Sep. 23rd, 2008

spiceofbroadway: (Bella - All About Pets)
It's going to be a bit of a challenge to write up my notes--the seminar tended to jump from topic to topic, especially when people were asking a lot of questions--but I'll give it my best shot.

According to Dr. Dodds, yearly vaccinations were originally recommended for dogs and cats not because there was evidence that they needed them that often, but because it was a mechanism to get pets into the vet's office for an annual check-up. When you compare the number of vaccinations that a dog typically gets in its relatively short lifetime to the number of vaccinations that a person gets in their much longer lifetime--well, it's a bit ridiculous, really. The core vaccinations for dogs (the ones every dog should have) are distemper, adenovirus 2, parvovirus, and rabies. The core vaccinations for cats are feline parvovirus, herpes virus, calicvirus, and rabies. As I mentioned in my last post, I'm not sure what adenovirus is, never mind the what the difference is between adenovirus 1 and 2. I know that Lucy was vaccinated for feline leukemia when she went from being an indoor to an outdoor cat, but I don't know why that's not one of the core vaccinations.

For dogs, parvovirus is the most serious and common disease right now. There have been a number of parvo outbreaks in the U.S. in recent years. There's not much distemper around in the pet population anymore, because of vaccination programs, but it still exists in wildlife and feral dogs and can enter the pet population through contact with those animals. As I mentioned yesterday, there's very little rabies in Ontario. There's no difference between the one-year and three-year rabies vaccine except for the label on the bottle, so dogs don't need to be vaccinated for rabies annually. The goal of Dr. Dodds' rabies challenge study is to evaulate the duration of rabies immunity conferred by the vaccine. She thinks it lasts for seven years or more, perhaps even the lifetime of the dog. When vaccinating your dog for rabies, ask for a vaccine that doesn't have mercury or thimerosal in it (Imrab makes this kind of vaccine).

Another serious illness that dogs can contract is canine influenza, and there is no vaccine for it. Its symptoms look a lot like kennel cough, which isn't life threatening. The difference is that canine influenza comes with a fever, while kennel cough doesn't. If your dog starts to cough and is running a fever, it should be taken to the vet and started on a course of antibiotics immediately as the risk of pneumonia is very high.

The optimal age for vaccinating is 12+ weeks for puppies and 10 weeks for kittens. The earliest safe age to vaccinate puppies and kittens is six weeks, but Dr. Dodds said that vaccinations really shouldn't be given before eight weeks. The age at which vaccinations are effective depends on when the maternal antibodies wear off--if maternal antibodies are still present when a puppy is vaccinated, the antibodies will neutralize the vaccine. This is why puppies get a series of vaccinations: because it's difficult to predict when the maternal antibodies will wear off, and there may be differences between individual dogs and between breeds. Dr. Dodds prefers single vaccinations to combinations, and she recommends giving them 3-4 weeks apart. Again, the most important one is parvo, so it should be given first. Females shouldn't be vaccinated just before becoming pregnant in order to increase antibodies in the pups, because their hormones are out of whack when they're in season, and this raises the risk of adverse reactions. Dogs shouldn't be vaccinated at all after 10 years of age.

It's considered safe to take puppies out into the world three days after their second vaccination. The problem, of course, is how to socialize a puppy while not exposing it to life-threatening viruses when it's still vulnerable, particularly if you're spacing individual vaccines 3-4 weeks apart. Dr. Dodds suggested taking puppies to public places where dogs aren't common, such as parking lots outside of stores and malls, or inviting healthy dogs to your home. Carrying the puppy and having people play with it in your (or their) arms instead of letting it touch the ground in public places will also reduce the risk of exposure. Puppies can attend puppy obedience classes after their first round of shots because owners who take their puppies to classes are generally a clean and responsible lot, so the risk of infection is relatively low. However, there is still a risk, because nothing is risk free, so puppy owners should have this explained to them.

The only vaccination required by law in Ontario is rabies--everything else is a recommendation and is optional. Vets incur no legal liability by not recommending vaccinations, except for rabies, because everything on the label is a recommendation. Ontario law doesn't clearly specify a minimum age at which puppies should be vaccinated for rabies--it says something like "three months or older," which may be interpreted by individual public health officers either as "it must be given at three months of age" or "it must be given sometime after three months of age."

