by Lynn Broom, Longmead Veterinary Practice

THIS is the second of two articles on how physical factors can affect behaviour.

Conditions can be present from birth or a young age. Certain breeds and coat colours – such as white Boxers – have an increased risk of deafness and this may lead to training difficulties. Abnormal vision due to abnormal eye development can lead to slow uptake with training or difficulty with certain tasks. Progressive conditions of the eyes such as progressive retinal atrophy can lead to complete blindness in young adult dogs which may cause anxiety or aggression.

The female hormone cycle can lead to significant temperament changes which are usually temporary. Bitches in season can become aggressive. False pregnancies typically develop four to nine weeks after a season and can cause mammary swelling and milk production. Some, however, may only display temperament changes and these might not be recognised as hormonal changes.

False pregnancies can make bitches territorial, possessive – collecting or guarding toys – anxious or aggressive causing a normally friendly dog to become aggressive to other dogs, even those they live with. In most bitches this is a temporary state which self-resolves but some get ‘stuck’ in a false pregnancy and may need medication to reverse the changes. Spaying during a false pregnancy can lead to ongoing behavioural changes which do not self-resolve due to ovary removal. Bitches displaying ongoing temperament changes may benefit from a prolonged course of medication to attempt to reverse these changes.

Entire male dogs develop many testosterone-driven behaviours such as scent marking. Many of these behaviours are ‘learnt’ and do not resolve with castration. Anxious male dogs may actually become more anxious and develop more severe fear-related aggression following castration and it is important to recognise this so that castration can be avoided if necessary or until the anxiety problems have been addressed. Entire male cats are much more likely to scent mark and fight, leading to an increased risk of infections, and castration usually reduces this behaviour.

READ MORE: Physical causes of dog behavioural issues, part one

Diseases affecting the brain can cause behavioural changes. Metabolic causes such as liver disease or diabetes mellitus can change an animal’s temperament and they may present as being quieter or aggressive. Cats with hyperthyroidism and generally older animals can develop symptoms of dementia which may lead to behavioural changes, loss of house training and an increase in vocalisation.

Physical changes such as brain tumours may cause significant behavioural changes and previously friendly dogs can become unpredictably aggressive. Recurrent seizures or long lasting seizures can cause permanent brain damage which can also lead to temperament changes.

Dogs with long term dietary issues such as chronic diarrhoea can be more anxious because the gut microbiome can affect brain activity. Diets deficient in certain vitamins and minerals can also make dogs more anxious because the brain functions more efficiently on a complete nutritionally balanced diet.

Certain medications may also cause behavioural changes. For instance, some dogs become hyperactive and excitable on high doses of steroids. If your pet develops temperament changes since starting a medication it is worth reviewing potential side-effects in case the two are related.

Contact your own vet if you wish to consider any of these conditions as a cause of your pet’s own behaviour issues.