Both give you the opportunity to attach a leash to keep your dog under control. This is especially important in the city so that your pet does not run in front of a car, but also in other situations it can be important to secure your dog. What effect the harness or collar physically and behaviourally has on your four-legged friend you can find out here:
Collar
+ easy to put on
+ For double security with fearful dogs
+As an alternative to the harness, if the dog is not yet used to it or has a wound in the area of the harness, for example
– Changing body language. Common reason for aggression problems on the leash. By pulling the head up we change the body language, which can have a strange effect on the foreign dog.
– Disconnections. Because always, if your dog wants to run to another, it runs into the collar and connects the pain with fellow dogs. This happens with all sorts of things, anything your pet sees while he feels the pain can be associated with negativity.
– Pain stimulus, can also lead to fear. Unsafe dogs become even more anxious by the constant pain stimuli.
– By jerking the leash (intentionally or not), in the worst case the cervical vertebrae can shift and your darling can be paralysed.
– The neck is very sensitive.
– The pull of the collar mainly presses on:
- Larynx (difficulty swallowing, pain),
- Thyroid gland (inflammation, hypo function),
- Trachea (cartilage rings constricted – shortness of breath),
- Esophagus (difficulty swallowing),
- Carotid artery, lymph vessels and knots (swelling, injuries, weakened immune system – thymus gland reduces T-cell production, Pain),
- Veins and arteries (poor blood supply in the brain-high blood pressure/intestinal pressure-blood deficiency of the brain, glaucoma),
- Nervous system (injuries of the nerves),
- Nerves (neurological functions disturbed),
- Spinal cord (narrowing of the spinal canal) all of them can suffer damage (written in brackets).

– Neck muscles affect the entire musculoskeletal system. The muscles are squeezed by the counter pull and tense up, which can manifest itself in pain in the entire front body.
– Skin irritations
– Hair loss
– Increasedintraocularpressure causes many eye problems.
– Irritant cough can be triggered.
– Damage to the (neck) spine and back problems.
– Arthrosis and herniateddisc are favoured.
– Even if it sounds paradoxical, some dogs try to flee from the pain and pull even more when walking on a leash.
– If it is not close to slip many dogs easily out, because always at least one finger must fit between them, the security is often not given.
No-Go’s: Under no circumstances may it be used with a flexi- or towline. The sudden stop aggravates these dangers.
Also tying or securing in the car is strictly forbidden, as well as everything where your dog should build up tension (mantrailing, …).
The collar must be over two cervical vertebrae wide, in order to minimize damage as much as possible.
Harness
+ Good distribution of the pressure, relieves sensitive areas
+ Shape individually adaptable and therefore comfortable to wear
+ Extras, such as additional rings and handles attachable
+ Has no influence on body language
+ Variants for special requirements (train dog sport, safety harness, mantrailing, …)
+ In emergency situations the dog is easier to handle
+ Escape-proof. Very frightening dogs should wear a safety harness
+ If your dog is injured or elderly, you can help him walk. Even in an emergency it is easier to hold your four-legged friend by the harness.
– Not well-fitting harnesses can restrict the movement or scrub
– Some dogs find it uncomfortable to put on, often because it has been trained incorrectly or does not sit well

Summary
For walks without a leash a collar is no problem, but as soon as your darling is leashed you should change to a harness. Even if your darling is on a leash and doesn’t pull, would you put the belt around your neck when driving? You never build an accident, but what if…?