Reprinted from the JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION, Vol. 200, No. 12 Pages 1970-1972.
©American Veterinary Medical Association. 1992. All Rights Reserved.
A 10-year-old 7-kg castrated domestic shorthair car was examined because of lethargy, decreased appetite, and weight loss of several months’ duration. The owner also believed the cat to be drinking more water than in the past. Weigh loss of 2kg over the preceding 12 months was evident from the medical record.
The cat appeared depressed and had a matted, unkempt coat. The cervical region was extended, and the head was held low and directly in front of the body. The cat was afebrile (37.8 C), obese, and hydrated. Palpation revealed the cervical region to be rigidly extended with tense musculature. A hard mass was palpable in the midcervical region. Neurologic examination did not reveal abnormalities, except the rigidly extended neck.
The cat had been evaluated 5 months earlier because of lethargy, change-of-voice, a lump in the neck, and abnormal “staring.” At that time, the diet was reported to be dry-pelleted cat food and fresh beef liver. Results of physical examination, CBC, serum biochemical analysis, and thyroxine evaluations done at that time were within normal limits. Also, cervical and thoracic radiographs at that time were considered normal.
At this evaluation, cervical radiography revealed a bone-dense, cervical mass ventral to the C1-C2 intervertebral space (Fig 1). The substance of this mass was intimately associated with these vertebrae. Much of the normal vertebral architecture appeared to be obliterated, and the trachea and cervical soft tissue were deviated ventrally and laterally. The dorsal spinous processes of cervical vertebrae C3 and C4 were abnormally large.
Thoracic radiography revealed ventral, vertebral bony proliferation extending from thoracic vertebrae T2 through T7, with the most severe lesions associated with T2 through T5 (Fig 2). In addition, the sternebrae were similarly involved, with marked bony proliferation evident throughout the length of the sternum and along several of the costal cartilages. The most caudal costal cartilages were most severely affected.
Retrospective evaluation of the cervical and thoracic radiographs taken at the original examination 5 months earlier revealed the cervical vertebral and thoracic vertebral and sternal lesions, respectively. The thoracic vertebral lesion was less severe at that time, although the other lesions were well developed.
This cat was still on a diet of dry-pelleted cat food and fresh beef liver daily. The history physical examination findings and radiographic signs are consistent with a clinical diagnosis of hypervitaminosis A.
Blood samples were withdrawn and submitted for a CBC, serum biochemical analysis, feline leukemia virus antigen test (ELISA),a and a serum vitamin A assay. The CBC revealed leukocytosis (WBC = 20, 800 cells/dl) and mature neutrophilia (16,432 segmented neutrophils/dl). Serum hiochemical analysis revealed mild hyperglycemia (glucose = 217mg/dl) and hypercholesterolemia (cholesterol = 270 mg/dl). The feline leukemia virus antigen test result was negative. Serum vitamin A concentration was markedly high (315.4 µg/dl; normal, 20 to 80 µg/dl).
Hypervitaminosis A in the cat was first described as deforming cervical spondylosis.1 The pathophysiologic characteristics of the disease were later described by Seawright et al,2 in
Australia
. Numerous investigators later recognized the disease in other parts of the world.3,4 The disease is usually caused by the excessive intake of vitamin A through diets high in raw liver, usually beef or sheep liver. Excessive intake of vitamin A supplements can also produce the disease.
The disease develops most commonly in cats from
2
to 9 years old, and no breed or gender predilection has been recognized. Months or years of a diet high in liver precede signs of toxicosis.5 Early in the disease, cats are lethargic and resent handling. After several months, cervical stiffness or forelimb lameness may develop. Signs of cutaneous pain over the cervical and forelimb regions increase as osseous proliferation impinges on spinal nerves6. Ankylosis follows in the cervical diarthrodial joints. The elbows and occasionally the shoulders maybe affected, as well as the rest of the spine.
Additionally, an unkempt coat, weight loss, constipation, and a kangaroo-like sitting posture may be seen. An unkempt coat is likely a result of the affected cat’s inability to groom. Weight loss and constipation can he attributed to inactivity and muscle atrophy. The kangaroo-like sitting posture is likely a sign of spinal ankylosis.2
In this case, the history was suggestive of the disease. The cat was examined because of lethargy, signs of depression, and anorexia. A diet high in raw beef liver was mentioned. Although the owner described increased thirst, evidence of polydipsia or polyuna was not found. However, a urinalysis was not done. The physical examination findings of rigidly extended head and neck cervical mass, and unkempt coat are also characteristic of hypervitaminosis A.
