Treating meat goats for neurological ills
Practitioners provide veterinary care for a growing number of meat goats in the United States — animals known to develop neurological disease.
Such conditions can be frustrating to treat. Many neurological diseases can present with similar signs, and diagnostics are limited. But because some neurological diseases have herd implications or are zoonotic, practitioners must attempt to list the most likely diagnoses so treatment and/or preventative measures can be taken.
Take a historyDue to the limitations of physical examinations and diagnostics for neurological diseases, a thorough history is extremely important. Many times, a management or feeding change has taken place that leads to neurological disease. Remember: Many neurological signs are not caused by diseases of the nervous system but are secondary to other systemic diseases.
Brain or spinal cord?
A thorough physical examination is important. Injury to the animal and personnel must always be considered when trying to restrain diseased goats for examination, especially large males. Because many neurological signs stem from other systemic diseases like pregnancy toxemia, a complete general physical examination should be performed before concentrating on the neurological examination. Trying to observe the animal in its surroundings before restraint is key. Mentation, head posture, gait abnormalities, tremors and head tilt should be noted. Blindness can be difficult to prove because animals can avoid obstacles using their other senses.
The main objective is to classify the disease as a brain disease or a spinal- cord disease. Although multi-focal diseases can occur, they are less common. Gait abnormalities, especially ataxia, can be present with brain and spinal-cord disease. Also, generalized weakness from other diseases can be difficult to differentiate from true neurological ataxia. Cerebral disease should be suspected if changes in mentation, head pressing, blindness, bizarre behavior or seizures are observed. Cerebellar diseases usually cause hypermetria and intention tremors. Circling, ataxia, proprioceptive deficits and/or cranial nerve signs are seen with brain-stem disease. Blindfolding might worsen cerebellar or brain-stem disease signs.
Once the animal is observed at a distance, the practitioner often has an idea if the disease involves the brain or spinal cord. Cranial-nerve examination must be performed to help further differentiate brain disease, or if no brain signs are seen from distant observations, to rule out brain disease so spina-cord disease can be the focus. Localization of spinal-cord disease is the same as in other species.
A goat's size makes it a candidate for diagnostic procedures commonly used in small animals, such as plain and contrast radiography, computed tomography and magnetic resonance imagery. However, the cost of these procedures might be prohibitive.
Cerebrospinal fluid (CSF) is collected easily from the lumbosacral space and can provide valuable information. A 20-gauge, 1.5-inch needle is used for neonates and an 18-gauge, 1.5-inch needle for adult goats. Ambulatory patients can be tapped standing. Non-ambulatory patients should be placed in lateral recumbency or in sternal recumbency in a dog-sitting position with the rear legs forward on either side of the animal. The pelvis must be straight and level. Light sedation and a local anesthetic will help with restraint. The lumbosacral area should be clipped and surgically prepared. Wearing sterile gloves, the indention of the lumbosacral junction should be palpated. A needle is inserted into the deepest part of the indention, directly on midline. Keep the needle perpendicular to the spine from the side view, and straight up and down from the rear view. If bone is encountered, redirect the needle slightly cranial or caudal until the needle drops into the lumbosacral space. Advance the needle slowly until a slight pop is felt. The animal usually jumps slightly when the needle punctures the dura mater. CSF should flow from the needle or can be gently aspirated with a syringe. If the needle is in the lumbosacral space and advanced until bone is encountered again, back the needle out 1 mm to 2 mm, and try to aspirate. Place the fluid in an EDTA tube for fluid analysis and a plain tube if cultures are desired.
Normal, non-traumatically obtained fluid should be perfectly clear with no discoloration, sediment or turbidity. It is best to have the sample analyzed locally within one hour. If this is not possible, place half of the sample in an equal volume of 40 percent ethanol to preserve the cells (inform the laboratory that this has been done), or centrifuge half the sample to concentrate the cells and prepare slides to be sent with the rest of the fluid.