Risk factors for behavior-related euthanasia among dominant-aggressive dogs: 110 cases (1989-1992)

Establishing a prognosis for dogs with dominance-related aggression is difficult. Some dominant-aggressive dogs respond well to treatment; others continue to be serious risks for their owners. A study was performed to identify characteristics of dominance-related aggression and to identify risk factors associated with whether the aggressive behavior led to euthanasia. Medical records of 110 dogs with dominance-related aggression were examined retrospectively; characteristics of owner-directed aggression and eventual outcome of the dogs were recorded. By means of logistic regression, 2 different models were found to describe the association between behavior characteristics and outcome. In the first model, severe aggression in response to benign dominance challenges and body weight > 18.2 kg were associated with outcome. In the second model, unpredictability of aggression and a history of being purchased were associated with outcome. We concluded that dominance-related aggressive behavior can be subclassified according to severity and type and that outcome (ie, euthanasia) may be predictable in some cases.

Friendliness to humans and defensive aggression in cats: the influence of handling and paternity

This study was undertaken to examine and reduce the stress and aggressiveness associated with fear of handling in laboratory cats (Felis sylvestris catus). Thirteen litters of kittens from a specific pathogen-free breeding colony were divided into three treatment groups: two were early weaned, removed from the colony and caged individually with or without handling up to 8 weeks of age, and the third served as a control group, removed from the colony just before testing. Behavior tests measuring degree of friendliness to humans and response to physical restraint were performed at ages 8, 12, 16, and 20 weeks. Serum cortisol concentrations were measured after each test. Results indicate that litter and sire influenced tractability but that handling or individual caging of kittens did not. Posttest serum cortisol concentrations were below normal adult levels in most kittens, including those reacting fearfully during testing and aggressively during restraint, and, therefore, are not a reliable indicator of stress in juvenile cats.

Thirst and salt appetite in horses treated with furosemide

When a preliminary experiment in sodium-replete ponies revealed an increase, but not a significant increase, in salt consumption after furosemide treatment, the experiment was repeated using sodium-deficient horses in which aldosterone levels might be expected to be elevated to test the hypothesis that a background of aldosterone is necessary for salt appetite. Ten Standardbred mares were injected intravenously with furosemide or an equivalent volume of 0.9% sodium chloride as a control to test the effect of furosemide on their salt appetite and blood constituents. Sodium intake and sodium loss in urine, as well as water intake and urine output, were measured and compared to determine accuracy of compensation for natriuresis and diuresis. Plasma protein and packed cell volume showed significant increases in response to furosemide treatment (F = 29.31, P less than 0.001 and F = 11.20, P less than 0.001, respectively). There were no significant changes in plasma sodium concentration or osmolality in response to the treatment (P greater than 0.05). The furosemide-treated horses consumed 126 +/- 14.8 g salt, significantly more than when they were given the control injection (94.5 +/- 9.8 g; t = 2.22, P = 0.05). In response to furosemide, horses lost 962 +/- 79.7 and consumed 2,170 +/- 5 meq sodium; however, compared with control, they lost 955 meq more sodium and ingested only 570 meq more sodium, so they were undercompensating for natriuresis. The furosemide-treated horses drank 9.6 +/- 0.8 kg of water, significantly more than when they received the control injection (6.4 +/- 0.8 kg; t = 6.9, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Investigating equine ingestive, maternal, and sexual behavior in the field and in the laboratory

Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which can be determined using combinations of field observations of harem groups and laboratory studies of stallions exposed to female urine or feces in the absence of the donor mare. Ingestive behavior may include food, salt, or water intake. Direct and indirect measurements of intake can be made and used to answer questions regarding the ability of horses to control their energy intake when the diet is diluted, the effect of feral equids on the ecology of an area, and the abilities of horses to compensate for dehydration and hypovolemia.

Animal behavior and animal welfare

The value of behavioral techniques in assessing animal welfare, and in particular assessing the psychological well being of animals, is reviewed. Using cats and horses as examples, 3 behavioral methods are presented: (1) comparison of behavior patterns and time budgets; (2) choice tests; and (3) operant conditioning. The behaviors of intact and declawed cats were compared in order to determine if declawing led to behavioral problems or to a change in personality. Apparently it did not. The behavior of free ranging horses was compared with that of stabled horses. Using two-choice preference tests, the preference of horses for visual contact with other horses and the preference for bedding were determined. Horses show no significant preference for locations from which they can make visual contact with other horses, but they do prefer bedding, especially when lying down. Horses will perform an operant response in order to obtain light in a darkened barn or heat in an outside shed. These same techniques can be used to answer a variety of questions about an animal's motivation for a particular attribute of its environment.