A titre measures the immunity conferred by vaccinations and by natural exposure. Because of the lower limits of lab tests, any measurable titre is considered protective--a measurable level = committed immune memory cells. The number provided on a titre test (e.g., 1:256) refers to the number of dilutions it took before antibodies could no longer be detected. A higher second number in the ratio (1:1024) is better than a lower number (1:16), but any measurable titre is a good titre. However, in Ontario, public health officers will not accept titres as evidence of vaccination.

After vaccination, a dog's titre will rise for about three months, after which time it will stabilize and return to the dog's basal level. Once the animal has stabilized, its titre should stay at its basal level and not decrease with time. This is only true for virus vaccinations, not bacteria vaccinations (such as lepto), but I don't know why. This is why Dr. Dodds doesn't think that dogs need to be repeatedly vaccinated against viral diseases. You can't boost an immune system that is already on guard for a specific disease, and over-vaccination can backfire and weaken a dog's immune system. [On a human note, annual flu shots are recommended for susceptible individuals because cold and flu viruses mutate quickly--this year's flu is not the same as last year's flu, and immunity to one doesn't provide immunity to another. That's why you can catch colds and the flu throughout your life. I don't know why these viruses mutate quickly while other don't.] Titres should be done several months after vaccinating (so that you're not measuring the temporary spike) and then again in several years.

Inoculated dogs will shed virus, so dogs that come into contact with them may show a measurable titre even if they haven't been vaccinated themselves. Dogs can also be exposed to a virus in the environment without necessarily becoming sick, so they can produce positive titres that way too. Rabies is always fatal, however, so a dog can only produce a measurable rabies titre through vaccination. I'm a little fuzzy on why rabies virus can't be shed by vaccinated dogs--I'm guessing it's because the the rabies vaccine is a killed virus rather than a modified live virus. A modified live virus will reproduce in the dog's body, but a killed one won't. In any event, Dr. Dodds was quite clear on this point: positive rabies titres can only be gained by vaccination. She has had the occasional positive titre from an unvaccinated dog come up, but it's always been a false positive as a result of a clerical error.

The rabies vaccination is the strongest vaccination given to dogs, and it's one of the ones most likely to cause adverse effects. Rabies vaccinations should be given separately (i.e., 3-4 weeks before or after) from other vaccinations when the dog is healthy, not in heat, etc. Dogs with chronic conditions (e.g., hypothyroidism) shouldn't be vaccinated at all. A letter of exemption from a vet is acceptable in lieu of a rabies vaccination in Ontario, so owners of geriatric dogs (> 10 years old) or dogs with chronic health problems should get one of these from their vet. Adverse reactions from the rabies vaccination can include changes in temperament.

To be continued...


Bella's right eye was kind of runny yesterday evening, and the white part of her eye was an interesting shade of pink. I made an appointment with the vet for this afternoon. The vet examined Bella's eye, said her cornea appeared to be clear and unscratched, noted that the accumulated goop (which I hadn't wiped off because I wanted her to see it) was slightly green and the tissues around her eye were a little swollen, and concluded that it was conjunctivitis. I have cream to put in both eyes to clear it up/prevent the other one from becoming infected. Bella's eye looks a little more gooey than usual, but it doesn't seem to be causing her any discomfort and she's not squinting or blinking any more than normal. She sure doesn't like having the cream put in, though. But, then, neither would I. And she can't go to doggy daycare tomorrow because she might be contagious. :-(

While I was at the vet's, I also had a Lyme test done to see if that's what made her sick in July. It came back negative (she was also negative for heartworm--they do both at once). I talked to the vet about whether her illness could have been a reaction to the vaccination, but she was inclined to say no until I mentioned that Bella had been having a false pregnancy at the time of the vaccination (it was a different vet than the one who told me about the false pregnancy). Then she conceded that it might have been. Since parvo is an immunosuppressive virus, it might also have been the start of an opportunistic infection that moved in while her immune system was below par after the parvo vaccination. There's no way to know. I think I'll bring Bella in for titres--including a rabies titre--after her next heat. If the rabies titre comes back positive, then I'll ask if they'll sign a waiver for rabies shots on the condition that I have rabies titres done every three years. I'm also going to email Jean Dodds and ask her opinion. Mairon has emailed her a few times, and she said that she's always gotten an answer.


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