Q: My three guinea pigs live together and they keep getting mites. I use dust-free wood shavings and hay. I clean their cage out regularly. Could the mites be coming from the grass I pull for them? Peter Tilley, Oxford

A: These are likely to be sarcoptic mange mites and they do not live in the bedding or the grass – they live on your pigs.

They can be carried by guinea pigs without any signs and then can suddenly flare up when they are stressed in some way.

They cause intense itching and the affected pigs scratch almost constantly, lose hair, get scabby and lose weight.

They can be treated by anti mite injections or spot-on products but these bugs can be persistent and often take three to four treatments, a week apart.

Treat all three animals at the same time.

Q: Our cat is 18 months old, and has a diet of dry food, but we are concerned as she seems to drink a vast quantity of water.

Her bowl is filled with fresh water two to three times a day and on top of this, when she notices a member of the family going to the bathroom, she always rushes in and climbs into the sink, wanting us to give her more water from the tap. She seems otherwise in good health.

S Mays, Woodstock

A: Cats on dry diets do drink a lot of water and they need to. Tinned cat food contains a lot of water and so cats fed this, drink less, although your cat does seem to drink a lot.

The volume she is drinking may well be within normal limits but it is difficult to know without a proper measure.

There are many diseases where excessive drinking is a key sign, such as diabetes.

It is worth a visit to your vet and take a urine sample.

To get this, get some pea gravel and boil it for five minutes, let it dry and cool and use it in her litter tray.

It does not absorb the urine and you can pour it into a sterile container.

If you can’t do this, don’t worry, it is quite easy to get a sample at the clinic.

Q I have a 15-month-old Staffordshire bull terrier male. When I first had him, I trained him to do his business outside and he did.

Just lately, however, through the night, he seems to urinate and defecate in the kitchen.

What can I do to stop him doing this? Nothing has changed with what we do with him, ie walks etc.

Sharon Gosling, Henley

A: Just when you think the training is done this happens. Your best plan is to start the whole process again. Use a reward-based programme with treats when he does what you want.

There may be a stress behind this like separation anxiety.

A cage may help which would become his bedroom when left alone.

Could he be frustrated? In my experience Staffi’s are often poorly socialised, never allowed a good run and spend their life pulling their owners around on the end of a lead so make sure his walks are fun and he has plenty of games.

A dog appeasing pheromone (DAP) diffuser may help. This dispenses calming pheromones into the atmosphere and is available from your vet.