent heartworm disease in dogs, the range and number of cases grows annually. The following is taken from the Heartworm Society website. See the site for details about treatment of heartworm infection. Key Epidemiology Points:- Heartworm infection has been diagnosed in all 50 US states and around the globe
- Factors contributing to spread of the parasite: environmental & climatic change, relocation of microfilaremic dogs, expanded territory of microfilaremic wild canids
- Climate of adequate temperature & humidity to support a viable mosquito population and enough heat to allow the mosquito ingested microfilariae to develop into infective, third-stage larvae (L3) in the mosquito before transmission to host.
- Length of the heartworm transmission season depends on microclimates (e.g., urban heat), habitats and adaptation of the mosquito vector, variations in larval development, temperature fluctuations, and life span of mosquitoes.
- Risk of heartworm transmission never reaches zero because of microenvironments in winter months.
- Once a reservoir of microfilaremic domestic and wild canids exists beyond veterinary care, the presence of one or more competent host mosquitoes makes transmission possible and eradicaton improbable.
- Essential: reservoir of infection (host), transmitting vector, and susceptible host.
- Vector is infected by a blood mean from host. Microfilariae mature through larval stages 1-3 in host. L3 larvae are infective in the susceptible host and molt into stage 4 larvae. Those molt into juvenile/immature adults (d 50-70) while migrating through the body to reach small pulmonary arteries
- Sexual maturity is about d 120 after infection; dog develops circulating microfilariae average of 7-9 mos after infection.
- Macrocyclic lactone class of drugs (ivermectin, milbemycin oxime, moxidectin, selamectin). When given according to label these are highly effective. Dogs should be heartworm negative (meaning no immature worms) using preventives
- Oral – ivermectin, milbemycin oxime; monthly
- Topical – moxidectin, selamectin; monthly
- Parenteral (subcutaneous) – slow release formulation of moxidectin; every 6 months
- A dog can become infected because of a skipped or delayed just one dose, especially in highly endemic areas
- There are resistant heartworm subpopulations, especially in the SE US
- Recommended year-round to prevent infection and enhance compliance. If given seasonal, begin at least 1 mo prior to start of season and continue for up to 6 mos after – depending on product used.
- Control of mosquitos; reduce outdoor exposure during key mosquito feeding periods
- Remember that it is possible for an animal to become infected because of skipped or delayed administration of a single preventive dose.
- Ivermectin: Heartgard, Heartgard+, Iverhart +, Iverhat MAX, Tri-Heart Plus. A monthly oral.
- Milbemycin oxime: Interceptor® (only milbemycin); Sentinel®, Sentinel Spectrum®, Trifexis®
- Milbemycin prevents heartworm disease, treats hookworms, roundworms
- Combined with lufenuron or spinosad – flea prevention is added
- Use of higher doses than recommended can cause side effects in dogs with MDR1 gene mutation.
- Monthly oral
- Moxidectin: Advantage Multi®, Advocate®, ProHeart®. Prevent heartworms and treat intestinal parasites (hookworms, roundworms, whipworms); combined with imidacloprid treats fleas. Monthly oral. A slow release injectable also made.
- Selamectin: Revolution®, Paradyne®, Stronghold®, Chanhold®. In dogs, these treat fleas, ear mites, scabies, and certain ticks; prevent heartworm. A monthly topical.
More
Fleas and Ticks
- Fleas, Linda Aronson, DVM
- Preventive Products. Some treat both fleas and ticks, some just one pest.
- Topical flea: Activyl®, Advantage® II, Cheristin®
- Oral flea: Capstar®, Sentinel® (growth regulator only)
- Topical combination products: Frontline®, K9 Advantixx® II (dogs only), Revolution®, Vectra 3D® (dogs only), Effipro® Plus, Effitix® (dogs only)
- Oral combination products (dogs only): NexGard®, Trifexis®, Simparica™
- The FDA has warned of the potential of neurological side-effects from the isoxazoline flea and tick products – Simparica Trio, Nexgard, Credelio, Bravecto
- Ticks and tick associated diseases, Linda Aronson, DVM
- Tick associated diseases, Linda Aronson, DVM
- NEW. Ticks, VCA Hospitals. Has color photographs of different types of ticks relevant to dogs.
Internal Parasites
Internal Parasites. Adult dogs infrequently have serious problems with intestinal worm parasites unless they have a weakened immune system. Young puppies can be more seriously affected. Disease is avoided by intermediate host management: preventive treatment in the case of sheep, control measures in the case of fleas, good sanitation in the case of whipworm (handwashing for humans or avoiding contaminated soil eating for dogs). Intestinal non-worm parasites include Coccidia, Giardia, and Spirochetes (Leptospira and Lyme disease). These invasive parasites live in a dog’s intestinal tract; what makes them particularly dangerous is that a dog can be infected with these yet appear well. It may not be clear that the dog is carrying the parasites until stress or another immune-compromising factor arises. Information on leptospirosis and Lyme disease are found in the general health infectious disease section.
Intestinal worm parasites are listed below.
| Parasite | Organism | Host | Clinical Features |
|---|---|---|---|
| Roundworm | Toxacara canis, catii | Cat, dog, fox | Poor growth, development. Eggs in feces can infect human |
| Whipworm | Trichuris vulpis | Soil transmitted | Live in large intestine. Chronic watery and/or bloody diarrhea. Wt. loss |
| Hookworm | Ancylostoma sp | Whatever animal infected with hookworm | Attach to small intestine lining, suck blood, can cause severe anemia |
| Tapeworm | Diplydium caninum | Fleas | Most common in puppies; cause stunted growth, digestive upset |
| Taenia sp | Rodents, rabbits | Very old, very young, immunocompromised can be very ill. Poor growth, intestinal blockage, poor condition | |
| Echinococcus | Sheep, humans | Cysts can develop in lung or brain. More common in dogs with proximity to sheep. |