The history and physical examination findings obtained at first examination, 5 months earlier, were also suggestive of hypervitaminosis A. A diet high in raw liver, a voice change, weight loss, and a staring posture are characteristic of this syndrome. The voice change perceived by the client was probably attributable to direct pressure by the ventral cervical vertebral mass of proliferative bone on the larynx, laryngeal muscles, and nerves.
The radiographic lesions of bony proliferation of the cervical vertebrae, the sternum, and the costal cartilages are characteristics of the disease. The cervical vertebral and sternal lesions were apparent in the earlier radiographs; however, the thoracic vertebral lesion was less pronounced, compared with the later radiographs.
In cases of hypervitaminosis A, laboratory findings are nonspecific. Neutrophilic leukocytosis is consistent with a stress leukogram: however lymphopenia and eosinopenia were not found. Hyperglycemia is common in cats stressed by disease or hospitalization. Hypercholesterolemia, often found in cats with hyperthyroidism was not explained in this case. Thyroxine concentration at the first examination was normal; however, it was not evaluated at the second examination. The finding of high serum vitamin A concentration (4 times normal) was suggestive of hypervitaminosis A. The serum alkaline phosphatase activity was normal in this cat, although Riser et al3 reported it to he high in one case.
The cat of this report was given a single intramuscular injection of 1 mg of dexamethasone sodium phosphate and was discharged from our hospital. We prescribed 13 mg of phenylbutazone to be given
PO
every 12 hours for analgesia. The owner was advised to cease the feeding of liver and to feed only a balanced feline diet. The owner was further advised to encourage the cat to eat with treats and handfeeding. A follow-up appointment was not kept, and evaluation of the case was lost to follow up.
Six months later, the cat was euthanatized for reasons unrelated to the condition of hypervitaminosis A. It was reported that the cat had been eating fairly well, although the stiff-necked posture remained.
A necropsy was performed. The cat was slightly thin, and the cervical region and skull were rigidly extended and immobile. A firm mass was palpable in the ventral, midcervical region. The skull, cervical portion of the spine, and thoracic cage were dissected free and cleaned of their respective soft tissues.
Severe cervical vertebral spondylopathy was found from the atlanto-occipital articulation caudal to the third thoracic vertebral body. The entire cervical spine was solidly fused, and bony proliferation was evident on all sides of the vertebrae. Many of the intervertebral foramina were virtually obliterated by new bone formation. A large bony mass was ventral to the C1-C2 intervertebral interspace. The sternum and costal cartilages were obscured by a 0.5-cm-thick collar of bone, which was brittle.
On the basis of findings in the cat of this report, I recommend that in the case of any sick cat on a diet consisting wholly or partly of raw liver, hypervitaminosis A should be suspected. The feeding of raw liver should he stopped and a balanced feline diet instituted. Analgesics should be used as required. Those cats that are anorectic should be evaluated for concurrent disease and treated appropriately. With the cessation of feeding of raw liver, progression of lesions will stop and pain will lessen; however, ankylotic lesions will remain.
From
Warwick
Animal
Hospital
,
1950 Elmwood Ave
,
Warwick
,
RI
02888
.
Dr.
Goldman
’s present address is The Animal Medical Center,
510 E 62nd St.
New York City
,
NY
10021
.
aLeukassay FII, Pitman-Moore Inc, Washington Crossing, NJ.
1.
Seawright
AA
, English PB. Deforming cervical spondylosis in the cat. J Pathol Bacteriol 1964;88:503509.2.
Seawright
AA
, English PB, Gartner RJW. Hypervitaminosis A of the cat. Adv Vet Sci Comp Med 1970;14:127.
3. Riser WH, Brodey RS,
Shirer
JF
. Osteodystrophy in mature cats: a nutritional disease. J Am I Vet Radiol Soc 1968;
9:37
46.
4. Lucke VM, Baskerville A, Bardgett PL, et al. Deforming cervical spondylosis in the cat associated with hypervitaminosis A. Vet Rec 1968:82:141142.
5. English PB, Seawright AA. Deforming cervical spondylosis of the cat. Aust Vet J 1964;40:376381.
6.
Herron
MA
. Hypervitaminosis A. In: Bojrab MJ,ed. Pathophysiology in small animal surgery.
Philadelphia
: Lea & Febiger, 1981:685686.