The results obtained in these experiments justify the conclusion that young growing dogs can stand larger doses of caffein than full-grown and older dogs.
Attention may also be called here to the difference in the symptoms produced by caffein in very young and in adult dogs. It was often noticed in these experiments that the symptoms in older subjects when given toxic doses of caffein set in rather abruptly and ended in instantaneous death. We failed to observe this phenomenon after the administration of large amounts of caffein to very young dogs, in which tonic and clonic convulsions alternating with paresis were observed. These symptoms set in rather gradually and lasted several hours (see experiment No. 8), resembling the rabbit in this regard.
SUMMARY.
The toxicity of caffein for adult dogs is about the same, whether given by mouth or injected subcutaneously. The resistance of puppies to caffein is much greater than that of adults.
Table 12.—Administration by mouth; dogs. (Series A.)
| No. | Weight. | Caffein per kilo | Results. | Remarks. |
|---|---|---|---|---|
| Kilos. | Gram. | |||
| 47 | 13.60 | 0.144 | Survived | Vomiting observed. |
| 55 | 12.75 | .200 | do. | Stiffness of muscles; no other symptoms. |
| 56 | 7.95 | .200 | Found dead next day | |
| 52 | 13.60 | .147 | Survived | |
| 57 | 6.50 | .230 | do. | Vomited after 1 hour; convulsions after 1 hour and 45minutes. |
| 39 | 23.10 | .120 | do. | Increased frequency of respiration, thirst, loss of appetite, vomited rest of day when he drank water, salivation, restlessness, passed feces frequently. |
| 48 | 11.50 | .174 | do. | Vomiting observed. |
| 48 | 12.00 | .200 | Found dead next day | No vomiting observed. Second dose was given 8 days after first. |
| 54 | 13.40 | .200 | Survived | Vomiting observed. |
| 49 | 13.15 | .152 | Found dead next day | |
| 38 | 14.50 | .120 | do. | Symptoms after 1½ hours: Dog had a temperature of 104° F. before caffein was given; vomited 3 hours after caffein was fed. |
| 18 | 10.80 | .145 | do. |
Table 13.—Subcutaneous injection; dogs. (Series B.)
| No. | Weight. | Caffein per kilo | Results. | Remarks. |
|---|---|---|---|---|
| Kilos. | Gram. | |||
| 62 | 9.30 | 0.161 | Survived | Restlessness and vomiting one-half hour after injection. |
| 61A | 14.00 | .160 | Found dead next day | |
| 63 | 12.00 | .150 | Survived | Restlessness 1 hour after injection. |
| 64 | 14.00 | .150 | do. | Restlessness and thirst 45 minutes after injection. |
| 59 | 7.20 | .160 | Died 1 hour and 20 minutes after injection. | Marked restlessness, but no convulsion. |
| 61 | 14.60 | .143 | Survived | Symptoms observed in 1½ hours. |
Table 14.—Administration by mouth to puppies. (Series C.)
| No. | Weight. | Caffein per kilo. | Results. | Remarks. |
|---|---|---|---|---|
| Kilos. | Gram. | |||
| 8 | 3.10 | 0.354 | Found dead next day | Vomited in 4 hours after feeding; restlessness, loss of appetite, thirst, incoordination of muscles, convulsions. |
| 9 | 3.15 | .350 | Survived | Muscular incoordination and stiffness, restlessness, vomited 1 hour after caffein was given. |
| 10 | 1.60 | .350 | Died in 3 hours | Convulsion; no vomiting. |
| 11 | 1.26 | .200 | Found dead | Salivation; convulsions. |
| 12 | 1.28 | .200 | Survived | No symptoms. |
| 15 | 1.20 | .250 | do. | Subcutaneous injection. |
| 16 | 3.50 | .300 | Died in 1 hour | Convulsions 45 minutes after caffein was fed. |