Allen Roussel, DVM, MS, Dipl. ACVIM, Dipl. ECBHM, Texas A&M University, believes that physical examination of cattle should begin with observation of the animal from a distance. This is particularly important when one suspects neurological or musculoskeletal disease, he said at the 2010 Western Veterinary Conference.
The animal should be observed at rest for several minutes and then in motion. Note the general condition of the animal and the breed, as some neurological diseases are heritable. When the animal is at rest, pay particular attention to the animal’s awareness of its surroundings which reflects cerebral function. Note if the animal is depressed, hyper-excited, or otherwise responsive to external stimuli, if it is head pressing, wandering aimlessly, vocalizing abnormally, behaving abnormally or aggressively. Diseases such as polioencephalomalacia, lead poisoning, nervous ketosis, bovine spongiform encephalopathy, rabies, brain or pituitary abscess, nervous coccidiosis, and salt poisoning/water deprivation cause these signs.
Before the animal is disturbed, observe the character and rate of respiration, look for a jugular pulse (indicative of right heart failure), and for signs of abdominal pain like bruxism, restlessness, kicking at the belly, or straining. Also look carefully for muscle fasciculation, twitching of the ears or eyelids, tail position and switching and abnormal attempts at swallowing which may indicate nervous system or metabolic disease such as hypomagnesemia, lead toxicity, tetanus, or rabies.
Lameness is often detectable in cattle at rest by observing how the animal bears or shifts weight on the limbs. An easy way to assess weight bearing is to observe how far the dewclaws are from the ground. If the dewclaws are higher on one side, the animal is not bearing full weight on that side. Abdominal contour should also be assessed at a distance and from behind the animal. While the animal is in the open and not confined in a chute, careful attention should be paid to the muscle mass, particularly over the rump and hindquarters. In unilateral neurological disease, as well as chronic upper limb lameness, atrophy of the muscles will occur, and asymmetry of the muscles will be obvious.
If the animal is recumbent, observe if and how it rises. It is best to observe an animal in motion as it moves away from and towards the examiner, as well as from each side. To optimally evaluate gait, it should move at its own pace with only slight prompting from an assistant. It should be driven and not led (unless it is very well halter broken) so that the head and neck are free to move. The carriage of the head and neck sometimes give important clues about neurological disease. Observation should be carried out from directly behind the animal and then from each side, with particular attention being paid to the carriage and placement of the legs, to ability of the animal to walk in a straight line, to knuckling, and to other signs of weakness. If hind limb ataxia is suspected, the animal should be pulled from side to side by the tail so that the examiner can assess if the animal is able to place its back feet under itself correctly.
Another important observation to make when the animal is moving is to assess its vision. The menace response can be misleading in cattle, particularly young cattle. Therefore, cattle suspected of blindness should be moved through a maze or an obstacle course where they will have to turn to avoid running into objects. In this way their visual capacity can be properly assessed.