There is no specific syndrome or infection called "herd disease", so this is a general term meaning "a disease affecting a population of animals". In this context, a herd disease is any disease affecting a herd, which in the United States is generally a collection of ruminants, of which the only domestic species is cattle.

Examples of herd diseases include Moraxella bovis, the bacteria responsible for pink eye or conjunctivitis and primarily affects white-faced cattle like Herefords and baldies; bovine viral diarrhea virus (BVDV), which is perpetuated in the herd through persistently infected (PI) shedders infected in utero; and Mycobacterium avium paratuberculosis, the causative agent of Johne's disease and perpetuated in the herd through chronic shedders infecting calves at birth.

i dont know all but ya there are some Acetonaemia

A disease commonly seen in high producing dairy cows, or in cows on a poor diet.

Acute Bovine Liver Disease

Previously known as phytotoxic hepatitis, it is a disease of beef and dairy cattle.

Botulism

Although instances of botulism affecting humans are rare, it is a common disease in animals and birds.

Bovine Pestivirus

Also known as bovine viral diarrhoea virus, or BVD or BVDV, or mucosal disease virus.

Brucellosis

Causes mass abortion in cattle herds.

BSE (Mad Cow Disease)

An emergency animal disease that would have serious consequences for the cattle industry.

Facial Eczema

Facial eczema (FE) is a type of sunburn (sometimes called photosensitisation) affecting exposed areas of pale skin of cattle.

Foot and Mouth Disease

A highly contagious animal disease that can also affect other livestock species.

Grass Tetany (Hypomagnesaemia)

Magnesium deficiency. It can affect stock in late autumn, winter and spring. This is not the same disease as perennial rye grass staggers.

Milk Fever (Hypocalcaemia)

An abnormally low level of blood calcium.

Perennial Ryegrass Staggers

Caused by toxins in the leaves of perennial rye grass. This is not the same disease as grass tetany.