Occurrence of Fox Ketosis and Comprehensive Prevention and Treatment Techniques

The fox is a carnivore with a relatively small gastrointestinal capacity, and its intestinal length is only 4 to 5 times its body length; therefore, it is only suited to a diet based mainly on animal feed. If scientific feeding and management are not attended to in production, ketosis is easily triggered, and this should be taken very seriously.

Between 1993 and 1995 alone, the author encountered 3 cases of large-scale outbreaks in the western Liaoning region. Although timely diagnosis and treatment prevented excessive economic losses, the growth and development of young foxes and the health of adult foxes were greatly affected. By the pelting period, young foxes were on average smaller in body size, and the culling rate of adult foxes increased markedly compared with previous years. If timely and accurate diagnosis and treatment are not carried out, not only will large economic losses be caused to the raiser, but there is even a risk of the entire group being wiped out.

1. Occurrence of Fox Ketosis

1.1 Clinical Symptoms and Diagnosis

Sick foxes show decreased or completely lost appetite, a dry nose mirror, listlessness, reduced activity, and ocular discharge. In most sick foxes, body temperature, respiration, and heartbeat are basically normal; the urine is acidic. The occurrence of this disease also shows the following characteristics: young foxes are more severely affected than adults; individuals with a vigorous appetite are mostly more severely ill; and blue foxes are more severely affected and have a higher incidence rate than silver-black foxes.

The disease generally has a relatively long course, often occurs as a large-scale outbreak, and sudden death is rarely seen. An outbreak in one fox group does not spread to nearby fox farms. A preliminary diagnosis can be made based on clinical symptoms and outbreak characteristics.

1.2 Relationship with Feed and Feeding Management

July to August is precisely the period of vigorous growth and development for young foxes. To meet the needs of their rapid growth and development, feeds of the high-fat, medium-protein, and low-carbohydrate type are usually used in feeding, causing metabolic disorders in foxes.

Because the carbohydrate level is too low, the fox body can no longer meet its energy needs by relying solely on the burning of carbohydrates and requires a certain amount of fat and protein to provide energy. However, when fat and protein are catabolized and burned in the body, they do not completely generate carbon dioxide and water as carbohydrates do, but instead produce large amounts of intermediate products such as pyruvic acid, namely ketone bodies. When the production of ketone bodies and their transformation and utilization lose balance, ketosis can be triggered in severe cases.

When the feed ratio is unscientific, insufficient drinking water can induce and aggravate the condition of ketosis.

1.3 Seasonality

Fox ketosis mostly occurs in the hotter weather of July to August. The fox is a long-haired fur animal with underdeveloped skin sweat glands and is very sensitive to heat. In this season the weather is hot, and the fox body loses a relatively large amount of water; therefore, it is especially easy for various other factors to act together to promote the occurrence of ketosis.

In summer, fox farms with poor shading and poor ventilation are more prone to the disease. The several cases of fox ketosis encountered by the author all occurred in this season, and it occurred less often in other seasons.

1.4 Effect of Vitamin B1 on the Occurrence of Ketosis

Vitamin B1 is one of the components of cocarboxylase. Cocarboxylase can decarboxylate and detoxify pyruvic acid, an intermediate product of metabolism in tissues; therefore, when vitamin B1 is deficient, the synthesis of cocarboxylase is affected, and pyruvic acid accumulates in large amounts in brain tissue and blood, causing ketosis. In fox rearing, when freshwater fish that have not undergone cooking treatment are fed, the thiaminase in their bodies, as well as oxidative rancidity of the feed, can greatly destroy vitamin B1, leading to the accumulation of ketone bodies in the fox body.

2. Prevention and Treatment Measures

2.1 Treatment

For severely ill foxes, in order to reduce the production of more ketone bodies from fat breakdown and promote the elimination of ketone bodies, 20% glucose is infused intravenously. To ensure the normal synthesis of cocarboxylase and promote the transformation of ketone bodies, 0.5 mg of vitamin B1 is added daily during infusion. To correct acid-base balance, sodium bicarbonate injection is administered intravenously. According to the clinical manifestations of the condition, in order to prevent secondary infection, antibiotic drugs may be added during infusion. In feeding, the feed must be adjusted and the amount of drinking water increased.

2.2 Feed Adjustment

Feed therapy should generally be adopted for affected fox groups. Reduce the proportion of animal feed, especially the proportion of fat-rich feed, and increase the proportion of carbohydrate-rich cereal feed and the proportion of vegetables in the daily ration. Adding an appropriate amount of white sugar to the feed helps rapidly raise the blood glucose level of foxes and reduce the production of ketone bodies. Adding 2 to 3 mg of vitamin B1 per day to the feed can improve the body's decarboxylation and detoxification capacity. After 7 to 15 days of adjustment, once the fox group returns to normal, normal feeding can be resumed.

2.3 Prevention

During the vigorous growth period of young foxes in July to August, feeds of the high-fat, medium-protein, and low-carbohydrate type should be used. When handling the relationship among the three major nutrients, protein should be taken as the core. First determine the protein supply at the medium level for the year (highest during the winter fur growth period), then select the corresponding fat and carbohydrate levels from the table of relationships among the three major nutrients, and within the floating range choose the upper limit for fat while choosing a relatively low level for carbohydrates.

Under no circumstances should one mistakenly choose the highest level of fat from different periods, causing the fat level to be too high; nor should one choose the lowest level of carbohydrates from different periods, causing the carbohydrate level to be too low. In this way, due to disordered nutrient supply, nutritional metabolic disorders occur in the fox body, thereby triggering ketosis.

The fox is a carnivorous animal, and attention must be paid to adding vegetables to the feed to meet the fox body's need for vitamins and promote normal peristalsis of the digestive tract; attention must also be paid to adding various vitamin additives to meet vitamin needs in different periods. To keep the fox body in normal metabolism and prevent the occurrence of ketosis, 0.4 mg of vitamin B1 should be added to the daily ration, and for the Arctic fox the amount should be increased further.

In hot seasons, free access to drinking water should be provided for fox groups. Morning feeding should be appropriately moved earlier, evening feeding should be appropriately delayed, and noon supplementary feeding should be done quickly to reduce oxidative rancidity of the feed. When freshwater fish are used to raise foxes, the freshwater fish must be fed cooked. Pay attention to ventilation in the fox farm, frequently sprinkle water on the ground to lower the temperature, and avoid direct sunlight exposure to the foxes.