Continued from page 234

selectively bred for specific purposes. Today, I admire the gaited breeds, the warmbloods, the Morgans, the Arabians, the racehorses, the ponies - all breeds - as well as the stock horses, which were nay first love.

There is another thing I 've changed my mind about, and that is the intel- ligence of the horse. Although I have always loved horses, for much of my life I did not regard them as particularly intelligent. I was wrong. Horses are extremely intelligent creatures and I have decided that we humans are not nearly as intelligent as we generally think we are. A glance at any newspaper headline is good evidence to that effect. What we are good at is superimposing one kind of learned technology upon another, each of them the product of somebody else's genius.

It took hundreds of thousands of years for mankind to invent the spear, and the bow and arrow popped up a mere ten thousand years ago. Seems obvious now, doesn't it?

Finally, I have not changed my mind about horsemanship. It has noth- ing to do with riding ability. Some of the finest horsemen I have known did not ride. They include circus trainers, teamsters, farriers, and veterinarians. Conversely, I have known great riders who were miserable horsemen. I had one client who was a world class rider of Olympic caliber, but who was such a poor horseman that I didn't want him near me when I was treating his horses. I would give him something to hold, like a bucket or a dose syringe to keep him busy and to prevent him from holding his own horses when I was working on them. This is much more diplomatic than saying, "Look, get out of my way and stand back. Your presence agitates these horses and I don't want you near me while I 'm treating them."

HAIR PATTERNS AND DERMAL CLEAVAGE LINES OF THE

HORSE

James R. Rooney, DVM

While of no immediate or obvious clinical or performance importance, the hair pattern and the cleavage (split line) pattern of the dermis of the horse is or could be of basic interest to veterinarians and horsemen. The cleavage pattern does have relevance in the pathogenesis and repair of wounds of the skin.

The hair pattern in man and animals, including the horse, were considered by Kidd. 1-31 am aware of only one paper on the cleavage line or split line pattern of the dermis of the horse. 4

This is not a report of original work but, rather, a paraphrase and commentary on the work of Schoupp6 and Kidd, publication justified, I believe, by the intrinsic interest of the material and its relative inaccessibility to the modern reader. Author's Address: 204 Sportsman Neck Road, Queenstown, MD 21658

HAIR PATTERN

Kidd 1'2 described the pattern of the hair coat in man and a number of animals and speculated on reasons for that pattern. The basic pattern for the horse is shown in Figures 1 and 2 copied from Kidd and Smithy On the lateral view, Figure 2, only the pattern of the hair in the flank is common (that marked A,B,C and the unmarked feathering just cranial to that). The pattern A,B,C, on the chest, Figure 1, is most common, though G is not at all uncommon. Any or all of the patterns on the forehead, Figure 1, are common.

Kidd indicated that the zebra and the ass do not show such distinctive hah" patterns as in the horse. 2 The mule was said to show more rudimentary patterning than in the horse. The Prezwalski horse w as also said to lack the obvious patteming of the domestic horse.

Kidd considered muscle pull as one cause of hair patterning, v2 As tersely noted by EUeberger-Banm, 3 neither this nor any other explanation which has

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Figure 1. Head and chest hair pattern of horses from Kidd in Smith. ~

236 JOURNAL OF EQUINE VETERINARY SCIENCE

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In a one-on-one relaxed atmosphere at the Aspen Lodge Guest Ranch in beautiful Estes Park, Colorado, Aug. 23-27, 2000.

5th Annual JEVS Equine Vet Seminar See page 216 for details.

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238 JOURNAL OF EQUINE VETERINARY SCIENCE

been offered for hair pattern in man or animals bears scrutiny. One is particularly careful of Kidd's frankly Lamarkian evaluations.

CLEAVAGE LINES OF DERMIS

The dermis or corium is largely composed of collagen fibers. These fibers

are organized in distinctive tensile patterns in different parts of the body. The pattern may be recognized by inserting an awl through the epidermis into the dermis and observing the orientation of the sprit or cleavage so formed. The technique has been used in skin, cartilage, and bone for the determination of the principal orientation of collagen fibers,

Schoupp6 was led to the investigation

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it ~i ;* J , I,[, L, upper cervical ~, ,," feathering, and crest.

M, N, O, rniddle cervical w feathering, and crest.

3 P, lower cervica[ whorl, lea ! ,~, G,~ / hag, and crest.

Figure 2. Lateral view of hair patterns of horses from Kidd in Smith. a

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Figure 3. The cleavage lines of the dermis from Schoupp& 6

of the cleavage lines of the horse's dermis by the observation in the surgical clinic of the veterinary college in Vienna that most wounds of the skin had distinctive patterns depending upon their location. 4

Cleavage lines in the human dermis were-first reported by Dupuytren, 6 and worked out in detail by Langer. 7 A number of human anatomical texts, Gray's Anatomy for example, refer to these as "Langer's fines." Schoupp6 studied the cleavage lines in nine dead horses and one deeply anesthetized horse, using Langer's method. The hair was chemically removed and the cleavage lines produced with an awl 13 cm long and 1.3 cm in diameter at the base. Photographs and drawings are in the original paper. The pattern of the cleavage fines, lateral view, is shown in Figure 3. 4 The lines ran transversely across the chest. The cleavage lines were less clear and developed in foals.

Schoupp6 4 concluded: 1. There are cleavage fines in the

dermis of the horse oriented parallel to the predominant orientation of the collagen fibers.

2. The cleavage line pattern is consistent among adult horses with only small variations.

3. There was no correlation between the hair coat pattern and the cleavage line pattern. In his paper Schoupp6 superimposed the hair patterns on the cleavage line patterns, showing the lack of correlation, Fig. 4.

4. Lacerations, lacerations with bruising (the type of wound often caused by kicks) , and "platzwunden"* largely are oriented according to the cleavage pattern.

5. Those wounds healed best which were parallel to the cleavage fines.

6. Langer 7 suggested that the cleavage lines were oriented in the direction of muscle shortening, as Kidd had suggested

*The translation of this word is uncertain but seems to indicate a process l ike the splitting open of the skin by, e,g., a hematoma:

Volume 20, Number 4, 2000 239

for the hair coat pattern, but this was not the case for the horse, as shown in the drawings of Schoupp6.

No ready explanation is apparent for either the orientation of the hair coat or the cleavage lines in horses, and both might reward reexamination with modem methods.

REFERENCES

1. Kidd W: The significance of the hair slope in certain mammals. Proceedings Zoological Society, London 1900;3:676- 685.

2. Kidd W: Certain habits of animals traced in the arrangement of their hair. Proceedings Zoological Society, London 1902;2:145-158.

3. Zietzschmann O, Ackerknecht E, Grau H: Elleberger-Baum Handbuch Der Vergleichenden Anatomie Der Hausfiere. Berlin: Springer-Verlag 1943.

4. Schoupp~ K, von: Ueber die Spaltbarkeit der Pferdekutis. Archiv

Figu patt~

wissenschftliche und Praktische Tierheil- kunde 1913;39:112-125.

5. Smith F: A Manual of Veterinary Physiology. 5th Ed, Chicago: Alex Eger, 1921.

6. Dupuytren: Ueber die Verletzungen durch Kriegswaffen. Cited in Schouppe

1836, 7. Langer: Ueber die Spaltbarke# der

Kutis. Sitzungberichte der mathematisch- naturwissenschaftlichen Klasse der kaiser- lichen. Akademie der Wissenschaften XLIV: 1861:19-46.

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