Feeding and drinking behavior problems

The physiologic and behavioral basis of normal canine and feline feeding is given in detail. Abnormalities of ingestive behavior include obesity and anorexia in both species, flank or blanket sucking in Doberman Pinschers, coprophagia and stone chewing in dogs, and wool chewing in cats. Drinking behavior is discussed briefly, and the abnormalities of hypernatremia (a failure of thirst) and psychogenic polydipsia and polyphagia are reviewed.

Ingestive behavior

In summary, horses spend 60% or more of their time eating when grazing or when feed is available free choice. Grasses are their preferred food, but they supplement the grass with herbs and woody plants. Sweetened mixtures of oats and corn are the most preferred concentrate. Horses can increase or decrease the time spent eating and amount eaten to maintain caloric intake. Their intake is stimulated by drugs such as diazepam and by the presence of other horses. Horses stop eating when gastric osmolality increases; increases in plasma osmolality, protein, and glucose accompany digestion. Foals eat several times an hour and begin sampling solid food at the same time that their dam is eating. Several areas of particular importance to the equine industry have not been investigated. These areas include the effect of exercise on short- and long-term food intake and the influence of reproductive state on the feeding of mares.

Taste aversion learning in horses

The ability of ponies to learn to avoid a relatively novel food associated with illness was tested in three situations: when illness occurred immediately after consuming a feed; when illness occurred 30 min after consuming a feed; and when illness was contingent upon eating one of three feeds offered simultaneously. Apomorphine was used to produce illness. The feeds associated with illness were corn, alfalfa pellets, sweet feed and a complete pelleted feed. The ponies learned to avoid all the fees except the complete feed when apomorphine injection immediately followed consumption of the feed. However, the ponies did not learn to avoid a feed if apomorphine was delayed 30 min after feed consumption. They could learn to avoid alfalfa pellets, but not corn, when these feeds were presented with the familiar "safe foods," oats and soybean meal. Ponies apparently are able to learn a taste aversion, but there were constraints on this learning ability. Under the conditions of this study, they did not learn to avoid a food that made them sick long after consumption of the food, and they had more difficulty learning to avoid highly palatable feeds.

Stimuli of thirst in donkeys (Equus asinus)

A study of the stimuli of thirst was conducted on six feral donkeys. Donkeys were found to be stimulated to drink by overnight water deprivation, by the diuretic furosemide, and by hypertonic saline infusion, all in the absence of heat stress or work. Donkeys compensate accurately for the fluid deficit caused by overnight water deprivation. After 19 hr without water, they drank 8.8 +/- 2.4 (mean +/- SE) liters within 60 min. Their undeprived overnight intake was 8.4 +/- 1.5 liters. However, latency was longer and water intake was less than that of ponies with the same changes in blood parameters, suggesting that donkeys have a higher thirst threshold than ponies. Further, plasma volume fell less in donkeys, but osmotic changes were similar to those reported in ponies exposed to the same deprivation. Donkeys infused with 250 ml of 15% NaCl drank 0.7 +/- 0.6 liters of water within 45 min, and osmolality increased from 287 to 297 mosmol/kg water; they drank no water in the same time period when infused with 250 ml 0.9% NaCl (p less than 0.05). Donkeys injected IV with 2 mg/kg furosemide drank 3.8 +/- 1.1 liters within 3 hr. Plasma protein increased from 6.9 to 7.8 g/dl. When injected with 0.9% NaCl they drank 1.0 +/- 0.5 liters (p less than 0.05). In sum, the positive thirst responses of these donkeys to cellular and extracellular dehydration were similar to those earlier demonstrated in ponies, but the results suggest a less sensitive response, albeit combined with a better internal defense of blood volume.

The role of the Flehmen response in the behavioral repertoire of the stallion

The role of the Flehmen response in equine behavior was investigated under field and laboratory conditions. In Experiment 1, a field study made of five stallions on pasture with between three and eighteen mares each during the season indicated the following: 1) The Flehmen response was most frequently preceded by nasal, rather than oral, investigation of substances; 2) The stallions' rate of Flehmen varied with the estrous cycles of the mares; 3) The rate of Flehmen response did not show a variation with time of day; and 4) The Flehmen response was most frequently followed by marking behaviors rather than courtship behaviors. The results suggest that the Flehmen response is not an immediate component of sexual behavior, e.g., courtship of the stallion but may be involved in the overall monitoring of the mare's estrous cycle. Therefore the Flehmen response may contribute to the chemosensory priming of the stallion for reproduction. In Experiment 2 stallions were presented with urine or feces of mares in various stages of the reproductive cycle as well as with their own or other males' urine or feces. The occurrence of sniffing and Flehmen was used to determine the discriminatory ability of the stallions. Stallions can differentiate the sex of a horse on the basis of its feces alone, but cannot differentiate on the basis of urine. This ability may explain the function of fecal marking behavior of stallions.

