my spaniel has an infestation of parasites which the local vet cannot identify?

they are generally the size of a match-head, often smaller and look like little black dots. in the cooler part of the day-we live in spain- some abandon the dog to set off by foot-wehave found them climbing four feet up the walls! teatment shampoos seem to make no difference, and they are full of blood. the dog has a cough, which fades with anti biotics but returns at the end of treatment-could this be connected? the vet says the dogs heart and lungs are ok.

You could get your vet to give you a number for a specialist in parasites?

It is possible that the cough and infestation are connected, but it is odd that the vet cannot identify the parasite in question. Does your pet travel? Is it possible that the parasite is not indigenous to Spain and therefore the vet is unfamiliar with it? I would guess the parasite is some sort of tick and ticks can carry a variety of different microbes which cause disease. Is your dog on any flea/tick medication? If so, what? Also, can you count the number of these creatures on your pet? Can you find them attached on your dog? How many legs? Any pattern on the parasite? Different shampoos don't usually have much of an effect on ticks as their heads are usually buried in the pets skin. Might want to try frontline plus, which kills a variety of ticks. I can provide a better answer with a little more info.