An 18 month old huntaway presented to our Huntly clinic after hours with vomiting, diarrhoea and lethargy. After examining the dog the owner and I discussed whether he could have eaten anything unusual (no, he had been kennelled lately). I looked at his vaccination history and he had been vaccinated three times as a puppy for parvovirus and twice for leptospirosis but, he had not had his annual booster.

Due to his young age, history from his owner and presentation I decided to test for parvovirus and found he was positive. The owner and I had a discussion about the vaccine he had as a puppy and discussed why he wasn’t protected.

The reason we give three vaccines as a puppy is because of the mother’s antibodies are passed on to the puppy through the milk; these can interfere with the vaccination and they wane at different ages in each dog. The three vaccines are to protect the puppy (as best we can!) during this risky time and, also so that we can give the best chance for the vaccine to work. This is why we recommend dogs don’t walk out in heavily populated areas or socialise with unvaccinated dogs until ten days after their last vaccine booster (the vaccine must be given time to work properly before expecting good protection).

Most animals will respond well to the 12 or 16 week vaccine, but in rare cases their maternal antibodies interfere with the vaccine or their immune response isn’t strong enough. The yearly booster is designed to catch these dogs that are then susceptible and might otherwise be unprotected.

Luckily because of his age, this dog wasn’t as severely affected as a young pup would be, therefore he was sent home on medication and the owner spent the next week nursing him back to health. Unfortunately many younger dogs aren’t so lucky as their immune system is so weak and parvovirus dehydrates them so quickly, they can be extremely hard to save. These dogs need isolation, hospitalisation on fluids, antibiotics to stave off secondary infections and anti-nausea medication, and nearly 50% of these cases don’t make it despite the aggressive supportive treatment.

Our current recommendation for parvovirus vaccinations is 3 vaccines as a puppy at 8 weeks, 12 weeks and 16 weeks, then at 12 months of age. After this, three yearly vaccine boosters are sufficient. Leptospirosis requires two vaccines four weeks apart at any age over eight weeks, followed by annual boosters.