Vasopressin in dehydrated and rehydrated ponies

Six pony mares deprived of water for 24 hours showed significant increases in plasma vasopressin (2.8 pg/ml) and osmolality (9 mosmol/kg). When water was made available the ponies drank rapidly (5 of 6 drank to satiety within 90 seconds) and corrected their fluid deficits precisely. Vasopressin did not return to predehydration levels until osmolality did after 15 minutes of access to water. The horse differs from rodents and humans, but is similar to pigs in that vasopressin levels do not fall before osmolality returns to normal. Oropharyngeal factors, therefore, may not be as important in vasopressin release in horses as in other species.

A tuna fish diet influences cat behavior

When observed in their home cages, cats fed commercial tuna fish cat food were less active, vocalized less, and spent more time on the floor and more time eating than cats fed commercial beef cat food. There were no differences in response to human handling between the two groups. There were no differences in learning ability on a two-choice point maze or in reversal learning in the same maze between beef- and tuna-fed cats. The behavior of the groups differed in a 15-min open field test only in the number of toys contacted. Cats fed the tuna had elevated tissue levels of mercury and selenium.

Body temperature and behaviour of mares during the last two weeks of pregnancy

Average daily core body temperature and behavioural patterns of pregnant mares were studied, in search of definitive signs of parturition within 24 h of the event. Nineteen pony mares were sampled twice daily for core body temperature. A significant temperature drop, averaging 0.1 degrees C (0.2 degrees F) was observed during the day prior to parturition. Between 18.00 h and 06.00 h, during the two weeks before parturition, Thoroughbred and Standardbred mares (n = 52) spent an average 66.8 per cent of their time standing, 27.0 per cent eating, 4.9 per cent lying in sternal recumbency, 1.0 per cent lying in lateral recumbency, and 0.3 per cent walking. On the night before parturition, mares spent significantly less time lying in sternal recumbency than on previous nights and on the night of parturition all behaviour patterns except eating were significantly different from the nights of the two weeks before parturition. There was an increase in walking (5.3 per cent), lying in sternal recumbency (8 per cent) and lying in lateral recumbency (5.3 per cent) whereas standing (53.3 per cent) was decreased. In 58 observed pregnancies, 54 mares (97 per cent) foaled in a recumbent position and 50 mares (86 per cent) foaled between 18.00 h and 06.00 h.

Effect of meal frequency on fluid balance and behavior of ponies

Twelve ponies were fed their total daily ration either as one large meal or divided into six small meals. Pre- and post-feeding behavior was recorded six times a day. Blood samples were taken for 30 min before and two hr after the meal. Plasma protein increased from 7.0 to a peak of 7.3 g/dl with small meals and from 7.3 to 8.1 g/dl with large meals, and returned to pre-feeding levels by 90 min post-feeding. Hematocrit rose from 33.3 to 34.1% with small meals and from 33.0 to 36.0% with large meals. These rapid and short-lived increases indicate a decrease in plasma volume. Plasma osmolality rose with feeding from 283 to 285 mosmoles/kg with small meals and from 281 to 288 mosmoles/kg with large meals. Water availability had no significant effect on blood changes. Digestibility and rate of passage were measured with chromic oxide, but there were no differences. Vocalizing (neighing) and walking occurred more often before than after feeding, while eating bedding and engaging in other oral behaviors were more frequent after feeding.

Abnormal behavior

Farm animals exhibit abnormalities of sexual, maternal, and other social behaviors as well as many stereotyped behaviors. The types and incidence of these abnormal behaviors may depend on the species, its diet, and the environmental conditions under which it is normally maintained. An understanding of the causes of various abnormal behavior patterns will enable the producer and veterinarian to better manage populations of livestock and improve their well-being.

Maternal behavior

Parturition in mares is rapid and is followed by a brief period of sensitivity to imprinting on a foal. There is large individual variation in normal maternal style, but normal mothers actively defend their foal, remain near the foal when it is sleeping, tolerate or assist nursing, and do not injure their own foal. Disturbance of a mare and foal during the early imprinting period can predispose a mare to rejection of her foal; therefore, it should be avoided. There are a variety of forms of foal rejection and numerous etiologies. Therefore, each case should be evaluated individually.

Stable vices and trailer problems

Stable vices include oral vices such as cribbing, wood chewing, and coprophagia, as well as stall walking, weaving, pawing, and stall kicking. Some of these behaviors are escape behaviors; others are forms of self-stimulation. Most can be eliminated by pasturing rather than stall confinement. Trailering problems include failure to load, scrambling in the moving trailer, struggling in the stationary trailer, and refusal to unload. Gradual habituation to entering the trailer, the presence of another horse, or a change in trailer type can be used to treat these problems.

Techniques for taking a behavioral history

A thorough behavioral history is essential for adequate assessment of a given case. In reviewing the chief complaint, a description of what actually happened, rather than the owner's interpretation of what happened, is required. Other behavior problems, environment, rearing history, and training need to be reviewed. Sample question sets for some common problems are given.